The Meteorology of the Arctic Region: Encyclopedia Arctica 7: Meteorology and Oceanography
The Meteorology of the Arctic Region
THE METEOROLOGY OF THE ARCTIC REGION
By
Sverre Petterssen, W. C. Jacobs,
and B. C. Haynes
EA: Meteorology [Sverre Petterssen, W.C. Jacobs and B.C. Haynes]
THE METEOROLOGY OF THE ARCTIC REGION
| Page | |
| Introduction | 1 |
| Composition and Structure | 4 |
| Inversions and Lapse Rates | 19 |
| Acoustic Phenomena | 25 |
| Optical Phenomena | 37 |
| Air Masses and Fronts | 46 |
| Cyclones and Anticyclones | 52 |
| Atmospheric Pressure | 56 |
| Surface Wind | 66 |
| Upper-Air Winds | 98 |
| Air Temperature | 107 |
| Precipitation, Snowfall, Thunderstorms | 164 |
| Humidity | 211 |
| Cloudiness and Ceilings | 228 |
| Fog and Visibility | 264 |
| Sunshine, Illumination | 287 |
| Information on Diagram | 302 |
| Reference to Literature | 304 |
| Legend to Diagrams | 308 |
Note
: The diagrams referred to in this paper are of a dimension too
large to be included in the present binding. These diagrams
may be consulted in the Stefansson Collection where they are
filed. (December, 1954)
INTRODUCTION
From the broadest point of view the climatic regions of the
world may be divided into five principal types, vis.,
A.
Tropical Rainy Climates
, which comprise the tropical rain
forests, the tropical monsoon systems, and the adjoining savannas.
B.
Dry Climates
, which comprise the deserts and steppes in
subtropical and adjacent latitudes.
C.
Warm Temperate Climates
, which comprise the part of the
midlatitude rainy belt that is not normally covered by snow in
winter.
D.
Snow-Forest Climates
, which comprise the mid and high
latitude belt with extensive forests and snow cover during the
winter.
E.
Polar Climates
, which comprise the tundra regions and the
fields of perpetual snow and ice.
Fig. 1 The distribution of these types of climatic regions in the nor–
thern hemisphere is shown in Fig. 1. Each of these regions may be
divided into sub-regions, depending upon the amount rainfall,
seasonal variations, and other limiting factors that affect the
natural vegetation. In this respect the Polar Climate may be said
to be the simplest of all principal climatic types, inasmuch as it
suffices to divide it into two subtypes, namely the
Tundra Climate
and the
Frost Climate
.
The Frost Climate occupies the regions of perpetual snow and
ice, while the Tundra Climate is characterized by bare ground during
the warm season. The vegetation typical of the tundra consists
largely of mosses, lichens and grasses with dwarf trees in sheltered
places. Along its equatorward border the tundra merges with the
vegetation of the snow-forest climatic zone of the northern hemi–
sphere, and the border between these two climatic zones has been
found to coincide very nearly with the line along which the mean
July temperature is 50°F (10°C). Using this isotherm as a criterion,
it is convenient to extend the border between the Polar Climate and
the adjoining regions across the oceans, as shown in Fig. 1.
From a meteorological point of view it is convenient to define
the Arctic Region as the region around the North Pole occupied by
Polar Climates (Fig. 1.), excluding the isolated islands of such
climates that occur in certain mountainous regions in lower lati–
tudes. It should be noted, however, the weather conditions typical
of the arctic are normally encountered also in the regions occupied
by the snow-forest climate (i.e., regions D in Fig. 1).
Fig. 2 The normal distribution of the air temperature as a function
of latitude and as a mean for all meridians is shown in Fig. 2.
Using the 10°C July isotherm as the line of demarkation between the
arctic region and the adjacent climatic zones, it will be seen that
the mean position of this isotherm is about 66°N. The area of the
arctic region, as defined above, is therefore about one-twelvth of
the area of the northern hemisphere. Using the correspondence iso–
therm of the warmest month in the southern hemisphere as the border
of the antarctic region, it will be seen from Fig. 2 that this
isotherm is found about 48°S, indicating that the area of the
antarctic region is about three times as large as that of the
[:
]
arctic region.
COMPOSITION AND STRUCTURE
Composition of Dry Air
. - The air consists of mixture of a number
of gases. Most of these are present in a perfectly mixed state,
with the result that their relative amounts are constant all over
the world, at least up to 25-30 km. (80,000 - 100,000 ft.). The
most important of the constituents are given in Table I, which is
summarized from a recent publication of the International Meteoro–
logical Organization
[
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. The amounts are expressed in terms
of mol. fractions, which for all practical purposes may be taken
to indicate the volume percentage occupied by each gas.
| TABLE I. - Principal Constituents of Dry Air . | |
|---|---|
| Nitrogen | 78.09 per cent |
| Oxygen | 20.95 per cent |
| Argon | 0.93 per cent |
| Carbon Dioxide | 0.03 per cent |
In addition to these principal constituents, there are traces
of Neon, Helium, Krypton, Hydrogen, Xenon, Ozone and Radon, but
their amounts are so small that they are of no practical importance.
The amount of carbon dioxide is not quite constant. The vege–
table world continuously consumes carbon dioxide which, again, is
produced by the animal world, through burning of fuels, volcanic
action, and various processes of decay in the soil. Although these
processes are not always balanced, the oceans, by dissolving the
excess of carbon dioxide, so effectively regulate it that no great
variations arise. In view of the absence of local sources, the
amount of carbon dioxide in the arctic is likely to be rather less
than the normal for the atmosphere as a whole.
Ozone, which is present in minute amounts in the atmosphere,
shows a considerable variation with season, latitude and height;
it also varies with the weather situation.
Extensive investigations by Dobson
[
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, Tönsberg
[ ],
^
and
^
Langlo Olson
[
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, Craig
[
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and others have revealed the fol–
lowing broad features of the distribution and variation of the
amount of ozone.
(a) The amount of ozone per unit volume increases with
elevation, reaches a maximum value somewhere between 20 and 30 km.
(65 - 100,000 ft.) and then decreases.
Fig. 3 (b) The total amount of ozone (in a vertical air column) has
a pronounced annual variation with a maximum in spring and a minumum
in late autumn (Fig. 3).
(c) The total amount of ozone in middle latitudes varies
aperiodically with the general weather situation, the amount being
larger when the air current is from a northerly direction than when
it is from a southerly direction.
From the foregoing discussion it follows that the composition of
the dry atmosphere in the arctic region is essentially the same as
elsewhere, except that the arctic region is particularly rich in
ozone, and probably slightly deficient in carbon dioxide content.
Water Vapor
. - The air also contains a variable amount of water
vapor. In many respects the water vapor is the most important
constituent of the atmosphere. The maximum amount of water vapor
that the air can absorb depends entirely upon the temperature; the
higher the temperature of the air the more water vapor can it hold,
the air being saturated with moisture when the maximum is reached.
The amount of water present in the air is conveniently
expressed by the pressure that it exerts. This pressure is usually
expressed in millibars, 1 mb. corresponding to 0.75 mm. or 0.029
inches of mercury under standard conditions.
The maximum amount of water vapor, or the
saturation vapor
pressure
, various temperatures is given in Table II. Comparing
these figures with the curves in Fig. 2, it will be seen that the
maximum vapor pressure corresponding to the mean temperatures in
the vicinity of the North Pole would be about 0.1 mb. in January,
6.0 mb. in July, and 2.8 mb. as a mean for the year. The amount of
water vapor in the arctic may, therefore, vary by several thousand
percent during the year.
| TABLE II. Saturation Vapor Pressure (E, in millibars) at various temperatures . E w refers to a water surface , and E i to ice surface . | ||||||
|---|---|---|---|---|---|---|
| T(°C) | T(°F) | E w | T(°C) | T(°F) | E w | E i |
| 30 | 86.0 | 42.4 | −5 | 23 | 4.21 | 4.02 |
| 28 | 82.4 | 37.8 | −10 | 14 | 2.86 | 2.60 |
| 26 | 78.8 | 33.6 | −15 | 5 | 1.91 | 1.65 |
| 24 | 75.2 | 29.8 | −20 | −4 | 1.25 | 1.03 |
| 20 | 68 | 23.4 | −30 | −22 | 0.51 | 0.38 |
| 15 | 59 | 17.0 | −40 | −40 | 0.19 | 0.13 |
| 10 | 50 | 12.3 | −50 | −68 | 0.06 | 0.04 |
| 5 | 41 | 8.7 | −60 | −86 | 0.01 | |
| 0 | 32 | 6.1 | −70 | −104 | 0.003 |
Comparing the arctic region with the equatorial belt, it will
be seen from Fig. 2 Table II that the saturation vapor pressure
in the vicinity of the North Pole is about one-sixth in July, and
about one-four hundredth in January, of the saturation vapor pressure
near equator. Since the air normally is not quite saturated,
the contrasts of the actual amounts of water vapor will be somewhat
less. Nevertheless, the moisture content is expressed in ab–
solute amounts, the arctic region stands out as being excessively
dry during the cold season. This absolute dryness, together with
the low temperature, constitutes an environmental factor of great
importance.
Although the arctic air is dry, on an absolute scale, it is
not so in terms of relative humidity. Let e denote the actual
vapor pressure and E the saturation vapor pressure corresponding
to the air temperature. The relative humidity is then defined as
100 e/E, i.e., the actual vapor pressure expressed as a percentage
of the maximum value at the temperature in question. The distribu–
tion of the relative humidity, as a function of latitude and a
Fig. 4 mean for all meridians, is shown in Fig. 4. It will be seen that
the relative humidity in the arctic is normally about 10 per cent
higher than in middle latitudes, and about 5 per cent lower than
in the equatorial belt.
Impurities.
- Apart from the above-mentioned gaseous constituents,
the atmosphere contains a variety of impurities, such as dusts, soots
and salts.
The main source of dust is the dry climatic regions (Fig. 1).
The coarser material is never carried far from its source, but minute
dust particles are readily kept soaring by the turbulent motion and
carried long distances from their place of origin by the general
air currents. Before dusty air from the arid regions arrives in
the arctic, it will normally have been cooled so much that conden–
sation has occurred; the precipitation of water from the clouds
washes out the dust to a very large extent, with the result that
the air in the arctic region is particularly free of dust. This
is especially true in winter when the rate of cooling of the north–
ward moving air masses is largest.
The industrial regions and forest fires constitute the main
source of soot*, but since these sources are far removed from the
arctic, the impurities will normally have been removed, either
through precipitation or sedimentation, before the air arrives in
the arctic.
1
Observations show that the air normally contains considerable
amount of salts. Through the action of the winds, spray is whirled
up from the oceans, and when the spray droplets evaporate the salt
remains in the air. These minute salt particles constitute highly
effective nuclei of condensation, and are, therefore, washed out
of the air through the precipitation processes.
The arctic air masses are, therefore, characterized by ex–
tremely low values of turbidity, and this influences the visual
range very greatly. In the arctic, the sky, when clear, is
characterized by the brilliance of stars during periods of darkness,
and by intense blueness during periods of light or dusk. Distant
objects (e.g., mountain ranges) stand out with great clarity in
shape and detail.
The purity of the arctic air is noticeable even in low and
middle latitudes when these regions are invaded by arctic air masses.
As has been shown by Bergeron
[
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, the opalescent turbidity can
be used as a means of indentifying traveling air masses, and this
technique has been of importance in the development of the methods
of weather analysis and forecasting.
Troposphere and Stratosphere
. - Although the state of the atmosphere
is subject to incessant variations, the mean (or normal) state indi–
cates a division of the atmosphere into fairly well-defined layers.
This stratification of the atmosphere is not immediately apparent
in the distribution along the vertical of atmospheric pressure and
density, but it stands out clearly in the distribution of tempera–
ture.
Fig. 5 Some typical examples of the distribution along the vertical
of the air temperature are shown in Fig. 5, which is reproduced
from a recent publication of the Canadian Meteorological Service
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.
Disregarding for the moment the conditions near the earth’s surface,
it will be seen that the temperature decreases with elevation at a
fairly regular rate of about 60°C per km. (10°F per 3,000 ft.) up to
about 8 km. (26,000 ft.) in winter and to about 10 km. (33,000 ft.)
in summer. At higher levels the temperature is either constant or
increases slightly with elevation.
The lower part of the atmosphere, in which the temperature de–
creases with elevation, is called the
troposphere
, and the upper
part, in which the temperature is constant or increases with eleva–
tion, is called the
stratosphere
. The transition from the tropo–
sphere to the stratosphere, which usually is quite distinct, is
called the
tropopause
.
The examples shown in Fig. 5 represent the conditions on the
fringe of the arctic. In the central part of the arctic region
still lower temperatures would be observed, particularly in the
lower half of the troposphere.
Fig. 6 Fig. 7 The mean thermal structure of the atmosphere up to 20 km.
(62,000 ft.) above sea level is shown in Figs. 6 and 7 for winter
and summer respectively. These diagrams represent the mean con–
ditions for 18 meridional sections at intervals of 20 degrees
starting from Greenwich meridian. The observational material used
for the construction is that contained in “The Normal Weather Maps”
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. The northernmost parts of the diagrams are largely based
upon extrapolations and tests for consistency. Although this may
have led to errors in detail, there can be little doubt that the
diagrams represent the essential features of the thermal structure.
Considering first the conditions in January, it will be seen
that the mean positions of tropopause, which is found at about
8 km. (26, 000 ft.) in the polar region, rises slowly southward to
about 50°N, and then rises at a rapid rate to about 25°N, where it
becomes horizontal at about 17 km. (56,000 ft.).
It will be seen from Fig. 6 that there are five regions in the
atmosphere (below 20 km.) which are characterized by extreme tempera–
tures. The coldest region is found at about 17 km. (56,000 ft.)
above sea level in the equatorial belt, where the mean temperature
is about −75°C (−105°F). The next coldest region is found in the
vicinity of the arctic tropopause, where the mean temperature is
about −63°C (−81°F). The third coldest region is found at the sur–
face over the arctic fields of snow and ice, where the mean tempera–
ture varies between −25 and −41°C (−13 and −42°F). This lower cap
of cold air is separated from the upper cold region by a layer of
relatively warmer and fairly uniform air with temperatures in the
vicinity of −26°C (−13°F) at about 2 km. (6500 ft.) above the ice.
In contrast to these cold regions we find two warm regions,
one at low levels near the equator, and a second in the troposphere
in subpolar latitudes.
In summer (Fig. 7) the conditions are largely the same as in
winter, except that the cold regions in the arctic are less distinct.
In all seasons, the temperature in the troposphere decreases north–
ward, whereas in the stratosphere the temperature decreases, on the
whole, from the arctic toward the equator.
Fig. 8 The annual variation of temperature, as a mean for all meridians,
is shown in Fig. 8. It will be seen the maximum variation occurs
at low levels in the arctic. This variation decreases rapidly with
elevation and reaches a minimum of about 20°C (36°F) at about 3 km.
(10,000 ft.) above which level there is a slight increase up to
about 5-6 km. (16,000-20,000 ft.) and then a rapid decrease up to
10 km. (33,000 ft.) which is the mean summer position of the tropo–
pause. In the stratosphere the annual variation is relatively small.
Considering the conditions level for level, the annual variation of
temperature of the free atmosphere decreases from the pole to the
equator. The same is true of the conditions at the earth’s surface
if one considers the mean for all meridions It should be noted,
however, that the annual variation near the earth’s surface is
larger in Northern Russia, Siberia, and Canada than it is at the
pole (see p. ).
At heights greater than those shown in Figs. 6-8, ordinary
observations are so sparse that the meridional structure and annual
variation cannot be evaluated with much confidence. From observa–
tions of meteors and sound waves and from a few direct observations
by rockets and sounding balloons it is possible to piece togather
a picture of the broad features of the uppermost atmosphere, and
these may be summarized as follows. The stratosphere is almost
isothermal up to about 35 km. (21 miles); above this level the
temperature increases rapidly and reaches a maximum of about 75°C
(167°F) at a height of about 60 km. (37 miles) whereafter it de–
creases to about −25°C (−13°F) at about 80 km. (50 miles). This
warm layer is sometimes called the mesosphere.
Above the mesosphere lies the ionosphere which extends up to
great heights and merges gradually with empty space. The ionosphere
is characterized by free electric charges. Some of the gaseous par–
ticles are broken down into ions and free electrons by absorption of
the ultraviolet radiation from the sun, which also causes a dissocia–
tion of oxygen and nitrogen molecules into their atomic forms and
causes very high temperature at extreme heights. The ionosphere
is the abode of the aurora borealis; it is divided into several
layers that reflect radio waves in various wave lengths.
INVERSIONS AND LAPSE RATES
Fig. 9 Although the temperature normally decreases with height in the
troposphere as a whole, the lower part of the arctic region forms
an exception (see Fig. 6). Here the temperature normally increases
from the earth’s surface up to a distance which rarely exceeds 2 km.
(6,000 ft.) and sometimes may be as low as 200 m. (600 ft.) or less.
Some examples are shown in Fig. 9.
The rate at which the temperature decreases with elevation is
called the
lapse rate
. A layer through which the temperature in–
creases with elevation is called an
inversion
, and such layers are
characterized by
counterlapse
. The
base
of the inversion is the
level where the counterlapse commences, and the
top
of the inversion
is the level where the counterlapse changes into a lapse of tempera–
ture.
It is convenient to compare the observed lapse or counterlapse
with the adiabatic lapse rate, which is the rate at which a unit of
air would cool if it were thermally isolated and lifted against the
gravitational force. The adiabatic lapse rate, which is a critical
value for many processes, is expressed by the formula
<formula>Γa = g/Cp</formula>
where g is the acceleration of gravity and Cp
the specific heat
of air at constant pressure. Substituting the numerical values for
g and Cp, it is found that
<formula>Γa =1°C per 100 m. = 5.5°F per 1000 ft.</formula> for nonsaturated
air.
Above the top of the inversion the lapse rate is normally about
1/2 to 2/3 of the adiabatic rate. Occasionally, the adiabatic rate
may be approached, but it is never exceeded by any appreciable
amount.
In the inversion layer, the counterlapse may be very large;
numerical values as high as 5°C per 100 m. are quite common, and
close to the snow surface values as high as 1°C per meter are not
uncommon, particularly in calm and cloudless conditions in winter.
In calm air or when the winds are light the base of the
inversion is found at the earth’s surface. However, when the wind
Fig. 10 is sufficiently strong, friction along the earth’s surface causes
the lower layer to be mixed, and a normal lapse rate is established
in the lower layer while an inversion may be present at some distance
above the surface. These elevated inversions are usually less
intense than the ground inversions. Sverdrup
[
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investigated
the occurrence of inversions by the aid of kites carrying instruments.
Since kites could be used only when the wind speed was sufficiently
high, his results (Fig. 10) apply to elevated inversions. It will
be seen that the inversion is lower in winter than in summer.
Fig. 11 The intensity of the inversion increases with decreasing could
cover, and the most intense inversions occur after spells of calm
and clear weather. An example of the dependence of the inversion
on wind speed and cloud cover is shown in Fig. 11, which is reproduced
from a recent publication by the Canadian Meteorological Service
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.
The inversions are most strongly developed over land and ice.
When the arctic air streams over open water of appreciably higher
temperature (e.g., in winter), the inversion is destroyed through
heating of the surface layer. In such cases, an adiabatic, or
even superadiabatic, lapse rate develops above the water surface.
The same is true of arctic air that invades warm continents in
summer.
From the foregoing discussion it follows that the central
arctic is characterized by a well
^
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^
developed inversion layer, and
that along the fringe of the arctic extreme variations occur, with
changes from large counterlapses to the adiabatic or superadiabatic
lapses.
The processes leading to the formation and maintenance of the
arctic winter inversions have been investigated by Petterssen
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and Wexler
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. These involve the general circulation of the
atmosphere and the radiative and eddy flux of heat.
The snow surface, being an efficient radiator, will lose heat
toward space, and the air in contact with the snow will cool faster
than the air aloft. The snow surface will, therefore, act as a cold
source relative to the overlying layer of air. Since the atmospheric
pressure over the arctic is higher than over the adjacent oceans
(heat sources), the distribution of heat and cold sources is such
as to constitute a hindrance to the circulation, and a layer of
stagnant air develops over the arctic snow and ice fields. Since
the air is stagnant, it becomes subjected to continued cooling from
below. As the surface layer becomes very much colder then the over–
lying air, downward radiative flux of heat will tend to balance
the cooling of the ground. The maximum difference in temperature
between the top and the base of the inversion, which depends upon
the contents of moisture and carbon dioxide of the air, has been
determined by Wexler to be about
^
30
^
°C (
^
54
^
°F), and this
value agrees well with observation.
In summer the conditions are largely similar to those in winter,
except that the cold source is due mainly to the melting of snow,
while the air at higher levels is heated by radiation.
If the wind is sufficiently strong, the radiative cooling of
the surface layer will be offset by the downward eddy flux of heat,
and the inversions become weaker, or may disappear temporarily and
locally. If the sky is cloudy, the back
^
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^
radiation from the clouds
will have a similar effect.
The arctic inversions are of great importance in many ways,
notably in connection with propagation of sound and light.
ACOUSTIC PHENOMENA
No one who has lived in the arctic can have failed to observe
the frequent occurrence of supernormal audibility and the wide
variation in the audible range. For example, Captain Perry
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,
on his third voyage, noted a case where conversation was carried on
over a distance of 1.2 miles, and Collinson
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reported on a
case where spoken words were heard at a distance of 2 miles. The
most extraordinary case of abnormal sound effects in the arctic is,
perhaps, the one described by Wegener
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]
. On the Danish Green–
land expedition, 1907-08, observers at Pustervig, on the northeast
coast of Greenland, heard a tone of deep pitch (estimated at about
30 c.p.s.) which lasted for several hours and appeared to emanate
from a closed fjord called Dove Bay. This sound was heard on several
occasions when the fjord was filled with cold stagnant air.
These abnormal sound effects can readily be explained by
reference to the structure of the arctic atmosphere and the properties
of the snow and ice.
The range at which sound can be heard depends upon the temperature
of the air, the speed and direction of the wind, and the rate at
which sound energy is absorbed by the earth’s surface.
1.
Influence of Snow and Ice
.
-
It is well known that soft
snow falling through the air absorbs sound energy very effectively.
The same is true of soft snow on the ground. On the other hand,
a hard crusted snow surface absorbs but little energy, and a smooth
ice surface is an almost ideal reflector of sound. The rate at
which sound energy is absorbed depends upon the pitch. Kaye and
Evans
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measured the absorbtion coefficient of newly fallen
snow in England and found the values reproduced in Table III. It
| TABLE III. Absorbtion Coefficient of Newly Fallen Snow . | |||||
|---|---|---|---|---|---|
| Snow depth inches | Frequency (c.p.s.) | ||||
| 125 | 250 | 500 | 1000 | 4000 | |
| 1 | 0.15 | 0.40 | 0.65 | 0.75 | 0.85 |
| 4 | 0.45 | 0.75 | 0.90 | 0.95 | 0.95 |
will be seen that for a pitch higher than 500 cycles per second, a
snow cover 4 inches, or more, deep absorbs almost all sound energy.
Although comparable figures for hard snow surfaces are not available,
it is evident that the absorbtion coefficient decreases rapidly
with the hardness, and is almost negligible for a smooth ice sur–
face. The audible range will, therefore, be short over a soft snow
surface, relatively large over hard snow, and excessively large
over ice fields.
2.
Influence of air temperature
. - One of the major causes of
the supernormal audible range in the arctic is due to the distribution
of temperature, and in particular to the inversion layers described
in the foregoing section. Let
^
C
^
denote the speed of propagation
of the sound, and T the absolute temperature of the air. In still
air, the velocity of sound is proportional to the square root of the
absolute temperature. We may, therefore, write
<formula>C = A√(T)</formula>
where A is a constant for any given composition of the air. The
minor variations in composition, discussed in a foregoing section,
are too small to have any noticeable effect on the speed of propa–
gation
Although the air temperature may very vertically as well as
horizontally, the latter variation is usually negligible in com–
parison with the former, and as shall here be concerned to discuss
only the influence due to the variation along the vertical.
We consider first the idealized case when the temperature is
uniform in all directions (isothermal conditions). The speed of the
sound would then be uniform, and the “sound front” would be a
spherical shell expanding with a constant speed.
Fig. 12 Instead of the “sound front” it is more convenient to consider
the “sound beams” or “sound rays”. These are represented by lines
originating in the sound source and being everywhere perpendicular
to the sound front. The sound rays in an atmosphere of uniform
temperature are shown in Fig. 12A, where the sound source is at
the earth’s surface. The rays are straight lines through the source.
Since the energy of a sound impulse is distributed uniformly on a
spherical surface, it is evident that the sound intensity must be
inversely proportional to the square of the distance from the
source, or
<formula>I = I1/R2</formula>
where I
1
is the intensity at unit distance from the source, and
I is the intensity at the distance R from the source. In the fol–
lowing, we shall refer to eq. (2) as the inverse square law.
Let us now consider the case when the temperature decreases
along the vertical, as it normally does in middle and low latitudes.
The sound will travel faster in the horizontal than in the vertical
direction. The sound front will no longer be spherical, and the
sound rays will be curved upward as shown in Fig. 12B. The beams
that leave the source horizontally will lose contact with the earth’s
surface, and in the space below these beams, a sound shadow will be
found. This shadow refers to the beams, or the direct sound. A
certain amount of sound is, however, diffracted across the beams
into the shadow, but the intensity of this sound is small and it
decreases at rate which exceeds the inverse square law.
The conditions represented in Fig. 12B being typical of middle
and low latitudes, it is evident that most people’s experience
about sound from distant sources is based upon the rather faint
sound which is diffracted into the beam shadow. Above the beam
shadow, the beams are more concentrated in Fig. 12B than they are
in Fig. 12A, with the result the intensity of the sound is corre–
spondingly increased. It will, thus, be seen that when the tem–
perature decreases along the vertical, the sound tends to escape
upward, and but little energy is transmitted along the earth’s
surface.
As was shown in the foregoing section, inversion layers are
almost always present in the arctic. We shall, therefore, consider
this case in some detail. Since the temperature increases upward
through the inversion layer, the sound will travel faster vertically
than horizontally; the wave front will now be elongated upward, and
the sound beams will be curved downward. Fig. 12C shows the rays
from a sound source
( )
at the earth’s surface when tempera–
ture distribution is as shown to the right of the beams. It can
easily be shown that a beam that leaves the source at certain
critical angle will become tangent to the top of the inversion
layer where it splits, one branch (b) being curved downward and
the other branch (c) being curved upward. This critical angle
depends entirely upon the temperature difference between the top
and the base of the inversion, and is independent of the depth of
the inversion layer. The space between the beams b and c in
Fig. 12C is silent as far as direct sound is concerned.
The beams that leave the source at angles less than the critical
value, will be refracted toward the earth’s surface. A considerable
portion of this sound is, again, reflected from the earth’s surface,
and this together with sound that is diffracted across the beams
will penetrate into the part of the shadow that is below the top
of the inversion. On the other hand, beams that leave the source
at angles greater than the critical value, will penetrate the in–
version and escape into space.
Referring again to Fig. 12C, it is of interest to note that
the concentration of the beams is larger in the inversion layer and
less above this layer than in the radial case shown in Fig. 12A.
From this it follows that the sound intensity below the top of the
inversion decreases more slowly than indicated by the inverse square
law; above the top of the inversion, the reverse is true.
We shall next consider Fig. 12D which illustrates the con–
ditions when the sound source is above the top of the inversion.
The inversion layer will now act as a hindrance to the propagation
of sound toward the earth’s surface. Except where the sound source
is directly overhead, or nearly so, very little sound energy reaches
the earth’s surface. Thus, an aircraft flying above the top of
the inversion is not readily detected by acoustic means.
From the foregoing discussion it follows that an inversion
layer acts as a duct for sound emanating from sources below its top,
and as a cushion against sound that emanates from sources above its
top. Neither the duct nor the cushion is perfect, and their
efficiency (in still air) depends upon the intensity of the inver–
sion.
The sound intensity may become greatly supernormal when the
sound source is situated below an inversion in a fjord (or valley)
surrounded by steep walls. If the fjord is frozen and the mountain
sides covered by hard snow, an almost ideal sound channel is estab–
lished, sound being reflected from the ice, the mountain sides and
the top of the inversion. If the fjord has a local contraction, a
basin is formed which, when the dimensions are suitable, may form
a resonant box. The case described by Wegener (loc. cit.) apparently
belonged to this category of sound effects.
Although the mean state of the lower arctic atmosphere is
characterized by one inversion layer (see Fig. 6), multiple inver–
sions occur quite frequently, particularly over and near arctic
land masses (e.g. Greenland). The sound effects associated with
multiple inversions are extremely complex, and several zones of
shadow and zones of maximum intensity may occur, depending upon the
position of the source. Fig.12E shows, as an example, the sound
pattern of a source situated between two inversions. It will be
seen that the sound tends to become trapped between the top of the
lower and the base of the upper inversion, and that several shadow
zones may result.
3.
Influence of wind
. - If V denotes the speed of the wind,
the velocity of sound can be expressed by the formula
<formula>C = A√(T) + V</formula>
which is the same as the velocity in still air plus the velocity of the
medium through which the sound travels. Now the former of these
velocities is of the order of 300 m/sec. (700 mph) while the latter
is of the order of 10 m/sec. (20 mph). The direct influence of the
wind is, therefore, very small if the wind is uniform in all direc–
tions.
Owing to friction along the earth’s surface, the wind increases
with elevation up to about 500-1000 m. (i.e., 1500-3000 ft.). Al–
though the increase varies with the roughness of the ground, the
wind speed over a snow surface will normally be twice as large at
about 600 m. as is at 10 m. above the ground. Above this layer,
which is called the friction layer, the wind may increase or de–
crease with elevation depending upon the horizontal temperature
gradient.
The variation along the vertical of the wind has a marked
influence on the propagation of sound. To demonstrate the nature
of this influence, we consider Fig. 12F, in which it is assumed
that the temperature is uniform along the vertical, while the wind
distribution is as indicated to the left. The beams that go down–
wind will be curved toward the earth’s surface. A beam that leaves
the source at a certain critical angle, will just touch the level
where the wind becomes uniform, and at greater distance from the
source, a sound shadow will be found below this level. The beams
that go upwind will be curved away from the earth’s surface, above
which another sound shadow is found. The greatest concentration of
sound beams is found in the downwind direction in the layer where
the wind increases, and it is here that the supernormal audibility
is observed.
In the arctic both the wind and the temperature will normally
increase with elevation through the friction layer, with the result
that both effects combine to give supernormal sound intensity down–
wind. In the upwind direction, the temperature effect is counter–
acted by the wind effect, and except when the wind is very light,
the wind effect predominates.
4.
Sound ranging
. - From the foregoing discussion it follows
that for any given source intensity the audible range depends upon
the curvature of the sound beams in the vertical plane, and this
curvature is determined by the distribution along the vertical of
temperature and wind. Provided that soundings of temperature and
wind are available, the path of the sound beams can be reconstructed
and the position of the sound source identified. A convenient
method of sound ranging has been developed by Bedient
[ ]
.
For further information on propagation of sound in the atmosphere,
reference is made to the works of Wa
^
e
^
lchen
[
^
50
^
]
, Rothwell
[
^
36
^
]
,
Whipple
[
^
55
^
]
, Gutenberg
[
^
15
^
]
, and Saby and Nyborg
[
^
37
^
]
.
OPTICAL PHENOMENA
In addition to the aurora borealis, the abode of which is in
the ionosphere (see pp ), the sojourner in the arctic
will observe a number of optical phenomena of great beauty and in–
tensity. Some of these, such as the rainbow, the corona and the
halo, are not essentially different from those observed in middle
latitudes and will not be described here. The optical phenomena
which are most typical of the arctic and of some importance to the
arctic traveler are the
mirages
which are due to abnormal bending
of the light rays, and the
ice blinks
and the
water sky
which are
due to reflection of light from ice and water surfaces by the lower
face of a cloud layer.
The mechanism of the formation of mirages is readily explained
by reference to the fact that light travels slightly faster in thin
air than it does in denser air. Thus, since the air density decreases
with elevation (except in very rare cases), a slant beam of light
will be curved downward, and this curvature depends upon the rate
at which the density decreases across the beam. In the following
we shall be concerned to discuss the bending of light beams between
points on the surface. Since these beams are quasi-horizontal it
suffices to consider the lapse of density along the vertical.
Using the equation of state and the hydrostatic relationship,
it is readily shown that the rate of decrease of density (^p^
)
with height (z) is expressed by
<formula>-(∂p/∂z) = (p/RT2)((g/R) – Γ)</formula>
where p denotes pressure, T absolute temperature, Γ lapse rate
of temperature, R the gas constant, and g the acceleration of
gravity.
Since g and R are physical constant and p varies but
little in any given place, it will be seen that the lapse rate of
density (and the refractive index) is determined almost exclusively
by the temperature conditions.
Travelers in the arctic have noticed a marked annual variation
in the optical phenomena, and this can readily be explained by
reference to equation (1). Let us assume for the moment that the
lapse rate of temperature is the same in winter as in summer.
Under typical arctic conditions the absolute temperature would be
about 275°A in summer and about 230°A in winter. It is then readily
seen that the refractive index is normally about 40 per cent greater
in winter than in summer. In addition to this effect of the annual
variation of temperature there is a large annual variation in the
lapse rate of temperature (see Fig. ), with the result that
the refractive index may vary several hundred per cent during the
annual cycle. In fact, the largest variations are due to the change
in lapse rate of temperature.
As was shown in a foregoing section (p. ) the temperature
of the troposphere normally decreases with elevation such that
= 0.6°C per 100 meters (or 3.3°F per 1000 ft.), and this
together with the first term within the parentheses of eq. (1)
accounts for the normal refraction of light in the atmosphere. In
the arctic, however, the lapse rate may vary within very wide limits,
thus giving rise to abnormal bendings of the light beams.
1.
The superior mirage
occurs in connection with temperature
inversions (p. ). In the inversion layer the temperature in–
creases with elevation, and the lapse rate of temperature (i.e., )
is negative. It will then be seen from formula (1) that the den–
sity decreases along the vertical at an abnormally fast rate, with
a consequent abnormal downward refraction of the light beam. An ob–
ject seen through the inversion layer will become distorted so that
it appears elongated in the vertical direction. For example, a
relatively flat strip of coast land may appear as an erect strip
and give the false impression of being a steep cliff; irregulari–
ties in the coast line will appear like columns, and the distor–
tions produce a picture which resembles architectural pseudo–
prostyle. In pronounced cases, the erect image is surmounted by
an inverted image, and in rare cases the inverted image is, again,
surmounted by second erect image.
Fig. 13 An example of a superior mirage is shown in Fig. 13. The
upper picture shows the natural shape of Gundahl’s Knold while the
lower picture shows strong vertical distortion due to the presence
of an intense inversion.
The superior mirage may occur without inverted image and dis–
tortion, in which case objects which are actually below the obser–
ver’s true horizon will appear above his apparent horizon. This
phenomenon is called looming. This, together with the pronounced
purity of the arctic air (p. ), probably accounts for many
instances of erroneous estimates of distances and reports of dis–
covered land masses and mountains in places where none exist. In
1818 Captain John Ross saw snow-covered peaks in Lancaster Sound
(74°N, 85°W), at an estimated distance of thirty miles, which appeared
to bar his way into the Northwest Passage. Subsequent explorations
have made it evident that the peaks seen by Ross were those of
North Somerset Islands (73°N, 93°W) at a distance of about 200
miles. Pearly and his companions clearly saw on two occasions in
1906 an extensive mountainous snow-covered land northwest of Cape
Colgate (82°N, 91°W) in Grant Land at an estimated distance of 130
miles, and named it Crocker Land. In 1914 MacMilland and Green
sighted Crocker Land and sledged 130 miles in its direction, seeing
the mountains once on the journey but never reaching them. The
exact location of Crocker Land is still a mystery, and it appears
certain that the sightings were caused by looming of unusual in–
tensity.
The distance over which an object may loom depends upon the
height of the inversion and the difference in temperature between
the top and the base of the inversion. In calm and cold weather
the inversions are likely to be deep and intense; distances esti–
mated in such conditions are likely to be much in error.
It is of interest to note that looming is a local phenomenon;
at some point closer to the loomed object than the observer, the
object will not be visible. The effect may be likened to the
“skipping” of radio waves which permits reception close to the
transmitting station and at considerable distance from it, but not
at intermediate distances. As a consequence of this, it is readily
seen that for an aircraft that sees a loomed sun, there must be
points both above and below the aircraft for which the sun will
Fig. 14 have set, and twilight will prevail both above and below an
aircraft illuminated by the loomed sun. These conditions are shown
diagrammatically in Fig. 14.
2.
The inferior mirage
forms when the temperature decreases
with elevation at an excessive rate. These mirage, which are
common occurrences is southern deserts, may be observed locally in
the arctic, particularly where cold air from the ice fields is
heated by streaming over open water, or where bare land adjacent
to ice, is heated in sunshine. The superheated layer is usually
quite shallow (4 to 10 ft.), and within it the lapse rate of tem–
perature is large and positive. It will be seen from formula (1)
above that the density decreases with elevation at a subnormal rate;
in extreme cases when
[Math Formula]
is greater than g/R, the lapse of
density is reversed, and the light beams may be curved away from
the earth’s surface. In such cases, the true horizon disappears,
and an apparent horizon is formed below the true horizon leaving
a gap between the apparent horizon and the inferior mirage of objects
Fig. 15 above the true horizon. An example of an inferior mirage is shown
in Fig. 15.
As with the superior mirage, the inferior mirage results in
a change in the apparent distance of objects. In the case of in–
ferior mirage, the effect is that of disappearance over the apparent
horizon of previously seen objects which are known to be above the
true horizon. This phenomenon is called sinking.
Fig. 16 Fig. 17 3.
The Fata Morgana
is a combination of superior and inferior
mirage occurring when a superheated layer is surmounted by a
single or multiple inversion. Two examples of these extraordinary
optical distortions are shown in Figs. 16 and 17. A most vivid
account of such deformations has been rendered by Koch
[
^
23
^
]
in
the description of his journey across Greenland on 12 April 1913.
4.
Optical haze
, or shimmer, occurs in a layer of air next
to the ground within which the lapse rate of temperature is ex–
cessive. Within this layer small-scale convective currents develop
with the warmer lumps of air ascending and the colder descending.
The differences in the refractive index of these lumps cause a
blurring of objects seen through the layer. Optical haze occurs
quite frequently in the arctic in the same meteorological condi–
tions as the inferior mirage; it makes it difficult to identify
details in the landscape and is annoying for telescopic observa–
tions, particularly range finding by the aid of coincidence range–
finder.
5.
Ice blink and water sky
. - In the summer season (when the
sun is above the horizon at a small angle of elevation) light is
reflected and scattered between the ice surface and the base of
low layers of clouds. The whitish glare that is often seen on low
clouds is due to refection of light from distant ice fields. Some–
times, these reflections are quite intense and are thus called ice
blink. Conversely, if there are patches or lanes of open water in
the ice, dark patches or lanes will be seen on the base of cloud
layers. This is called water sky. Observations on water sky and
ice blink are extremely useful for navigation on the ice, for they
indicate, as if seen in a mirror, what lies beyond the horizon.
AIR MASSES AND FRONTS
The concept of air masses, introduced by Bergeron
[
^
3
^
]
,
is much used in modern meteorology and denotes a vast body of air
whose physical properties are more or less uniform in the horizontal
direction. The air, being almost transparent relative to high–
temperature radiation, absorbs only a small portion of the direct
solar radiation, and the earth’s surface, which is an efficient
absorber, takes up a large portion of this radiation, converts it
into sensible heat and gives it back to the atmosphere, partly
through low-temperature radiation but mostly through eddy motion,
or mixing. Consequently, the physical properties of the earth’s
surface constitute a predominant factor in the formation of the air
masses.
The air masses typical of the arctic region in winter are
characterized by low temperature at all levels, extreme absolute
dryness and excessively stable stratification. Some examples of
typical winter conditions are shown in Table IV. It will be seen
that the relative humidity at high levels is very low; this condition
is due to the circumstance that the air, on account of radiative
cooling aloft, takes part in a sinking, or settling motion. As
a result of this prevailing sinking motion and relative dryness,
high clouds are extremely rare over the central arctic in winter
(see p. ).
| TABLE IV. Typical Temperature (T) and Relative Humidity (R) of Arctic Air Masses in Winter | ||||||
|---|---|---|---|---|---|---|
| Eureka Sound (8 ft. above MSL) Jan. 19, 1949. | Fairbanks (440 ft. above MSL) Jan. 14, 1949 | International Falls (1112 ft above MSL) Jan. 28, 1949. | ||||
| Height | T(°C) | R (%) | T(°C) | R(%) | T(°C) | R(%) |
| Station level | −45.0 | 25 | −32.8 | 42 | −17.2 | 68 |
| 2,000 ft. | −25.4 | 50 | −18.1 | 68 | −17.2 | 67 |
| 4,000 ft. | −24.8 | 54 | −17.5 | 75 | −15.7 | 67 |
| 6,000 ft. | −23.4 | 35 | −17.0 | 67 | −14.0 | 32 |
| 8,000 ft. | −21.8 | 24 | −20.6 | 53 | −13.7 | 40 |
| 10,000 ft. | −24.9 | - | −22.6 | 28 | −14.0 | 31 |
| 15,000 ft. | −35.1 | - | −31.4 | - | −19.3 | 32 |
| 20,000 ft. | −44.7 | - | −40.5 | - | 29.3 | - |
Fig. 18 The source region of arctic air masses in winter is shown in
Fig. 18. On the North American and on the Eurasian sides it borders
onto the source regions of polar continental air masses. These
latter air masses are in many respects similar to the arctic regions,
except that the air masses are more shallow and have less extreme
properties.
It will be seen from Fig. 18 that warm air from the North
Atlantic (polar maritime air) normally invades the arctic in the
region between Iceland and Norway as far east as Novaya Zemlya.
Less frequently, warm air from the Pacific invades the arctic along
the west coast of Alaska. On the other hand arctic air invades the
midlatitude belt most frequently over the eastern parts of North
America and Siberia. On the whole, more arctic air is shed
southwards than warm air northwards at low levels, the differences
being made up by an excess of northward transport of warm air at
greater heights in the troposphere.
The southward flow of arctic air is by no means a steady one;
it appears to occur in outbursts of considerable strength, at in–
tervals of 3 to 10 days, the outburst being associated with intense
traveling cyclones. These outbreaks of arctic air may sometimes
reach as far south as 25°N, and are the main cause of cold spells
in low latitudes. The preferred regions for these outbreaks of
arctic air are the eastern part of North America and the western
part of the North Atlantic, and the eastern part of Siberia and the
adjoining part of the North Pacific.
Fig. 19 In summer the arctic source region is less effective, owing
to the sun’s being above the horizon, and the contrast between the
arctic and neighboring air masses is less extreme. The source region
of arctic air masses in summer is shown in Fig. 19 in relation to
neighboring sources. Some examples of typical arctic air masses in
summer are given in Table V. On the whole, the relative humidity
aloft is higher in summer than in winter, and, as a result, the
amount of high clouds reaches a maximum in the warm season.
Fig. 20 Fig. 21 Fig. 22 The transition from the arctic to the neighboring air masses
is usually not continuous. The mean circulation of the atmosphere
is such that there is a tendency for the air masses from neighboring
source regions to be brought together along zones of convergence,
Along these zones of convergence, which are called
fronts
, or
frontal zones, more or less abrupt transition in wind, temperature,
humidity, and weather will be found. The mean positions of these
principal frontal zones are shown in Figs. 20 and 21 for winter
and summer respectively. It will be seen that, on the average,
the arctic front is not continuous around the pole; it is normally
absent in the preferred regions of outbreaks of arctic air. A
schematic meridional cross-section of the principal air mass sources
and frontal zones is shown in Fig. 22.
| TABLE V. Typical Temperature (T) and Relative Humidity (R) of Arctic Air Masses in Summer | ||||||
|---|---|---|---|---|---|---|
| Eureka Sound (8 ft. above MSL) July 1, 1950. | Fairbanks (440 ft. above MSL) July 20, 1946 | International Falls (1112 ft. above MSL) July 12, 1946. | ||||
| Height | T(°C) | R (%) | T(°C) | R(%) | T(°C) | R(%) |
| Station level | 7.2 | 61 | 14.0 | 88 | 17.0 | 70 |
| 2,000 ft. | 3.5 | 62 | 10.2 | 88 | 17.6 | 59 |
| 4,000 ft. | −0.3 | 64 | 5.3 | 92 | 12.5 | 59 |
| 6,000 ft. | −4.2 | 59 | 1.8 | 92 | 10.5 | 22 |
| 8,000 ft. | −7.9 | 63 | −0.6 | 98 | 8.3 | - |
| 10,000 ft. | −11.0 | 66 | −2.9 | 100 | 5.3 | - |
| 15,000 ft. | −18.3 | 86 | −10.8 | 16 | −2.0 | 20 |
| 20,000 ft. | −28.1 | 62 | −20.5 | 58 | −11.6 | - |
CYCLONES AND ANTICYCLONES
The frontal zones discussed in the foregoing section are
rarely stable. On account of the contrasts in energy stored along
frontal zones, perturbations (known as cyclones, depressions, or
lows) develop and travel along the frontal zones, generally from
the east to the west with a component toward the north. In the
areas between the cyclones, regions of high pressure, or anti–
cyclones, develop and travel, generally eastward with component
toward the south. Most of these traveling cyclones remain in the
sup-polar belt and affect the fringe of the arctic region; some
of them, however, move into and cross the arctic.
Fig. 23 An example of such a chain of fronts, cyclones and anticyclones
around the arctic is shown in Fig. 23. It will be seen that, on
this occasion, the arctic front is well developed over North
America and over northern Siberia. The polar front, too, is well
developed, more or less in its normal position. A series of cy–
clones is associated with the frontal systems, with anticyclones
in between.
Fig. 24 As compared with middle and low latitudes, the arctic region
is a relatively quiet area as far as traveling disturbances are
concerned. The mean meridional distribution of frequencies of
cyclogenesis (formation of cyclones), cyclones, anticyclogenesis
(formation of anticyclones), and anticyclones is shown in Fig. 24
as a mean for all longitudes.
In summer most anticyclones form about 50°N and move southward
such that their mean position if about 38°N. There is, however,
a secondary maximum of anticyclogenesis at about 75°N and a rela–
tively large maximum north of this latitude. It will further be
seen that most cyclones form about in latitude 50°N and move such
that their mean latitude is about 60°N. It has been shown by
Petterssen
[
^
32
^
]
that this poleward tendency of cyclone move–
ment is due to the thermal structure of the atmosphere and the
rotation of the earth.
In winter the frequency distribution is, in principle, the
same as in summer. In all seasons the arctic region as a whole
is characterized by a low frequency of cyclones and a relatively
high frequency of anticyclones.
The low frequency of cyclones is not typical of the entire
arctic region. As has been shown by Petterssen
[
^
32
^
]
, general
dynamical principles require that cyclonic circulation (vorticity)
must be produced in the cold sources above cold land and ice fields
and exported along isentropic surfaces downward to sea level along
the arctic coast. Hence all the bays of open water along the
fringe of the arctic will be characterized by cyclonic activity.
These areas of maximum cyclonic activity are also regions of
generally bad weather.
Fig. 25 Fig. 26 Figures 25 and 26 show the geographical distribution of
cyclone centers in winter and summer, respectively. The following
regions in arctic and subarctic latitudes are characterized by high
frequency of cyclones: The Gulf of Alaska and the Aleutian Chain
(winter and summer), the Baffin Bay and Davis Strait (winter and
summer), the waters south and west of Iceland (winter and summer),
the Norwegian Sea (winter and summer), the Barentz Sea (mostly winter).
Fig. 27 Fig. 28 The corresponding frequencies of anticyclones are shown in Figs.
27 and 28. It will be seen that winter anticyclones are quite fre–
quent over the central arctic, with a maximum over the north coast
of Alaska. In summer (Fig. 28) anticyclones are rare on the out–
skirts of the arctic, but quite frequent over the ice pack.
ATMOSPHERIC PRESSURE
Until seventy years ago, all theoretical considerations concerning
the general atmospheric circulation postulated a zonal system of westerly
winds circulating about a low-pressure area centered at the North Pole.
Subsequent expeditionary data on winds and pressures within the Arctic,
however, failed to verify this simple concept. Furthermore, as early as
1888, Helmholtz
^
[
18
]
^
had deduced from hydrostatic considerations that
the prevailing low Arctic temperatures should produce a shallow surface
anticyclone in polar regions. As a result of the mounting evidence from
Arctic observations, together with the general acceptance of the Helmholtz
theory, it became popular during the next four decades to consider the
existence of a permanent polar anticyclone even though the details of the
Arctic pressure distribution remained essentially undetermined.
However, from charts published in 1929 depicting the monthly
averages of temperature, pressure, and cloudiness, Baur
^
[
1
]
^
was able to
show that the centers of high atmospheric pressure tended to correspond
closely to the regions of minimum hemispherical temperature. He traced
the movement of the principal Arctic center of maximum pressure (and
minimum temperature) from a winter position in Eastern Siberia to a
position north of the Canadian Archipelago in spring, i.e., at a time
when the sub-Arctic continental regions become relatively warm in comparison
to the Arctic Ocean. He then made note of a continued easterly movement
of the centers to a position northeast of Greenland and Spitzbergen in
early summer. In early autumn Baur found a secondary maximum in pressure
over the Polar Sea which he ascribed to the effects of rapid cooling in
the Canadian Archipelago and adjoining ice pack, but on his series of
charts this center is soon superceded by the Siberian high and a weaker
counterpart over the Yukon Territory.
The next published series of charts showing the distribution of
pressure over the Arctic was prepared by Sverdrup, Peterson and Loewe
^
[
42
]
^
and drew heavily upon the analyses of Baur, Birkeland and Føyn
^
[
1
]
^
. Dorsey
^
[
12
]
^
has more recently revised Sverdrup’s charts upon the
basis of modern observational data. Dorsey also has considered the charts
prepared by Dzerdzeyevski
^
[
13
]
^
in 1945 - a series which had made use of
the pressure data obtained near the pole by the Russian North pole Expedition.
The charts prepared by Dorsey are apparently the most up-to-date and
^
figs 29-32 here
^
are the ones presented here as Figures
^
29
^
to
^
32
^
. While the accuracy of
the pressure field indicated for the Arctic Ocean, Greenland, and the
Canadian Archipelago may be open to some question, it is, nevertheless,
probable that the charts do contain the essential characteristics of the
true pressure field at the surface. The prevailing wind directions usually
agree with the isobars and the locations of the principal cyclone tracks
and frontal systems are in accord with the resulting wind distribution.
In winter (January, Figure
^
29
^
), the Arctic pressure field is
dominated by the extensive anticyclonic system centered over the Asiatic
Continent and extending as a ridge toward the Chukchi Peninsula and two
very large low-pressure areas - one centered southwest of Iceland and
extending northeastward over the Barents Sea and northwestward over Davis
Strait, and a second centered over the Aleutians and occupying the entire
Bering Sea and Gulf of Alaska. A secondary anticyclone with a central
pressure in excess of 1020 mb is centered over the Mackenzie River Valley.
In spring (April, Figure
^
30
^
), high pressure exists over the greatest
part of the Arctic Ocean and it is during this season that pressures reach
their annual maxima over the Canadian Archipelago and northern Greenland.
Meanwhile, the Siberian anticyclone has so weakened in intensity that it
can no longer be discerned in the mean isobaric pattern. The Aleutian
low weakens somewhat during this season but retains approximately the same
position as in winter. The Icelandic low, on the other hand, is very much
less intense and occupies its southernmost position of the year (south
of Greenland).
During summer (July, Figure
^
31
^
), the pressure gradients at
their weakest over the Arctic. This is to be expected when one considers
that summer is also the season of minimum thermal contrast between polar
and temperate zones. It is during this season that the so-called
circumpolar belt of low pressure is located at its highest latitude. The
Polar Sea during this season is occupied by a true anticyclone as a result
of the contrast between the low surface temperatures over the cold sea
and the relatively higher temperatures which exist at the same time over
surrounding coastal and inland regions. (see Figure
^
45
^
.)
In autumn (October, Figure
^
32
^
), there is a return to a pressure
distribution which is more typical of winter conditions. The Icelandic
and Aleutian lows increase in intensity as the deep cyclonic disturbances
over the northern North Atlantic and North pacific become more frequent.
Meanwhile, the Siberian high has begun to make its appearance, although
a closed anticyclone still remains over the Arctic Ocean north of Greenland
and the Canadian Archipelago as pointed out in a previous paragraph.
At this point it should, perhaps, be mentioned that the details
of the pressure distribution over interior Greenland have little meaning
as shown on the sea-level pressure charts. It is possible, on the basis
of theoretical considerations and actual pressure data, to construct an
idealized picture of the pressure field which would obtain over the region
were Greenland not in existence. However, such a picture has no physical
or meteorological significance. Greenland is not merely a positive
topographic feature but it is, in itself, an important air-mass source
because of the altitude and extent of the Ice Cap and because of the
abnormally steep horizontal (and vertical) temperature gradients which
are produced by the temperature contrasts between ice fields and coasts
^
[
42
]
^
. It is because of these facts that there is found to be so little
connection between the pressure field as charted and the wind speeds and
prevailing directions which are recorded for various points over Greenland
or along its coastline.
Pressure Fluctuations
. - The pressure variabilities observed from
day to day at any Arctic location are directly related to the number
and intensity of migratory cyclones and anticyclones which pass near
enough to affect the area (see pages to ). The extreme ranges
occur during winter in connection with intense cyclonic activity and at
most Arctic meteorological stations both the absolute maximum pressures
and the absolute minimum pressures have been recorded during one of the
colder months. For example, the absolute maximum pressure for a Kara Sea
location occurred at Ostrov Domashnii on February 17, 1933 (1058.5 mb),
while the absolute minimum pressure for the same area occurred at Ostrov
Belyi on November 19, 1933 (950.1 mb)
^
[
45
]
^
. The average daily variability
of pressure shows a characteristic annual course with the maximum values
in winter (8 to 10 mb) and the minimum values in summer. In some Arctic
areas there appears to be an additional secondary maximum in April. The
monthly pressure variations also show the same general trend as the daily
variations, as is illustrated by the following typical Arctic data
^
[
43
]
^
:
Monthly Pressure Variation (in mbs)
| Yrs | |||||||||||||
| Location | Rec | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Arctic Ocean Fram and Maud | 5 | 52.9 | 53.0 | 41.0 | 40.5 | 32.6 | 28.1 | 32.9 | 27.5 | 42.8 | 41.0 | 44.1 | 49.4 |
| Central Canadian Archipelago | 15 | 42.7 | 45.7 | 39.6 | 35.5 | 30.8 | 26.8 | 26.1 | 27.7 | 33.2 | 34.1 | 37.6 | 42.0 |
Extreme pressure changes of as much as 50 mb in 24 hours have been recorded
at some stations on the coasts of the Arctic Ocean in connection with the
passage of an intense cyclone or anticyclone.
The mean monthly pressure values in individual years and even the
annual pressures for different years may deviate considerably from long–
term averages
^
[
45
]
^
. For example, the mean annual pressure at Yugossky
Shar was 1031.1 mb in 1933 and 994.3 mb in 1914. These differences are
completely accounted for by differences in the frequencies of cyclonic
activity between the individual months or years.
The preceding discussion applies only to true Arctic conditions
In lower latitudes around the periphery of the Arctic, the non-periodic
variations in pressure are of greater magnitude.
Pressures in the Upper Atmosphere
^
Pressures in the Upper Atmosphere
^
. - When Helmholtz
^
[
19
]
^
deduced the
existence of a polar anticyclone upon the basis of hydrostatic considera–
tions, by the same reasoning he also concluded that low pressure must exit
aloft over the Arctic to compensate for high pressure at the surface. Modern
information concerning pressures aloft over the Arctic verify the basic
concept of Helmholz but the relations between the surface pressure and the
pressure aloft are not as simple as was at first believed. The Siberian
high in winter appears to be a relatively shallow phenomenon and is probably
superceded by relatively low pressures at a comparatively low altitude.
Details concerning the vertical structure of the atmosphere at low levels
over this region are lacking, however. The essentials of the vertical
distribution of pressure elsewhere within the Arctic can probably best be
described by examining the pressure field at the 700-mb level.
Namias
^
[
30
]
^
has recently prepared upper
^
-
^
level charts illustrating
the height of the 700-mb surface over the Northern Hemisphere. His
^
(slightly revised)
^
January and July charts are given as Figures and , with the altitudes
^
Figs. 33 and 34 here
^
of the pressure surface represented by isolines plotted for 100-ft
intervals. The January chart (Figure ) shows the pressure field to have
a rather simple structure with two closed low-pressure centers - one over
the southeast portion of the Canadian Archipelago and a second in the
sub-Arctic over the Kamchatka Peninsula. The July chart (Figure
^
34
^
),
on the other hand, shows much weaker pressure gradients than the winter
chart, and the pressures are higher as would be expected on the basis of
the higher surface temperatures. Three closed low-pressure areas are
shown within the Arctic during this season, the most important of which
is centered very nearly over the Pole. This is also an expected condition
when it is considered that the Arctic Ocean is essentially a “cold sources”
during warmer months in the Northern Hemisphere.
SURFACE WIND
It is extremely difficult to generalize upon the surface wind
field in the Arctic because of several circumstances which are of
peculiar importance at high latitudes. In the first place, the
character of the wind regime at most coastal points and at many
inland locations is largely determined by local factors which are
not amenable to regional generalization. Secondly, the periodic
changes and spa
e
^
t
^
ial deformations in the general wind field are no
less variable than are the highly irresolute Arctic pressure distri–
butions which produce the winds in the first place. (See page .)
The third, but not the least important, difficulty is occasioned by
the fact that the scanty observational data available for analysis
do not represent a homogeneous period of record at all points of
observation. For this reason it is often difficult to ascertain
whether the differences in the wind conditions between two weather
stations represent true regional differences in the circulation or
whether they merely indicate that the observations were recorded
during different years — a difficulty which is particularly serious
when wind observations obtained on shipboard within the Polar Sea are
The General Wind Circulation
. - The Arctic circulation is, of course,
dominated by the polar anticyclone which, during all seasons except
winter, is centered somewhere over the Arctic Ocean. So far as can
be determined from the scanty observational materials available, the
prevailing wind directions over the Arctic Ocean and surrounding
coasts appear to correspond to the mean pressure distribution. It is
apparent that easterly winds prevail over the well-explored portions
of the Arctic Ocean, over Iceland, the northern portions of Greenland,
and Alaska, and that northeasterly winds prevail in interior Alaska
and Greenland, all of which fits the prescribed mean pressure field.
(See Figs.
^
29
^
to
^
32
^
.)
Wind conditions over the interior and coastal portions of Arctic
Eurasia, however, appear to be less well-defined. The Siberian anti–
cyclone dominates the interior and coastal circulations during winter,
but during other seasons the winds are regionally highly irregular.
Along the Siberian coasts of the Arctic Ocean in summer there appears
to exist a large onshore wind component resulting from summer heating
over the interior.
In the more southerly portions of the Arctic, and particularly
in the peripheral maritime regions of frequent cyclone activity, the
surface winds are highly variable and do not exhibit a pronounced
“prevailing” direction. At several stations, for example, the
frequency data show that during the course of a year the winds tend
to blow almost as often from one direction as from any other. In
such regions the non-periodic features of the circulation far outweigh
any periodic or permanent characteristics.
The preceding generalization of the Arctic surface circulation
appears to be about as complete a description as possible of the
large-scale aspects of Arctic winds. The remaining periodic and
regional differences in the surface circulation are the result of
local factors which will be described in greater detail.
Surface Wind Speeds
. - A large proportion of the description given
by polar explorers have stressed the prevalence
^
of
^
high winds and have
almost invariably given the impression that the Arctic is indeed a
stormy and inhospitable place. One fairly recent publication on
Arctic weather conditions, for example, presents a 3 1/2 page
discussion of winds and storms and, of this discussion, at least 3
pages describe extreme winds reported by various Arctic expeditions
since 1836. It is true that in some restricted areas within the
Arctic the almost continuous high winds are the most noticeable
feature of the climate. It is also true that excessive winds have at
one time or another been reported from nearly every Arctic observing
station. These circumstances, however, do not suffice to ascribe an
unusual severity to Arctic wind conditions.
According to Sverdrup
/
^
[
42
]
^
/
, relatively low wind velocities are
characteristic of the Arctic Ocean and Canadian Archipelago. The annual
mean wind speed as recorded over the Polar Sea was only 10 mph during
the
Fram
Expedition from 1893 to 1896, and 9 mph during the
Maud
Expedition of 1922 to 1924. Summarizing the observed conditions,
Sverdrup states, “It is remarkable that very high wind velocities are
so rare.” The highest wind speed observed on
Fram
was 40 mph,
and on the
Maud
Expedition, 34 mph; the latter, however, is an hourly
mean value. The Russian North Pole Expedition of 1937
/
^
[
5
]
^
]
/
found
that high winds occasionally do occur near the North Pole since they
reported from the Pole on June 8 and 9 to the effect that gusts had
attained speeds of 60 feet per second (41 mph).
The relative frequencies of high wind speeds at various Arctic
points can be judged from the data on the average monthly number of
days with winds of gale, force, which are presented in Table
^
VI
^
.
^
Table VI here
^
| Table VI. Mean number of days with “gales”* | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | |||||||||||||||
| 004 | 5 | 4 | 4 | 3 | 2 | 1 | ** | ** | 2 | 3 | 5 | 4 | 33 | .. | |
| 006 | 5 | 4 | 3 | 3 | 2 | 4 | 1 | 2 | 4 | 3 | 4 | 4 | 39 | 7 | |
| 007 | 5 | 3 | 3 | 5 | 2 | 3 | 1 | 2 | 7 | 8 | 5 | 7 | 50 | 5-6 | |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | 2 | 1 | ** | 1 | 1 | 0 | 1 | 1 | 2 | 5 | 3 | 2 | 19 | 5 | |
| 101 | 8 | 9 | 8 | 1 | 1 | .. | 1 | 4 | 5 | 11 | 18 | 14 | .. | 0-2 | |
| 103 | 14 | 19 | 13 | 7 | 4 | 9 | 9 | 7 | 7 | 10 | 13 | 12 | 121 | 2 | |
| 104 | 4 | 2 | 3 | 3 | 1 | ** | ** | 1 | 1 | 2 | 1 | 4 | 21 | 10 | |
| 106 | 1 | 2 | 4 | 4 | 7 | 6 | 4 | 6 | 3 | 6 | 4 | 2 | 50 | 6-7 | |
| Alaska, Inland: | |||||||||||||||
| 155 | 0 | 2 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 7 | 1-3 | |
| 156 | 1 | 0 | ** | ** | ** | ** | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 10 | |
| Canada, Coastal and Insular: | |||||||||||||||
| 222 | 4 | 2 | 2 | 4 | 3 | 1 | 2 | 1 | 2 | 6 | 4 | 7 | 38 | 2-3 | |
| 224 | 3 | 1 | 2 | 2 | 1 | ** | 1 | 1 | 1 | 1 | 4 | 3 | 17 | 2-3 | |
| 225 | 8 | 8 | 7 | 5 | 4 | 3 | 3 | 3 | 4 | 5 | 8 | 8 | 66 | 5-6 | |
| 228 | 3 | 4 | 5 | 4 | 3 | 1 | 1 | 3 | 5 | 8 | 5 | 7 | 50 | 3 | |
| Greenland, Iceland, Coastal and Insular: | |||||||||||||||
| 301 | 1 | 1 | 1 | ** | 1 | 2 | 1 | 2 | 2 | 1 | 1 | ** | 12 | 5-6 | |
| 302 | 4 | 4 | 1 | 1 | 3 | 2 | 3 | 3 | 4 | 2 | 2 | ** | 28 | 2-3 | |
| 304 | 1 | 2 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 2 | 2 | ** | 15 | 10 | |
| 305 | 10 | 11 | 10 | 6 | 8 | 2 | 5 | 3 | 6 | 10 | 7 | 5 | 82 | 3-4 | |
| 306 | 2 | 2 | 1 | 1 | ** | 1 | ** | 1 | 1 | 3 | 1 | 1 | 14 | 5 | |
| 308 | 10 | 6 | 9 | 10 | 6 | 4 | 6 | 3 | 8 | 10 | 8 | 6 | 84 | 2 |
| Table VI. Mean number of days with “gales”* (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland, Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 309 | 4 | ** | 2 | ** | ** | ** | ** | 1 | 1 | 2 | 2 | 2 | 15 | 4-5 |
| 310 | 4 | 5 | 6 | 3 | 2 | ** | 1 | ** | 5 | 5 | 5 | 8 | 43 | 2-3 |
| 311 | 4 | 2 | 1 | 1 | 1 | ** | ** | ** | ** | 1 | 2 | 1 | 11 | 2-3 |
| 312 | 4 | 2 | 2 | 1 | 2 | 2 | 1 | 1 | 2 | 2 | 2 | 2 | 22 | 6-7 |
| 313 | 21 | 22 | 24 | 17 | 9 | 5 | 5 | 5 | 8 | 15 | 15 | 20 | 167 | 3-4 |
| 314 | 4 | 1 | 2 | 3 | ** | 5 | 2 | 2 | 3 | 2 | 2 | 2 | 29 | 4-5 |
| 315 | 6 | 2 | 2 | 2 | 1 | 1 | ** | 1 | ** | 1 | 3 | 5 | 23 | 4-5 |
| 316 | 10 | 15 | 15 | 9 | 10 | 4 | 3 | 3 | 13 | 5 | 12 | 21 | 121 | 2 |
| 317 | 7 | 5 | 4 | 2 | 1 | 1 | ** | 1 | 3 | 2 | 4 | 5 | 36 | 10 |
| 318 | 4 | 5 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 2 | 3 | 2 | 22 | 8 |
| 319 | 9 | 7 | 6 | 6 | 1 | 2 | 1 | 1 | 3 | 3 | 6 | 10 | 54 | 2-3 |
| 320 | 12 | 10 | 8 | 7 | 4 | 4 | 3 | 4 | 6 | 9 | 10 | 8 | 84 | 10 |
| 321 | 19 | 17 | 19 | 15 | 12 | 11 | 4 | 8 | 8 | 10 | 12 | 19 | 153 | 4-5 |
| 330 | 2 | 2 | 1 | 1 | 1 | 1 | ** | 1 | 1 | 1 | 2 | 2 | 14 | 16 |
| 331 | 3 | 2 | 1 | 1 | ** | ** | 0 | ** | ** | 1 | 2 | 3 | 13 | 16 |
| 332 | 3 | 2 | 1 | 2 | 1 | 1 | ** | 1 | 2 | 2 | 1 | 1 | 17 | 9 |
| 334 | 3 | 2 | 2 | 1 | ** | ** | 0 | ** | 1 | 2 | 2 | 2 | 15 | 14 |
| 335 | 1 | 1 | 1 | ** | ** | 0 | 0 | ** | ** | ** | 1 | 1 | 5 | 15 |
| 337 | ** | 0 | 0 | ** | 0 | 0 | 0 | 0 | 0 | 0 | ** | ** | 1 | 11 |
| 339 | 2 | 1 | 1 | ** | ** | ** | 0 | ** | 1 | 1 | 1 | ** | 9 | 10 |
| 340 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 2 | 1 |
| Greenland, Iceland, Inland: | ||||||||||||||
| 361 | ** | ** | 0 | ** | 0 | 0 | 0 | 0 | ** | ** | 0 | ** | 1 | 16 |
| Table VI. Mean number of days with “gales”* (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 110 | 9 | 7 | 5 | 3 | 3 | 2 | 2 | 4 | 6 | 8 | 11 | 69 | 10 |
| 401 | 11 | 8 | 7 | 9 | 3 | 3 | 2 | 2 | 6 | 6 | 11 | 11 | 79 | 1 |
| 406 | 7 | 7 | 6 | 4 | 3 | 2 | 1 | 2 | 3 | 4 | 6 | 7 | 52 | 19 |
| 408 | 5 | 5 | 4 | 3 | 2 | 1 | 1 | 2 | 2 | 3 | 5 | 5 | 38 | 31 |
| 412 | 2 | 2 | 2 | 1 | 0 | ** | 0 | ** | 1 | 1 | 2 | 2 | 13 | 28 |
| 414 | 2 2 | 2 | 1 | ** | ** | ** | 0 | ** | ** | 1 | 2 | 1 | 9 | 26 |
| 415 | 4 | 4 | 4 | 2 | 3 | 2 | 2 | 1 | 2 | 3 | 5 | 4 | 36 | 18 |
| 417 | 6 | 3 | 3 | 6 | 2 | 2 | 0 | 1 | 3 | 4 | 5 | 4 | 37 | .. |
| 420 | 3 | 3 | 2 | 1 | ** | ** | ** | ** | 1 | 2 | 2 | 3 | 17 | 26 |
| 421 | ** | 0 | ** | ** | 0 | 0 | 0 | ** | ** | 0 | ** | ** | ** | 8 |
| 423 | 0 | 0 | 0 | ** | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ** | 7 |
| 425 | 2 | 1 | 2 | 1 | 2 | 2 | 1 | 1 | 2 | 2 | 1 | 1 | 19 | 18 |
| 426 | ** | ** | ** | 0 | 0 | 0 | 0 | 0 | ** | 0 | ** | 0 | 1 | 17 |
| 428 | 2 | 2 | 2 | 1 | 2 | 2 | 1 | 1 | 2 | 2 | 2 | 2 | 20 | 18 |
| 429 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ** | 1 | 1 | 1 | 1 | 8 | 18 |
| Europe, Inland: | ||||||||||||||
| 450 | ** | ** | ** | 1 | 0 | 1 | 0 | 0 | ** | ** | ** | 1 | 3 | 7 |
| 451 | ** | ** | ** | ** | 1 | ** | 0 | ** | 1 | 1 | 1 | ** | 4 | 14 |
| 455 | 0 | 0 | 0 | 0 | 0 | 0 | ** | 0 | 0 | 0 | 0 | 0 | ** | 8 |
| 456 | ** | ** | 0 | ** | ** | ** | ** | 0 | 1 | ** | 0 | 0 | 1 | 7 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 14 | 8 | 11 | 11 | 7 | 11 | 10 | 10 | 8 | 9 | 13 | 14 | 126 | 7-8 |
| 502 | 9 | 8 | 6 | 8 | 6 | 6 | 6 | 5 | 4 | 3 | 8 | 8 | 76 | 4-5 |
| Table VI. Mean number of days with “gales”* (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 503 | 8 | 4 | 4 | 2 | 2 | 4 | 3 | 2 | 3 | 3 | 6 | 6 | 47 | 7-8 |
| 506 | 6 | 5 | 5 | 5 | 5 | 3 | 1 | 2 | 3 | 6 | 7 | 5 | 53 | 24 |
| 507 | 11 | 10 | 13 | 13 | 10 | 11 | 8 | 6 | 8 | 6 | 8 | 11 | 114 | 17 |
| 508 | 4 | 3 | 5 | 4 | 3 | 2 | 1 | 2 | 4 | 5 | 5 | 4 | 41 | 6 |
| 509 | 5 | 6 | 6 | 6 | 7 | 2 | 2 | 4 | 4 | 8 | 10 | 5 | 65 | 6-7 |
| 510 | 11 | 19 | 8 | 7 | 5 | 3 | 1 | 3 | 5 | 6 | 9 | 8 | 75 | 19 |
| 513 | 1 | 1 | 0 | 1 | ** | 2 | 3 | 2 | 2 | 2 | 1 | 2 | 18 | 4 |
| 515 | ** | ** | 2 | 1 | 1 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 15 | 5 |
| 517 | 8 | 3 | 6 | 2 | 3 | 3 | 1 | 2 | 8 | 7 | 8 | 4 | 55 | 3 |
| 518 | 10 | 9 | 8 | 8 | 7 | 5 | 3 | 2 | 5 | 7 | 10 | 9 | 82 | 26 |
| 519 | 6 | 6 | 5 | 6 | 6 | 2 | 1 | 2 | 5 | 7 | 8 | 8 | 60 | 22 |
| 521 | 4 | 4 | 5 | 4 | 5 | 2 | 1 | 3 | 4 | 5 | 4 | 4 | 46 | 13 |
| 522 | 1 | ** | 1 | 1 | 1 | 1 | ** | 2 | 1 | 0 | 0 | 1 | 9 | 5 |
| 523 | 10 | 6 | 8 | 5 | 5 | 4 | 2 | 4 | 5 | 7 | 4 | 8 | 68 | 3 |
| 525 | 5 | 5 | 5 | 5 | 5 | 3 | 6 | 6 | 6 | 6 | 8 | 8 | 68 | 9 |
| 526 | 3 | 2 | 3 | 2 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 21 | 14 |
| 527 | 4 | 4 | 4 | 2 | 1 | ** | 2 | 1 | 2 | 2 | 4 | 3 | 29 | 12 |
| 531 | 1 | ** | 2 | ** | 0 | 1 | 0 | 0 | 0 | 2 | 2 | 3 | 11 | 4 |
| Asia, Inland: | ||||||||||||||
| 550 | 4 | 4 | 2 | 2 | 1 | 0 | 1 | ** | 1 | 1 | 2 | 3 | 19 | 5 |
| 551 | 6 | 6 | 2 | 2 | 2 | 0 | 2 | 4 | 0 | 1 | 5 | 6 | 35 | 1 |
| 553 | 5 | 6 | 7 | 5 | 3 | 2 | 1 | 2 | 3 | 4 | 5 | 4 | 48 | 18 |
| 554 | 7 | 10 | 8 | 11 | 10 | 7 | 6 | 7 | 6 | 7 | 12 | 9 | 100 | 4 |
| 556 | ** | ** | ** | ** | ** | 2 | 2 | 1 | 1 | ** | ** | 0 | 7 | 17 |
| Table VI. Mean number of days with “gales”* (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 558 | 0 | 0 | ** | 0 | ** | 1 | 1 | 1 | ** | 1 | 0 | 0 | 4 | 8 |
| 560 | ** | 2 | 3 | 2 | 2 | 2 | 2 | 1 | 2 | 1 | 2 | 1 | 20 | 8 |
| 561 | 1 | 1 | 1 | 1 | 1 | ** | ** | ** | ** | ** | ** | ** | 5 | 11 |
| 562 | ** | 2 | 3 | 1 | 3 | 2 | ** | 1 | 2 | 1 | 3 | 1 | 18 | 10 |
| 563 | 2 | 2 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 17 | 6 |
| 566 | ** | ** | 1 | ** | 1 | 1 | 1 | ** | 1 | 1 | 1 | 0 | 7 | 13 |
| 568 | ** | ** | 1 | 1 | 2 | 2 | 1 | 1 | 1 | 1 | ** | ** | 10 | 18 |
| 571 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 4 | 0 | 1 | 6 | 1 |
| 572 | 1 | 1 | 1 | ** | ** | 1 | ** | ** | 1 | ** | 1 | 1 | 7 | 16 |
| 573 | 2 | 2 | 2 | 3 | 3 | 2 | 2 | 1 | 3 | 2 | 2 | 2 | 25 | 9 |
| 574 | 1 | ** | ** | ** | 1 | ** | 0 | ** | ** | ** | 1 | ** | 5 | 10 |
| 575 | 1 | ** | 0 | 0 | 0 | 0 | 0 | ** | ** | ** | ** | ** | 2 | 18 |
| 576 | ** | 1 | 1 | 2 | 1 | 2 | 1 | 1 | ** | ** | 1 | 1 | 11 | 13 |
Data from coastal stations along the Arctic Ocean indicate that
average wind speeds at most points are higher than over the ocean
areas, but even here the wind speeds are low except where strongly
influenced by local factors. In general, the average wind speeds at
coastal points are of the order of 10 to 15 mph except at more exposed
locations where averages of 15 to 20 mph are fairly common. (See
Table
^
VII
^
.) However, the coastal areas may also experience excessively ^
Table VII here
^
high winds at times. For example, on February 8, 1909, ^
Note: Possibility that this may be an incorrect date See Reference title, J.P.J.
^
a temporary
weather station
s
at Winter Harbor, Melville Island, recorded a 1-hour
average wind speed of 86 mph and a speed of over 100 mph for a
20-minute period. The average speed for the 24-hour period was in
excess of 60 mph
/
^
[
6
]
^
/
.
Wind speeds over inland areas at low elevations within the Arctic
are usually much lower than those over either the Polar Sea or its
coasts. The mean annual wind speed at Verkhoyansk, for example, is
only 3.2 mph and at Yakutsk, 3.9 mph.
| Table VII. Average specified wind speed (mph) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 001 | 11 | 9 | 10 | 11 | 13 | 14 | 12 | 11 | 13 | 14 | 14 | .. | .. | 1 |
| 002 | 11 | 9 | 8 | 8 | 11 | 12 | 12 | 11 | 11 | 10 | 9 | 10 | 10 | 1 |
| 004 | 21 | 21 | 18 | 17 | 13 | 14 | 12 | 14 | 16 | 18 | 19 | 18 | 17 | .. |
| 006 | 14 | 14 | 11 | 11 | 13 | 13 | 11 | 12 | 16 | 14 | 14 | 12 | 13 | 5-6 |
| 007 | 15 | 13 | 13 | 13 | 14 | 14 | 13 | 15 | 17 | 18 | 17 | 16 | 15 | 5-6 |
| 008 | 11 | .. | .. | .. | .. | .. | 8 | 11 | 7 | 8 | 9 | 10 | .. | 0-1 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 10 | 10 | 11 | 12 | 11 | 11 | 13 | 13 | 14 | 15 | 12 | 10 | 12 | 3-17 |
| 101 | 15 | 18 | 18 | 11 | 11 | 12 | 13 | 15 | 15 | 17 | 22 | 19 | 16 | 1 |
| 103 | 22 | 24 | 21 | 17 | 15 | 16 | 18 | 15 | 17 | 17 | 22 | 20 | 19 | 1 |
| 104 | 9 | 9 | 9 | 9 | 7 | 7 | 8 | 8 | 9 | 9 | 9 | 9 | 8 | 18-30 |
| 106 | 4 | 5 | 6 | 6 | 6 | 5 | 4 | 4 | 4 | 5 | 5 | 5 | 5 | 8 |
| Alaska, Inland: | ||||||||||||||
| 155 | 6 | 8 | 8 | 8 | 7 | 7 | 8 | 7 | 7 | 7 | 7 | 6 | 7 | 3 |
| 156 | 3 | 4 | 5 | 6 | 7 | 6 | 6 | 6 | 5 | 5 | 4 | 4 | 5 | 8 |
| Canada, Coastal and Insular: | ||||||||||||||
| 206 | 12 | 11 | 10 | 13 | 14 | 12 | 9 | 13 | 12 | 15 | 15 | 14 | 13 | 6 |
| 207 | 3 | 4 | 2 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 3 | 4 | 3 | 4 |
| 209 | 5 | 4 | 3 | 3 | 5 | 3 | 2 | 2 | 1 | 3 | 3 | 3 | 3 | 6 |
| 211 | 4 | 4 | 4 | 4 | 6 | 8 | 9 | 8 | 7 | 7 | 7 | 3 | 5 | 4 |
| 216 | 8 | 8 | 7 | 7 | 7 | 7 | 8 | 9 | 10 | 10 | 10 | 8 | 8 | 8 |
| 221 | 15 | 15 | 14 | 14 | 14 | 12 | 8 | 13 | 15 | 17 | 15 | 16 | 14 | 8 |
| 222 | 3 | 3 | 2 | 3 | 3 | 2 | 3 | 4 | 4 | 4 | 3 | 2 | 3 | 1-2 |
| Table VII. Average specified wind speed (mph) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada Coastal and Insular (cont.): | ||||||||||||||
| 223 | 11 | 11 | 11 | 13 | 12 | 12 | 10 | 11 | 12 | 13 | 15 | 13 | 12 | 15 |
| 224 | 11 | 7 | 9 | 9 | 11 | 8 | 9 | 8 | 9 | 9 | 11 | 10 | 9 | 5-6 |
| 227 | 18 | 18 | 17 | 17 | 14 | 13 | 13 | 13 | 15 | 18 | 19 | 18 | 16 | 15 |
| 228 | 15 | 15 | 14 | 14 | 13 | 12 | 11 | 13 | 16 | 17 | 17 | 15 | 14 | 12 |
| Canada, Inland: | ||||||||||||||
| 251 | 3 | 3 | 3 | 3 | 4 | 4 | 5 | 3 | 3 | 3 | 3 | 3 | 3 | 3-7 |
| 253 | 9 | 9 | 10 | 8 | 9 | 8 | 8 | 9 | 9 | 11 | 8 | 8 | 9 | 5 |
| 254 | 5 | 4 | 7 | 7 | 10 | 10 | 10 | 8 | 6 | 7 | 5 | 4 | 7 | 6-21 |
| 255 | 2 | 3 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 3 | 2 | 5 | 7 |
| Greenland, Iceland, Coastal and Insular: | ||||||||||||||
| 301 | 2 | 2 | 3 | 1 | .. | 6 | 3 | 2 | 4 | 6 | 2 | 2 | .. | 5 |
| 302 | 7 | 10 | 10 | 9 | 6 | 6 | 6 | 7 | 10 | 10 | 9 | 8 | 8 | 2 |
| 304 | 5 | 4 | 4 | 4 | 5 | 6 | 4 | 4 | 5 | 6 | 6 | 6 | 5 | 30 |
| 307 | 10 | 8 | 6 | 5 | 5 | 6 | 7 | 6 | 8 | 9 | 11 | 9 | 7 | .. |
| 308 | 5 | 5 | 5 | 4 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 12 |
| 314 | 14 | 14 | 13 | 11 | 9 | 9 | 8 | 9 | 4 | 11 | 12 | 12 | 11 | 30 |
| 317 | 6 | 6 | 5 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 5 | 5 | 4 | 30 |
| 318 | 4 | 4 | 3 | 2 | 2 | 2 | 1 | 1 | 2 | 2 | 3 | 2 | 2 | 30 |
| 320 | 13 | 12 | 12 | 11 | 8 | 10 | 8 | 7 | 9 | 10 | 11 | 11 | 10 | 23 |
| 330 | 12 | 11 | 10 | 9 | 6 | 6 | 5 | 6 | 8 | 9 | 10 | 10 | 8 | 16 |
| 331 | 14 | 14 | 13 | 12 | 11 | 11 | 9 | 9 | 10 | 12 | 12 | 13 | 12 | 4 |
| 338 | 9 | 10 | 9 | 9 | 9 | 8 | 7 | 7 | 8 | 8 | 9 | 9 | 7 | 15 |
| 340 | 6 | 6 | 4 | 4 | 4 | 4 | 3 | 3 | 4 | 4 | 5 | 5 | 5 | 19 |
| Greenland, Iceland, Inland: | ||||||||||||||
| 351 | 11 | 9 | 13 | 12 | 9 | 9 | 9 | 8 | 11 | 10 | 9 | 14 | 10 | 2 |
| Table VII. Average specified wind speed (mph) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 16 | 15 | 12 | 12 | 11 | 10 | 8 | 9 | 13 | 15 | 15 | 17 | 13 | 10 |
| 401 | 20 | 17 | 14 | 15 | 13 | 11 | 8 | 10 | 13 | 15 | 18 | 18 | 14 | 1 |
| 407 | 10 | 10 | 9 | 7 | 5 | 6 | 5 | 4 | 5 | 7 | 8 | 9 | 7 | 10 |
| 408 | 22 | 21 | 21 | 19 | 16 | 16 | 13 | 14 | 17 | 19 | 21 | 21 | 18 | 28 |
| 412 | 17 | 16 | 16 | 13 | 11 | 11 | 10 | 10 | 13 | 13 | 14 | 16 | 13 | 28 |
| 415 | 10 | 9 | 9 | 8 | 9 | 10 | 9 | 7 | 8 | 9 | 10 | 9 | 9 | 10 |
| 417 | 18 | 17 | 15 | 15 | 16 | 16 | 14 | 14 | 15 | 15 | 16 | 17 | 16 | .. |
| 421 | 8 | 8 | 8 | 8 | 9 | 9 | 7 | 8 | 8 | 7 | 7 | 7 | 8 | 8 |
| 423 | 10 | 11 | 11 | 11 | 12 | 12 | 10 | 10 | 11 | 11 | 11 | 11 | 11 | 8 |
| 424 | 10 | 9 | 9 | 8 | 8 | 8 | 8 | 8 | 9 | 10 | 10 | 10 | 9 | 26 |
| 425 | 11 | 9 | 10 | 9 | 11 | 10 | 9 | 10 | 11 | 10 | 12 | 10 | 10 | 10 |
| 426 | 10 | 10 | 10 | 9 | 9 | 9 | 9 | 9 | 10 | 10 | 10 | 11 | 10 | 10 |
| 428 | 12 | 10 | 11 | 9 | 10 | 9 | 10 | 10 | 11 | 11 | 12 | 10 | 10 | 25 |
| 429 | 8 | 9 | 9 | 9 | 10 | 9 | 9 | 8 | 8 | 8 | 8 | 8 | 9 | 6 |
| Europe, Inland: | ||||||||||||||
| 451 | 3 | 2 | 3 | 3 | 5 | 8 | 4 | 2 | 2 | 1 | 2 | 3 | 3 | 10 |
| 452 | 10 | 11 | 11 | 10 | 11 | 13 | 11 | 10 | 11 | 11 | 9 | 9 | 11 | 25 |
| 453 | 8 | 6 | 7 | 6 | 7 | 7 | 6 | 5 | 6 | 7 | 6 | 7 | 7 | 10 |
| 454 | 14 | 13 | 14 | 14 | 13 | 13 | 13 | 13 | 12 | 13 | 14 | 13 | 13 | 11 |
| 455 | 6 | 7 | 7 | 7 | 8 | 8 | 6 | 6 | 7 | 7 | 6 | 6 | 7 | 8 |
| 456 | 4 | 5 | 6 | 8 | 9 | 8 | 7 | 7 | 9 | 6 | 5 | 4 | 7 | 8 |
| 457 | 7 | 7 | 8 | 6 | 7 | 6 | 5 | 5 | 6 | 7 | 7 | 7 | 7 | 36 |
| 458 | 6 | 6 | 7 | 6 | 7 | 7 | 7 | 6 | 6 | 6 | 6 | 6 | 6 | 30 |
| Table VII. Average specified wind speed (mph) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 21 | 16 | 18 | 19 | 17 | 18 | 18 | 18 | 19 | 19 | 21 | 21 | 19 | 7-8 |
| 501 | 16 | 14 | 12 | 12 | 13 | 13 | 12 | 14 | 17 | 15 | 17 | 16 | 14 | 5-6 |
| 502 | 15 | 16 | 14 | 15 | 16 | 15 | 13 | 17 | 18 | 14 | 15 | 15 | 15 | 4-5 |
| 503 | 16 | 13 | 13 | 12 | 13 | 14 | 13 | 13 | 14 | 13 | 14 | 15 | 14 | 7-8 |
| 505 | 26 | 25 | 23 | 21 | 18 | 17 | 16 | 13 | 17 | 20 | 22 | 20 | 20 | 13 |
| 506 | 17 | 16 | 14 | 15 | 14 | 13 | 12 | 12 | 15 | 16 | 19 | 17 | 15 | 24 |
| 507 | 15 | 16 | 16 | 18 | 16 | 17 | 14 | 13 | 15 | 13 | 15 | 17 | 15 | 17 |
| 509 | 14 | 16 | 15 | 17 | 17 | 15 | 14 | 15 | 15 | 17 | 18 | 13 | 15 | 6-7 |
| 510 | 19 | 19 | 16 | 17 | 16 | 16 | 15 | 16 | 17 | 16 | 18 | 17 | 17 | 19 |
| 511 | 12 | 9 | 8 | 11 | 14 | 14 | 17 | 14 | 15 | 15 | 13 | 10 | 13 | 4 |
| 512 | 14 | 11 | 8 | 8 | 11 | 10 | 9 | 11 | 12 | 11 | 11 | 9 | 10 | 7 |
| 513 | 6 | 6 | 6 | 8 | 9 | 11 | 12 | 10 | 10 | 9 | 7 | 9 | 8 | 4 |
| 514 | 12 | 10 | 10 | 11 | 12 | 13 | 11 | 11 | 13 | 12 | 12 | 12 | 12 | 7 |
| 515 | 8 | 8 | 9 | 9 | 9 | 12 | 12 | 12 | 11 | 9 | 9 | 9 | 10 | 9 |
| 517 | 12 | 11 | 11 | 9 | 9 | 7 | 9 | 8 | 13 | 15 | 15 | 12 | 11 | 10 |
| 518 | 18 | 18 | 16 | 16 | 15 | 14 | 12 | 12 | 15 | 17 | 20 | 18 | 16 | 26 |
| 519 | 17 | 18 | 16 | 16 | 16 | 15 | 12 | 13 | 16 | 17 | 19 | 17 | 16 | 22 |
| 520 | 9 | 10 | 11 | 13 | 13 | 15 | 12 | 12 | 12 | 11 | 12 | 8 | 11 | 12 |
| 521 | 15 | 14 | 14 | 16 | 17 | 15 | 14 | 14 | 15 | 16 | 17 | 15 | 15 | 13 |
| 523 | 13 | 11 | 12 | 11 | 11 | 11 | 10 | 13 | 14 | 17 | 14 | 12 | 12 | 2 |
| 525 | 11 | 11 | 12 | 13 | 11 | 10 | 12 | 12 | 11 | 13 | 15 | 16 | 12 | 7 |
| 527 | 13 | 14 | 12 | 11 | 9 | 10 | 11 | 11 | 11 | 12 | 13 | 13 | 12 | 14 |
| 528 | 12 | 14 | 11 | 11 | 10 | 6 | 6 | 7 | 13 | 15 | 12 | 13 | 11 | 3 |
| 530 | 23 | 25 | 22 | 19 | 17 | 11 | 12 | 12 | 14 | 16 | 20 | 18 | 17 | 10 |
| 531 | 7 | 5 | 6 | 4 | 4 | 4 | 4 | 4 | 4 | 6 | 7 | 8 | 5 | 4 |
| Table VII. Average specified wind speed (mph) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland: | ||||||||||||||
| 550 | 9 | 9 | 8 | 9 | 10 | 9 | 9 | 9 | 8 | 8 | 7 | 8 | 8 | 5 |
| 552 | 5 | 6 | 7 | 10 | 11 | 11 | 10 | 9 | 10 | 10 | 7 | 6 | 8 | 18 |
| 553 | 15 | 16 | 15 | 15 | 15 | 13 | 11 | 12 | 13 | 15 | 14 | 13 | 14 | 18 |
| 555 | 8 | 9 | 10 | 10 | 11 | 10 | 8 | 9 | 10 | 10 | 9 | 7 | 9 | 4 |
| 556 | 1 | 2 | 2 | 4 | 6 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 3 | 21 |
| 566 | 2 | 3 | 3 | 4 | 5 | 5 | 4 | 4 | 4 | 5 | 3 | 3 | 4 | 24 |
| 567 | 4 | 4 | 5 | 6 | 7 | 6 | 5 | 5 | 5 | 6 | 5 | 4 | 5 | 12 |
| 568 | 3 | 3 | 3 | 5 | 6 | 5 | 5 | 5 | 5 | 4 | 3 | 3 | 4 | 21 |
| 576 | 1 | 1 | 2 | 2 | 3 | 3 | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 13 |
In a discussion of the frequency distribution of various wind
speeds, Simpson
/
^
[
39
]
^
/
has pointed out that at a given locality the
frequency with which winds of different velocities occur is closely
associated with the type of pressure distribution characteristic of
the region, i.e., whether cyclonic or anticyclonic. He says:
“In one type the relative frequency increases as the velocity
decreases right down to calms; this type is associated with
anticyclonic pressure conditions. In the other
/
^
[
^
type
/
^
]
^
the
frequency increases as the wind decreases down to a certain
velocity after which the frequency decreases as the wind
decreases and calms may have a very small frequency; this type
is associated with cyclonic pressure distribution.”
This seems to be a reasonably useful method for classifying wind–
speed distributions at Arctic locations. It is not established,
however, that one is justified in assuming that a “cyclonic” type of
frequency distribution indicates a predominance of cyclonic curvature
to isobars over the region (or vice-versa).
Sverdrup
/
^
[
43
]
^
/
has performed the Simpson type of analysis upon
the wind data obtained at several coastal points on the Arctic Ocean
as well as upon those recorded from the
Maud
over the Ocean proper.
He found the “cyclonic type” of velocity distribution most frequent
over the Polar Sea during all seasons, with a tendency toward an
“anticyclonic type” at coastal locations, particularly during winter.
Sverdrup
/
^
[
^
loc. cit.
/
^
]
^
also found a good agreement between the type of
wind-speed distribution and the annual variation of pressure, i.e.,
the higher the barometric pressure the more nearly the frequency
distribution approaches the “anticyclonic type.” A similar analysis
of data from inland Arctic locations has not been performed, but (from
the high frequency of calms and low wind speeds) it can be deduced
that the anticyclonic type would greatly predominate during the colder
months.
Vertical Wind Distribution Within the Surface Layar
. - It has already
been pointed out that the existence of a surface temperature inversion
is characteristic of the Arctic during all seasons except over areas
with a continental type of climate during the warmer months. The
altitude and magnitude of the surface inversion varies systematically
with season, remaining fairly uniform during colder months and
becoming more variable during warmer months. A consideration of these
variations from place to place and from season to season is of consid–
erable importance to conclusions regarding the variations of winds
within the surface layers of the atmosphere over the Arctic. It is
for this reason that the relationships between the vertical temperature
structure of the surface layer of air and the local wind conditions
will be discussed in some detail.
It is a matter of common knowledge among meteorologists that
the atmospheric mixing rate (eddy conductivity) is small within a
surface inversion layer, and smallest when the temperature increase
within the inversion is greatest. A low inversion, therefore,
effectively “seals-off” the surface layer against frictional drag
by the atmospheric layer above the inversion. In other words, the
circulation below the surface inversion layer has a strong tendency
to act independently of the rest of the atmosphere. This circumstance
is one of the several reasons why it is so difficult to describe the
general Arctic surface circulation in broad regional terms. (See
page .)
The wind velocity near the surface depends partly upon the
transport of kinetic energy from above (which serves to move
the surface layer of air) and partly upon friction at the ground
(which serves to slow down the movement of air near the surface).
Assuming the friction at the ground to be constant, the lowest wind
velocities at the surface occur when a sharp surface temperature
inversion is present because it is under these conditions that the
transport of kinetic energy from above is least. By identical
reasoning it can be pointed out that the highest velocities at the
surface will occur when the surface inversion is weakest or entirely
absent. In the presence of a strong surface inversion the ratio
between the wind speed at the surface and that, say at 1500 feet, is
large. When the inversion is weak or non-existent, the ratio is
small
[
^
43
^
]
. This circumstance is clearly indicated by the following
data which show the vertical distribution of wind velocity as related
to altitude of the base of the inversion, and which have been averaged
by Sverdrup for a number of Arctic points
^
[
^
loc. Cit.
/
^
]
^
:
| Altitude of Base of Inversion | Zero to 330 feet | 330 to 660 feet | 660 to 980 feet | Greater than 980 feet |
| Altitude of wind Measurement (ft) | Wind speed (mph) | Wind Speed (mph) | Wind Speed (mph) | Wind Speed (mph) |
| 1970 | 23.7 | 25.3 | 29.1 | 28.4 |
| 1640 | 24.2 | 26.2 | 30.6 | 28.2 |
| 1310 | 25.1 | 25.9 | 30.2 | 27.3 |
| 980 | 25.9 | 26.9 | 29.5 | 27.5 |
| 660 | 25.9 | 25.9 | 25.9 | 24.2 |
| 330 | 22.1 | 20.1 | 22.8 | 21.3 |
| 20 | 10.5 | 13.2 | 13.4 | 15.7 |
Over the pack-ice, Sverdrup found large ratios in winter
between the velocities at 1,600 feet and those on the surface, the
maximum ratio thus coinciding with the presence of a low and sharp
temperature inversion which is characteristic of this season. During
spring and autumn he found the ratio to be small because in these
seasons the inversion lies higher and is less pronounced. A secondary
maximum in the ratio was found to occur in summer ^over^ the pack-ice
but not at the coast. The reason for the difference here is that over
the pack-ice in summer the surface temperature cannot depart much from
freezing, whereas the temperatures can rise well above freezing at the
coast with a consequent destruction of the surface inversion. (See
page .)
Details of the vertical structure of the surface wind field are
similar over the interior Arctic. The existence of exceedingly
strong surface temperature inversions during winter accounts for the
prevalence of calms at interior stations during this season, even
though winter is the period during which the arctic circulation reaches
its greatest intensity. Calms are much less frequent everywhere during
the warmer months when the inversion is either weak or absent.
Sverdrup
/
^
[
^
loc. cit.
/
^
]
^
has also shown that under inversion conditions
there is a clockwise turning of the wind with altitude. The lower
(or stronger) the temperature inversion, the greater the degree of
turning. When the base of the inversion is at an altitude of less than
330 feet his data show an average deviation of 26 degrees between the
direction of the wind at the surface and the direction observed at
330 feet. When the base of the inversion is at an altitude greater
than 1,000 feed, the average turning is only 4 degrees.
It should, perhaps, be pointed out here that the velocity
profiles described in this subsection are typical of conditions
found over more-or-less level surfaces and do not apply to conditions
as they occur within a “fallwind” or “katabatic” flow. This latter
phenomenon will be described in a subsequent section.
Local Influences on Surface Winds
. - No one can examine detailed
Arctic wind data from coastal and inland points without being
impressed by the fact that local surface wind speed and direction are
largely determined by exposure of the station (and wind instruments)
and by the location of the area with respect to land and water bodies
and to the regional orography. As an example of the influence of
exposure, Sverdrup
[
^
42
^
]
cites one case where a series of observations
made between 1900 and 1902 at a station on Kllesmere Island showed an
average wind speed of 11.2 mph, whereas a series of observations made
in the same area during the interval 1899 to 1900 gave an average
wind speed of only 2.1 mph. The reason for this marked difference
is that the winter lodgings were located in a more sheltered location
during the first year of observations than was the case during the
succeeding years. ^
figs. 35 and 36 here
^
At many coastal points, particularly along the costs of
Greenland and Iceland, the direction and speed of the surface winds
are so local in character that they may bear little or no relation–
ship to winds in the offing. In Iceland, the numerous fjords
indenting the west, north, and east sides of the island contribute
their quota of gorge and channel winds. Similarly, at many places
along coastal Greenland sheltering bluffs or the trend of fjords
largely determine the local wind directions. For example, there are
very few northerly and northwesterly winds at Godhavn, a fact which
is due to the location of the observing station on the shore below
the southerly bluffs of Disko Island. In the same manner, the wholly
different frequencies of north, northeast, and east winds at Godhavn
and Jakobshavn, stations quite near each other, are entirely the
result of different topographic influences. In contrast, at Jakobshavn
and Holsteinsborg, the latter a station much farther from Jakobshavn
than Godhavn, the distribution of wind directions is quite similar
because of a similarity in topographic features
/
^
[
42
]
^
/
.
Regional Influences on Surface Winds
. - All expeditions to the Ice
Cap region of Greenland have commented on the fact that the surface
winds ordinarily are directed from the interior toward the coast.
This wind regime is merely a large-scale example of a “gravitational”
or “katabatic” wind system. These downslope winds result from the
presence of the cold layer of stable air which forms over the Ice Cap
and which subsequently flows down the slopes of the Ice Cap under the
influence of gravity. The speed of the flow depends first upon the
steepness of the slope; secondly, upon the temperature (density)
contrast between the stable surface air and the warmer air above;
and, lastly, upon the pressure gradient between the inland ice and the
coast. Near the summits of the Ice Cap the winds are more variable,
since their direction and speed depend more upon the magnitude and
direction of the pressure gradient then upon the activity of the cold
air. These katabatic or downslope winds, while they are particularly
characteristic of the Greenland climate, are not limited to this
region. They are an important climatic feature in other Arctic regions
of diverse topography, such as along the coasts of northern Norway,
^
Spitzbergen,
^
at Wrangle Island, and in parts of Alaska. Winds of this character
can occur in any part of the Arctic where there is sufficient area
at high elevation to allow the accumulation and downslope flow of
air which is very cold relative to air in the free atmosphere at the
same elevation.
Williwaws
, also known as
Takus
or
kniks
, are a form
of this katabatic wind that occurs along parts of the Alaskan coast.
They are most frequently encountered
below
^
along
^
precipitous coastlines.
In many instances the cold air supply which initiates the fallwind
is of limited supply and, for this reason, williwaws are often of
short duration since they cease as soon as the cold air is exhausted.
The depth of the katabatic wind is seldom more than five or
six hundred feet, even along the Greenland Ice Cap. These winds
are strongest and deepest when the temperature contrast between the
coast and the interior is greatest. For this reason they tend to
present a maximum frequency in the morning hours and a minimum in
the afternoon, although there are local exceptions to this general
rule, particularly nearer the centers of origin of the winds (as in
the interior of the Ice Cap). They are also somewhat stronger on
clear days than on cloudy days when interior temperatures are above
average. In contrast to the vertical distribution of wind speeds in
other types of Arctic wind systems (see page ), the maximum wind
speeds are found near the surface, i.e., winds are stronger below the
surface inversion than above.
Another regional factor affecting the wind regime along Arctic
coasts is exactly opposite in both cause and effect to the fallwinds
just described. In this case the wind is directed inland from a
relatively cool ocean toward a heated continental interior. This
phase of a monsoonal (seasonal reversal of circulation) wind regime
occurs during summer, as would be expected, and is well-developed on
a fairly large scale in portions of Siberia and Alaska. This component
of the surface wind is seldom very great and at no times do the wind
speeds approach the extreme values found in the katabatic flow. Thermal
lows develop during the warmest months in the interiors of Siberia and
Alaska, replacing winter anticyclones in each case. This substitution
results in a tendency toward a reversal of the circulation between
winter and summer. Actually there are few localities where a complete
180-degree reversal of the circulation takes place between the seasons.
In most cases the effect is merely one of several factors which
influence the circulation and may only serve to deviate the wind
slightly from the direction which would prevail were there no marked
temperature contrasts between land and sea.
Diurnal Variation of Wind
. - The land- and sea-breeze effect is
seldom as well-developed in Arctic regions as in more southerly
latitudes — largely because there is no important diurnal variation
in surface heating and cooling. Nevertheless there is a tendency
toward a diurnal reversal in wind direction along Arctic coasts
during warmer months, particularly when pressure gradients are weak.
For example, in some parts of Greenland there is a tendency during
summer for winds to blow inward along the fjords during daytime and
outward during the night
^
[
42
]
^
.
The wind speed at most Arctic stations also shows a diurnal
variation, both inland and at the coast. At locations surrounded
by moderate elevations the chan
^
g
^
es in wind speed are directly related
to changes in stability, i.e., velocities are least during night hours
when stability is greatest and greatest during afternoon hours when
surface heating is at a maximum. Along the Arctic coast, Sverdrup
^
[
43
]
^
found that the maximum wind speeds occur generally between 1200h
and 1400h and the minima between 0400h and 0600h. The diurnal variation
over the pack-ice is similar but of smaller magnitude, as would be
expected from the smaller diurnal range in stability. (See Fig
^
37
^
.) ^
fig. 37 here
^
A diurnal period in the wind is also noticeable at higher
altitudes and on slopes (as along the Greenland Ice Cap) but in
these cases the phase is reversed, i.e., the minimum wind speeds
occur during the afternoon and the maximum speeds during night or
early morning hours. This type of diurnal variation in the case of
slope stations is related to the nighttime augmentation of the
katabatic-type flow through radiational cooling in the interior. At
locations on mountain ridges or peaks, a similar diurnal variation
takes place, but in these cases the cause is the lessened frictional
drag at the higher wind levels, lowered by increased stability at
the surface.
Annual Variation of wind speed
. - Most of the factors involved in the
annual variation of winds over the Arctic have, of necessity, been
discussed in preceding paragraphs. All that remains is to describe
the more important factors affecting the seasonal variations of wind
speed as they apply to various types of Arctic topographies.
Wind speeds nearly everywhere along Arctic coasts and over the
polar sea are lowest during summer. At this time pressure gradients
are weakest because of the weakening of thermal contrasts between
high and middle latitudes and between continents and seas. However,
at locations within the continental interiors, winter is the period of
low wind speeds for the reasons that have already been pointed out on
page . The maximum wind speeds at interior stations tend to occur
in late spring or early summer (see data for Yakutsk and Verkhoyansk
in Table
^
VII
^
), but, again, there are local exceptions. Elsewhere the
maximum wind speeds tend to occur during late autumn or winter at
times of maximum cyclonic activity.
UPPER-AIR WINDS
It was pointed out in the section on upper-air pressures that the
Arctic anticyclones are relatively shallow phenomena, and hence there
is a tendency for the direction of the pressure gradient aloft to reverse
itself at comparatively low altitudes. (Compare Figures
^
29
^
to
^
32
^
and
^
33
^
to
^
34
^
.) Pilot balloon observations over the Arctic Basin have, in
all cases, confirmed this tendency toward reversal. Sverdrup
^
[
43
]
^
has
shown that the predominance of easterly winds at the surface is confined
largely to the levels below 10,000 feet, and that they are replaced by
prevailing westerly winds at higher altitudes above the region of his
observations. This general turning of the wind to a westerly direction
is dynamically in accordance with the observed fact that the average
temperature within the
^
lower atmospheric
^
layer
^
s
^
of the west winds
decreases toward the
north from the region represented by the upper-air soundings. It is
admitted, however, that the average wind aloft over other portions of
the Arctic may be from directions other than westerly. (See Fig.
^
39
^
.)
Variation of Wind with Altitude
. — Some aspects of the vertical
distribution of winds in the lower layers of the Arctic atmosphere have
already been discussed in the section on surface winds. It was pointed
out that there exists a strong tendency for a clockwise turning of the
wind direction from the ground upward through a sharp surface temperature
inversion. The data show, however, that this turning is largely confined
to the lowest five or six hundred feet of the atmosphere. In the region
of Sverdrup’s observations
^
[
43
]
^
, it is found that for surface wind
directions of east, southeast, or south, a much less rapid clockwise
turning of the wind continues above the surface inversion layer. For
all other surface winds, the direction of turning is counterclockwise.
A very rapid turning between 26,000 and 30,000 feet is noted by Sverdrup
in the data which correspond to surface wind directions from southwest
(through west) to northeast. He concludes that this accelerated turning
marks the transition from a tropospheric to a stratospheric circulation.
These results, however, cannot in any way be taken as representative
of average conditions over the entire Arctic. The degree and direction
of turning is locally dependent upon the average direction and magnitude
of the pressure gradient at all altitudes above the area represented by
vertical soundings. These qualities of the pressure gradients aloft in
the Arctic will be shown to be more complex than is the case in the region
of the lower-latitude westerlies.
The wind speeds over the Arctic normally increase from the surface
upward to a level at or below the base of the stratosphere (tropopause)
above which they may decrease in intensity. The tendency for the height
of maximum wind speed to occur at or near the tropopause is clearly
illustrated by the following data from the
Maud
pilot balloon ascents
^
[
43
]
^
:
| Altitude of Tropopause (feet) | 26,200 | 29,500 | 32,800 | 36,100 | 39,400 | 42,600 | 45,900 |
| Altitude of Wind Maximum (feet) | 26,200 | 28,500 | 30,500 | 32,800 | 34,800 | 37,100 | 39,400 |
Observations obtained during the
Canadian
^
Wordie
^
Expedition of 1937 to northwest
Greenland and the Canadian Arctic
^
[
8
]
^
indicate further that the height
of the level of maximum wind speed and the height of the tropopause both
vary directly with surface pressure — a condition which is merely
another reflection of the well-know meteorological fact that the
stratosphere is lower over cyclone centers than over anticyclones. The
expeditionary data show that the altitude of the level of maximum wind
speed varies from about 26,000 feet to 37,000 feet, averaging about
10,000 feet lower in winter than in summer. The latter finding, again,
is in line with present knowledge concerning the annual variation of
the tropopause height. (See pages to .)
In contrast to conditions in the westerlies, where the wind speeds
tend to increase with altitude throughout the troposphere, the easterly
winds of the Arctic Basin are strongest near the ground and, on the
average, decrease to their minima between 10,000 and 13,000 feet. As a
measure of the great degree of independence between the surface anti–
cyclonic circulation and the westerly circulation at higher altitudes,
Sverdrup
^
[
43
]
^
noted that, in many cases, the transition from easterly
to westerly winds was very sharp, almost as if the pilot balloon had
passed through a marked front. It thus appears that a characteristic
boundary surface is present over the Arctic, and that it exists at an
average altitude of between 10,000 and 13,000 feet.
This systematic change with altitude of the
average
wind is well
illustrated by the following data from the
Maud
Expedition
^
[
43
]
^
:
| Level (feet) | 0 | 3,300 | 6,600 | 13,100 | 19,700 |
| Wind resultant from: | s88° E. | s36° E. | s16° E. | s66° W. | s89° W. |
| Resultant velocity (mph) | 2.0 | 4.0 | 3.4 | 4.3 | 6.0 |
Regional and Seasonal Differences in Upper Winds
. — The January and
July distributions of streamlines and the mean vector winds over Arctic
and temperate latitudes at the 10,000- and 20,000-foot levels are shown
by Figures
^
38
^
to
^
41
^
. In addition, the several available wind roses
which apply to the 40,000-foot level are entered on the 20,000-foot ^
figs. 38 to 41 here
^
charts.
These charts show that much of the westerly zonal flow characteristic
of the wind field at lower latitudes is lost within the Arctic where
closed circulations exist in the
mean
flow — circulations which are
assymmetrical with respect to the pole. This circumstance is to be
interpreted as meaning that the upper-air wind field is considerably
more complex over the Arctic than over temperate regions.
The average upper winds north of the Arctic Circle are weaker than
are the midlatitude westerlies. At 10,000 fact, for example, the resultant
winds in the Arctic average about 20 knots compared to averages of 25 to 30
knots in midlatitudes. In the lower latitudes the westerly winds increase
with height throughout the troposphere, with average velocities at 40,000
feet probably exceeding 100 knots in some areas in winter. In the Arctic
the increase in the wind velocity with height is less rapid and, as has
already been shown, winds reach their maximum velocity (of about 30 knots) at
around 30,000 feet.
The mean wind velocities show little seasonal variation at the higher
altitudes. For this reason the differences between the mean upper winds
over the Arctic and those over midlatitudes are small in summer and large
in winter. However, in this connection, it should be pointed out that the
“mean wind” values, whether scaled from upper-level pressure charts or
computed from upper-air soundings, do not have the same meaning as those
for “average wind speed.” The former are vector quantities and the fact
the mean wind is of low velocity may merely signify that the wind directions
and speeds are highly variable from day to day and tend to cancel one another.
A more representative picture of the regional differences in the upper
winds is obtained through an examination of the frequency distributions
of wind directions and speeds at individual weather stations. This is
at least true within the limits of reliability of the observational
samples and the adequacy of areal coverage.
^
figs. 42 and 43 here
^
Unfortunately, upper-air wind data over the Arctic are very scanty
and probably not too representative. A large fraction of the data has
been obtained from pilot balloon soundings which must, of necessity, have
been carried out during intervals of favorable weather. In portions of
the Arctic, winds from one direction tend to bring the clearest skins and,
as a consequence, the winds-aloft data obtained during such situations may
extend to high altitudes. Winds from other quadrants may more often be
associated with low cloudiness, blowing snow, or other visibility-reducing
factors and observations will be limited in number and altitude. For
these reasons, the upper-air data obtained from pilot balloon soundings
tend to be heavily weighted by “fair weather” situations. These facts
should be kept in mind when making seasonal and regional comparisons of
the wind-rose data shown on Figures
^
38
^
to
^
43
^
.
The most outstanding feature of the upper-air winds over the Arctic,
as shown by the wind roses, is their extreme day-to-day variability. It
is for this reason that the
mean
flow picture described in the preceding
paragraphs has a minimum of practical significance. Aerial reconnaissance
over the Arctic Basin has shown that the Arctic is subject to the incursion
of well-developed cyclones and migratory anticyclones, and is not a region
of continuously weak circulation as might be inferred from the streamline
pattern which describes the mean flow.
Nevertheless, the maximum wind speeds observed in the Arctic seldom
equal those which are commonly observed in the lower-latitude westerlies.
North of the 70th parallel, wind speeds exceeding 100 knots are rare at
any altitude although the U. S. Air Force reconnaissance flights over
the Arctic have recorded 65-knot winds at the Pole at an altitude of
15,000 feet and 80-knot winds within 5 degrees of the Pole at approxi–
mately the same altitude (January 9, 1949)
^
[
49
]
^
.
The greatest variability in the winds occurs nearly everwhere in
the Arctic during summer when the upper-level circulation is weakest.
Conversely, the winds exhibit their maximum directional constancy during
winter.
Because of the great regional and seasonal variabilities in the
upper-wind frequencies over the Arctic, not further attempt will be made
here to describe the detail that is shown by the various station wind
roses. It should be noted that most of the summarized data apply to the
land areas, and even here they represent only the relatively lower altitudes.
These latter two limitations introduce the further complication of orographic
distortion of the pattern of wind frequencies. This distortion will be most
noticeable in the wind roses presented for stations in Greenland and Alaska,
where the elevated Ice Cap and interior high mountains, respectively, affect
the regional wind fields well above the 10,000-foot level.
AIR TEMPERATURE
It has been shown previously that during most of the year the
Arctic is covered by a shallow layer of cold air which, because of
its great stability, is effectively isolated from the atmosphere
above. As a result, the air temperature is largely determined by
to local temperature of the ice, land, or snow surface. Over the
ice pack of the Arctic Ocean the local temperature of the ice is
primarily dependent upon the loss or gain of heat by radiation, upon
conduction of heat from the atmosphere, and upon the transport of
heat through the ice from the warm water below. Variations in
temperature caused by the transport of air from other regions occur
in every season, but the temperature at the ice surface is very
conservative and always tends to return to the equilibrium temperature
locally appropriate to the season. This tendency is particularly
pronounced over the Arctic Ocean in summer when the ice is melting.
During this season the air temperature seldom deviates far from the
freezing point, even near the coast where temperatures over the land
may be considerably higher.
Over the land areas of the Arctic conditions are somewhat
different. During the colder months the cold layer may become
thicker than over the ocean; particularly at the bases of mountain
ranges where the surface “pool” of cold air is augmented by cold
air drainage from higher elevations. At times of strong winds the
surface air may become mixed to considerable altitudes, and, because
the transport of heat downward from the upper layers may be relatively
large, the temperature of the surface becomes a less dominating factor
than over the Arctic Ocean. During summer months the air temperature
over land may rise considerably above freezing because of the general
absence of a moderating snow cover and the effects of extended insolation
received during the long summer days of the Arctic.
A very common misconception of the Arctic is that it is a
region of eternal ice and snow and an area of continual intense
cold. Greenland is a land possessing these qualities over much of
its surface, but the analogy has been incorrectly drawn when
Greenland is taken as typical of all Arctic regions. Greenland
consists almost entirely of a high plateau with occasional peaks
extending above 10,000 feet. Because of the high elevation and
relatively heavy precipitation, it is largely covered by ice. In
general, however, most Arctic lands possess neither of these
characteristics, and over much of the area the scanty snows melt
rapidly with the approach of summer.
Moreover, the North Pole is not the coldest part of the
Northern Hemisphere. On the basis of separate considerations of
loss of heat by radiation from the ice and the amount of heat
conducted through the ice from below, (Sverdrup
^
[
43
]
)
^
has computed
that the most probable absolute minimum temperature over the pack-ice
is between the limits −58° and −62° F. It should be pointed out,
however, that the computations are based upon ice thicknesses
observed by Sverdrup and would not apply where the ice characteristics
depart markedly from those observed by him. On the
Maud
Expedition
(1918-1925) Sverdrup nowhere encountered temperatures below −46° F.
over the pack-ice, although Mohn
^
[
28
]
^
reports a minimum of −62° F.
recorded by the
Fram
, March 1894, at latitude 79°48′ N., longitude
135° E.
Even though it is to be expected that coastal stations would
exhibit lower minima than should occur over the ocean areas, there
are ^several^ Arctic coastal stations that have never recorded temperatures
below −52° F. (Herschel Island, for example). This evidence indicates
that it is unlikely ^that^ temperatures near the Pole ever fall very
much below −60° F.
In contrast to conditions over the Arctic Ocean, temperatures
over the continental portions of the Arctic may fall below −80° F.
during winter, and even regions well beyond the confines of the Arctic
may experience temperatures well below −60° F. The lowest official
temperature on record for North America, −81° F., occurred at Snag
Airport, Yukon Territory, February 3, 1947. There are points in the
United States (as at Havre, Montana) that have recorded temperatures
as low as −68° F. — eight degrees lower than is probably near the
Pole.
The lowest temperature ever observed at the surface of the earth
is −93.6° F. (−69.8° C.), recorded prior to 1920 at Verkhoyansk,
Siberia, well over 1,500 miles from the geographic pole
[
^
54
^
]
. For
many years this station enjoyed the distinction of recording the
coldest winter weather of the globe, and the Verkhoyansk region came
to be known as the “Cold Pole of the Earth.” We now have reason to
believe, however, that temperatures at high elevations within the Ant–
arctic Continent are probably lower than any at the surface in the
Northern Hemisphere and that the true “Cold Pole” will be found some–
where near the South Pole.
In 1929 a meteorological station was inaugurated in the Oimekon
River district of Siberia, some 400 miles southeast of Verkhoyansk
and, from the brief climate record available, it is noted that the
winter temperatures have consistently averaged lower than those recorded
at Verkhoyansk during the same period. It is quite possible, therefore,
that this station may establish a new record low temperature for the
Northern Hemisphere.
It has been pointed out that the summer temperature in the pack–
ice never deviates much from the freezing point. In coastal waters
above-freezing summer temperatures are, therefore, found only within
ice-free areas, but even here the air temperature must remain near
freezing because the surface temperature of the water never rises
much above 32° and the air temperature seldom differs greatly from the
water temperature. Sverdrup’s observations show that warm air from
inland is often transported considerable distances from the coast,
but it is cooled so effectively in the lower layers by contact with
the ice or cold water that a strong temperature inversion is almost
immediately formed. During summer along the immediate coast relatively
high temperatures may be observed for short periods at times of
offshore winds, but when the wind reverses the temperature
s
^
^
almost
immediately falls to near 32°, confirming the conception that an abrupt
change in temperature at sea level takes place when one departs from
the coast.
^
figs. 44 and 45 here
^
During the three summer months the mean maximum temperatures over
the Arctic pack-ice, as recorded on the
Fram
and
Maud
, are as follows:
| June | July | August | |
| Fram | 37.0° F. | 37.0° F. | 36.3° F. |
| Maud | 37.0° F. | 37.2° F. | 36.5° F. |
The absolute maximum observed on the
Fram
expedition was 39.2° F.
(June 1896) and on the
Maud
expedition, 38.3° F. (June 1923).
^
tables VIII to XIII here
^
In contrast to summer conditions over the pack-ice, most coastal
stations regularly record temperatures above 50° F., and at some
stations temperatures as high as 85° F. have been observed. Even
higher temperatures are recorded at inland stations which are removed
from the moderating effects of water bodies. A maximum temperature of
100° F. has been recorded above the Arctic Circle, and there are a few
inland Arctic stations at lower altitudes that have not recorded
temperatures above 90°.
| Table ^ VIII ^. Absolute maximum temperature (°F.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 002 | .. | .. | .. | .. | 36 | 39 | 38 | 37 | 34 | .. | .. | .. | 39 | 1-3 |
| 003 | .. | .. | .. | .. | .. | 38 | 38 | 37 | 35 | .. | .. | .. | 38 | 1-3 |
| 004 | 38 | 39 | 44 | 40 | 49 | 54 | 59 | 59 | 49 | 48 | 41 | 40 | 59 | 7 |
| 006 | 35 | 29 | 29 | 22 | 33 | 40 | 43 | 42 | 41 | 33 | 31 | 32 | 43 | 5-6 |
| 007 | 31 | 29 | 24 | 27 | 32 | 41 | 46 | 49 | 41 | 33 | 31 | 32 | 49 | 5-6 |
| 008 | 14 | 32 | .. | .. | 28 | 34 | 36 | 33 | 27 | 2 | 10 | 21 | .. | 0-1 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 33 | 35 | 33 | 42 | 45 | 65 | 78 | 73 | 59 | 42 | 39 | 34 | 78 | 25-30 |
| 101 | 31 | 32 | 21 | 35 | 45 | 59 | 57 | 55 | 53 | 43 | 27 | 32 | 59 | 1 |
| 102 | 32 | 34 | 40 | 47 | 64 | 81 | 82 | 75 | 65 | 57 | 38 | 33 | 82 | 12-18 |
| 103 | 25 | 39 | 35 | 35 | 43 | 55 | 63 | 63 | 57 | 45 | 29 | 39 | 63 | 2 |
| 104 | 42 | 45 | 44 | 60 | 66 | 79 | 84 | 80 | 66 | 58 | 50 | 40 | 84 | 33-35 |
| 105 | 33 | 33 | 37 | 45 | 50 | 64 | 71 | 68 | 62 | 53 | 54 | 42 | 71 | 4-8 |
| 106 | 56 | 55 | 56 | 63 | 71 | 92 | 81 | 82 | 73 | 63 | 62 | 53 | 92 | 22-25 |
| Alaska, Inland: | ||||||||||||||
| 150 | 39 | 35 | 37 | 47 | 81 | 81 | 85 | 75 | 57 | 47 | 41 | 37 | 85 | 3-4 |
| 151 | 27 | 19 | 13 | 37 | 45 | 67 | 83 | 67 | 57 | 37 | 29 | 21 | 83 | 1-2 |
| 152 | 35 | 34 | 49 | 59 | 75 | 88 | 89 | 86 | 72 | 51 | 34 | 36 | 89 | 5-7 |
| 153 | 40 | 41 | 50 | 60 | 85 | 100 | 93 | 87 | 79 | 61 | 40 | 37 | 100 | 22-27 |
| 154 | 47 | 51 | 53 | 59 | 76 | 90 | 79 | 84 | 76 | 62 | 60 | 49 | 90 | 16-18 |
| 155 | 40 | 43 | 53 | 64 | 82 | 90 | 89 | 90 | 78 | 67 | 42 | 46 | 90 | 35-37 |
| 156 | 41 | 47 | 56 | 65 | 86 | 95 | 99 | 90 | 80 | 67 | 54 | 58 | 99 | 35 |
| 157 | 41 | 45 | 56 | 68 | 85 | 92 | 95 | 87 | 79 | 68 | 48 | 42 | 95 | 30-35 |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | 14 | 21 | 26 | 32 | 50 | 60 | 61 | 52 | 54 | 40 | 34 | 21 | 54 | 4-5 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular (cont.): | ||||||||||||||
| 211 | 28 | 36 | 27 | 34 | 51 | 63 | 75 | 64 | 56 | 44 | 23 | 34 | 75 | 10 |
| 213 | 9 | 26 | 40 | 26 | 41 | 60 | 68 | 63 | 49 | 37 | 32 | 15 | 68 | 6-8 |
| 214 | 23 | 38 | 23 | 25 | 39 | 48 | 65 | 62 | 51 | 41 | 31 | 17 | 65 | 5 |
| 216 | 10 | 11 | 20 | 33 | 47 | 72 | 78 | 71 | 58 | 42 | 24 | 14 | 78 | 15 |
| 221 | 12 | 4 | 15 | 31 | 39 | 63 | 75 | 68 | 55 | 39 | 28 | 14 | 75 | 16 |
| 222 | 26 | 30 | 22 | 27 | 43 | 61 | 77 | 70 | 55 | 39 | 31 | 27 | 77 | 5 |
| 223 | 30 | 31 | 34 | 39 | 44 | 65 | 73 | 67 | 55 | 41 | 32 | 29 | 73 | 8-10 |
| 225 | 34 | 24 | 25 | 38 | 44 | 60 | 70 | 67 | 55 | 42 | 36 | 34 | 70 | 4 |
| 226 | 48 | 53 | 43 | 42 | 55 | 69 | 70 | 66 | 62 | 56 | 52 | 36 | 70 | 7-8 |
| 227 | 34 | 33 | 35 | 36 | 42 | 58 | 63 | 58 | 49 | 40 | 34 | 32 | 63 | 5-8 |
| 228 | 39 | 31 | 41 | 62 | 87 | 88 | 96 | 87 | 84 | 62 | 45 | 34 | 96 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | 44 | 49 | 45 | 53 | 77 | 85 | 87 | 88 | 71 | 55 | 44 | 46 | 86 | 8 |
| 252 | 15 | 24 | 40 | 57 | 74 | 83 | 84 | 80 | 68 | 52 | 33 | 21 | 84 | 44 |
| 253 | 41 | 50 | 48 | 59 | 79 | 84 | 82 | 83 | 80 | 59 | 46 | 47 | 83 | 6 |
| 254 | 11 | 22 | 32 | 52 | 72 | 85 | 84 | 80 | 69 | 47 | 27 | 20 | 84 | 13 |
| 255 | 34 | 38 | 46 | 55 | 74 | 79 | 81 | 81 | 72 | 59 | 37 | 26 | 84 | 9 |
| 256 | 37 | 47 | 52 | 68 | 86 | 94 | 92 | 92 | 81 | 73 | 43 | 35 | 94 | 32 |
| 258 | 23 | 28 | 40 | 61 | 76 | 83 | 86 | 84 | 74 | 63 | 36 | 22 | 86 | 17 |
| 259 | 32 | 33 | 38 | 60 | 76 | 81 | 84 | 82 | 67 | 63 | 38 | 24 | 84 | 11 |
| 260 | 37 | 36 | 40 | 60 | 70 | 82 | 82 | 86 | 67 | 63 | 41 | 37 | 86 | … |
| 262 | 25 | 31 | 42 | 62 | 78 | 82 | 88 | 83 | 75 | 63 | 40 | 33 | 88 | 29 |
| 263 | 31 | 35 | 49 | 66 | 81 | 85 | 87 | 85 | 78 | 67 | 44 | 33 | 87 | 32 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | 37 | 37 | 35 | 37 | 41 | 59 | 59 | 55 | 45 | 41 | 39 | 35 | 59 | 2-3 |
| 304 | 50 | 50 | 48 | 50 | 55 | 63 | 68 | 64 | 61 | 51 | 52 | 47 | 68 | 30 |
| 305 | 55 | 49 | 53 | 47 | 63 | 71 | 71 | 61 | 53 | 51 | 59 | 55 | 71 | 4-5 |
| 306 | 45 | 50 | 48 | 44 | 56 | 61 | 64 | 59 | 59 | 63 | 48 | 49 | 64 | 5 |
| 307 | 34 | 41 | 36 | 45 | 53 | 66 | 69 | 59 | 50 | 47 | 35 | 38 | 69 | 5 |
| 308 | 48 | 41 | 47 | 45 | 49 | 60 | 63 | 54 | 62 | 47 | 52 | 40 | 63 | 12 |
| 309 | 53 | 47 | 50 | 48 | 57 | 63 | 63 | 62 | 60 | 51 | 47 | 47 | 63 | 13 |
| 310 | 45 | 41 | 45 | 41 | 49 | 61 | 63 | 65 | 49 | 39 | 39 | 39 | 65 | 2-3 |
| 311 | 41 | 40 | 43 | 50 | 56 | 65 | 74 | 59 | 52 | 44 | 38 | 38 | 74 | 6 |
| 312 | 49 | 51 | 49 | 51 | 67 | 73 | 71 | 71 | 63 | 57 | 59 | 47 | 73 | 6-7 |
| 313 | 55 | 51 | 45 | 43 | 55 | 69 | 63 | 59 | 61 | 57 | 47 | 49 | 69 | 4-5 |
| 314 | 61 | 51 | 58 | 62 | 64 | 69 | 76 | 71 | 69 | 65 | 56 | 55 | 76 | 30 |
| 315 | 43 | 45 | 45 | 57 | 61 | 71 | 69 | 63 | 71 | 53 | 45 | 41 | 71 | 4-5 |
| 316 | 29 | 45 | 37 | 39 | 47 | 65 | 61 | 55 | 61 | 31 | 35 | 39 | 65 | 1 |
| 317 | 46 | 50 | 46 | 49 | 61 | 69 | 73 | 68 | 66 | 55 | 56 | 49 | 73 | 10 |
| 318 | 54 | 58 | 60 | 59 | 68 | 72 | 74 | 71 | 69 | 67 | 64 | 60 | 74 | 30 |
| 319 | 49 | 47 | 49 | 53 | 57 | 69 | 65 | 63 | 61 | 59 | 55 | 49 | 69 | 1-2 |
| 320 | 52 | 48 | 44 | 50 | 62 | 68 | 64 | 62 | 62 | 58 | 57 | 54 | 68 | 10 |
| 321 | 39 | 51 | 43 | 55 | 61 | 63 | 65 | 63 | 59 | 55 | 45 | 43 | 65 | 4-5 |
| 331 | 49 | 50 | 51 | 59 | 63 | 66 | 72 | 67 | 63 | 58 | 52 | 52 | 72 | 14 |
| 334 | 49 | 50 | 49 | 56 | 64 | 70 | 75 | 79 | 65 | 59 | 53 | 50 | 79 | 56 |
| 337 | 48 | 47 | 53 | 65 | 70 | 83 | 71 | 67 | 62 | 58 | 49 | 48 | 83 | 4 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 351 | 6 | −9 | 4 | 10 | 16 | 23 | 27 | 22 | 17 | 8 | −2 | −3 | 27 | 1 |
| 361 | 45 | 50 | 49 | 66 | 67 | 75 | 83 | 74 | 70 | 60 | 51 | 48 | 83 | 16 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 35 | 32 | 33 | 33 | 41 | 50 | 51 | 53 | 45 | 53 | 45 | 39 | 53 | 10 |
| 401 | 33 | 31 | 32 | 31 | 32 | 46 | 53 | 45 | 41 | 35 | 33 | 31 | 53 | 1 |
| 406 | 45 | 50 | 48 | 60 | 73 | 83 | 86 | 83 | 68 | 56 | 50 | 47 | 86 | 49 |
| 407 | 42 | 42 | 41 | 50 | 68 | 81 | 80 | 74 | 70 | 54 | 45 | 44 | 81 | 10 |
| 408 | 42 | 41 | 46 | 56 | 69 | 78 | 76 | 77 | 61 | 53 | 44 | 42 | 78 | 55 |
| 412 | 49 | 49 | 51 | 64 | 74 | 80 | 85 | 79 | 71 | 65 | 52 | 51 | 85 | 55 |
| 414 | 44 | 46 | 46 | 57 | 66 | 79 | 82 | 76 | 67 | 57 | 50 | 46 | 82 | 55 |
| 415 | 45 | 41 | 46 | 58 | 83 | 86 | 90 | 85 | 67 | 56 | 44 | 42 | 90 | 38 |
| 417 | 35 | 34 | 34 | 36 | 54 | 61 | 67 | 68 | 54 | 46 | 38 | 36 | 68 | 6 |
| 420 | 48 | 50 | 55 | 70 | 76 | 84 | 87 | 81 | 74 | 66 | 55 | 51 | 87 | 55 |
| 421 | 50 | 54 | 64 | 70 | 84 | 98 | 91 | 86 | 75 | 68 | 55 | 50 | 98 | 50 |
| 424 | 47 | 43 | 53 | 67 | 77 | 84 | 88 | 64 | 74 | 59 | 49 | 46 | 88 | 44 |
| 425 | 41 | 42 | 50 | 64 | 81 | 88 | 90 | 94 | 73 | 63 | 51 | 44 | 94 | 44 |
| 426 | 42 | 43 | 55 | 72 | 86 | 94 | 97 | 93 | 85 | 69 | 56 | 46 | 97 | 157 |
| 428 | 41 | 39 | 54 | 67 | 83 | 90 | 94 | 89 | 77 | 65 | 60 | 39 | 94 | 95 |
| 429 | 37 | 36 | 44 | 69 | 80 | 88 | 87 | 86 | 74 | 59 | 45 | 38 | 88 | 33 |
| Europe, Inland: | ||||||||||||||
| 450 | 45 | 46 | 51 | 60 | 75 | 86 | 90 | 84 | 75 | 59 | 45 | 44 | 90 | 46 |
| 451 | 42 | 43 | 46 | 57 | 78 | 85 | 90 | 85 | 69 | 57 | 46 | 44 | 90 | 44 |
| 453 | 41 | 41 | 45 | 53 | 73 | 83 | 87 | 83 | 77 | 56 | 42 | 42 | 87 | 10 |
| 454 | 51 | 53 | 57 | 70 | 79 | 87 | 95 | 86 | 84 | 67 | 58 | 56 | 95 | 20 |
| 455 | 54 | 54 | 59 | 72 | 82 | 90 | 97 | 88 | 79 | 70 | 56 | 49 | 97 | 53 |
| 456 | 43 | 45 | 52 | 59 | 66 | 77 | 82 | 84 | 79 | 66 | 61 | 46 | 84 | 44 |
| 457 | 44 | 46 | 52 | 78 | 84 | 90 | 95 | 88 | 74 | 66 | 51 | 45 | 95 | 44 |
| 458 | 42 | 43 | 51 | 74 | 82 | 84 | 89 | 87 | 72 | 58 | 46 | 45 | 89 | 27 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 35 | 35 | 33 | 39 | 52 | 49 | 62 | 59 | 56 | 42 | 39 | 35 | 62 | 7-8 |
| 501 | 30 | 31 | 20 | 28 | 34 | 50 | 71 | 71 | 58 | 33 | 31 | 33 | 71 | 5-6 |
| 502 | 27 | 25 | 15 | 29 | 37 | 52 | 66 | 58 | 58 | 32 | 33 | 29 | 66 | 4-5 |
| 503 | 28 | 24 | 30 | 26 | 36 | 48 | 67 | 63 | 56 | 35 | 31 | 29 | 67 | 7-8 |
| 504 | 15 | 9 | 12 | 25 | 40 | 69 | 66 | 64 | 43 | 32 | 17 | 22 | 69 | 4 |
| 505 | 34 | 35 | 34 | 41 | 56 | 71 | 76 | 73 | 65 | 46 | 41 | 37 | 76 | 38 |
| 506 | 34 | 32 | 34 | 37 | 45 | 74 | 79 | 67 | 63 | 50 | 43 | 35 | 79 | 24 |
| 507 | 41 | 42 | 40 | 41 | 55 | 56 | 66 | 68 | 55 | 53 | 42 | 43 | 68 | 17 |
| 508 | 34 | 32 | 29 | 33 | 35 | 66 | 74 | 62 | 57 | 38 | 33 | 33 | 74 | 5 |
| 509 | 29 | 28 | 33 | 33 | 38 | 80 | 79 | 72 | 62 | 42 | 33 | 33 | 80 | 6-7 |
| 510 | 31 | 32 | 27 | 32 | 45 | 67 | 73 | 69 | 56 | 40 | 32 | 33 | 73 | 19 |
| 511 | 26 | 6 | −1 | 24 | 38 | 60 | 69 | 72 | 52 | 31 | 14 | 5 | 72 | 2 |
| 512 | 25 | 13 | 22 | 36 | 74 | 75 | 91 | 81 | 68 | 45 | 25 | 18 | 91 | 7 |
| 513 | −7 | 11 | 21 | 30 | 68 | 85 | 84 | 80 | 68 | 35 | 21 | 12 | 85 | 7 |
| 514 | 17 | 7 | 14 | 21 | 50 | 60 | 68 | 72 | 54 | 38 | 18 | 22 | 72 | 11 |
| 515 | 4 | −1 | 12 | 27 | 64 | 85 | 89 | 87 | 67 | 41 | 17 | 10 | 89 | 12 |
| 516 | 26 | 16 | 18 | 27 | 42 | 60 | 64 | 63 | 49 | 37 | 26 | 30 | 64 | 3 |
| 517 | 22 | 29 | 30 | 33 | 49 | 63 | 65 | 62 | 47 | 38 | 35 | 32 | 65 | 10 |
| 518 | 35 | 33 | 34 | 40 | 53 | 78 | 78 | 77 | 68 | 50 | 38 | 36 | 78 | 26 |
| 519 | 33 | 31 | 34 | 40 | 49 | 74 | 80 | 76 | 66 | 47 | 37 | 33 | 80 | 22 |
| 520 | 33 | 34 | 38 | 48 | 70 | 82 | 85 | 81 | 68 | 57 | 49 | 35 | 85 | 33 |
| 521 | 32 | 29 | 33 | 36 | 34 | 72 | 73 | 78 | 59 | 48 | 35 | 33 | 78 | 4 |
| 522 | 11 | 22 | 31 | 36 | 60 | 77 | 88 | 84 | 58 | 38 | 34 | 19 | 88 | 11 |
| 523 | 28 | 13 | 24 | 34 | 52 | 61 | 75 | 66 | 51 | 36 | 24 | 38 | 75 | 3 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: (cont.) | ||||||||||||||
| 524 | 33 | 31 | 30 | 32 | 38 | 63 | 75 | 77 | 58 | 50 | 36 | 30 | 77 | 4 |
| 525 | 43 | 39 | 35 | 38 | 45 | 59 | 67 | 58 | 55 | 44 | 43 | 36 | 67 | 7 |
| 526 | 34 | 35 | 38 | 40 | 65 | 77 | 82 | 80 | 67 | 53 | 38 | 32 | 82 | 12 |
| 527 | 34 | 35 | 35 | 42 | 46 | 70 | 75 | 71 | 62 | 46 | 41 | 34 | 75 | 15 |
| 529 | 37 | 35 | 37 | 39 | 46 | 64 | 73 | 61 | 58 | 50 | 44 | 40 | 73 | 4 |
| 530 | 35 | 31 | 30 | 37 | 52 | 66 | 74 | 69 | 55 | 47 | 36 | 34 | 74 | 7 |
| 531 | 35 | 36 | 35 | 47 | 54 | 68 | 77 | 68 | 59 | 53 | 33 | 28 | 77 | 4 |
| Asia, Inland; | ||||||||||||||
| 550 | 26 | 26 | 35 | 44 | 53 | 76 | 85 | 83 | 68 | 40 | 43 | 31 | 85 | 4-5 |
| 551 | −3 | 16 | 18 | 35 | 48 | 81 | 84 | 78 | 69 | 39 | 15 | 19 | 84 | 3 |
| 552 | 24 | 14 | 28 | 43 | 58 | 85 | 86 | 83 | 67 | 48 | 23 | 23 | 86 | 18 |
| 553 | 30 | 28 | 34 | 38 | 52 | 79 | 85 | 77 | 66 | 47 | 34 | 35 | 85 | 14 |
| 554 | 27 | 24 | 31 | 41 | 50 | 76 | 83 | 84 | 66 | 48 | 32 | 29 | 84 | 17 |
| 556 | 2 | 14 | 38 | 52 | 71 | 94 | 93 | 88 | 72 | 48 | 33 | 32 | 94 | 33 |
| 558 | 8 | 17 | 30 | 42 | 74 | 94 | 92 | 85 | 67 | 51 | 24 | 9 | 94 | 13 |
| 559 | −11 | −10 | 30 | 37 | 64 | 91 | 86 | 87 | 66 | 49 | 20 | 6 | 91 | 3 |
| 560 | 30 | 32 | 46 | 58 | 77 | 84 | 86 | 84 | 76 | 64 | 39 | 36 | 86 | 10 |
| 561 | 32 | 33 | 44 | 61 | 82 | 88 | 92 | 87 | 81 | 63 | 38 | 35 | 92 | 9 |
| 562 | 32 | 32 | 41 | 60 | 81 | 85 | 90 | 85 | 77 | 62 | 38 | 35 | 92 | 9 |
| 563 | 29 | 33 | 49 | 54 | 71 | 84 | 91 | 86 | 74 | 56 | 38 | 32 | 91 | 46 |
| 565 | 24 | 34 | 53 | 62 | 72 | 95 | 103 | 88 | 83 | 62 | 32 | 24 | 103 | 13 |
| 566 | 26 | 35 | 48 | 57 | 85 | 92 | 95 | 92 | 80 | 59 | 39 | 30 | 95 | 23 |
| 567 | 21 | 30 | 41 | 60 | 78 | 93 | 96 | 93 | 78 | 64 | 34 | 22 | 96 | 25 |
| 568 | 16 | 15 | 40 | 55 | 82 | 90 | 100 | 92 | 78 | 58 | 35 | 26 | 100 | 33 |
| Table ^ VIII ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 570 | 10 | 23 | 40 | 59 | 70 | 86 | 99 | 89 | 77 | 59 | 26 | 5 | 99 | 17 |
| 571 | 14 | .. | 14 | 32 | 54 | .. | .. | 72 | 68 | 52 | 23 | 14 | .. | 0-1 |
| 572 | 37 | 35 | 38 | 46 | 58 | 82 | 84 | 80 | 70 | 47 | 40 | 34 | 84 | 21 |
| 573 | 37 | 35 | 47 | 76 | 89 | 90 | 95 | 91 | 81 | 60 | 44 | 37 | 95 | 21 |
| 574 | 37 | 41 | 52 | 69 | 86 | 95 | 96 | 91 | 79 | 66 | 47 | 37 | 96 | 37 |
| 576 | 28 | 31 | 51 | 60 | 79 | 91 | 100 | 96 | 79 | 58 | 35 | 32 | 100 | 25 |
| Table ^ IX ^. Absolute minimum temperature (°F.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 002 | −59 | −58 | −62 | .. | .. | .. | .. | .. | .. | .. | .. | −50 | −62 | 3 |
| 003 | −46 | −46 | −43 | .. | .. | .. | .. | .. | .. | .. | .. | −41 | −46 | 2 |
| 004 | 0 | −2 | −1 | 5 | 15 | 23 | 31 | 30 | 23 | 11 | 8 | −1 | −2 | 7 |
| 006 | −52 | −53 | −50 | −40 | −16 | 13 | 24 | 17 | 0 | −24 | −32 | −43 | −53 | 5-6 |
| 007 | −41 | −37 | −39 | −26 | −2 | 13 | 24 | 24 | 13 | −6 | −28 | −39 | −41 | 5-6 |
| 008 | −48 | −12 | .. | .. | 2 | 18 | 28 | 18 | −11 | −32 | −32 | −32 | .. | 0-1 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | −52 | −56 | −52 | −42 | −18 | 8 | 22 | 20 | 4 | −25 | −43 | −55 | −56 | 25-30 |
| 101 | −25 | −37 | −31 | −17 | −5 | 22 | 28 | 30 | 28 | 2 | −11 | −29 | −37 | 1 |
| 102 | −55 | −50 | −58 | −29 | −15 | 20 | 30 | 26 | 18 | −17 | −37 | −49 | −58 | 12-18 |
| 103 | −31 | −39 | −37 | −21 | −11 | 24 | 34 | 32 | 22 | 0 | −13 | −25 | −39 | 2 |
| 104 | −47 | −41 | −38 | −30 | −6 | 20 | 28 | 23 | 16 | −4 | −26 | −42 | −47 | 34-35 |
| 105 | −27 | −31 | −31 | −18 | 3 | 25 | 30 | 32 | 21 | 15 | 0 | −25 | −31 | 4-9 |
| 106 | −33 | −32 | −19 | −15 | 20 | 29 | 34 | 31 | 19 | −6 | −18 | −36 | −36 | 22-25 |
| Alaska, Inland: | ||||||||||||||
| 150 | −50 | −58 | −58 | −32 | −14 | 31 | 39 | 23 | 15 | −28 | −50 | −52 | −58 | 3-5 |
| 151 | −53 | −63 | −53 | −37 | −17 | 24 | 32 | 26 | 14 | −21 | −53 | −51 | −63 | 1-2 |
| 152 | −62 | −55 | −47 | −39 | −4 | 32 | 32 | 21 | −2 | −12 | −48 | −58 | −62 | 5-8 |
| 153 | −67 | −70 | −50 | −41 | −3 | 25 | 25 | 22 | 7 | −30 | −61 | −71 | −71 | 23-27 |
| 154 | −46 | −40 | −34 | −25 | 3 | 28 | 30 | 30 | 18 | −5 | −27 | −40 | −46 | 17-18 |
| 155 | −76 | −68 | −57 | −40 | −4 | 23 | 29 | 18 | 3 | −27 | −55 | −68 | −76 | 36-40 |
| 156 | −66 | −54 | −44 | −25 | 4 | 32 | 34 | 28 | 12 | −28 | −38 | −59 | −66 | 11 |
| 157 | −75 | −74 | −56 | −38 | 2 | 23 | 25 | 16 | 2 | −28 | −54 | −69 | −75 | 32-36 |
| Table ^ IX ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | −49 | −45 | −43 | −37 | −19 | 12 | 29 | 22 | 5 | −9 | −31 | −41 | −49 | 4-5 |
| 211 | −51 | −57 | −49 | −37 | −14 | 11 | 22 | 24 | 9 | −12 | −42 | −41 | −57 | 10 |
| 213 | −56 | −56 | −55 | −43 | −22 | 16 | 28 | 27 | 13 | −13 | −41 | −50 | −56 | 6-8 |
| 214 | −41 | −47 | −45 | −28 | −12 | 15 | 27 | 25 | 16 | −5 | −25 | −40 | −47 | 5 |
| 216 | −45 | −44 | −40 | −33 | −9 | 21 | 34 | 30 | 18 | −9 | −29 | −39 | −45 | 15 |
| 221 | −47 | −46 | −39 | −28 | −7 | 20 | 33 | 34 | 21 | −2 | −30 | −38 | −46 | 16 |
| 222 | −57 | −52 | −51 | −35 | −20 | 13 | 30 | 28 | 8 | −13 | −32 | −43 | −57 | 5 |
| 223 | −40 | −42 | −32 | −26 | −8 | 10 | 25 | 26 | 20 | 4 | −21 | −34 | −42 | 8-10 |
| 225 | −40 | −43 | −39 | −29 | −9 | 19 | 31 | 30 | 20 | −6 | −32 | −36 | −43 | 4 |
| 226 | −46 | −46 | −45 | −32 | −15 | 24 | 30 | 31 | 20 | 2 | −22 | −42 | −46 | 7-8 |
| 227 | −30 | −32 | −22 | −14 | 2 | 16 | 27 | 27 | 14 | −2 | −10 | −18 | −32 | 5-8 |
| 228 | −57 | −52 | −52 | −26 | −14 | 13 | 22 | 25 | 15 | −17 | −53 | −47 | −57 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | −56 | −56 | −50 | −44 | −14 | 20 | 30 | 29 | 12 | −22 | −50 | −54 | −56 | 8 |
| 252 | −52 | −45 | −34 | −9 | 21 | 32 | 36 | 30 | 18 | −1 | −30 | −43 | −52 | 44 |
| 253 | −60 | −57 | −31 | −14 | 19 | 28 | 29 | 17 | 20 | 1 | −43 | −54 | −60 | 6 |
| 254 | −54 | −51 | −44 | −28 | 8 | 31 | 35 | 27 | 15 | −13 | −41 | −52 | −54 | 13 |
| 255 | −44 | −42 | −29 | −5 | 22 | 34 | 37 | 30 | 23 | 7 | −29 | −37 | −44 | 9 |
| 256 | −65 | −64 | −50 | −45 | −11 | 22 | 26 | 18 | 4 | −27 | −47 | −64 | −65 | 32 |
| 258 | −49 | −44 | −34 | −14 | 22 | 33 | 39 | 32 | 24 | 2 | −24 | −41 | −49 | 17 |
| 259 | −46 | −44 | −37 | −16 | 15 | 28 | 41 | 35 | 25 | 3 | −25 | −42 | −46 | 11 |
| 260 | −53 | −55 | −40 | −23 | 4 | 31 | 44 | 38 | 19 | 3 | −30 | −41 | −55 | … |
| 262 | −51 | −46 | −40 | −18 | 16 | 28 | 34 | 28 | 20 | 0 | −25 | −45 | −51 | 29 |
| 263 | −54 | −50 | −36 | −9 | 19 | 28 | 35 | 30 | 19 | 3 | −28 | −45 | −54 | 32 |
| Table ^ IX ^. Absolute maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | −33 | −39 | −35 | −23 | −9 | 22 | 30 | 24 | 6 | −11 | −29 | −37 | −39 | 2-3 |
| 304 | −37 | −40 | −38 | −26 | 8 | 10 | 24 | 24 | 14 | 0 | −17 | −4 | −40 | 30 |
| 305 | −9 | −21 | −11 | 1 | 8 | 28 | 33 | 30 | 26 | 16 | −3 | −3 | −21 | 4-5 |
| 306 | −20 | −24 | −17 | −15 | 2 | 25 | 35 | 36 | 24 | 10 | 4 | −6 | −24 | 5 |
| 307 | −39 | −48 | −41 | −36 | −10 | 21 | 27 | 23 | 4 | −23 | −31 | −36 | −48 | 5 |
| 308 | −37 | −38 | −42 | −30 | 0 | 22 | 28 | 26 | 10 | −13 | −27 | −38 | −42 | 12 |
| 309 | −28 | −27 | −24 | −14 | 1 | 24 | 31 | 34 | 20 | 11 | −1 | −11 | −28 | 13 |
| 310 | −15 | −25 | −21 | −9 | 4 | 24 | 32 | 34 | 26 | 18 | −3 | 0 | −25 | 2-3 |
| 311 | −28 | −35 | −32 | −16 | 10 | 30 | 35 | 35 | 25 | −1 | −10 | −22 | −35 | 23 |
| 312 | −35 | −37 | −37 | −17 | 4 | 30 | 32 | 24 | 12 | −13 | −35 | −33 | −37 | 6-7 |
| 313 | −9 | −21 | −17 | −3 | 8 | 28 | 33 | 30 | 26 | 18 | −1 | 1 | −21 | 4-5 |
| 314 | −10 | −16 | −10 | −5 | 10 | 22 | 29 | 30 | 22 | 11 | 2 | −9 | −16 | 30 |
| 315 | 4 | −11 | 2 | 10 | 18 | 24 | 28 | 30 | 28 | 18 | 14 | 6 | −11 | 4-5 |
| 316 | 0 | −7 | −7 | 1 | 3 | 24 | 22 | 28 | 28 | 14 | 6 | 2 | −7 | 1 |
| 317 | −4 | −10 | −8 | −1 | 13 | 25 | 29 | 28 | 25 | 10 | 3 | −4 | −10 | 10 |
| 318 | −12 | −16 | −12 | −5 | 14 | 28 | 33 | 31 | 16 | 9 | 0 | −7 | −16 | 30 |
| 319 | 0 | −7 | 4 | 12 | 26 | 30 | 30 | 34 | 26 | 10 | 6 | −3 | −7 | 1-2 |
| 320 | 5 | 10 | 6 | 8 | 20 | 28 | 30 | 31 | 29 | 23 | 15 | 8 | 5 | 10 |
| 321 | 8 | 1 | 4 | 14 | 14 | 24 | 30 | 28 | 28 | 24 | 14 | 12 | 1 | 4-5 |
| 331 | 6 | 8 | 8 | 13 | 24 | 32 | 39 | 34 | 27 | 18 | 10 | 10 | 6 | 14 |
| 334 | −23 | −13 | −22 | −11 | 10 | 20 | 27 | 27 | 23 | 12 | 1 | −5 | −23 | 51 |
| 337 | 9 | 12 | 14 | 25 | 23 | 31 | 38 | 35 | 31 | 22 | 15 | 15 | 9 | 4 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 351 | −84 | −84 | −85 | −74 | −46 | −22 | −19 | −31 | −42 | −79 | −74 | −83 | −85 | 1 |
| 361 | −36 | −14 | −20 | −11 | 3 | 21 | 27 | 26 | 10 | 1 | −13 | −22 | −36 | 16 |
| Table ^ IX ^ . Absolute minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | −38 | −39 | −39 | −29 | −4 | 15 | 30 | 22 | 2 | −19 | −38 | −33 | −39 | 10 |
| 401 | −35 | −45 | −35 | −33 | −5 | 17 | 24 | 21 | −8 | −27 | −34 | −32 | −45 | 1 |
| 406 | 1 | −2 | −3 | 9 | 15 | 27 | 33 | 31 | 26 | 14 | 7 | 2 | −3 | 49 |
| 407 | −5 | −5 | −1 | 5 | 20 | 30 | 36 | 36 | 29 | 16 | 8 | −5 | −14 | 10 |
| 408 | −8 | −11 | −2 | 6 | 14 | 25 | 30 | 30 | 24 | 8 | 6 | −3 | −11 | 55 |
| 412 | 3 | −4 | 3 | 11 | 20 | 31 | 35 | 36 | 30 | 10 | 5 | −4 | −4 | 55 |
| 414 | 0 | −1 | 3 | 6 | 17 | 23 | 34 | 30 | 24 | 8 | 3 | 2 | −1 | 55 |
| 415 | −45 | −36 | −38 | −18 | 3 | 27 | 30 | 29 | 17 | −10 | −23 | −39 | −45 | 27 |
| 417 | −23 | −29 | −33 | −21 | −4 | 15 | 30 | 25 | 17 | 3 | −5 | −23 | −33 | 6 |
| 420 | 3 | 2 | 8 | 14 | 25 | 33 | 38 | 36 | 30 | 19 | 12 | 0 | 0 | 55 |
| 421 | −31 | −26 | −20 | 0 | 18 | 28 | 37 | 35 | 25 | 5 | −9 | −24 | −31 | 50 |
| 424 | −23 | −21 | −16 | 12 | 25 | 34 | 42 | 32 | 28 | 14 | −5 | −18 | −23 | 44 |
| 425 | −41 | −41 | −32 | −16 | 10 | 26 | 30 | 24 | 16 | −5 | −24 | −34 | −41 | 44 |
| 426 | −28 | −38 | −19 | 1 | 22 | 33 | 43 | 37 | 28 | 9 | 1 | −39 | −39 | 37 |
| 428 | −49 | −41 | −35 | −18 | 8 | 26 | 34 | 33 | 20 | −5 | −22 | −45 | −49 | 37 |
| 429 | −47 | −43 | −47 | −25 | 4 | 23 | 28 | 25 | 13 | −14 | −45 | −52 | −52 | 38 |
| Europe, Inland: | ||||||||||||||
| 450 | −50 | −50 | −44 | −25 | −7 | 22 | 30 | 25 | 9 | −18 | −33 | −44 | −50 | 46 |
| 451 | −59 | −59 | −46 | −34 | −6 | 23 | 27 | 19 | 3 | −27 | −43 | −52 | −59 | 44 |
| 453 | −43 | −43 | −34 | −23 | 0 | 25 | 30 | 28 | 16 | −9 | −21 | −37 | −43 | 10 |
| 454 | −8 | −15 | −10 | 6 | 14 | 31 | 35 | 35 | 27 | 9 | 1 | −10 | −15 | 20 |
| 455 | −26 | −27 | −24 | −6 | 14 | 28 | 34 | 33 | 23 | 0 | −16 | −29 | −29 | 53 |
| 456 | −45 | −49 | −36 | −17 | 0 | 23 | 28 | 25 | 19 | −8 | −29 | −40 | −49 | 44 |
| 457 | −37 | −35 | −25 | 2 | 18 | 29 | 38 | 32 | 20 | 6 | −12 | −35 | −37 | 44 |
| 458 | −36 | −37 | −25 | −12 | 10 | 25 | 33 | 31 | 20 | 2 | −13 | −32 | −37 | 27 |
| Table ^ IX ^ . Absolute minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | −33 | −30 | −31 | −26 | −3 | 13 | 23 | 26 | 11 | −4 | −20 | −29 | −33 | 7-8 |
| 501 | −55 | −46 | −48 | −39 | −15 | 15 | 25 | 24 | 16 | −17 | −48 | −46 | −55 | 5-6 |
| 502 | −53 | −50 | −49 | −41 | −13 | 11 | 28 | 26 | 14 | −23 | −37 | −45 | −53 | 4-5 |
| 503 | −50 | −45 | −44 | −43 | −14 | 10 | 26 | 23 | 2 | −21 | −39 | −46 | −50 | 7-8 |
| 504 | −46 | −44 | −43 | −35 | −18 | 19 | 27 | 25 | 16 | −5 | −24 | −41 | −46 | 4 |
| 505 | −42 | −39 | −47 | −25 | −10 | 1 | 14 | 30 | 9 | 0 | −29 | −32 | −47 | 37 |
| 506 | −45 | −40 | −43 | −30 | −11 | 13 | 24 | 22 | 18 | 4 | −22 | −37 | −45 | 24 |
| 507 | −38 | −39 | −41 | −28 | −10 | 13 | 25 | 27 | 7 | −12 | −23 | −41 | −41 | 17 |
| 508 | −52 | −54 | −43 | −32 | −10 | 11 | 26 | 28 | 14 | −6 | −38 | −43 | −54 | 5 |
| 509 | −60 | −49 | −45 | −32 | −10 | 12 | 28 | 27 | 14 | −20 | −40 | −46 | −60 | 6-7 |
| 510 | −52 | −55 | −46 | −35 | −13 | 6 | 27 | 26 | 11 | −18 | −39 | −49 | −55 | 19 |
| 511 | −54 | −64 | −54 | −35 | −17 | 9 | 31 | 29 | 10 | −21 | −40 | −57 | −64 | 2 |
| 512 | −54 | −57 | −47 | −30 | −14 | 18 | 29 | 27 | 18 | −27 | −49 | −50 | −57 | 7 |
| 513 | −63 | −60 | −52 | −39 | −19 | 20 | 31 | 27 | −1 | −34 | −50 | −58 | −63 | 5 |
| 514 | −54 | −48 | −42 | −37 | −15 | 11 | 26 | 24 | 12 | −16 | −40 | −46 | −54 | 11 |
| 515 | −63 | −61 | −55 | −49 | −22 | 11 | 30 | 23 | 2 | −30 | −47 | −58 | −63 | 12 |
| 516 | −46 | −41 | −42 | −25 | −10 | 22 | 28 | 28 | 19 | −12 | −30 | −40 | −46 | 3 |
| 517 | −43 | −43 | −50 | −34 | −13 | 14 | 23 | 24 | 6 | −10 | −28 | −34 | −50 | 10 |
| 518 | −47 | −46 | −44 | −33 | −12 | 5 | 25 | 24 | 14 | −7 | −28 | −43 | −47 | 26 |
| 519 | −50 | −58 | −47 | −32 | −15 | 10 | 23 | 25 | 18 | −16 | −39 | −51 | −58 | 22 |
| 520 | −63 | −65 | −53 | −28 | −14 | 20 | 33 | 30 | 15 | −18 | −53 | −61 | −65 | 18 |
| 521 | −55 | −50 | −49 | −33 | −20 | 11 | 30 | 28 | 20 | −19 | −37 | −52 | −55 | 4 |
| 522 | −60 | −60 | −55 | −37 | −24 | 27 | 33 | 27 | 12 | −24 | −52 | −55 | −60 | 7 |
| 523 | −44 | −46 | −42 | −31 | −19 | 10 | 28 | 28 | 10 | −22 | −29 | −33 | −46 | 3 |
| Table ^ IX ^ . Absolute minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont): | ||||||||||||||
| 524 | −43 | −39 | −39 | −29 | −24 | 19 | 27 | 27 | 23 | −1 | −27 | −35 | −43 | 4 |
| 525 | −48 | −48 | −43 | −22 | −13 | 17 | 27 | 27 | 20 | −12 | −36 | −39 | −48 | 7 |
| 526 | −59 | −52 | −52 | −23 | −3 | 28 | 35 | 25 | 8 | −21 | −39 | −50 | −59 | 12 |
| 527 | −50 | −48 | −43 | −39 | −10 | 21 | 35 | 30 | 14 | −9 | −34 | −49 | −50 | 15 |
| 528 | −39 | −48 | −35 | −27 | −12 | 14 | 29 | 29 | 23 | 1 | −20 | −28 | −48 | 3 |
| 529 | −24 | −38 | −31 | −26 | −8 | 23 | 32 | 36 | 26 | 12 | −3 | −38 | −38 | 4 |
| 530 | −38 | −37 | −40 | −21 | −5 | 16 | 31 | 28 | 16 | 0 | −24 | −31 | −40 | 7 |
| 531 | −53 | −58 | −25 | −16 | 5 | 18 | 32 | 27 | 17 | −22 | −37 | −49 | −58 | 4 |
| Asia, Inland: | ||||||||||||||
| 550 | −72 | −65 | −54 | −37 | −14 | 19 | 34 | 29 | 8 | −30 | −60 | −57 | −72 | 4-5 |
| 551 | −61 | −66 | −60 | −42 | −18 | 8 | 32 | 31 | 7 | −29 | −49 | −56 | −66 | 3 |
| 552 | −72 | −75 | −61 | −43 | −10 | 17 | 30 | 25 | −4 | −36 | −59 | −72 | −75 | 12 |
| 553 | −63 | −62 | −52 | −39 | −17 | 11 | 31 | 22 | 4 | −24 | −53 | −55 | −63 | 14 |
| 554 | −70 | −67 | −56 | −39 | −25 | 8 | 31 | 29 | −4 | −29 | −54 | −64 | −70 | 17 |
| 556 | −90 | −94 | −77 | −66 | −30 | 19 | 28 | 18 | 2 | −48 | −72 | −84 | −94 | 33 |
| 558 | −71 | −72 | −61 | −42 | −16 | 22 | 33 | 24 | 9 | −30 | −53 | −72 | −72 | 9 |
| 559 | −66 | −67 | −54 | −41 | 0 | 28 | 35 | 20 | 7 | −30 | −46 | −55 | −67 | 3 |
| 560 | −55 | −44 | −48 | −17 | 1 | 25 | 38 | 32 | 18 | 12 | −41 | −57 | −57 | 10 |
| 561 | −49 | −41 | −39 | −14 | 5 | 29 | 34 | 30 | 20 | −21 | −42 | −52 | −52 | 9 |
| 562 | −60 | −56 | −47 | −27 | −9 | 22 | 39 | 28 | 13 | −20 | −57 | −67 | −67 | 18 |
| 563 | −75 | −78 | −63 | −39 | −16 | 20 | 29 | 22 | 5 | −46 | −68 | −78 | −78 | 13 |
| 565 | −75 | −70 | −56 | −37 | −11 | 17 | 31 | 21 | 2 | −39 | −60 | −74 | −75 | 13 |
| 566 | −76 | −72 | −50 | −31 | 3 | 28 | 36 | 28 | 13 | −26 | −59 | −69 | −76 | 23 |
| 567 | −76 | −68 | −58 | −34 | −9 | 28 | 32 | 21 | −3 | −32 | −60 | −72 | −76 | 11 |
| Table ^ IX ^ . Absolute minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont): | ||||||||||||||
| 568 | −81 | −84 | −56 | −39 | −1 | 24 | 36 | 27 | 13 | −31 | −64 | −76 | −84 | 33 |
| 570 | −76 | −76 | −56 | −31 | −3 | 26 | 34 | 26 | 11 | −34 | −60 | −73 | −76 | 17 |
| 571 | −51 | −56 | −54 | −34 | .. | .. | .. | .. | .. | 3 | −56 | −54 | .. | 0-1 |
| 572 | −75 | −72 | −57 | −40 | −14 | 23 | 27 | 22 | 4 | −34 | −61 | −65 | −75 | 17 |
| 573 | −51 | −36 | −40 | −8 | 6 | 30 | 39 | 32 | 21 | −4 | −40 | −49 | −51 | 16 |
| 574 | −65 | −58 | −46 | −20 | 4 | 30 | 39 | 32 | 8 | −16 | −49 | −60 | −65 | 34 |
| 576 | −66 | −63 | −49 | −30 | −5 | 23 | 31 | 23 | 4 | −29 | −49 | −59 | −66 | 26 |
| 577 | −72 | −66 | −54 | −32 | 7 | 26 | 30 | 22 | 7 | −33 | −53 | −72 | −72 | 9 |
| Table ^ X ^ . Mean temperature (°F.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 001 | −19 | −24 | −23 | −9 | 11 | 24 | 29 | 26 | 17 | 4 | −5 | .. | … | 0-1 |
| 002 | −32 | −32 | −23 | −9 | 12 | 29 | 32 | 29 | 16 | −7 | −20 | −26 | −3 | 2-3 |
| 003 | −27 | −22 | −23 | −7 | 10 | 29 | 32 | 31 | 21 | 6 | −12 | −21 | 1 | 2 |
| 004 | 23 | 22 | 21 | 25 | 30 | 36 | 41 | 42 | 38 | 32 | 27 | 24 | 30 | 11 |
| 005 | 15 | 12 | 12 | 18 | 28 | 35 | 40 | 39 | 35 | 29 | 21 | 19 | 25 | .. |
| 006 | −14 | −13 | −18 | −8 | 14 | 29 | 34 | 32 | 26 | 13 | −2 | −13 | 7 | 5-6 |
| 007 | −9 | −8 | −15 | −1 | 17 | 30 | 33 | 33 | 31 | 19 | 3 | −5 | 11 | 5-6 |
| 008 | −16 | 8 | .. | .. | 14 | 28 | 32 | 30 | 10 | −5 | −12 | −7 | … | 0-1 |
| Alaska, Coastal, and Insular: | ||||||||||||||
| 100 | −17 | −17 | −15 | 0 | 20 | 35 | 40 | 39 | 31 | 17 | 0 | −12 | 10 | 26-31 |
| 101 | −1 | −7 | −11 | 13 | 24 | 35 | 42 | 42 | 38 | 27 | 8 | 1 | 23 | 1 |
| 102 | −10 | −6 | −1 | 14 | 30 | 44 | 53 | 51 | 41 | 24 | 6 | −4 | 20 | 13-19 |
| 103 | −4 | −2 | −5 | 12 | 26 | 36 | 46 | 44 | 39 | 30 | 11 | 5 | 5 | 2 |
| 104 | 3 | 6 | 9 | 20 | 34 | 46 | 50 | 50 | 42 | 29 | 16 | 8 | 26 | 34-36 |
| 105 | 1 | 2 | 7 | 20 | 30 | 39 | 46 | 48 | 43 | 32 | 26 | 11 | 25 | 4-8 |
| 106 | 12 | 19 | 24 | 35 | 45 | 54 | 57 | 56 | 48 | 36 | 22 | 13 | 35 | 23-26 |
| Alaska, Inland: | ||||||||||||||
| 150 | −2 | −2 | −4 | 16 | 36 | 52 | 59 | 48 | 39 | 22 | 2 | −5 | 20 | 3-5 |
| 151 | −23 | −45 | −15 | −4 | 20 | 42 | 52 | 43 | 37 | 9 | −9 | −16 | 13 | 1-2 |
| 152 | −11 | −7 | 0 | 21 | 40 | 57 | 56 | 52 | 41 | 22 | 0 | −7 | 22 | 7-8 |
| 153 | −21 | −16 | 0 | 22 | 43 | 58 | 61 | 55 | 42 | 21 | −6 | −20 | 20 | 21-27 |
| 154 | 7 | 9 | 12 | 27 | 40 | 53 | 54 | 53 | 45 | 31 | 17 | 8 | 30 | 17-19 |
| 155 | −12 | −4 | 6 | 25 | 44 | 57 | 58 | 53 | 41 | 24 | 1 | −10 | 24 | 34-41 |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Alaska, Inland: (cont.) | ||||||||||||||
| 156 | −11 | −1 | 10 | 29 | 47 | 58 | 60 | 55 | 44 | 27 | 3 | −7 | 26 | 36-38 |
| 157 | −13 | −4 | 8 | 27 | 45 | 56 | 59 | 54 | 42 | 25 | 4 | −11 | 24 | 30-34 |
| Canada, Coastal and Insular: | ||||||||||||||
| 200 | −34 | −37 | −28 | −11 | 16 | 32 | 37 | 35 | 15 | −9 | −22 | −27 | −3 | 8 |
| 201 | −37 | −43 | −24 | −12 | 16 | 33 | 37 | 34 | 15 | −9 | −26 | −30 | −4 | 3 |
| 202 | −34 | −20 | −26 | −11 | 13 | 34 | 37 | 33 | 20 | −2 | −15 | −23 | 1 | 5 |
| 203 | −36 | −26 | −30 | −13 | 11 | 33 | 40 | 34 | 15 | −2 | −15 | −26 | −1 | 2 |
| 204 | −21 | −23 | −14 | −2 | 17 | 34 | 41 | 38 | 28 | 12 | −5 | −18 | 7 | 5 |
| 205 | −26 | −26 | −23 | −9 | 17 | 37 | 41 | 38 | 26 | 5 | −7 | −23 | 4 | 3 |
| 206 | −15 | −14 | −12 | 2 | 24 | 37 | 49 | 40 | 28 | 15 | −3 | −16 | 11 | 3 |
| 207 | −32 | −32 | −24 | −3 | 16 | 34 | 39 | 35 | 23 | 1 | −12 | −22 | 2 | 3 |
| 209 | −32 | −30 | −21 | −4 | 16 | 34 | 38 | 35 | 22 | 7 | −8 | −26 | 3 | 5 |
| 210 | −18 | −26 | −18 | −5 | 16 | 32 | 41 | 36 | 26 | 9 | −9 | −17 | 6 | 5 |
| 211 | −20 | −27 | −17 | −4 | 20 | 36 | 43 | 41 | 30 | 14 | −6 | −17 | 8 | 10 |
| 213 | −26 | −29 | −21 | −2 | 20 | 36 | 42 | 41 | 32 | 15 | −5 | −21 | 7 | 18 |
| 214 | −14 | −16 | −12 | −2 | 20 | 33 | 39 | 39 | 32 | 21 | 3 | −9 | 11 | 5 |
| 215 | −19 | −14 | −10 | 2 | 20 | 36 | 44 | 42 | 32 | 15 | −4 | −15 | 11 | 9 |
| 216 | −19 | −19 | −16 | 0 | 22 | 38 | 50 | 46 | 36 | 18 | −6 | −16 | 11 | 13 |
| 217 | −23 | −25 | −22 | −5 | 14 | 37 | 49 | 44 | 33 | 11 | −11 | −23 | 7 | 13 |
| 219 | −24 | −25 | −18 | 2 | 23 | 30 | 40 | 35 | 28 | 13 | −7 | 21 | 7 | 4 |
| 220 | −20 | −25 | −9 | 8 | 28 | 36 | 42 | 42 | 36 | 21 | 3 | −10 | 13 | 2 |
| 221 | −27 | −25 | −16 | 2 | 21 | 37 | 49 | 47 | 38 | 22 | −2 | −17 | 11 | 18 |
| 222 | −25 | −20 | −14 | 2 | 19 | 35 | 46 | 46 | 32 | 18 | 1 | −17 | 10 | 8 |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: (cont.) | ||||||||||||||
| 223 | −14 | −14 | −4 | 9 | 25 | 35 | 42 | 42 | 35 | 25 | 9 | −6 | 15 | 14 |
| 224 | −15 | −12 | −3 | 11 | 28 | 38 | 46 | 44 | 36 | 25 | 12 | −4 | 17 | 22 |
| 225 | −11 | −19 | −10 | 6 | 24 | 36 | 45 | 43 | 34 | 24 | 12 | −5 | 15 | 3 |
| 226 | −16 | −16 | −7 | 8 | 25 | 37 | 45 | 44 | 37 | 25 | 11 | −8 | 15 | 12 |
| 227 | −1 | −2 | 8 | 16 | 27 | 33 | 38 | 39 | 35 | 29 | 21 | 7 | 21 | 15 |
| 228 | −19 | −17 | −6 | 14 | 30 | 43 | 54 | 52 | 42 | 27 | 6 | −11 | 18 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | −19 | −16 | −10 | 9 | 31 | 49 | 56 | 50 | 38 | 20 | −4 | −17 | 16 | 20 |
| 251 | −21 | −15 | −7 | 10 | 34 | 53 | 58 | 53 | 39 | 19 | −7 | −16 | 17 | 28 |
| 252 | −21 | −12 | 4 | 29 | 46 | 57 | 60 | 55 | 42 | 26 | 1 | −14 | 23 | 41 |
| 253 | 8 | 13 | 22 | 33 | 46 | 55 | 56 | 54 | 46 | 36 | 14 | 7 | 32 | 6 |
| 254 | −24 | −19 | −10 | 14 | 38 | 54 | 59 | 56 | 40 | 21 | −6 | −20 | 17 | 31 |
| 255 | −4 | 3 | 16 | 33 | 46 | 55 | 58 | 55 | 46 | 34 | 7 | −4 | 29 | 9 |
| 256 | −19 | −13 | −2 | 19 | 41 | 55 | 59 | 54 | 42 | 25 | −1 | −15 | 20 | 30 |
| 257 | −19 | −13 | −2 | 19 | 41 | 55 | 59 | 54 | 42 | 25 | −1 | −15 | 20 | 31 |
| 258 | −18 | −11 | 1 | 26 | 45 | 56 | 62 | 57 | 46 | 29 | 4 | −12 | 24 | 42 |
| 259 | −16 | −10 | 0 | 23 | 40 | 50 | 59 | 57 | 46 | 32 | 9 | −7 | 24 | 45 |
| 260 | −13 | −13 | 1 | 21 | 38 | 54 | 61 | 58 | 45 | 34 | 8 | −9 | 24 | .. |
| 261 | −17 | −10 | −2 | 21 | 41 | 52 | 60 | 54 | 45 | 31 | 10 | −9 | 23 | 24 |
| 262 | −16 | −9 | 3 | 26 | 45 | 54 | 60 | 56 | 45 | 30 | 10 | −9 | 25 | 25 |
| 263 | −13 | −5 | 8 | 31 | 48 | 56 | 61 | 57 | 46 | 32 | 10 | −6 | 27 | 30 |
| Greenland, Iceland, Coastal and Insular: | ||||||||||||||
| 300 | −33 | −36 | −30 | −11 | 15 | 33 | 38 | 35 | 17 | −7 | −19 | −24 | −2 | .. |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland, Iceland, Coastal and Insular: (cont.) | ||||||||||||||
| 301 | −11 | −12 | −7 | 5 | .. | 35 | 39 | 38 | 28 | 13 | 2 | −11 | … | 5 |
| 302 | −7 | −12 | −10 | −1 | 22 | 35 | 41 | 38 | 27 | 15 | 5 | −9 | 12 | 3-4 |
| 303 | −7 | −17 | −8 | −3 | 19 | 34 | 40 | 36 | 25 | 6 | −5 | −6 | 9 | 2 |
| 304 | −4 | −6 | −1 | 10 | 27 | 37 | 43 | 42 | 35 | 25 | 16 | 6 | 19 | 30 |
| 305 | 19 | 14 | 18 | 23 | 33 | 40 | 45 | 43 | 38 | 32 | 25 | 23 | 30 | 4-5 |
| 306 | 7 | 8 | 13 | 20 | 33 | 42 | 49 | 46 | 37 | 29 | 22 | 18 | 27 | 5 |
| 307 | −4 | −6 | −7 | 3 | 21 | 35 | 39 | 38 | 30 | 13 | 6 | 0 | 14 | 15 |
| 308 | 1 | −2 | 2 | 10 | 24 | 35 | 40 | 38 | 32 | 19 | 9 | 4 | 18 | 5 |
| 309 | 11 | 7 | 12 | 20 | 33 | 42 | 46 | 45 | 39 | 29 | 23 | 18 | 27 | 13 |
| 310 | 13 | 3 | 6 | 13 | 27 | 38 | 42 | 42 | 36 | 27 | 20 | 17 | 24 | 2-3 |
| 311 | 3 | 3 | 10 | 19 | 36 | 44 | 48 | 48 | 39 | 27 | 18 | 9 | 25 | 23 |
| 312 | 4 | 2 | 4 | 16 | 36 | 49 | 50 | 46 | 37 | 24 | 13 | 8 | 24 | 6-7 |
| 313 | 18 | 12 | 12 | 20 | 32 | 41 | 44 | 43 | 38 | 30 | 25 | 21 | 28 | 4-5 |
| 314 | 16 | 16 | 21 | 27 | 37 | 42 | 47 | 46 | 40 | 31 | 24 | 19 | 31 | 30 |
| 315 | 23 | 21 | 24 | 28 | 35 | 41 | 45 | 45 | 40 | 33 | 27 | 27 | 25 | 4-5 |
| 316 | 13 | 16 | 18 | 22 | 27 | 38 | 42 | 39 | 40 | 22 | 21 | 20 | 26 | 1 |
| 317 | 18 | 16 | 19 | 25 | 34 | 41 | 45 | 43 | 38 | 30 | 23 | 20 | 29 | 36 |
| 318 | 19 | 20 | 24 | 32 | 41 | 46 | 50 | 48 | 42 | 35 | 27 | 22 | 34 | 30 |
| 319 | 25 | 24 | 27 | 31 | 39 | 45 | 45 | 46 | 40 | 33 | 27 | 25 | 35 | 1-2 |
| 320 | 22 | 23 | 26 | 31 | 37 | 41 | 43 | 42 | 39 | 35 | 29 | 25 | 33 | 37 |
| 321 | 25 | 24 | 27 | 30 | 36 | 41 | 44 | 44 | 41 | 35 | 30 | 27 | 34 | 4-5 |
| 330 | 34 | 35 | 35 | 36 | 43 | 49 | 52 | 51 | 45 | 38 | 35 | 35 | 41 | 17 |
| 331 | 32 | 33 | 35 | 39 | 44 | 49 | 52 | 51 | 46 | 39 | 35 | 33 | 41 | 14 |
| Table ^ X ^ . Mean temperature (°F.) (^cont^.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland, Iceland, Coastal and Insular: (cont.) | ||||||||||||||
| 334 | 28 | 27 | 26 | 26 | 35 | 42 | 45 | 45 | 42 | 36 | 31 | 29 | 35 | 21 |
| 336 | 30 | 30 | 31 | 36 | 43 | 49 | 52 | 51 | 46 | 37 | 33 | 33 | 39 | 10 |
| 337 | 32 | 33 | 36 | 40 | 45 | 49 | 52 | 51 | 48 | 40 | 36 | 35 | 41 | 11 |
| 340 | 33 | 33 | 33 | 36 | 42 | 48 | 51 | 50 | 46 | 39 | 36 | 34 | 40 | 18 |
| Greenland, Iceland, Inland: | ||||||||||||||
| 350 | −24 | −33 | .. | .. | .. | .. | .. | .. | 1 | −17 | −28 | −24 | … | 0-1 |
| 351 | −42 | −53 | −40 | −24 | −5 | 4 | 12 | 1 | −8 | −32 | −46 | −37 | −22 | 1 |
| 361 | 22 | 24 | 24 | 29 | 36 | 45 | 50 | 46 | 40 | 33 | 25 | 25 | 33 | 17 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 1 | 2 | 7 | 2 | 18 | 30 | 34 | 33 | 28 | 18 | 8 | 2 | 14 | 10 |
| 401 | −4 | −5 | −10 | −1 | 16 | 29 | 33 | 32 | 23 | 13 | 3 | −2 | 10 | 1 |
| 403 | 3 | 1 | 2 | 7 | 23 | 35 | 42 | 41 | 32 | 21 | 11 | 7 | 19 | 19 |
| 404 | 11 | 4 | 5 | 16 | 27 | 35 | 40 | 39 | 32 | 24 | 14 | 12 | 21 | 15 |
| 405 | 4 | −7 | −5 | 9 | 21 | 32 | 38 | 37 | 28 | 16 | 10 | 8 | 16 | 15 |
| 406 | 26 | 24 | 26 | 30 | 37 | 44 | 50 | 51 | 44 | 36 | 29 | 26 | 35 | 50 |
| 407 | 24 | 22 | 24 | 29 | 39 | 47 | 54 | 53 | 44 | 36 | 31 | 28 | 36 | 10 |
| 408 | 21 | 20 | 23 | 28 | 35 | 42 | 48 | 48 | 44 | 34 | 28 | 24 | 33 | 20 |
| 409 | 33 | 32 | 33 | 38 | 43 | 50 | 54 | 54 | 50 | 43 | 38 | 33 | 42 | 60 |
| 410 | 34 | 33 | 33 | 36 | 41 | 46 | 50 | 51 | 47 | 42 | 38 | 35 | 41 | 60 |
| 411 | 30 | 29 | 30 | 35 | 42 | 50 | 55 | 54 | 47 | 40 | 34 | 31 | 40 | 60 |
| 412 | 29 | 28 | 20 | 36 | 42 | 50 | 55 | 54 | 48 | 40 | 34 | 29 | 39 | 60 |
| 413 | 30 | 28 | 29 | 33 | 39 | 46 | 50 | 51 | 46 | 39 | 33 | 30 | 38 | 60 |
| 414 | 26 | 25 | 26 | 32 | 39 | 47 | 52 | 51 | 44 | 36 | 30 | 27 | 36 | 60 |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: (cont.) | ||||||||||||||
| 415 | 11 | 11 | 17 | 29 | 38 | 48 | 55 | 51 | 43 | 31 | 20 | 13 | 31 | 35 |
| 416 | 17 | 15 | 18 | 25 | 32 | 40 | 47 | 47 | 42 | 33 | 26 | 20 | 30 | 21 |
| 417 | 13 | 9 | 6 | 16 | 28 | 36 | 45 | 48 | 41 | 32 | 25 | 18 | 26 | 6 |
| 418 | −1 | 1 | 6 | 19 | 31 | 42 | 54 | 50 | 41 | 28 | 13 | 5 | 24 | 17 |
| 419 | 12 | 11 | 18 | 28 | 37 | 47 | 53 | 51 | 44 | 32 | 21 | 14 | 31 | 60 |
| 420 | 32 | 31 | 32 | 38 | 44 | 51 | 55 | 55 | 50 | 42 | 36 | 32 | 41 | 60 |
| 421 | 21 | 20 | 26 | 35 | 45 | 55 | 60 | 58 | 50 | 39 | 31 | 23 | 39 | 26 |
| 423 | 11 | 10 | 16 | 28 | 40 | 53 | 58 | 55 | 45 | 34 | 23 | 14 | 32 | 33 |
| 424 | 21 | 20 | 25 | 34 | 46 | 57 | 62 | 60 | 51 | 42 | 32 | 25 | 40 | 92 |
| 425 | 12 | 12 | 18 | 30 | 41 | 51 | 58 | 54 | 45 | 34 | 24 | 16 | 33 | 35 |
| 426 | 18 | 18 | 25 | 37 | 49 | 58 | 64 | 60 | 51 | 41 | 30 | 22 | 39 | 35 |
| 428 | 8 | 10 | 17 | 30 | 41 | 53 | 60 | 55 | 46 | 34 | 21 | 12 | 32 | 35 |
| 429 | 6 | 7 | 15 | 28 | 38 | 50 | 57 | 52 | 43 | 31 | 19 | 10 | 30 | 40 |
| Europe, Inland: | ||||||||||||||
| 450 | 5 | 6 | 12 | 24 | 36 | 49 | 54 | 50 | 41 | 27 | 16 | 8 | 27 | 22 |
| 451 | 4 | 5 | 12 | 25 | 37 | 49 | 55 | 51 | 42 | 28 | 14 | 5 | 27 | 60 |
| 453 | 12 | 7 | 16 | 27 | 40 | 52 | 58 | 53 | 42 | 30 | 22 | 18 | 31 | 30 |
| 454 | 26 | 28 | 32 | 39 | 46 | 52 | 58 | 55 | 48 | 40 | 32 | 28 | 40 | 20 |
| 455 | 20 | 21 | 27 | 37 | 48 | 59 | 61 | 58 | 49 | 39 | 30 | 22 | 40 | 29 |
| 456 | 9 | 9 | 17 | 29 | 41 | 51 | 55 | 51 | 43 | 31 | 22 | 12 | 31 | 20 |
| 457 | 16 | 15 | 24 | 35 | 47 | 56 | 63 | 58 | 49 | 37 | 28 | 21 | 37 | 20 |
| 459 | 3 | 8 | 19 | 33 | 46 | 56 | 62 | 56 | 45 | 31 | 18 | 7 | 32 | 35 |
| 460 | −1 | 4 | 13 | 27 | 26 | 49 | 58 | 53 | 43 | 29 | 14 | 4 | 28 | 35 |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 3 | 2 | −5 | 5 | 19 | 30 | 35 | 36 | 32 | 24 | 13 | 5 | 17 | 7-8 |
| 501 | −15 | −12 | −19 | −4 | 17 | 31 | 38 | 37 | 32 | 15 | −3 | −11 | 9 | 5-6 |
| 502 | −19 | −14 | −19 | −6 | 15 | 32 | 40 | 37 | 32 | 13 | −6 | −14 | 8 | 4-5 |
| 503 | −17 | −13 | −19 | −7 | 15 | 30 | 35 | 34 | 29 | 14 | −2 | −12 | 7 | 7-8 |
| 505 | 13 | 8 | 5 | 15 | 25 | 35 | 44 | 44 | 38 | 29 | 23 | 15 | 24 | 17 |
| 506 | 8 | 3 | 0 | 12 | 23 | 34 | 43 | 43 | 39 | 30 | 23 | 13 | 23 | 24 |
| 507 | 6 | 2 | −3 | 10 | 24 | 34 | 42 | 43 | 36 | 27 | 19 | 9 | 21 | 17 |
| 508 | −5 | −7 | −11 | 2 | 19 | 31 | 39 | 41 | 36 | 23 | 11 | 0 | 15 | 5 |
| 509 | −12 | −11 | −12 | 2 | 20 | 28 | 48 | 46 | 37 | 20 | 2 | −10 | 14 | 6-7 |
| 510 | −10 | −7 | −12 | 2 | 19 | 33 | 40 | 41 | 35 | 20 | 3 | −7 | 13 | 19 |
| 511 | −30 | −34 | −29 | −8 | 13 | 32 | 42 | 42 | 32 | 5 | −16 | −29 | 2 | 2 |
| 512 | −20 | −18 | −20 | −1 | 24 | 39 | 48 | 47 | 36 | 14 | −10 | −16 | 10 | 7 |
| 514 | −22 | −23 | −20 | −7 | 15 | 33 | 37 | 37 | 32 | 15 | −7 | −18 | 6 | 11 |
| 515 | −34 | −32 | −23 | −8 | 19 | 40 | 52 | 43 | 33 | 10 | −14 | −27 | 5 | 12 |
| 517 | −11 | −13 | −10 | 1 | 17 | 33 | 37 | 35 | 29 | 18 | 4 | −5 | 11 | 10 |
| 518 | 5 | 0 | −1 | 12 | 24 | 35 | 44 | 45 | 40 | 29 | 20 | 8 | 22 | 26 |
| 519 | −1 | −4 | −5 | 10 | 23 | 35 | 43 | 44 | 39 | 26 | 14 | 1 | 19 | 22 |
| 520 | −14 | −8 | 0 | 13 | 28 | 45 | 57 | 52 | 41 | 24 | 2 | −7 | 19 | 33 |
| 521 | −7 | −9 | −7 | 9 | 23 | 38 | 51 | 50 | 40 | 24 | 7 | −7 | 18 | 13 |
| 522 | −39 | −33 | −16 | 3 | 28 | 51 | 54 | 48 | 35 | 10 | −10 | 27 | 9 | 10 |
| 523 | −20 | −15 | −10 | −4 | 18 | 34 | 39 | 37 | 30 | 17 | −1 | −8 | 10 | 3 |
| 524 | −14 | −18 | −12 | 14 | 18 | 34 | 40 | 41 | 36 | 21 | 3 | −9 | 12 | 4 |
| 525 | −5 | −8 | −3 | 8 | 22 | 35 | 42 | 40 | 35 | 24 | 10 | 1 | 17 | 7 |
| Table ^ X ^ . Mean temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: (cont.) | ||||||||||||||
| 526 | −11 | −9 | 1 | 15 | 33 | 49 | 56 | 52 | 41 | 22 | 3 | −8 | 20 | 16 |
| 527 | −10 | −6 | −4 | 5 | 25 | 41 | 51 | 49 | 39 | 23 | 5 | −7 | 17 | 23 |
| 529 | 6 | 3 | 6 | 18 | 29 | 39 | 45 | 44 | 38 | 28 | 16 | 11 | 24 | 4 |
| 530 | 1 | −3 | 1 | 13 | 25 | 38 | 45 | 43 | 37 | 26 | 13 | 5 | 20 | 7 |
| 531 | −5 | −6 | 11 | 22 | 33 | 44 | 51 | 53 | 45 | 26 | 5 | −5 | 23 | 4 |
| Asia, Inland: | ||||||||||||||
| 550 | −22 | −13 | −14 | 5 | 22 | 42 | 54 | 48 | 38 | 13 | −11 | −18 | 12 | 4-5 |
| 551 | −28 | −22 | −20 | −5 | 22 | 39 | 54 | 48 | 35 | 13 | −12 | −16 | 9 | 3 |
| 553 | −14 | −10 | −9 | 4 | 21 | 40 | 54 | 49 | 39 | 20 | −3 | −13 | 15 | 14 |
| 556 | −58 | −48 | −24 | 9 | 36 | 56 | 60 | 52 | 36 | 6 | −34 | −51 | 3 | 38 |
| 557 | −49 | −34 | −20 | 7 | 29 | 50 | 53 | 50 | 38 | 9 | −22 | 40 | 6 | 3 |
| 559 | −40 | −32 | −17 | −9 | 34 | 55 | 58 | 50 | 39 | 14 | −18 | −34 | 10 | 10 |
| 560 | −10 | −4 | 6 | 22 | 35 | 50 | 60 | 53 | 42 | 28 | 4 | −8 | 23 | 9-10 |
| 563 | −18 | −10 | 2 | 15 | 31 | 48 | 61 | 55 | 41 | 20 | −4 | −17 | 19 | 46 |
| 565 | −33 | −21 | −3 | 21 | 41 | 60 | 67 | 58 | 42 | 21 | −11 | −31 | 18 | 13 |
| 566 | −32 | −19 | −1 | 23 | 43 | 60 | 67 | 58 | 44 | 23 | −6 | −26 | 20 | 25 |
| 567 | −38 | −24 | −4 | 18 | 40 | 59 | 65 | 58 | 42 | 17 | −15 | −35 | 15 | 25 |
| 568 | −46 | −33 | −9 | 17 | 41 | 60 | 66 | 59 | 43 | 17 | −20 | −40 | 13 | 77 |
| 569 | −21 | −19 | −13 | 5 | 21 | 42 | 47 | 42 | 33 | 12 | −12 | −14 | 10 | 1 |
| 570 | −44 | −31 | −8 | 25 | 41 | 58 | 65 | 58 | 44 | 19 | −11 | −34 | 15 | 17 |
| 572 | −20 | −14 | −10 | 5 | 28 | 50 | 57 | 50 | 37 | 17 | −4 | −15 | 15 | 25 |
| 576 | −23 | −14 | 1 | 21 | 39 | 56 | 63 | 55 | 41 | 21 | −3 | −18 | 20 | 33 |
| 577 | −14 | −9 | 3 | 24 | 43 | 57 | 62 | 55 | 40 | 23 | 1 | −20 | 22 | 9 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 004 | 27 | 27 | 25 | 28 | 32 | 38 | 43 | 44 | 39 | 33 | 28 | 26 | 33 | 7 |
| 006 | −5 | −6 | −13 | −1 | 18 | 32 | 36 | 35 | 29 | 19 | 4 | −5 | 12 | 5-6 |
| 007 | 1 | 0 | −8 | 4 | 20 | 32 | 35 | 36 | 33 | 22 | 8 | 3 | 15 | 5-6 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | −11 | −11 | −7 | 8 | 25 | 40 | 47 | 44 | 35 | 22 | 6 | −5 | 16 | 25-29 |
| 101 | 5 | −1 | −6 | 20 | 30 | 39 | 46 | 45 | 42 | 31 | 13 | 6 | 28 | 1 |
| 102 | −1 | 0 | 4 | 23 | 36 | 50 | 58 | 56 | 46 | 30 | 12 | 3 | 26 | 8-12 |
| 103 | 2 | 5 | 2 | 19 | 31 | 41 | 50 | 49 | 43 | 34 | 17 | 13 | 29 | 2 |
| 104 | 11 | 13 | 17 | 27 | 41 | 53 | 56 | 55 | 48 | 35 | 21 | 14 | 32 | 33-35 |
| 105 | 7 | 9 | 9 | 22 | 33 | 42 | 48 | 48 | 43 | 35 | 25 | 12 | 27 | 6-7 |
| 106 | 19 | 27 | 33 | 44 | 54 | 62 | 65 | 64 | 57 | 44 | 30 | 20 | .. | 22-25 |
| Alaska, Inland: | ||||||||||||||
| 150 | 6 | 6 | 8 | 26 | 45 | 62 | 69 | 57 | 46 | 29 | 11 | 2 | 28 | 3-4 |
| 151 | −16 | −18 | −7 | 8 | 28 | 50 | 63 | 51 | 39 | 17 | −2 | −11 | 21 | 1-2 |
| 152 | −2 | 1 | 14 | 35 | 51 | 70 | 67 | 63 | 51 | 30 | 8 | 1 | 32 | 6-7 |
| 153 | −11 | −6 | 13 | 35 | 56 | 70 | 72 | 66 | 52 | 28 | 2 | −11 | 30 | 19-21 |
| 154 | 16 | 17 | 22 | 36 | 50 | 63 | 63 | 61 | 53 | 38 | 24 | 15 | 38 | 16-18 |
| 155 | −4 | 5 | 18 | 36 | 56 | 70 | 71 | 65 | 51 | 31 | 8 | −2 | 34 | 33-38 |
| 156 | −2 | 5 | 22 | 42 | 58 | 70 | 71 | 64 | 53 | 35 | 12 | 0 | 36 | 11 |
| 157 | −6 | 6 | 21 | 40 | 58 | 70 | 72 | 67 | 52 | 34 | 11 | −3 | 35 | 26-32 |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | −13 | −16 | −6 | 8 | 25 | 39 | 48 | 42 | 32 | 16 | 0 | −12 | 14 | 7 |
| 205 | −20 | −19 | −16 | −1 | 24 | 43 | 48 | 43 | 32 | 10 | −1 | −18 | 10 | 3 |
| 206 | −9 | −7 | −6 | 9 | 30 | 43 | 56 | 45 | 32 | 19 | 4 | −11 | 17 | 3 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular (cont.): | ||||||||||||||
| 210 | −12 | −20 | −10 | 2 | 22 | 37 | 47 | 41 | 30 | 14 | −3 | −11 | 11 | 5 |
| 211 | −13 | −20 | −9 | 5 | 27 | 41 | 51 | 47 | 34 | 20 | −1 | −10 | 14 | 10 |
| 212 | −11 | −14 | −3 | 8 | 28 | 40 | 47 | 43 | 36 | 20 | 6 | −5 | 16 | 3-4 |
| 213 | −19 | −22 | −13 | 7 | 28 | 42 | 48 | 46 | 35 | 20 | 1 | −14 | 13 | 18 |
| 214 | −6 | −9 | −4 | 6 | 27 | 38 | 46 | 46 | 36 | 26 | 9 | −2 | 18 | 5 |
| 215 | −13 | −8 | −3 | 9 | 26 | 42 | 51 | 47 | 36 | 20 | 2 | −10 | 17 | 9 |
| 216 | −12 | −12 | −8 | 9 | 30 | 45 | 58 | 52 | 42 | 23 | 1 | −9 | 18 | 13 |
| 217 | −15 | −17 | −14 | 4 | 27 | 43 | 57 | 50 | 36 | 17 | −4 | −17 | 14 | 13 |
| 221 | −21 | −19 | −9 | 9 | 27 | 43 | 57 | 53 | 42 | 27 | 5 | −11 | 17 | 18 |
| 222 | −17 | −12 | −5 | 12 | 27 | 41 | 54 | 53 | 37 | 24 | 8 | −10 | 18 | 8 |
| 223 | −8 | −8 | 3 | 16 | 30 | 40 | 49 | 48 | 39 | 29 | 15 | 0 | 21 | 14 |
| 224 | −8 | −5 | 5 | 19 | 34 | 44 | 53 | 50 | 41 | 30 | 17 | 2 | 23 | 22 |
| 225 | −5 | −12 | −1 | 14 | 30 | 42 | 51 | 49 | 39 | 29 | 16 | 4 | 21 | 3 |
| 226 | −9 | −9 | 2 | 17 | 32 | 42 | 52 | 49 | 42 | 30 | 17 | −2 | 22 | 12 |
| 227 | 5 | 4 | 14 | 21 | 31 | 37 | 42 | 43 | 38 | 32 | 24 | 12 | 25 | 15 |
| 228 | −11 | −8 | 4 | 24 | 38 | 52 | 65 | 62 | 49 | 34 | 13 | −3 | 26 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | −11 | −9 | −2 | 19 | 40 | 59 | 66 | 59 | 44 | 25 | 3 | −10 | 24 | 20 |
| 251 | −13 | −6 | 4 | 22 | 44 | 64 | 68 | 63 | 46 | 25 | 0 | −8 | 26 | 28 |
| 252 | −14 | −4 | 16 | 41 | 59 | 70 | 73 | 67 | 52 | 33 | 7 | −8 | 33 | 41 |
| 253 | 15 | 23 | 31 | 43 | 58 | 67 | 67 | 65 | 55 | 42 | 21 | 15 | 42 | 6 |
| 254 | −14 | −10 | 3 | 27 | 50 | 67 | 72 | 70 | 49 | 29 | 2 | −11 | 28 | 31 |
| 255 | 5 | 15 | 29 | 44 | 59 | 67 | 70 | 67 | 56 | 41 | 14 | 4 | 39 | 9 |
| 256 | −12 | −4 | 9 | 31 | 53 | 68 | 71 | 65 | 51 | 31 | 5 | −8 | 30 | 30 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland (cont.): | ||||||||||||||
| 257 | −12 | −4 | 9 | 31 | 53 | 68 | 71 | 65 | 51 | 31 | 5 | −8 | 30 | 31 |
| 258 | −10 | 0 | 13 | 38 | 56 | 68 | 74 | 68 | 56 | 36 | 11 | −4 | 34 | 42 |
| 259 | −6 | 1 | 12 | 34 | 50 | 60 | 70 | 67 | 55 | 40 | 17 | 2 | 34 | 45 |
| 260 | −5 | −4 | 12 | 32 | 46 | 63 | 69 | 66 | 50 | 39 | 15 | −1 | 32 | … |
| 261 | −11 | −3 | 7 | 31 | 51 | 62 | 70 | 65 | 52 | 36 | 15 | −4 | 31 | 24 |
| 262 | −8 | 1 | 15 | 38 | 56 | 67 | 74 | 69 | 55 | 38 | 18 | 0 | 35 | 26 |
| 263 | −1 | 10 | 24 | 45 | 61 | 70 | 75 | 71 | 59 | 43 | 21 | 5 | 40 | 30 |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | 1 | −4 | −2 | 9 | 28 | 41 | 46 | 43 | 33 | 23 | 13 | −1 | 19 | 3-4 |
| 304 | 2 | 0 | 7 | 18 | 34 | 43 | 49 | 48 | 40 | 29 | 21 | 11 | 25 | 30 |
| 305 | 24 | 19 | 23 | 28 | 37 | 46 | 50 | 49 | 42 | 35 | 29 | 29 | 35 | 4-5 |
| 306 | 13 | 16 | 18 | 26 | 38 | 46 | 54 | 50 | 41 | 32 | 26 | 22 | 32 | 5 |
| 307 | 26 | 28 | 27 | 32 | 41 | 59 | 61 | 56 | 46 | 39 | 28 | 27 | 39 | 5 |
| 308 | 12 | 12 | 14 | 22 | 33 | 43 | 49 | 45 | 39 | 25 | 19 | 15 | 27 | 12 |
| 309 | 16 | 14 | 18 | 26 | 39 | 48 | 51 | 50 | 42 | 33 | 28 | 23 | 32 | 13 |
| 310 | 18 | 9 | 12 | 20 | 31 | 43 | 47 | 46 | 39 | 31 | 24 | 21 | 29 | 2-3 |
| 311 | 26 | 15 | 24 | 26 | 40 | 49 | 50 | 50 | 44 | 32 | 26 | 18 | 38 | 2-3 |
| 312 | 11 | 10 | 13 | 24 | 45 | 57 | 58 | 55 | 44 | 30 | 21 | 14 | 32 | 6-7 |
| 313 | 22 | 18 | 17 | 25 | 37 | 47 | 50 | 48 | 42 | 34 | 28 | 25 | 33 | 4-5 |
| 314 | 21 | 21 | 27 | 34 | 44 | 50 | 55 | 53 | 45 | 35 | 29 | 24 | 36 | 30 |
| 315 | 27 | 26 | 30 | 35 | 42 | 47 | 51 | 50 | 45 | 37 | 31 | 29 | 38 | 4-5 |
| 316 | 18 | 23 | 23 | 29 | 32 | 45 | 49 | 47 | 45 | 26 | 26 | 25 | 32 | 1 |
| 317 | 25 | 26 | 30 | 36 | 44 | 50 | 55 | 52 | 46 | 35 | 31 | 28 | 38 | 10 |
| 318 | 25 | 27 | 32 | 39 | 48 | 54 | 57 | 55 | 48 | 40 | 33 | 28 | 40 | 30 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 319 | 31 | 30 | 33 | 36 | 45 | 53 | 52 | 52 | 45 | 38 | 32 | 31 | 41 | 1-2 |
| 320 | 31 | 33 | 32 | 41 | 46 | 50 | 52 | 52 | 48 | 42 | 36 | 33 | 41 | 10 |
| 321 | 29 | 28 | 31 | 34 | 40 | 47 | 50 | 50 | 46 | 39 | 33 | 31 | 38 | 4-5 |
| 331 | 38 | 38 | 40 | 44 | 49 | 54 | 57 | 56 | 51 | 44 | 39 | 38 | 46 | 14 |
| 334 | 33 | 32 | 31 | 35 | 40 | 47 | 49 | 50 | 46 | 40 | 36 | 34 | 39 | 21 |
| 337 | 36 | 38 | 42 | 46 | 51 | 57 | 57 | 57 | 54 | 47 | 41 | 38 | 47 | 4 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 361 | 29 | 31 | 30 | 36 | 42 | 54 | 58 | 54 | 47 | 39 | 31 | 29 | 40 | 15 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 10 | 5 | 1 | 8 | 22 | 34 | 38 | 37 | 30 | 22 | 14 | 9 | 19 | 10 |
| 401 | 6 | 2 | −4 | 5 | 20 | 32 | 36 | 36 | 27 | 18 | 10 | 6 | 16 | 1 |
| 406 | 26 | 25 | 28 | 34 | 40 | 49 | 55 | 54 | 46 | 37 | 31 | 27 | 37 | 20 |
| 407 | 39 | 36 | 39 | 44 | 56 | 67 | 74 | 67 | 57 | 47 | 42 | 41 | 51 | 10 |
| 408 | 23 | 23 | 26 | 31 | 38 | 44 | 51 | 51 | 46 | 36 | 30 | 26 | 35 | 20 |
| 412 | 30 | 30 | 33 | 39 | 46 | 52 | 58 | 58 | 51 | 41 | 35 | 30 | 42 | 20 |
| 414 | 26 | 26 | 30 | 35 | 43 | 51 | 57 | 56 | 47 | 37 | 31 | 27 | 39 | 20 |
| 415 | 12 | 11 | 23 | 35 | 43 | 52 | 57 | 55 | 47 | 34 | 22 | 14 | 34 | 18 |
| 420 | 32 | 33 | 36 | 42 | 48 | 53 | 60 | 59 | 52 | 44 | 37 | 33 | 44 | 20 |
| 421 | 28 | 28 | 35 | 43 | 54 | 65 | 69 | 66 | 58 | 45 | 37 | 29 | 46 | 26 |
| 423 | 19 | 18 | 25 | 36 | 48 | 62 | 66 | 63 | 52 | 39 | 29 | 21 | 40 | 33 |
| 424 | 26 | 26 | 32 | 43 | 55 | 63 | 71 | 66 | 57 | 45 | 37 | 31 | 46 | 20 |
| 425 | 13 | 13 | 24 | 37 | 47 | 55 | 62 | 59 | 50 | 38 | 25 | 16 | 36 | 18 |
| 426 | 19 | 20 | 28 | 42 | 55 | 63 | 68 | 64 | 54 | 44 | 31 | 22 | 42 | 18 |
| 428 | 9 | 11 | 22 | 36 | 47 | 57 | 64 | 59 | 49 | 36 | 23 | 12 | 35 | 18 |
| 429 | 7 | 8 | 20 | 33 | 44 | 53 | 61 | 57 | 47 | 33 | 19 | 8 | 33 | 18 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Inland: | ||||||||||||||
| 450 | 14 | 15 | 23 | 35 | 44 | 57 | 62 | 59 | 48 | 33 | 24 | 17 | 36 | 22 |
| 451 | 5 | 8 | 23 | 33 | 43 | 55 | 63 | 59 | 48 | 32 | 17 | 8 | 33 | 20 |
| 454 | 29 | 32 | 37 | 44 | 52 | 57 | 63 | 61 | 53 | 44 | 35 | 30 | 45 | 20 |
| 455 | 27 | 29 | 36 | 46 | 59 | 70 | 71 | 66 | 58 | 46 | 36 | 29 | 48 | 29 |
| 456 | 17 | 19 | 27 | 39 | 50 | 60 | 64 | 59 | 51 | 37 | 28 | 20 | 39 | 20 |
| 457 | 22 | 22 | 32 | 44 | 56 | 65 | 72 | 66 | 55 | 42 | 33 | 26 | 45 | 20 |
| 458 | 19 | 18 | 29 | 40 | 51 | 62 | 70 | 64 | 54 | 39 | 29 | 23 | 41 | 20 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 11 | 9 | 1 | 10 | 23 | 33 | 40 | 40 | 35 | 28 | 18 | 11 | 22 | 7-8 |
| 501 | −4 | −3 | −12 | 3 | 21 | 35 | 43 | 41 | 36 | 20 | 3 | −3 | 15 | 5-6 |
| 502 | −8 | −5 | −14 | 1 | 19 | 35 | 45 | 42 | 35 | 18 | 1 | −6 | 14 | 4-5 |
| 503 | −8 | −5 | 13 | 0 | 19 | 33 | 40 | 37 | 32 | 18 | 3 | −6 | 13 | 7-8 |
| 505 | 19 | 14 | 11 | 20 | 29 | 39 | 49 | 49 | 41 | 33 | 37 | 20 | 29 | 17 |
| 506 | 15 | 9 | 7 | 18 | 27 | 37 | 49 | 48 | 42 | 33 | 27 | 18 | 28 | 24 |
| 507 | 12 | 8 | 4 | 16 | 28 | 39 | 48 | 48 | 39 | 31 | 24 | 15 | 26 | 17 |
| 508 | 4 | 1 | −4 | 10 | 24 | 33 | 44 | 45 | 38 | 27 | 17 | 7 | 20 | 5 |
| 509 | −3 | −1 | −5 | 10 | 25 | 41 | 55 | 51 | 41 | 25 | 9 | −2 | 20 | 6-7 |
| 510 | 0 | 2 | −4 | 9 | 24 | 36 | 45 | 45 | 38 | 24 | 10 | 1 | 19 | 19 |
| 511 | −28 | −30 | −23 | 1 | 20 | 37 | 47 | 47 | 35 | 10 | −11 | −22 | 7 | 2 |
| 513 | −42 | −29 | −10 | 3 | 25 | 47 | 54 | 47 | 35 | 10 | −17 | −25 | 8 | 4 |
| 514 | −16 | −17 | −13 | −1 | 21 | 36 | 43 | 41 | 34 | 19 | −4 | −12 | 11 | 6 |
| 515 | −35 | −32 | −21 | −2 | 24 | 43 | 55 | 45 | 36 | 10 | −14 | −28 | 7 | 8 |
| 517 | −4 | −7 | −2 | 8 | 22 | 37 | 42 | 40 | 32 | 21 | 7 | 1 | 16 | 11 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 518 | 12 | 7 | 6 | 19 | 28 | 39 | 51 | 50 | 43 | 32 | 25 | 14 | 27 | 26 |
| 519 | 8 | 4 | 2 | 17 | 28 | 40 | 51 | 49 | 42 | 30 | 20 | 8 | 25 | 22 |
| 522 | −39 | −31 | −10 | 11 | 34 | 54 | 58 | 51 | 38 | 11 | −10 | −24 | 12 | 5 |
| 523 | −13 | −8 | −4 | 4 | 25 | 39 | 46 | 42 | 33 | 23 | 6 | −2 | 16 | 3 |
| 525 | 2 | 0 | 4 | 14 | 27 | 38 | 47 | 45 | 29 | 28 | 16 | 8 | 22 | 7 |
| 526 | −10 | −7 | 6 | 21 | 37 | 53 | 61 | 57 | 47 | 26 | 5 | −5 | 24 | 10 |
| 527 | −9 | −5 | 1 | 10 | 31 | 44 | 55 | 52 | 41 | 25 | 5 | −5 | 20 | 9 |
| 531 | 1 | 1 | 17 | 30 | 38 | 49 | 55 | 57 | 50 | 32 | 10 | 0 | 28 | 4 |
| Asia, Inland: | ||||||||||||||
| 551 | .. | −9 | −19 | 5 | 31 | 47 | 59 | 46 | 41 | 18 | 0 | .. | .. | 0-1 |
| 553 | −5 | 0 | −1 | 13 | 27 | 45 | 61 | 55 | 44 | 24 | 4 | −5 | 22 | 18 |
| 554 | −18 | −17 | −3 | 9 | 24 | 45 | 63 | 57 | 41 | 18 | −1 | −14 | 17 | 4 |
| 556 | −58 | −40 | −10 | 19 | 43 | 61 | 66 | 58 | 44 | 12 | −30 | −51 | 10 | 15 |
| 558 | −42 | −29 | −8 | 12 | 35 | 57 | 62 | 53 | 41 | 15 | −16 | −34 | 12 | 12 |
| 559 | −39 | −28 | −7 | 19 | 42 | 62 | 67 | 56 | 44 | 16 | −13 | −33 | 15 | 8 |
| 560 | −3 | 4 | 15 | 30 | 42 | 57 | 67 | 59 | 49 | 31 | 9 | −1 | 30 | 9 |
| 562 | −9 | 1 | 16 | 29 | 44 | 57 | 67 | 63 | 51 | 31 | 9 | −5 | 29 | 18 |
| 563 | −19 | −6 | 10 | 21 | 38 | 53 | 66 | 61 | 46 | 24 | −3 | −17 | 23 | 13 |
| 566 | −26 | −10 | 12 | 33 | 50 | 67 | 75 | 66 | 51 | 28 | 0 | −24 | 27 | 11 |
| 567 | −37 | −18 | 6 | 25 | 45 | 63 | 69 | 53 | 47 | 22 | −11 | −35 | 20 | 11 |
| 568 | −45 | −28 | 1 | 26 | 50 | 68 | 73 | 67 | 50 | 22 | −15 | −38 | 19 | 17 |
| 570 | −39 | −22 | −5 | 31 | 47 | 66 | 71 | 65 | 51 | 24 | −6 | −40 | 21 | 9 |
| 572 | −17 | −10 | −2 | 12 | 33 | 55 | 63 | 60 | 43 | 20 | 1 | −13 | 20 | 14 |
| 573 | −2 | 9 | 23 | 39 | 56 | 66 | 71 | 67 | 56 | 37 | 18 | 4 | 37 | 15 |
| Table ^ XI ^ . Mean daily maximum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 574 | −5 | 6 | 23 | 38 | 52 | 66 | 73 | 69 | 55 | 35 | 15 | −2 | 35 | 18 |
| 575 | −14 | 0 | 22 | 38 | 53 | 69 | 74 | 69 | 53 | 33 | 11 | −9 | 33 | 17 |
| 576 | −20 | −6 | 14 | 32 | 47 | 65 | 72 | 66 | 51 | 29 | 4 | −15 | 28 | 18 |
| Table ^ XII ^ . Mean daily minimum temperature (°F.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 004 | 22 | 22 | 20 | 24 | 27 | 33 | 38 | 39 | 35 | 29 | 24 | 22 | 28 | 7 |
| 006 | −23 | −25 | −25 | −15 | 10 | 27 | 31 | 30 | 22 | 4 | −10 | −22 | 1 | 5-6 |
| 007 | −13 | −16 | −21 | −7 | 12 | 27 | 30 | 31 | 28 | 16 | −3 | −12 | 6 | 5-6 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | −23 | −24 | −22 | −8 | 14 | 29 | 34 | 33 | 27 | 12 | −6 | −18 | 4 | 25-28 |
| 101 | −7 | −13 | −16 | 7 | 19 | 30 | 38 | 38 | 35 | 23 | 4 | −5 | 19 | 1 |
| 102 | −14 | −14 | −15 | 7 | 25 | 38 | 46 | 46 | 37 | 21 | 2 | −9 | 14 | 8-11 |
| 103 | −9 | −9 | −12 | 4 | 22 | 27 | 41 | 40 | 36 | 26 | 6 | −2 | 19 | 2 |
| 104 | −4 | −2 | 1 | 12 | 28 | 38 | 44 | 44 | 36 | 24 | 10 | 1 | 20 | 34-35 |
| 105 | −7 | −3 | 1 | 17 | 26 | 35 | 43 | 43 | 39 | 30 | 21 | 6 | 21 | 2-6 |
| 106 | 5 | 9 | 13 | 27 | 36 | 44 | 49 | 47 | 39 | 29 | 16 | 6 | 27 | 23-25 |
| Alaska, Inland: | ||||||||||||||
| 150 | −10 | −11 | −15 | 5 | 27 | 42 | 49 | 40 | 32 | 15 | −6 | −12 | 11 | 3-4 |
| 151 | −30 | −31 | −24 | −16 | 13 | 34 | 42 | 35 | 26 | 2 | −16 | −22 | 5 | 1-2 |
| 152 | −21 | −17 | −12 | 5 | 28 | 43 | 45 | 41 | 31 | 16 | −9 | −17 | 11 | 6-8 |
| 153 | −27 | −26 | −12 | 8 | 32 | 47 | 51 | 45 | 33 | 13 | −12 | −28 | 10 | 19-21 |
| 154 | −1 | 0 | 3 | 18 | 31 | 43 | 46 | 45 | 38 | 24 | 11 | 0 | 21 | 16-18 |
| 155 | −21 | −13 | −6 | 12 | 32 | 44 | 46 | 42 | 32 | 17 | −6 | −16 | 14 | 34-40 |
| 156 | −21 | −17 | −6 | 20 | 35 | 46 | 48 | 44 | 34 | 20 | −4 | −15 | 15 | 11 |
| 157 | −23 | −14 | −6 | 12 | 31 | 43 | 46 | 41 | 31 | 17 | −4 | −19 | 13 | 27-33 |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | −30 | −30 | −23 | −12 | 8 | 28 | 35 | 34 | 25 | 8 | −11 | −24 | 1 | 5 |
| 205 | −33 | −33 | −30 | −18 | 9 | 31 | 35 | 33 | 19 | 0 | −12 | −29 | −2 | 3 |
| Table ^ XII ^ . Mean daily minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec. | |
| Canada, Coastal and Insular (cont.) ^ : ^ | ||||||||||||||
| 206 | −21 | −22 | −18 | −6 | 18 | 32 | 41 | 36 | 24 | 12 | −10 | −21 | 5 | 3 |
| 210 | −25 | −33 | −25 | −13 | 9 | 28 | 35 | 32 | 21 | 3 | −15 | −23 | 0 | 5 |
| 211 | −27 | −34 | −26 | −13 | 12 | 30 | 36 | 35 | 26 | 9 | −12 | −23 | 1 | 10 |
| 212 | −25 | −30 | −18 | −9 | 15 | 30 | 36 | 34 | 29 | 11 | −4 | −18 | 4 | 3-4 |
| 213 | −32 | −35 | −29 | −11 | 12 | 30 | 36 | 36 | 28 | 10 | −11 | −27 | 1 | 16 |
| 214 | −21 | −24 | −20 | −11 | 12 | 28 | 33 | 33 | 28 | 16 | −4 | −15 | 5 | 5 |
| 215 | −25 | −20 | −18 | −5 | 15 | 30 | 37 | 36 | 28 | 11 | −10 | −21 | 5 | 9 |
| 216 | −26 | −27 | −23 | −8 | 15 | 32 | 42 | 40 | 31 | 12 | −13 | −22 | 4 | 13 |
| 217 | −31 | −33 | −31 | −14 | 6 | 31 | 41 | 38 | 28 | 5 | −17 | −30 | −1 | 13 |
| 221 | −33 | −31 | −23 | −6 | 15 | 32 | 40 | 41 | 33 | 17 | −9 | −24 | 4 | 18 |
| 222 | −33 | −28 | −23 | −9 | 11 | 28 | 38 | 39 | 27 | 11 | −7 | −24 | 3 | 8 |
| 223 | −19 | −21 | −12 | 2 | 20 | 30 | 35 | 36 | 31 | 23 | 4 | −11 | 10 | 14 |
| 224 | −21 | −19 | −10 | 3 | 22 | 33 | 38 | 37 | 32 | 21 | 6 | −10 | 11 | 22 |
| 225 | −18 | −25 | −19 | −3 | 18 | 32 | 38 | 37 | 30 | 19 | 7 | −13 | 9 | 3 |
| 226 | −23 | −24 | −15 | −1 | 18 | 31 | 39 | 39 | 32 | 20 | −6 | −15 | 9 | 12 |
| 227 | −7 | −7 | 3 | 11 | 24 | 30 | 33 | 34 | 32 | 26 | 17 | 3 | 17 | 15 |
| 228 | −27 | −25 | −16 | 4 | 22 | 34 | 43 | 43 | 35 | 20 | −2 | −19 | 9 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | −27 | −24 | −19 | −2 | 23 | 40 | 47 | 42 | 32 | 16 | −10 | −24 | 8 | 20 |
| 251 | −30 | −23 | −18 | −1 | 24 | 42 | 49 | 43 | 32 | 13 | −13 | −23 | 8 | 28 |
| 252 | −28 | −20 | −8 | 16 | 34 | 43 | 46 | 42 | 32 | 19 | −4 | −20 | 13 | 41 |
| 253 | 1 | 4 | 12 | 24 | 34 | 43 | 45 | 43 | 38 | 29 | 7 | −1 | 23 | 6 |
| 254 | −33 | −29 | −22 | 0 | 27 | 42 | 47 | 41 | 31 | 14 | −14 | −29 | 6 | 31 |
| Table ^ XII ^ . Mean daily minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec. |
| Canada, Inland (cont.): | ||||||||||||||
| 255 | −14 | 9 | 2 | 22 | 34 | 44 | 47 | 43 | 36 | 26 | 0 | −12 | 18 | 9 |
| 256 | −27 | −22 | −14 | 7 | 29 | 42 | 47 | 43 | 33 | 18 | −7 | −22 | 11 | 30 |
| 257 | −27 | −22 | −14 | 7 | 28 | 42 | 47 | 42 | 33 | 18 | −7 | −22 | 10 | 31 |
| 258 | −27 | −21 | −11 | 14 | 33 | 45 | 50 | 46 | 36 | 21 | −3 | −20 | 14 | 42 |
| 259 | −25 | −21 | −12 | 11 | 29 | 40 | 49 | 47 | 37 | 24 | 2 | −16 | 14 | 45 |
| 260 | −22 | −23 | −9 | 9 | 29 | 44 | 52 | 50 | 39 | 29 | 2 | −17 | 15 | … |
| 261 | −23 | −16 | −11 | 12 | 31 | 43 | 51 | 44 | 38 | 26 | 5 | −15 | 15 | 24 |
| 262 | −25 | −20 | −9 | 14 | 32 | 42 | 47 | 43 | 34 | 22 | 3 | −17 | 14 | 26 |
| 263 | −24 | −19 | −8 | 17 | 34 | 42 | 47 | 43 | 32 | 22 | 0 | −17 | 14 | 30 |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | −16 | −21 | −19 | −10 | 16 | 30 | 36 | 33 | 21 | 8 | −3 | −17 | 5 | 3-4 |
| 304 | −10 | −12 | −9 | 1 | 21 | 31 | 36 | 36 | 31 | 21 | 12 | 1 | 13 | 30 |
| 305 | 15 | 9 | 13 | 19 | 28 | 35 | 39 | 38 | 24 | 28 | 21 | 18 | 25 | 4-5 |
| 306 | −3 | −3 | 7 | 13 | 27 | 36 | 43 | 42 | 34 | 26 | 19 | 14 | 22 | 5 |
| 307 | −33 | −41 | −32 | −29 | −1 | 24 | 29 | 26 | 12 | −10 | −19 | −30 | −9 | 5 |
| 308 | −3 | −5 | −4 | 6 | 21 | 31 | 35 | 33 | 29 | 15 | 6 | 1 | 14 | 12 |
| 309 | 6 | 1 | 5 | 13 | 27 | 37 | 41 | 41 | 35 | 25 | 19 | 13 | 22 | 13 |
| 310 | 8 | −2 | −1 | 7 | 22 | 33 | 37 | 38 | 34 | 24 | 17 | 13 | 19 | 2-3 |
| 311 | 6 | 2 | 9 | 15 | 31 | 42 | 46 | 44 | 36 | 26 | 17 | 10 | 24 | 6 |
| 312 | −3 | −6 | −5 | 8 | 26 | 40 | 41 | 38 | 30 | 17 | 6 | −1 | 16 | 6-7 |
| 313 | 13 | 7 | 8 | 16 | 27 | 35 | 39 | 38 | 34 | 27 | 21 | 17 | 23 | 4-5 |
| 314 | 11 | 10 | 15 | 21 | 30 | 35 | 39 | 39 | 35 | 27 | 20 | 15 | 25 | 30 |
| 315 | 19 | 15 | 18 | 22 | 29 | 35 | 38 | 39 | 35 | 29 | 24 | 22 | 27 | 4-5 |
| Table ^ XII ^ . Mean daily minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 316 | 8 | 10 | 12 | 15 | 22 | 33 | 36 | 34 | 34 | 17 | 16 | 14 | 21 | 1 |
| 317 | 14 | 14 | 17 | 20 | 30 | 36 | 39 | 38 | 34 | 26 | 21 | 18 | 26 | 10 |
| 318 | 14 | 13 | 17 | 25 | 34 | 39 | 42 | 41 | 36 | 29 | 22 | 16 | 27 | 30 |
| 319 | 19 | 19 | 21 | 26 | 33 | 38 | 39 | 40 | 35 | 28 | 22 | 19 | 29 | 1-2 |
| 320 | 21 | 22 | 22 | 29 | 34 | 36 | 37 | 39 | 37 | 33 | 27 | 24 | 30 | 10 |
| 321 | 22 | 21 | 23 | 26 | 31 | 36 | 38 | 38 | 36 | 31 | 26 | 24 | 29 | 4-5 |
| 331 | 27 | 29 | 30 | 34 | 39 | 44 | 48 | 46 | 41 | 35 | 31 | 29 | 36 | 14 |
| 334 | 23 | 22 | 21 | 25 | 31 | 37 | 40 | 41 | 37 | 32 | 27 | 24 | 30 | 21 |
| 336 | 25 | 25 | 26 | 31 | 38 | 43 | 47 | 46 | 41 | 32 | 29 | 28 | 34 | 10 |
| 337 | 26 | 29 | 31 | 35 | 39 | 43 | 46 | 46 | 43 | 36 | 32 | 29 | 36 | 4 |
| 340 | 32 | 33 | 29 | 35 | 40 | 47 | 49 | 49 | 44 | 38 | 36 | 33 | 39 | 4 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 361 | 16 | 18 | 17 | 22 | 30 | 36 | 41 | 38 | 32 | 27 | 19 | 17 | 26 | 19 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | −6 | −10 | −14 | −5 | 14 | 27 | 31 | 31 | 24 | 14 | 2 | −5 | 9 | 10 |
| 401 | −11 | −13 | −18 | −9 | 11 | 26 | 30 | 29 | 19 | 7 | −4 | −9 | 5 | 1 |
| 406 | 21 | 20 | 23 | 27 | 33 | 41 | 46 | 46 | 40 | 32 | 26 | 22 | 31 | 20 |
| 407 | 3 | 3 | 6 | 13 | 26 | 32 | 41 | 39 | 32 | 22 | 14 | 8 | 23 | 10 |
| 408 | 18 | 17 | 20 | 25 | 32 | 39 | 45 | 45 | 41 | 31 | 26 | 21 | 30 | 20 |
| 412 | 24 | 24 | 25 | 30 | 38 | 44 | 51 | 50 | 43 | 35 | 30 | 25 | 35 | 20 |
| 414 | 22 | 20 | 22 | 27 | 35 | 42 | 47 | 46 | 40 | 31 | 27 | 23 | 32 | 20 |
| 415 | 4 | 1 | 8 | 21 | 31 | 40 | 46 | 44 | 37 | 27 | 14 | 10 | 23 | 18 |
| 420 | 27 | 28 | 29 | 34 | 40 | 45 | 51 | 51 | 45 | 37 | 32 | 28 | 37 | 20 |
| 421 | 13 | 12 | 17 | 26 | 35 | 45 | 51 | 49 | 42 | 33 | 24 | 16 | 30 | 26 |
| 423 | 4 | 2 | 7 | 19 | 32 | 44 | 50 | 47 | 39 | 28 | 17 | 6 | 25 | 33 |
| 424 | 17 | 15 | 22 | 31 | 41 | 49 | 57 | 54 | 47 | 36 | 30 | 22 | 35 | 20 |
| Table ^ XII ^ . Mean daily minimum temperature ( ^ ° ^ F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular (cont.): | ||||||||||||||
| 425 | 5 | 3 | 9 | 22 | 33 | 41 | 48 | 46 | 38 | 29 | 18 | 10 | 25 | 35 |
| 426 | 12 | 12 | 18 | 30 | 42 | 51 | 56 | 53 | 45 | 37 | 26 | 17 | 33 | 18 |
| 428 | 1 | 0 | 8 | 23 | 35 | 44 | 51 | 48 | 41 | 30 | 16 | 4 | 25 | 18 |
| 429 | −1 | −1 | 6 | 20 | 31 | 40 | 47 | 45 | 37 | 26 | 13 | 2 | 22 | 25 |
| Europe, Inland: | ||||||||||||||
| 450 | −4 | −4 | 1 | 13 | 28 | 40 | 45 | 42 | 33 | 21 | 8 | −1 | 19 | 22 |
| 451 | −6 | −9 | 0 | 14 | 29 | 40 | 45 | 41 | 34 | 20 | 7 | −3 | 18 | 20 |
| 454 | 23 | 24 | 26 | 33 | 40 | 46 | 52 | 50 | 43 | 35 | 29 | 25 | 36 | 20 |
| 455 | 12 | 12 | 17 | 27 | 37 | 48 | 51 | 49 | 42 | 32 | 23 | 15 | 30 | 29 |
| 456 | 0 | −1 | 6 | 19 | 31 | 41 | 45 | 43 | 35 | 25 | 15 | 3 | 23 | 20 |
| 457 | 10 | 9 | 17 | 27 | 37 | 47 | 53 | 50 | 42 | 33 | 24 | 16 | 30 | 20 |
| 458 | 6 | 5 | 13 | 24 | 34 | 44 | 51 | 48 | 40 | 29 | 21 | 12 | 27 | 20 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | −3 | −6 | −12 | −2 | 15 | 27 | 32 | 33 | 29 | 19 | 8 | 0 | 11 | 7-8 |
| 501 | −20 | −20 | −27 | −12 | 10 | 28 | 33 | 33 | 29 | 9 | −10 | −18 | 3 | 5-6 |
| 502 | −25 | −22 | −28 | −15 | 9 | 28 | 36 | 34 | 28 | 8 | −13 | −21 | 2 | 4-5 |
| 503 | −23 | −21 | −26 | −14 | 9 | 27 | 32 | 31 | 26 | 8 | −9 | −19 | 2 | 7-8 |
| 504 | −28 | −29 | −26 | −13 | 9 | 29 | 33 | 33 | 28 | 10 | −14 | −24 | 1 | 4 |
| 505 | −2 | −1 | −1 | 6 | 19 | 30 | 29 | 40 | 34 | 23 | 10 | 2 | 17 | 30 |
| 506 | 1 | −3 | −8 | 4 | 19 | 30 | 37 | 39 | 36 | 27 | 18 | 6 | 17 | 24 |
| 507 | −2 | −5 | −10 | 2 | 19 | 30 | 37 | 38 | 33 | 23 | 12 | 2 | 15 | 17 |
| 508 | −14 | −17 | −21 | −7 | 13 | 28 | 35 | 37 | 32 | 18 | 3 | −9 | 8 | 5 |
| 509 | −20 | −19 | −21 | −7 | 14 | 31 | 40 | 40 | 32 | 14 | −5 | −19 | 7 | 6-7 |
| 510 | −17 | −14 | −19 | − ^ 5 ^ | 14 | 29 | 36 | 37 | 32 | 15 | −4 | −14 | 8 | 19 |
| Table ^ XII ^ . Mean daily minimum temperature (°F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular, (cont.) | ||||||||||||||
| 511 | −33 | −39 | −36 | −16 | 6 | 26 | 38 | 36 | 30 | 0 | −21 | −35 | −4 | 2 |
| 512 | −24 | −26 | −28 | −9 | 14 | 32 | 41 | 41 | 32 | 7 | −17 | −26 | 3 | 7 |
| 513 | −48 | −37 | −25 | −14 | 12 | 36 | 42 | 37 | 26 | 0 | −23 | −32 | −2 | 4 |
| 514 | −29 | −30 | −26 | −13 | 9 | 32 | 33 | 33 | 29 | 11 | −14 | −24 | 1 | 11 |
| 515 | −40 | −40 | −31 | −19 | 10 | 34 | 42 | 35 | 27 | 3 | −18 | −33 | −2 | 14 |
| 517 | −18 | −20 | −17 | −6 | 11 | 29 | 32 | 32 | 26 | 13 | −3 | −11 | 6 | 11 |
| 518 | −2 | −8 | −9 | 4 | 19 | 31 | 37 | 39 | 35 | 23 | 15 | 0 | 15 | 26 |
| 519 | −9 | −11 | −13 | 2 | 13 | 31 | 37 | 39 | 35 | 20 | 6 | −7 | 12 | 22 |
| 520 | −21 | −18 | −8 | 5 | 22 | 38 | 49 | 46 | 37 | 20 | −5 | −17 | 12 | 18 |
| 521 | −13 | −13 | −15 | −1 | 16 | 30 | 41 | 43 | 36 | 24 | 0 | −12 | 10 | 3 |
| 522 | −43 | −32 | −26 | −12 | 13 | 39 | 44 | 40 | 30 | 4 | −16 | −37 | 0 | 10 |
| 523 | −27 | −22 | −17 | −12 | 12 | 29 | 33 | 32 | 27 | 12 | −7 | −15 | 4 | 3 |
| 524 | −20 | −20 | −18 | −5 | 10 | 30 | 35 | 36 | 31 | 17 | −1 | −13 | 7 | 4 |
| 525 | −12 | −15 | −9 | 2 | 17 | 31 | 37 | 36 | 32 | 20 | 5 | −6 | 11 | 7 |
| 526 | −19 | −14 | −7 | 6 | 26 | 38 | 44 | 43 | 32 | 15 | −7 | −18 | 12 | 5 |
| 527 | −18 | −15 | −11 | −5 | 18 | 34 | 46 | 43 | 32 | 18 | 1 | −13 | 11 | 9 |
| 529 | 0 | −5 | −2 | 12 | 23 | 34 | 41 | 39 | 35 | 24 | 11 | 5 | 18 | 4 |
| 530 | −6 | −9 | −7 | 6 | 19 | 32 | 38 | 37 | 31 | 21 | 8 | −2 | 14 | 7 |
| 531 | −16 | −20 | −1 | 10 | 24 | 38 | 45 | 45 | 36 | 16 | −6 | −15 | 13 | 4 |
| Asia, Inland: | ||||||||||||||
| 551 | ... | −17 | −36 | −12 | 15 | 39 | 48 | 37 | 31 | 2 | −14 | −26 | … | 0-1 |
| 552 | −45 | −40 | −25 | −6 | 17 | 38 | 46 | 42 | 29 | 6 | −27 | −39 | 0 | 12 |
| 553 | −23 | −18 | −17 | −5 | 14 | 35 | 46 | 42 | 34 | 14 | −11 | −21 | 7 | 18 |
| Table ^ XII ^ . Mean daily minimum temperature ( ^ ° ^ F.) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.) | ||||||||||||||
| 554 | −29 | −26 | −17 | −4 | 15 | 35 | 48 | 44 | 33 | 10 | −13 | −24 | 6 | 12 |
| 556 | −65 | −56 | −39 | −12 | 22 | 43 | 47 | 39 | 27 | −4 | −40 | −58 | −8 | 14 |
| 558 | −49 | −40 | −29 | −11 | 18 | 43 | 48 | 41 | 30 | 5 | −23 | −40 | −1 | 9 |
| 559 | −45 | −39 | −25 | −2 | 27 | 47 | 48 | 38 | 27 | 4 | −26 | −34 | 2 | 3 |
| 560 | −17 | −12 | −3 | 14 | 29 | 44 | 53 | 48 | 37 | 22 | 0 | −15 | 17 | 10 |
| 561 | −14 | −7 | 0 | 19 | 47 | 47 | 56 | 51 | 41 | 24 | 5 | −10 | 23 | 9 |
| 562 | −20 | −12 | 0 | 14 | 31 | 46 | 54 | 51 | 40 | 24 | 0 | −15 | 18 | 18 |
| 563 | −28 | −19 | −7 | 2 | 23 | 41 | 52 | 47 | 36 | 16 | −13 | −26 | 10 | 13 |
| 565 | −65 | −60 | −49 | −28 | 3 | 27 | 34 | 27 | 14 | −23 | −53 | −63 | −20 | 13 |
| 566 | −28 | −27 | −11 | 11 | 31 | 47 | 55 | 49 | 37 | 16 | −12 | −34 | 11 | 9 |
| 567 | −45 | −32 | −18 | 2 | 28 | 46 | 52 | 46 | 34 | 10 | −22 | −43 | 5 | 11 |
| 568 | −54 | −40 | −20 | 6 | 32 | 48 | 54 | 48 | 34 | 11 | −24 | −46 | 4 | 17 |
| 570 | −51 | −41 | −22 | 8 | 32 | 46 | 50 | 43 | 33 | 14 | −18 | −48 | 4 | 7 |
| 571 | −6 | −20 | −36 | −15 | .. | .. | .. | .. | .. | 18 | −23 | −31 | .. | 0-1 |
| 572 | −29 | −34 | −19 | −8 | 19 | 40 | 47 | 41 | 33 | 9 | −10 | −22 | 6 | 12 |
| 573 | −13 | −3 | 7 | 23 | 40 | 50 | 55 | 51 | 41 | 26 | 8 | −6 | 23 | 13 |
| 574 | −17 | −11 | 2 | 18 | 34 | 49 | 55 | 51 | 39 | 26 | 5 | −13 | 20 | 18 |
| 575 | −28 | −22 | −6 | 15 | 32 | 45 | 51 | 48 | 35 | 20 | −3 | −22 | 14 | 17 |
| 576 | −33 | −26 | −12 | 7 | 28 | 41 | 48 | 43 | 34 | 14 | −11 | −26 | 9 | 18 |
| Table XIII. Mean number of days with minimum temperature ^ ≤ ^ 32° F. ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 003 | 31 | 28 | 31 | 30 | 31 | 30 | 25 | 19 | 29 | 31 | 30 | 31 | 346 | 1-2 |
| 004 | 28 | 29 | 30 | 27 | 26 | 13 | * | 1 | 9 | 22 | 26 | 29 | 238 | .. |
| 006 | 31 | 28 | 31 | 30 | 31 | 27 | 20 | 27 | 27 | 31 | 30 | 31 | 343 | 5-6 |
| 007 | 31 | 28 | 31 | 30 | 31 | 29 | 23 | 22 | 24 | 31 | 30 | 31 | 340 | 5-6 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 31 | 28 | 31 | 30 | 30 | 23 | 13 | 16 | 27 | 31 | 30 | 31 | 321 | 22 |
| 101 | 31 | 28 | 31 | 30 | 30 | 21 | 1 | 1 | 9 | 29 | 30 | 31 | 272 | 1-2 |
| 102 | 31 | 28 | 31 | 30 | 25 | 6 | * | * | 6 | 28 | 30 | 31 | 246 | 8-12 |
| 103 | 31 | 28 | 31 | 30 | 29 | 20 | 0 | 1 | 7 | 27 | 30 | 31 | 265 | 2 |
| 104 | 31 | 28 | 31 | 29 | 22 | 5 | 1 | 2 | 11 | 25 | 29 | 31 | 245 | 33 |
| 105 | 31 | 28 | 31 | 30 | 30 | 11 | 0 | 0 | 2 | 23 | 28 | 31 | 245 | 2-6 |
| 106 | 31 | 28 | 29 | 24 | 9 | * | 0 | * | 6 | 19 | 29 | 31 | 200 | 23 |
| Alaska, Inland: | ||||||||||||||
| 150 | 31 | 28 | 31 | 30 | 21 | 2 | 0 | 4 | 17 | 28 | 30 | 31 | 253 | 3-4 |
| 151 | 31 | 28 | 31 | 30 | 31 | 16 | 1 | 12 | 28 | 31 | 30 | 31 | 300 | 1-2 |
| 152 | 31 | 28 | 31 | 30 | 19 | 1 | * | 3 | 18 | 30 | 30 | 31 | 252 | 5-8 |
| 153 | 31 | 28 | 31 | 29 | 16 | 1 | 0 | 2 | 15 | 30 | 30 | 31 | 244 | 23 |
| 154 | 31 | 28 | 31 | 28 | 18 | 1 | * | * | 7 | 25 | 27 | 31 | 227 | 17 |
| 155 | 31 | 28 | 31 | 29 | 15 | 1 | 1 | 4 | 14 | 29 | 30 | 31 | 244 | 31-36 |
| 156 | 31 | 28 | 31 | 28 | 13 | 1 | 0 | 1 | 14 | 28 | 28 | 30 | 233 | 5-6 |
| 157 | 31 | 28 | 31 | 29 | 18 | 3 | 1 | 6 | 16 | 28 | 30 | 31 | 252 | 5-6 |
| Table XIII. Mean number of days with minimum temperature ^ ≤ ^ 32° F. (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: | ||||||||||||||
| 222 | 30 | 28 | 31 | 30 | 31 | 24 | 1 | 2 | 23 | 31 | 30 | 31 | 292 | 2 |
| 224 | 30 | 28 | 31 | 30 | 29 | 15 | 1 | 0 | 18 | 31 | 30 | 31 | 273 | 1 |
| Canada, Inland: | ||||||||||||||
| 256 | 30 | 28 | 31 | 28 | 10 | 0 | 0 | 0 | 9 | 26 | 30 | 31 | 224 | 1-2 |
| Greenland, Iceland, Coastal and Insular: | ||||||||||||||
| 306 | 31 | 28 | 30 | 30 | 22 | 5 | 0 | 0 | 11 | 27 | 30 | 31 | 245 | 5 |
| 314 | 31 | 28 | 30 | 28 | 21 | 8 | 1 | 1 | 8 | 26 | 29 | 31 | 240 | 31 |
| 317 | 30 | 28 | 30 | 28 | 20 | 9 | 3 | 4 | 14 | 26 | 28 | 29 | 249 | 30 |
| 318 | 30 | 27 | 29 | 24 | 11 | 2 | 0 | * | 6 | 21 | 27 | 30 | 206 | 28 |
| 331 | 25 | 20 | 17 | 15 | 5 | 1 | 0 | * | 3 | 11 | 12 | 17 | 126 | 3-4 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 31 | 28 | 31 | 30 | 31 | 28 | 22 | 23 | 29 | 31 | 30 | 31 | 345 | 10 |
| 407 | 30 | 27 | 30 | 25 | 11 | 1 | 0 | 0 | 2 | 19 | 28 | 30 | 203 | 10 |
| 415 | 31 | 28 | 30 | 25 | 18 | 4 | 0 | * | 5 | 21 | 27 | 31 | 220 | 13 |
| 425 | 31 | 28 | 31 | 25 | 13 | 2 | * | 1 | 5 | 18 | 27 | 30 | 212 | 18 |
| 426 | 30 | 28 | 29 | 18 | 4 | 0 | 0 | 0 | 1 | 8 | 22 | 28 | 169 | 18 |
| 428 | 31 | 28 | 31 | 24 | 11 | 2 | 0 | 0 | 2 | 16 | 28 | 31 | 203 | 18 |
| 429 | 31 | 28 | 31 | 24 | 18 | 5 | * | 1 | 7 | 21 | 30 | 31 | 225 | 13 |
| Europe, Inland: | ||||||||||||||
| 451 | 31 | 28 | 31 | 28 | 19 | 3 | * | 3 | 11 | 25 | 29 | 31 | 239 | 55 |
| 453 | 31 | 28 | 31 | 27 | 17 | 3 | * | 3 | 13 | 22 | 27 | 30 | 232 | 10 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 31 | 28 | 31 | 30 | 31 | 29 | 18 | 11 | 22 | 31 | 30 | 31 | 323 | 7-8 |
| 501 | 31 | 28 | 31 | 30 | 31 | 23 | 13 | 15 | 21 | 31 | 30 | 31 | 315 | 5-6 |
| 503 | 31 | 28 | 31 | 30 | 31 | 28 | 20 | 25 | 27 | 31 | 30 | 31 | 343 | 7-8 |
| Table XIII. Mean number of days with minimum temperature ^ ≤ ^ 32° F. (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 507 | 31 | 28 | 31 | 30 | 30 | 19 | 2 | 1 | 13 | 30 | 30 | 31 | 275 | 17 |
| 508 | 31 | 28 | 31 | 30 | 31 | 27 | 9 | 2 | 15 | 31 | 30 | 31 | 295 | 6 |
| 509 | 31 | 28 | 31 | 30 | 31 | 17 | 2 | 1 | 15 | 30 | 30 | 31 | 276 | 6-7 |
| 510 | 31 | 28 | 31 | 30 | 30 | 24 | 6 | 6 | 15 | 31 | 30 | 31 | 292 | 19 |
| 511 | 31 | 28 | 31 | 30 | 31 | 23 | 2 | 8 | 18 | 31 | 30 | 31 | 294 | 5 |
| 512 | 31 | 28 | 31 | 30 | 29 | 17 | 5 | 1 | 10 | 31 | 30 | 31 | 274 | 4 |
| 513 | 31 | 28 | 31 | 29 | 25 | 12 | 1 | 6 | 22 | 31 | 30 | 31 | 279 | 6 |
| 514 | 31 | 28 | 31 | 30 | 31 | 25 | 15 | 13 | 23 | 31 | 30 | 31 | 319 | 8 |
| 515 | 31 | 28 | 31 | 30 | 31 | 13 | 1 | 9 | 24 | 31 | 30 | 31 | 291 | 7 |
| 518 | 31 | 28 | 31 | 30 | 31 | 20 | 5 | 3 | 8 | 24 | 30 | 31 | 271 | 26 |
| 519 | 31 | 28 | 31 | 30 | 30 | 20 | 5 | 2 | 9 | 27 | 30 | 31 | 275 | 22 |
| 521 | 31 | 28 | 31 | 30 | 29 | 23 | 5 | 2 | 12 | 28 | 30 | 31 | 280 | 3 |
| 522 | 31 | 28 | 31 | 30 | 30 | 3 | 0 | 2 | 20 | 31 | 30 | 31 | 267 | 4 |
| 523 | 31 | 28 | 31 | 30 | 30 | 21 | 11 | 14 | 24 | 31 | 30 | 31 | 312 | 3 |
| 525 | 31 | 28 | 31 | 30 | 30 | 19 | 1 | 2 | 15 | 29 | 30 | 31 | 277 | 7 |
| 526 | 31 | 28 | 30 | 28 | 23 | 3 | 0 | 1 | 14 | 26 | 30 | 31 | 245 | 12 |
| 527 | 31 | 28 | 31 | 30 | 30 | 10 | 0 | 0 | 13 | 29 | 30 | 31 | 263 | 12 |
| 531 | 31 | 28 | 31 | 28 | 26 | 4 | * | 1 | 8 | 29 | 30 | 31 | 247 | 4 |
| Asia, Inland: | ||||||||||||||
| 551 | 31 | 28 | 31 | 30 | 29 | 0 | 0 | 0 | 12 | 31 | 30 | 31 | 253 | 1 |
| 552 | 31 | 28 | 31 | 30 | 29 | 7 | 0 | 2 | 20 | 31 | 30 | 31 | 270 | 14 |
| 553 | 31 | 28 | 31 | 30 | 29 | 10 | * | 2 | 9 | 30 | 30 | 31 | 261 | 18 |
| Table XIII. Mean number of days with minimum temperature ^ ≤ ^ 32° F. (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 554 | 31 | 28 | 31 | 30 | 29 | 8 | * | 1 | 12 | 29 | 30 | 31 | 260 | 17 |
| 556 | 31 | 28 | 31 | 25 | 7 | * | 0 | 0 | 3 | 27 | 30 | 31 | 214 | 34 |
| 558 | 31 | 28 | 31 | 30 | 25 | 1 | 0 | 2 | 20 | 31 | 30 | 31 | 260 | 9 |
| 559 | 31 | 28 | 31 | 30 | 16 | 1 | 0 | 4 | 20 | 30 | 30 | 31 | 252 | 3 |
| 560 | 31 | 28 | 31 | 27 | 18 | 2 | 0 | 0 | 8 | 27 | 30 | 31 | 233 | 10 |
| 561 | 31 | 28 | 31 | 26 | 13 | * | 0 | * | 4 | 24 | 30 | 31 | 219 | 9 |
| 562 | 31 | 28 | 31 | 28 | 15 | 1 | 0 | * | 5 | 21 | 30 | 31 | 221 | 11 |
| 563 | 31 | 28 | 31 | 30 | 23 | 3 | 0 | 1 | 9 | 29 | 30 | 31 | 245 | 9 |
| 565 | 31 | 28 | 30 | 17 | 2 | 0 | 0 | 0 | 1 | 19 | 30 | 31 | 189 | .. |
| 566 | 31 | 28 | 31 | 29 | 13 | * | 0 | 1 | 1 | 28 | 30 | 31 | 223 | 23 |
| 567 | 31 | 28 | 31 | 30 | 21 | 1 | * | 1 | 13 | 30 | 30 | 31 | 247 | 12 |
| 568 | 31 | 28 | 31 | 31 | 30 | 15 | 1 | 0 | 1 | 12 | 30 | 30 | 238 | 33 |
| 570 | 31 | 28 | 31 | 29 | 16 | 0 | 0 | 3 | 14 | 30 | 30 | 31 | 243 | 7 |
| 571 | 31 | 28 | 31 | 30 | .. | .. | .. | .. | .. | 29 | 30 | 31 | .. | 0-1 |
| 572 | 31 | 28 | 31 | 30 | 28 | 3 | 0 | 3 | 18 | 30 | 30 | 31 | 263 | 14 |
| 573 | 31 | 28 | 31 | 25 | 8 | 0 | 0 | 0 | 4 | 23 | 29 | 31 | 211 | 9 |
| 574 | 31 | 28 | 31 | 26 | 13 | * | 0 | 0 | 5 | 23 | 30 | 31 | 219 | 11 |
| 575 | 31 | 28 | 31 | 28 | 15 | 1 | 0 | * | 10 | 28 | 30 | 31 | 233 | 18 |
| 576 | 31 | 28 | 31 | 30 | 21 | 2 | * | 2 | 14 | 30 | 30 | 31 | 250 | 13 |
Temperatures at moderate elevations in the Arctic differ
markedly from those recorded at lowland locations, primarily because
of the existence of the surface temperature inversion described in
previous sections. Temperatures at moderate elevations tend to
average considerably higher than those at lowland locations except
at inland points during summer when the surface inversion is non–
existent. At the highest Arctic elevations, however, temperatures
average lower than at most lowland locations, the differences being
most pronounced during the summer months. For example, over the
northern portion of the Greenland Ice Cap above 7,000 feet, July
temperatures may average between zero and 10° F. with extreme minima
as low as −20°. In winter, temperatures below −70° are probably
common. The lowest Greenland temperature on record, −84.6° F., was
obtained by the Wegener Expedition
[
^
54
^
]
at the Eismitte station
(70°54′ N.; 40°42′ W.; elevation 9,842 feet).
Annual Variation of Temperature
. - An examination of the annual
temperature curves for various locations reveals the existence of
three well-defined types, i.e., 1) maritime, 2) coastal, and 3)
continental.
(1)
Maritime
. - The very small temperature variation during
June, July, and August produces a flat curve in the graph of the
monthly mean temperatures (see
Fig.
^
Table X
^
). There is a similar tendency
toward a flat curve during the winter months without pronounced
monthly minima in the mean temperature. There is a definite tendency,
however, for the seasonal minima to occur in late winter or early
spring. (Over the Polar Sea the average winter temperature is of
the order of −30° F.)
(2)
Coastal
. - The coastal climate closely resembles the maritime,
the year consisting primarily of a long, cold winter and a short,
cool summer. There is a tendency toward a delayed seasonal maximum in
July or August. The
mean
summer temperature, while higher than over
the Arctic Ocean, remains below 50° F. The coldest month of the year
on the average is February, but in individual years the seasonal minima
may be delayed until March.
(3)
Arctic Continental
. - The interior arctic climate is
characterized by very low winter temperatures with a pronounced
winter minimum in January or February. Summer temperatures are
relatively very high and show pronounced monthly maxima in July with
a tendency toward higher temperatures in June than in August. The
annual ranges of
mean
temperature for individual localities may
exceed 100°. (The
absolute
range in temperature at Verkhoyansk is
188°.)
From the preceding discussion it is evident that the annual
range in temperature (difference in temperature between warmest and
coldest month) is directly related to topography and the degree of
maritime influence. Stations at high elevation exhibit a smaller
annual range in temperature than do low-level stations in the vicinity.
Maritime locations similarly show a smaller range in temperature than
do continental locations at the same latitude. In fact, as shown by
Fig.
^
46
^
, there is a close relation between the magnitude of the annual
range in mean temperature and distance from the seacoast.
Non-Periodic Changes in Temperature
. - The day-to-day variations in
temperature depend primarily upon the nearness of the region to the
major storm tracks and the temperature contracts between air masses
associated with passing frontal systems. Dynamic heating effects in
the lee of mountain ranges and the local effects of differences in
surface cover (water or ice versus land) are secondary causes of such
non-periodic variations. In general the magnitude of the interdiurnal
temperature variations throughout the Arctic is at a maximum in winter
and at a minimum in summer. The variations are at a minimum over the
open Arctic Ocean, where air-mass contrasts are lacking and dynamic
heating effects are exceptional. The variations are particularly
large in peripheral continental areas and in Alaska and coastal
Greenland, where considerable dynamic heating (chinook or foehn
effects) can occur in leeward locations during periods of strong
circulation.
Diurnal Variation of Temperature
. - The daily range in temperature
throughout the Arctic reflects the general characteristics of the
climatic picture. District insolational differences between day and
night, a dry-land cover, clear skies, low humidity, and an absence of
wind coupled with the presence of a shallow temperature inversion, are
all conducive to a large diurnal variation of temperature. Conversely,
long periods of daylight or darkness, snow, ice or water surface,
cloudy skies, and high surface winds coupled with a deep temperature ^
fig. 47 here
^
inversion (or no inversion), are all conducive to a small diurnal range
in temperature. In the period of winter darkness there are almost no
daily fluctuations in temperature on land; over the Arctic Ocean in
summer fluctuations are negligible since the temperature remains close
to freezing. In most maritime and coastal Arctic regions the
combination of circumstances, is such as to produce the maximum variation
in April. At this time there exists only a thin layer of cold air
below the inversion level, and it is only this layer that shares in
the daily temperature fluctuations. At the same time, the increased
insolation has begun to exert its diurnal effect. At inland ^locations^
farther south in the Arctic there is a tendency toward a secondary
maximum of variation in summer, after the land is free from snow and
the surface inversion has completely disappeared.
Geographic Distribution of Temperature
. - It is beyond the scope of
the present chapter to discuss in detail the regional and geographical
differences in temperature over the Arctic. Much of the geographical
distribution can be inferred from what has already been discussed;
additional generalized information will be found in the figures,
while more detailed local information is presented in the tables.
The general features of the Arctic temperature distribution are,
of course, determined by the general circulation of the atmosphere
in its relation to latitude, season, and the distribution of land
and sea. Of more specialized interest are the details of the circu–
lation in relation to major ocean currents and to important orographic
features.
It is clear from the isothermal chart for January (see Figure
^
44
^
)
that the deviations of the trend of isotherms from parallelism with
the latitude circles is closely related to the location of the
principal land and water masses. It can be noted that the low
temperature isotherms bend Equatorward over the continental land masses
and Greenland and bend Poleward over the Bering and Norweigian Seas
and Davis Strait where there is significant Poleward transport of
warm water. The effects of the Gulf Stream system can be noted in
the relatively high temperatures over European Arctic lands. The
effects of the transport of warm water through Bering Straits
similarly can be noted by comparing the higher temperatures along the
north coasts of Alaska and Siberia near the Straits with the relatively
low temperatures that exist at the same time farther westward along
the coasts of the East Siberian Sea and eastward over the Beaufort Sea
region.
A good example of the influence of a major topographic feature
on the temperature distribution is given by the steep temperature
gradient that can be noted along the southern Alaska coast on the
January isothermal chart. Here the mountain ranges close to the
coast act effectively as barriers between the stable Arctic air masses
to the north and east and the relatively warm maritime air over the
Gulf of Alaska. Those Arctic air masses which do arrive at the coast
after moving southward over the barrier have had much of their Arctic
“sting” removed through dynamical heating resulting from descent to
sea level pressures.
In contrast to the winter situation, the isotherms on the summer
chart (see Fig.
^
45
^
) are arranged more nearly parallel to the latitude
circles and the temperature gradients are less steep. If the low
temperatures found at higher altitudes on the Greenland Ice Cap and
elsewhere are disregarded, and only sea level temperature are considered,
it may be seen that in this season the cold pole of the Northern
Hemisphere actually exists over the Polar Sea.
PRECIPITATION, SNOWFALL, THUNDERSTORMS
Before entering into a detailed discussion of precipitation
characteristics of Arctic regions, it should be pointed out that observa–
tions regarding precipitation are, perhaps, the most unsatisfactory of
all Arctic meteorological records. During snowstorms it is often difficult
to determine whether snow is falling or is being whirled up from the surface.
The “dry” Arctic snow usually begins to drift at wind speeds of from 10 to
12 mph, and with high wind speeds the air is as thick with snow as would be
expected during a heavy snowstorm in extra-Arctic regions. Under these
circumstances, either driven snow will be blown into the recording gauge
or newly fallen snow will be blown out of the gauge. Over the Greenland
Ice Cap, observational difficulties are even more extreme because the
heavier precipitation is almost
^
i
^
nvariably associated with strong winds.
Nor can the accretion of snow cover be used as a measure of the actual
amounts of precipitation because of excessive drifting of surface snow
and concurrent ablation through evaporation or melting. The observational
difficulties known to exist in the Arctic caused the earlier permanent
meteorological stations to give up all attempts at direct measurement of
precipitation
^
[
42
]
^
.
Another complication arises in attempting to record the number of days
with measureable precipitation. Because of the exceedingly small moisture
concentration possible at very low temperatures (see Table
^
II
^
), the falling
snow during cold weather is very “fine” and there are many occasions when
precipitation is so slight as to defy measurement. The records for one
April at Goose Fjord, Ellesmere Island, for example, indicated that, while
precipitation fell on 11 days during the month, the precipitation amounts
for the 11 days totaled only 0.2 mm (less than 0.01 inch). At North
American Arctic stations a day with precipitation is considered as a
24-hour period during which 0.01 inch or more of rain or snow (melted) is
collected. Elsewhere a value of 0.1 mm is usually considered the limiting
amount, although some stations have recorded all days when precipitation
occurred, regardless of amount. These limitations of the data should be
kept in mind when attempting to make regional comparisons.
Precipitation over most of the Arctic is very light and the annual
amounts are so small that the region would be described as desert or
semi-desert were it located in southerly latitudes. Available data
indicate that over much of the Polar Basin the annual precipitation
amounts average less than 10 inches, while over the Siberian-American
portion of the Arctic Ocean and the whole northern part of the Canadian
Archipelago, the amounts are generally of the order of 4 inches or less
^
[
42
]
^
. The greatest portion of the annual precipitation falls in the
summer and as rain; snow, however, appears in every month, and sleet,
occasionally. Farther southward, near the regions of most frequent
frontal activity around the peripheral portions of the Arctic, the annual
precipitation amounts are more respectable. Some points in Greenland and
the European Arctic, for example, present an annual precipitation in excess
of 40 inches.
Form of Precipitation
. - Snow is the most frequent form of precipitation
but, as mentioned previously, it does not always account for the major
part of the measured quantity of precipitation. Over much of the Polar
Basin snow may be expected during all months of the year, and in the far
north the number of days with snow may exceed the number of days with rain
even during June. During July and August rain is normally the most
frequent form of precipitation in these regions, but by September snow
again predominates. On the other hand, many high latitude stations have
recorded rain during winter. During January 1937, for example, Domashnii
Ostrov (at approximately 80° N.) recorded 4 days with liquid precipitation
^
[
45
]
^
. Strictly speaking, the precipitation in nearly all of these
instances is more properly described as drizzle than as rain. The situa–
tions occur with temperatures which are unseasonably high but not always
above freezing. On February 10, 1939, for example, drizzle was observed
at Yugorsky Shar (on the Kara Sea) although the maximum temperature for
the date was −4° F.
^
[
45
]
^
.
Along the immediate coasts in the more southerly latitudes and in
some insular locations, rain is by far most frequent form of
precipitation, and even in January and February sleet or rain is common.
Days with precipitation occurring simultaneously in the forms of
rain and snow are comparatively rare over the true Arctic. Such days,
when they do occur, are characterized by unstable weather conditions and
are observed primarily in the transitional seasons of spring and autumn.
However, in the far north such occurrences are most frequent in summer,
while in the more southerly portions of the Arctic they are most frequent
in winter.
Sleet, which is precipitation in the form of small grains of ice and
which occurs when rain falls through a significant layer of air below 32° F.,
is of frequent occurrence along portions of the coasts of the Arctic Ocean.
It occurs most frequently during winter although it may be observed during
any month except July and August. The phenomenon appears to be particularly
prevalent in the coastal Kara Sea area. Ostrov Nedeneniia, for example,
records an average of 104 days a year with sleet, Gyao-Youro, 74 days, and
Russkii Ostrov and Mys Chelyuskin, each 66 days
^
[
45
]
^
.
Rime, a deposit of granular ice which is caused by the imp^in^gement
and freezing (without shattering) of sub-cooled for droplets on solid
surfaces and objects exposed to fog-laden winds, is observed over most
northern Arctic coastal regions throughout the year. In some locations
the phenomenon may occur on as many as 60 days per year (as at Tikaya
Bukhta) but averages of 15 to 20 days are probably more typical. Upon
occasion the rough deposit of ice may accumulate to rather impressive
amounts; Wiese
^
[
56
]
^
recorded 3 cm (1.2 inches) of accumulated rime
during a 24-hour period in March at a point along the coast of Novoya
Zemlya.
Hoarfrost is another form of precipitation of importance in the
Arctic, particularly in region where the total precipitation is low.
It is caused through direct condensation of atmospheric water vapor on
solid objects which are below freezing or on snow or ice surfaces. It
differs from rime in having a crystalline rather than a granular structure.
It also has a considerably lesser rate of accumulation. According to
measurements on the
Maud
Expedition, hoarfrost accounted for 15 percent
of the total precipitation collected over the Polar Sea. In general, the
amount of hoarfrost increases with increasing wind speed providing the
relative humidity of the air (with respect to ice) is greater than 100
percent. Over the Arctic pack-ice, however, the probability that hoarfrost
will occur decreases with increasing wind speed in agreement with the fact
that the humidity over the ice tends to decrease at higher wind velocities
^
[
43
]
^
. The probability of hoarfrost increased regularly with decreasing
temperature but the rate of accretion also decreases because of lessened
water vapor, and at very low temperatures the amount become too small to
measure.
Conditions are particularly favorable for hoarfrost formation over
the Greenland Ice Cap. Since the strong winds over the inland ice bring
large volumes of supersaturated air into surface contact, all conditions
are favorable for an increase in the deposit of crystals on the ice.
However, calculations by Sverdrup indicate that the total annual amounts
do not exceed 1.25 inches of water a year - a finding that does not permit
the conclusion that frost formation on the interior Ice Cap furnishes the
principal part of the ice accretion.
Still another form of precipitation fairly common in the Arctic is
one which is variously referred to as glaze, glaze ice, freezing rain or
simply as “ice storm”. It occurs when rain (or drizzle) falls on objects
or surfaces which are below freezing. The raindrops shatter on impact and
immediately freeze, forming a layer of clear ice on all objects exposed to
the rain. Glaze differs from rime and hoarfrost in presenting a clear,
glassy appearance instead of a rough and opaque granular or crystalline
structure. It becomes a phenomenon of considerable practical concern when
the deposits on telephone lines, antenna
^
e
^
, poles, or other structural objects
are heavy enough to cause structural failure.
Glaze is formed most frequently with surface air temperatures
between the limits of about 23° and 32° F. Under such conditions
temperatures a short distance over the surface are frequently above
freezing (see pages )
^
,
^
a requisite for rainfall formation. At air
temperatures much above 32° F. there is little opportunity for surface
freezing; at temperatures much below 20° the precipitation is almost
invariably snow although there are exceptions. (See page .)
Glaze occurs most frequently during spring and autumn except in the far
northern portions of the Arctic where summer is the season of maximum
frequency. At most coastal stations on the Polar Sea the number of days
with glaze is usually less than 10 but in some years a few localities
may record as many as 45 such days
^
[
45
]
^
.
From the standpoint of aviation activities in the Arctic, the
formation of rime, hoarfrost, and glaze is of considerable practical
concern. Any amount of frost or glassy ice on wings or stabilizers
of aircraft, however small it may be, should be removed before take-off
is attempted. A take-off into a fog of sub-cooled water droplets
(rime-forming condition) or into a rain at sub-zero temperatures (glaze
situation) can be particularly dangerous. Several cases of severe
prop-icing have been reported when running-up the engines in sub-cooled
fog, and severe wing icing has occurred not only during take-offs and
landings but even during taxiing for take-offs
^
[
33
]
^
. The rapidity with
which glaze ice or rime can accumulate on aircraft should never by
underestimated by those flying under Arctic conditions.
Annual Variation of Precipitation
. - Data from the Arctic Ocean indicate
that the probability of precipitation has a double annual period with
maxim in spring and autumn, a principal minimum in winter and a secondary
minimum in summer. This march of precipitation probability corresponds
to the annual variation of cloudiness at the coast but not to the varia–
tion of cloudiness over the pack-ice
^
[
43
]
^
. This lack of association
^
table XIV and XV here
^
merely reflects the fact that the stratus clouds characteristic of the
pack-ice are largely the result of local processes. They are in no way
related to the circulations forming a part of cyclonic systems which affect
the Arctic. Conversely, it must be assumed that coastal cloudiness is
essentially frontal phenomenon.
Sverdrup (loc. cit.) found that May has the greatest number of days
with precipitation and the midwinter months the smallest. The contrast
between summer winter precipitation frequencies appears to be greater
over the Polar Sea than in coastal areas.
| Table ^ XIV ^. Mean number of days with precipitation ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | |||||||||||||||
| 002 | c | 11 | 11 | 13 | 13 | 20 | 20 | 21 | 19 | 22 | 14 | 9 | 9 | 180 | 2 |
| 003 | c | 2 | 8 | 6 | 6 | 19 | 17 | 14 | 17 | 16 | 13 | 6 | 6 | 130 | 2 |
| 004 | c | 19 | 19 | 15 | 15 | 11 | 9 | 11 | 9 | 15 | 15 | 17 | 18 | 174 | … |
| 005 | c | 14 | 14 | 14 | 10 | 12 | 7 | 7 | 8 | 14 | 13 | 14 | 13 | 139 | … |
| 006 | e | 13 | 8 | 7 | 7 | 6 | 8 | 11 | 14 | 12 | 10 | 9 | 9 | 114 | 24 |
| 007 | e | 18 | 14 | 13 | 11 | 7 | 11 | 13 | 16 | 20 | 17 | 13 | 16 | 169 | 21 |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | c | 3 | 3 | 2 | 3 | 2 | 3 | 8 | 8 | 8 | 7 | 4 | 3 | 54 | 22-25 |
| 101 | c | 6 | 5 | 5 | 9 | 6 | 4 | 9 | 9 | 14 | 17 | 4 | 6 | 94 | 1-2 |
| 102 | c | 5 | 2 | 3 | 2 | 1 | 2 | 7 | 7 | 5 | 4 | 3 | 4 | 45 | 6-10 |
| 103 | c | 3 | 13 | 6 | 5 | 15 | 8 | 12 | 16 | 16 | 13 | 2 | 3 | 112 | 2-3 |
| 104 | c | 9 | 7 | 8 | 8 | 8 | 9 | 14 | 17 | 14 | 10 | 8 | 9 | 121 | 23-36 |
| 105 | c | 11 | 11 | 8 | 16 | 7 | 6 | 12 | 10 | 13 | 13 | 17 | 18 | 156 | 2-5 |
| 106 | c | 7 | 6 | 5 | 4 | 5 | 6 | 10 | 15 | 14 | 12 | 7 | 6 | 97 | 23-25 |
| Alaska, Inland: | |||||||||||||||
| 150 | c | 14 | 12 | 18 | 11 | 14 | 15 | 14 | 13 | 18 | 20 | 12 | 17 | 178 | 2-5 |
| 151 | c | .. | 8 | 21 | 18 | 15 | 22 | 19 | 25 | 23 | 26 | 21 | 28 | … | 0-2 |
| 152 | c | 5 | 5 | 4 | 3 | 4 | 7 | 10 | 7 | 8 | 6 | 5 | 4 | 68 | 5-8 |
| 153 | c | 5 | 4 | 3 | 2 | 3 | 6 | 7 | 9 | 6 | 5 | 5 | 3 | 58 | 20-27 |
| 154 | c | 9 | 6 | 8 | 7 | 8 | 11 | 16 | 20 | 18 | 10 | 8 | 9 | 130 | 17-19 |
| 155 | c | 8 | 7 | 7 | 4 | 7 | 10 | 14 | 15 | 13 | 9 | 8 | 7 | 109 | 30-31 |
| 156 | c | 10 | 6 | 6 | 4 | 9 | 10 | 13 | 15 | 10 | 11 | 10 | 7 | 111 | 11 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Alaska, Inland (cont.): | |||||||||||||||
| 157 | c | 7 | 5 | 5 | 5 | 8 | 11 | 13 | 13 | 11 | 8 | 7 | 7 | 100 | 33-36 |
| Canada, Coastal and Insular: | |||||||||||||||
| 204 | c | 5 | 3 | 5 | 4 | 6 | 7 | 6 | 8 | 7 | 9 | 8 | 4 | 72 | 4-5 |
| 206 | c | 6 | 6 | 7 | 6 | 8 | 5 | 8 | 14 | 10 | 9 | 6 | 2 | 87 | 5 |
| 208 | a | 4 | 8 | 19 | 9 | 19 | 9 | 6 | .. | 17 | 24 | 6 | 2 | … | 1 |
| 210 | c | 6 | 3 | 4 | 4 | 7 | 6 | 6 | 14 | 10 | 8 | 4 | 5 | 77 | 5 |
| 211 | c | 6 | 3 | 6 | 6 | 6 | 6 | 7 | 10 | 8 | 8 | 6 | 5 | 77 | 7 |
| 213 | c | 3 | 1 | 2 | 2 | 2 | 4 | 6 | 6 | 4 | 5 | 3 | 3 | 41 | 4-5 |
| 214 | c | 4 | 1 | 2 | 1 | 5 | 4 | 5 | 5 | 8 | 15 | 6 | 3 | 59 | 2-3 |
| 216 | c | 8 | 6 | 7 | 6 | 7 | 6 | 10 | 15 | 10 | 10 | 10 | 8 | 103 | 10 |
| 217 | c | 3 | 3 | 6 | 4 | 5 | 6 | 10 | 13 | 10 | 6 | 5 | 3 | 74 | 6 |
| 221 | c | 6 | 5 | 6 | 9 | 8 | 7 | 12 | 11 | 12 | 9 | 9 | 8 | 102 | 10 |
| 223 | c | 6 | 6 | 6 | 11 | 12 | 10 | 10 | 11 | 11 | 13 | 15 | 11 | 122 | 10 |
| 224 | c | 5 | 5 | 6 | 6 | 8 | 9 | 9 | 8 | 8 | 10 | 9 | 7 | 91 | 4-7 |
| 226 | c | 6 | 3 | 4 | 7 | 5 | 7 | 9 | 9 | 7 | 8 | 8 | 7 | 81 | 6-8 |
| 227 | c | 10 | 8 | 11 | 9 | 12 | 11 | 12 | 11 | 14 | 14 | 15 | 14 | 141 | 10 |
| 228 | c | 5 | 6 | 6 | 6 | 7 | 9 | 10 | 12 | 11 | 12 | 9 | 8 | 101 | 10 |
| Canada, Inland: | |||||||||||||||
| 250 | c | 4 | 5 | 4 | 4 | 4 | 5 | 9 | 10 | 10 | 8 | 8 | 5 | 76 | 10 |
| 252 | c | 8 | 6 | 8 | 5 | 9 | 11 | 13 | 14 | 11 | 11 | 11 | 10 | 117 | 10 |
| 253 | c | 7 | 7 | 8 | 3 | 5 | 9 | 13 | 11 | 10 | 11 | 12 | 8 | 104 | 5 |
| 254 | c | 7 | 7 | 8 | 6 | 8 | 6 | 9 | 14 | 10 | 12 | 12 | 7 | 106 | 10 |
| 255 | c | 9 | 7 | 5 | 7 | 9 | 12 | 12 | 14 | 12 | 12 | 15 | 13 | 127 | 8 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland (cont.): | |||||||||||||||
| 257 | c | 6 | 7 | 7 | 6 | 7 | 8 | 10 | 12 | 8 | 8 | 8 | 6 | 93 | 10 |
| 258 | c | 6 | 5 | 8 | 5 | 7 | 7 | 10 | 9 | 6 | 7 | 8 | 8 | 86 | 10 |
| 259 | c | 8 | 8 | 9 | 5 | 8 | 7 | 9 | 9 | 9 | 10 | 12 | 9 | 103 | 10 |
| 260 | c | 8 | 8 | 8 | 5 | 6 | 6 | 11 | 7 | 9 | 10 | 8 | 9 | 99 | … |
| 262 | e | 11 | 8 | 9 | 5 | 7 | 6 | 11 | 7 | 9 | 11 | 8 | 11 | 103 | … |
| Greenland and Iceland, Coastal and Insular | |||||||||||||||
| 302 | a | 17 | 10 | 11 | 14 | 13 | 13 | 16 | 12 | 15 | 17 | 17 | 15 | 170 | 3 |
| 303 | b | 18 | 10 | 11 | 6 | 9 | 6 | 3 | 6 | 6 | 8 | 12 | 14 | 107 | … |
| 304 | b | 4 | 4 | 6 | 5 | 7 | 6 | 7 | 8 | 10 | 11 | 10 | 6 | 84 | 50 |
| 305 | e | 13 | 14 | 15 | 12 | 14 | 6 | 10 | 10 | 18 | 18 | 15 | 17 | 162 | 3 |
| 307 | d | 7 | 4 | 5 | 3 | 4 | 3 | 4 | 5 | 5 | 4 | 6 | 6 | 56 | 5 |
| 308 | b | 9 | 8 | 7 | 4 | .. | 4 | 5 | 1 | 7 | 6 | 5 | 6 | … | 9 |
| 309 | b | 8 | 8 | 7 | 8 | 5 | 5 | 7 | 8 | 9 | 11 | 12 | 11 | 100 | 13 |
| 310 | c | 9 | 12 | 16 | 9 | 8 | 5 | 10 | 7 | 20 | 11 | 16 | 13 | 139 | 2 |
| 312 | c | 4 | 4 | 3 | 2 | 3 | 5 | 11 | 8 | 7 | 6 | 6 | 5 | 55 | 7 |
| 313 | c | 14 | 14 | 14 | 12 | 14 | 7 | 11 | 5 | 17 | 12 | 12 | 12 | 146 | 5 |
| 314 | c | 8 | 8 | 7 | 6 | 7 | 8 | 8 | 10 | 11 | 11 | 9 | 6 | 97 | 45 |
| 317 | b | 14 | 12 | 12 | 10 | 10 | 9 | 8 | 9 | 10 | 13 | 11 | 12 | 131 | 29 |
| 318 | b | 12 | 10 | 12 | 10 | 10 | 10 | 9 | 10 | 13 | 12 | 12 | 11 | 131 | 45 |
| 321 | c | 19 | 17 | 18 | 17 | 13 | 14 | 14 | 13 | 12 | 16 | 14 | 19 | 187 | 2-3 |
| 330 | e | 21 | 20 | 19 | 18 | 16 | 17 | 14 | 20 | 22 | 20 | 19 | 20 | 226 | 11 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular (cont.): | |||||||||||||||
| 331 | b | 21 | 19 | 18 | 16 | 14 | 14 | 14 | 19 | 19 | 17 | 19 | 21 | 211 | 16 |
| 333 | e | 21 | 17 | 18 | 15 | 17 | 16 | 15 | 21 | 21 | 19 | 20 | 20 | 220 | 11 |
| 334 | a | 10 | 10 | 10 | 9 | 8 | 6 | 8 | 10 | 11 | 12 | 12 | 11 | 117 | … |
| 335 | e | 14 | 11 | 12 | 12 | 9 | 10 | 13 | 14 | 13 | 17 | 14 | 14 | 153 | 15 |
| 336 | e | 11 | 12 | 11 | 9 | 5 | 7 | 10 | 12 | 12 | 13 | 11 | 12 | 125 | 11 |
| 337 | e | 18 | 16 | 17 | 16 | 17 | 15 | 17 | 19 | 23 | 19 | 18 | 21 | 216 | 11 |
| 338 | b | 13 | 13 | 13 | 10 | 10 | 11 | 8 | 11 | 14 | 12 | 14 | 14 | 142 | 15 |
| 339 | e | 14 | 10 | 12 | 11 | 8 | 9 | 10 | 12 | 13 | 13 | 10 | 11 | 133 | 7 |
| 340 | c | 19 | 16 | 16 | 15 | 13 | 11 | 11 | 16 | 16 | 18 | 16 | 18 | 186 | 14 |
| 341 | e | 19 | 13 | 18 | 13 | 13 | 10 | 15 | 13 | 16 | 14 | 18 | 21 | 183 | 8 |
| Greenland and Iceland, Inland: | |||||||||||||||
| 350 | e | 7 | 4 | .. | .. | .. | .. | .. | .. | .. | 11 | 13 | 10 | … | … |
| 351 | e | 19 | 13 | 18 | 21 | 19 | 15 | 20 | 17 | 15 | 18 | 15 | 13 | 203 | 1 |
| 360 | e | 17 | 15 | 15 | 15 | 17 | 14 | 15 | 21 | 18 | 17 | 14 | 16 | 194 | 7 |
| 361 | e | 14 | 10 | 11 | 10 | 5 | 7 | 12 | 13 | 10 | 14 | 10 | 10 | 126 | 11 |
| Europe, Coastal and Insular: | |||||||||||||||
| 400 | e | 13 | 14 | 11 | 10 | 10 | 9 | 12 | 15 | 13 | 16 | 13 | 12 | 147 | 1 |
| 401 | e | 9 | 7 | 8 | 9 | 12 | 12 | 13 | 18 | 18 | 15 | 13 | 9 | 144 | 2 |
| 403 | c | 12 | 12 | 12 | 10 | 7 | 6 | 6 | 6 | 9 | 11 | 11 | 12 | 114 | … |
| 406 | b | 14 | 16 | 15 | 13 | 13 | 12 | 12 | 10 | 16 | 17 | 16 | 13 | 167 | 12 |
| 408 | b | 14 | 16 | 12 | 11 | 10 | 9 | 10 | 11 | 15 | 15 | 16 | 15 | 155 | … |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular (cont.): | |||||||||||||||
| 411 | d | 20 | 19 | 15 | 13 | 14 | 12 | 12 | 13 | 19 | 20 | 20 | 16 | 194 | 50 |
| 412 | b | 12 | 11 | 13 | 11 | 11 | 11 | 12 | 13 | 17 | 15 | 16 | 13 | 155 | 20 |
| 414 | b | 16 | 15 | 13 | 13 | 11 | 12 | 11 | 13 | 17 | 16 | 17 | 14 | 170 | 20 |
| 415 | c | 13 | 13 | 12 | 13 | 16 | 15 | 15 | 16 | 18 | 17 | 17 | 14 | 179 | 25 |
| 417 | e | 25 | 21 | 19 | 18 | 18 | 14 | 11 | 16 | 22 | 22 | 22 | 23 | 231 | … |
| 420 | b | 15 | 11 | 13 | 11 | 12 | 11 | 12 | 13 | 15 | 15 | 15 | 14 | 157 | 20 |
| 421 | b | 12 | 11 | 12 | 9 | 11 | 10 | 12 | 13 | 11 | 14 | 12 | 15 | 142 | 36 |
| 422 | b | 15 | 13 | 12 | 10 | 11 | 10 | 13 | 17 | 17 | 18 | 16 | 15 | 166 | 30 |
| 423 | b | 15 | 12 | 12 | 9 | 9 | 9 | 12 | 12 | 12 | 14 | 14 | 14 | 144 | 27 |
| 424 | b | 19 | 16 | 14 | 13 | 12 | 13 | 12 | 16 | 15 | 17 | 18 | 19 | 184 | 36 |
| 425 | c | 14 | 13 | 11 | 12 | 13 | 12 | 16 | 16 | 16 | 16 | 16 | 17 | 170 | 18 |
| 426 | a | 22 | 19 | 14 | 12 | 14 | 13 | 16 | 19 | 16 | 16 | 19 | 22 | 203 | 18 |
| 427 | a | 13 | 13 | 11 | 11 | 11 | 10 | 11 | 13 | 16 | 16 | 15 | 15 | 155 | 25 |
| 428 | a | 16 | 15 | 13 | 11 | 12 | 12 | 12 | 14 | 15 | 17 | 17 | 17 | 171 | 25 |
| 429 | b | 8 | 7 | 5 | 7 | 10 | 9 | 11 | 12 | 14 | 11 | 10 | 7 | 112 | 17 |
| Europe, Inland: | |||||||||||||||
| 450 | b | 13 | 11 | 10 | 8 | 10 | 10 | 16 | 16 | 13 | 12 | 13 | 12 | 144 | 32 |
| 451 | d | 5 | 5 | 6 | 5 | 6 | 8 | 9 | 9 | 7 | 8 | 8 | 6 | 82 | … |
| 452 | c | 5 | 5 | 5 | 7 | 8 | 9 | 10 | 12 | 8 | 9 | 7 | 6 | 91 | … |
| 453 | b | 19 | 16 | 15 | 14 | 13 | 15 | 15 | 17 | 17 | 18 | 18 | 18 | 195 | 30 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Inland (cont.): | |||||||||||||||
| 454 | c | 21 | 17 | 17 | 17 | 20 | 19 | 21 | 23 | 22 | 20 | 19 | 18 | 234 | 31 |
| 455 | b | 12 | 10 | 10 | 9 | 12 | 12 | 14 | 15 | 12 | 13 | 12 | 13 | 144 | 38 |
| 456 | c | 14 | 12 | 13 | 10 | 10 | 11 | 15 | 18 | 13 | 15 | 14 | 15 | 160 | 26 |
| 457 | b | 19 | 16 | 15 | 14 | 14 | 16 | 15 | 18 | 16 | 19 | 19 | 19 | 200 | 36 |
| 458 | b | 19 | 17 | 15 | 14 | 14 | 15 | 15 | 17 | 17 | 19 | 19 | 20 | 201 | 35 |
| Asia, Coastal and Insular: | |||||||||||||||
| 500 | e | 8 | 7 | 9 | 10 | 11 | 12 | 13 | 17 | 18 | 14 | 10 | 9 | 138 | 3 |
| 501 | e | 13 | 9 | 7 | 9 | 11 | 13 | 14 | 18 | 19 | 16 | 10 | 12 | 151 | 18 |
| 502 | e | 14 | 14 | 9 | 13 | 16 | 16 | 19 | 24 | 23 | 17 | 11 | 11 | 186 | 19 |
| 503 | e | 8 | 9 | 6 | 4 | 6 | 10 | 12 | 14 | 13 | 13 | 12 | 10 | 116 | 22 |
| 505 | e | 17 | 15 | 13 | 12 | 13 | 12 | 11 | 15 | 18 | 17 | 16 | 14 | 173 | 14 |
| 506 | c | 14 | 12 | 11 | 11 | 9 | 9 | 12 | 13 | 15 | 17 | 14 | 14 | 151 | 18 |
| 507 | e | 12 | 10 | 12 | 9 | 8 | 8 | 9 | 11 | 16 | 16 | 13 | 14 | 134 | 6 |
| 508 | e | 19 | 18 | 15 | 13 | 11 | 10 | 11 | 19 | 21 | 22 | 18 | 16 | 192 | 13 |
| 509 | e | 21 | 16 | 15 | 13 | 14 | 15 | 12 | 20 | 22 | 23 | 18 | 16 | 204 | 15 |
| 510 | e | 13 | 12 | 12 | 10 | 9 | 13 | 12 | 20 | 20 | 18 | 15 | 14 | 169 | 17 |
| 511 | c | 4 | 6 | 1 | 2 | 10 | 8 | 2 | 8 | 12 | 4 | 11 | 7 | 75 | 2 |
| 512 | c | 9 | 9 | 7 | 5 | 4 | 10 | 11 | 12 | 14 | 12 | 9 | 6 | 108 | 3 |
| 513 | c | 8 | 12 | 9 | 9 | 8 | 12 | 14 | 14 | 17 | 13 | 12 | 12 | 141 | 7 |
| 514 | f | 0 | 0 | * | 0 | * | 2 | 2 | 2 | 1 | * | 0 | 0 | 8 | 11 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 515 | c | 4 | 6 | 5 | 4 | 11 | 13 | 12 | 13 | 13 | 9 | 9 | 6 | 107 | 9 |
| 517 | b | 8 | 7 | 7 | 6 | 8 | 8 | 9 | 12 | 10 | 10 | 7 | 7 | 99 | 11 |
| 518 | e | 14 | 11 | 13 | 11 | 12 | 12 | 11 | 16 | 21 | 19 | 17 | 17 | 175 | 9 |
| 519 | e | 13 | 11 | 9 | 11 | 13 | 12 | 11 | 17 | 21 | 19 | 16 | 14 | 167 | 12 |
| 520 | d | 8 | 8 | 7 | 5 | 8 | 8 | 10 | 11 | 11 | 10 | 10 | 10 | 107 | … |
| 521 | e | 15 | 11 | 12 | 12 | 15 | 14 | 10 | 16 | 18 | 18 | 15 | 14 | 171 | 25 |
| 522 | b | 8 | 10 | 8 | 8 | 6 | 6 | 13 | 14 | 14 | 14 | 12 | 9 | 120 | 5-8 |
| 523 | c | 6 | 10 | 11 | 9 | 8 | 6 | 10 | 14 | 18 | 12 | 9 | 7 | 120 | 3 |
| 525 | c | 8 | 7 | 8 | 8 | 5 | 4 | 10 | 12 | 14 | 12 | 12 | 10 | 110 | 8 |
| 526 | b | 8 | 8 | 9 | 6 | 7 | 9 | 10 | 12 | 9 | 10 | 9 | 8 | 106 | 16 |
| 527 | b | 10 | 10 | 9 | 7 | 9 | 9 | 11 | 12 | 10 | 8 | 10 | 9 | 115 | 14 |
| 531 | c | 3 | 3 | 6 | 4 | 7 | 11 | 9 | 12 | 13 | 10 | 7 | 4 | 88 | 4 |
| Asia, Inland: | |||||||||||||||
| 550 | e | 14 | 13 | 13 | 13 | 13 | 15 | 16 | 20 | 17 | 20 | 15 | 15 | 185 | 28 |
| 551 | c | 8 | 12 | 13 | 14 | 14 | 13 | 15 | 16 | 13 | 20 | 11 | 15 | 167 | 3 |
| 552 | c | 12 | 10 | 11 | 8 | 7 | 10 | 12 | 12 | 13 | 18 | 13 | 12 | 138 | 13 |
| 553 | e | 15 | 13 | 13 | 10 | 12 | 14 | 12 | 17 | 19 | 20 | 16 | 14 | 173 | 26 |
| 554 | b | 14 | 13 | 11 | 12 | 10 | 12 | 12 | 13 | 18 | 17 | 16 | 14 | 162 | 18 |
| 556 | b | 5 | 5 | 4 | 4 | 4 | 7 | 8 | 8 | 6 | 7 | 8 | 7 | 73 | 30 |
| 557 | c | 8 | 7 | 6 | 6 | 4 | 7 | 11 | 12 | 9 | 4 | 9 | 6 | 99 | 5 |
| 558 | c | 8 | 9 | 7 | 5 | 6 | 8 | 10 | 11 | 12 | 11 | 11 | 10 | 107 | 5 |
| Table ^ XIV ^. Mean number of days with precipitation (cont.) ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | |||||||||||||||
| 559 | c | 17 | 15 | 10 | 6 | 7 | 10 | 14 | 15 | 13 | 16 | 18 | 19 | 161 | 10 |
| 560 | c | 8 | 7 | 9 | 9 | 11 | 13 | 12 | 12 | 11 | 13 | 11 | 11 | 127 | 8 |
| 561 | c | 14 | 10 | 10 | 7 | 11 | 12 | 11 | 15 | 15 | 16 | 17 | 15 | 154 | 10 |
| 562 | c | 14 | 11 | 11 | 7 | 14 | 15 | 12 | 14 | 16 | 15 | 16 | 15 | 159 | 10 |
| 563 | c | 12 | 12 | 12 | 11 | 12 | 13 | 12 | 14 | 17 | 19 | 16 | 14 | 164 | 42 |
| 565 | e | 14 | 12 | 9 | 8 | 10 | 9 | 6 | 7 | 9 | 15 | 19 | 16 | 134 | 12 |
| 566 | b | 8 | 8 | 7 | 7 | 9 | 11 | 9 | 10 | 10 | 10 | 11 | 10 | 110 | 26 |
| 567 | c | 11 | 10 | 9 | 7 | 8 | 9 | 10 | 9 | 11 | 14 | 14 | 11 | 122 | 25 |
| 568 | b | 9 | 8 | 5 | 5 | 6 | 8 | 9 | 10 | 9 | 12 | 12 | 10 | 104 | 31 |
| 569 | e | 3 | 6 | 4 | 5 | 12 | 15 | 8 | 14 | 7 | 10 | 6 | 4 | 94 | 1 |
| 570 | e | 6 | 5 | 5 | 7 | 7 | 8 | 8 | 11 | 9 | 9 | 6 | 4 | 85 | 18 |
| 572 | e | 8 | 8 | 8 | 6 | 6 | 7 | 12 | 12 | 8 | 10 | 11 | 9 | 105 | 21 |
| 573 | c | 8 | 7 | 7 | 6 | 8 | 10 | 10 | 11 | 10 | 11 | 10 | 10 | 107 | 18 |
| 574 | c | 11 | 9 | 9 | 10 | 12 | 14 | 12 | 14 | 13 | 16 | 15 | 13 | 146 | 21 |
| 575 | c | 16 | 15 | 15 | 11 | 12 | 13 | 12 | 13 | 14 | 16 | 19 | 17 | 173 | 10 |
| 576 | b | 17 | 14 | 14 | 11 | 11 | 12 | 14 | 12 | 14 | 16 | 21 | 19 | 176 | 13 |
| 577 | e | 16 | 13 | 12 | 12 | 12 | 13 | 13 | 14 | 13 | 18 | 17 | 16 | 167 | … |
| Table ^ XV ^. Mean precipitation (inches) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 003 | 0.1 | 0.3 | 0.2 | 0.1 | 0.3 | 0.4 | 0.7 | 1.0 | 0.3 | 0.2 | 0.2 | 0.2 | 3.9 | 2 |
| 004 | 1.5 | 1.7 | 1.1 | 0.9 | 0.5 | 0.6 | 0.8 | 1.1 | 2.5 | 2.2 | 1.4 | 1.0 | 15.3 | 7 |
| 005 | 1.1 | 1.4 | 1.2 | 0.7 | 0.7 | 0.8 | 0.7 | 0.9 | 1.6 | 1.4 | 1.0 | 1.1 | 12.6 | 15 |
| 006 | 0.2 | 0.2 | 0.1 | 0.1 | 0.2 | 0.3 | 1.1 | 0.5 | 0.6 | 0.2 | 0.1 | 0.2 | 3.7 | 24 |
| 007 | 0.2 | 0.2 | 0.1 | 0.1 | * | 0.7 | 1.1 | 1.0 | 0.3 | 0.2 | 0.1 | 0.2 | 4.5 | 21 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 0.3 | 0.9 | 0.7 | 0.5 | 0.6 | 0.3 | 0.3 | 4.2 | 25-27 |
| 101 | 0.1 | 0.1 | 0.2 | 0.1 | 0.1 | 0.1 | 0.3 | 0.3 | 0.4 | 0.5 | * | 0.4 | 2.6 | … |
| 102 | 0.7 | 0.2 | 0.2 | 0.4 | 0.1 | 0.4 | 1.3 | 1.1 | 0.6 | 0.5 | 0.3 | 0.3 | 6.1 | 11 |
| 103 | 1.3 | 1.3 | 0.9 | 0.6 | 0.5 | 1.0 | 1.4 | 2.5 | 2.6 | 1.1 | 0.6 | 1.3 | 14.9 | 3-6 |
| 104 | 1.1 | 0.8 | 0.8 | 0.7 | 0.6 | 1.1 | 2.5 | 3.2 | 2.7 | 1.6 | 1.0 | 1.1 | 17.3 | 35-37 |
| 105 | 1.1 | 1.5 | 0.5 | 1.4 | 0.6 | 0.4 | 1.5 | 1.4 | 2.4 | 2.1 | 1.0 | 1.0 | 14.8 | 2-5 |
| 106 | 0.8 | 0.7 | 0.6 | 0.4 | 0.5 | 0.7 | 1.6 | 2.6 | 2.6 | 2.2 | 1.0 | 0.9 | 14.6 | 24-26 |
| Alaska, Inland: | ||||||||||||||
| 150 | * | * | 1.0 | 1.7 | 1.0 | 1.6 | 2.6 | 5.0 | 3.7 | 1.5 | * | * | 18.8 | 2-5 |
| 151 | … | … | … | * | * | 1.0 | 1.0 | 2.7 | * | 1.0 | * | * | … | 1-2 |
| 152 | 0.6 | 0.2 | 0.2 | 0.5 | 0.6 | 0.7 | 1.5 | 0.9 | 1.8 | 0.6 | 0.6 | 0.6 | 8.2 | 6-8 |
| 153 | 0.4 | 0.4 | 0.3 | 0.3 | 0.5 | 0.8 | 1.1 | 1.2 | 0.6 | 0.6 | 0.4 | 0.3 | 6.8 | 21-27 |
| 154 | 1.0 | 0.6 | 0.8 | 0.5 | 0.7 | 1.1 | 2.4 | 3.9 | 3.3 | 1.6 | 1.0 | 0.8 | 17.7 | 18-19 |
| 155 | 0.8 | 0.7 | 0.6 | 0.2 | 0.8 | 1.2 | 2.4 | 2.5 | 1.7 | 1.1 | 0.7 | 0.6 | 13.3 | 36-43 |
| 156 | 1.0 | 0.5 | 0.7 | 0.3 | 0.6 | 1.4 | 1.9 | 2.0 | 1.3 | 0.8 | 0.7 | 0.6 | 11.7 | 35-38 |
| 157 | 0.5 | 0.4 | 0.4 | 0.4 | 0.8 | 1.5 | 1.8 | 2.0 | 1.3 | 0.8 | 0.5 | 0.4 | 10.7 | 33-36 |
| Canada, Coastal and Insular: | ||||||||||||||
| 201 | 0.4 | 0.1 | 0.4 | 0.2 | 0.4 | 0.2 | 0.7 | 0.5 | 0.4 | 0.2 | 0.2 | 0.3 | 3.9 | 3 |
| Table ^ XV ^. Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular (cont.): | ||||||||||||||
| 204 | 0.4 | 0.2 | 0.5 | 0.5 | 0.5 | 0.8 | 0.9 | 1.8 | 0.5 | 1.4 | 0.8 | 0.2 | 8.6 | 5 |
| 208 | 0.9 | 0.8 | 0.9 | 0.4 | 1.5 | … | … | … | 0.9 | 0.4 | 0.3 | 0.2 | … | 0-1 |
| 211 | 0.4 | 0.2 | 0.4 | 0.3 | 0.6 | 0.6 | 0.6 | 1.5 | 0.7 | 0.7 | 0.4 | 0.4 | 6.8 | 10 |
| 212 | 0.1 | 0.2 | 0.4 | 0.2 | 0.4 | 1.0 | 1.1 | 1.8 | 1.5 | 1.7 | 0.7 | 0.2 | 8.6 | 4 |
| 213 | 0.2 | 0.1 | 0.1 | 0.3 | 0.4 | 0.4 | 1.3 | 1.0 | 0.9 | 0.6 | 0.5 | 0.4 | 6.2 | 5 |
| 214 | 0.2 | 0.2 | 0.1 | * | 0.4 | 0.2 | 0.9 | 1.2 | 0.4 | 1.1 | 0.8 | 0.1 | 5.7 | 5 |
| 215 | 0.2 | … | … | … | 0.5 | 1.2 | 0.8 | 1.1 | 0.6 | 0.8 | 0.1 | 0.3 | … | 0-6 |
| 216 | 0.6 | 0.4 | 0.6 | 0.8 | 0.6 | 0.8 | 1.3 | 1.9 | 1.0 | 1.2 | 0.8 | 0.6 | 10.7 | 13 |
| 217 | 0.7 | … | … | … | … | … | 2.0 | 1.2 | 0.9 | … | 0.1 | 0.1 | … | 0-1 |
| 220 | 0.3 | 0.3 | 0.6 | 0.5 | 0.7 | 2.3 | 3.4 | 1.2 | 2.2 | 0.6 | 0.9 | 0.7 | 13.6 | 4 |
| 221 | 0.4 | 0.5 | 0.5 | 0.9 | 0.7 | 1.0 | 1.8 | 1.5 | 1.4 | 1.3 | 0.8 | 0.9 | 10.9 | 20 |
| 222 | 0.2 | 0.4 | 0.2 | 0.5 | 0.6 | 0.5 | 1.5 | 1.7 | 1.5 | 0.7 | 0.5 | 0.1 | 8.5 | 6 |
| 223 | 0.6 | 0.6 | 0.6 | 1.1 | 0.8 | 1.0 | 1.7 | 1.9 | 1.7 | 1.3 | 1.5 | 0.8 | 13.6 | 14 |
| 224 | 0.7 | 0.7 | 0.6 | 1.0 | 1.3 | 1.5 | 1.8 | 1.7 | 1.5 | 1.5 | 1.2 | 0.5 | 14.1 | 6 |
| 225 | 0.3 | 0.3 | 0.2 | 0.5 | 1.2 | 0.6 | 1.6 | 1.4 | 1.7 | 0.7 | 0.4 | 0.5 | 9.5 | 3½ |
| 226 | 0.9 | 1.5 | 1.0 | 1.8 | 0.7 | 1.1 | 1.2 | 1.9 | 1.0 | 1.6 | 2.2 | 2.1 | 17.0 | 7 |
| 227 | 1.0 | 1.1 | 1.0 | 0.9 | 1.3 | 1.3 | 1.9 | 1.5 | 2.3 | 1.3 | 1.2 | 1.0 | 16.0 | 15 |
| 228 | 0.5 | 0.6 | 0.9 | 0.9 | 0.9 | 1.8 | 2.2 | 2.7 | 2.3 | 1.4 | 1.0 | 0.7 | 16.0 | 54 |
| Canada, Inland: | ||||||||||||||
| 250 | 0.6 | 0.5 | 0.4 | 0.5 | 0.6 | 0.8 | 1.3 | 1.3 | 0.9 | 0.8 | 0.8 | 0.5 | 9.0 | 20 |
| 251 | 0.6 | 0.5 | 0.4 | 0.6 | 0.5 | 1.l | 1.3 | 1.6 | 1.3 | 0.9 | 0.7 | 0.6 | 10.1 | 28 |
| 252 | 0.9 | 0.7 | 0.5 | 0.5 | 1.0 | 1.2 | 1.5 | 1.6 | 1.4 | 1.2 | 1.1 | 1.0 | 12.6 | 41 |
| 253 | 0.5 | 0.4 | 0.7 | 0.3 | 0.6 | 1.3 | 1.8 | 1.2 | 1.6 | 1.0 | 1.1 | 0.6 | 11.1 | 6 |
| 254 | 0.5 | 0.5 | 0.5 | 0.5 | 0.7 | 1.0 | 1.5 | 1.7 | 1.2 | 1.1 | 0.8 | 0.6 | 10.6 | 31 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland (cont.): | ||||||||||||||
| 255 | 1.1 | 0.7 | 0.6 | 0.6 | 1.2 | 2.4 | 1.9 | 1.6 | 1.4 | 1.3 | 1.7 | 1.3 | 15.8 | 9 |
| 256 | 0.5 | 0.5 | 0.4 | 0.4 | 1.2 | 1.3 | 2.0 | 1.9 | 1.1 | 0.8 | 0.6 | 0.5 | 11.2 | 30 |
| 257 | 0.5 | 0.5 | 0.4 | 0.4 | 1.2 | 1.3 | 2.0 | 1.9 | 1.1 | 0.8 | 0.6 | 0.5 | 11.2 | 31 |
| 258 | 0.7 | 0.7 | 0.5 | 0.7 | 1.4 | 1.5 | 2.0 | 1.5 | 1.3 | 1.1 | 0.9 | 0.8 | 13.0 | 42 |
| 259 | 0.6 | 0.5 | 0.5 | 0.7 | 0.9 | 1.3 | 1.3 | 1.8 | 1.5 | 1.0 | 0.9 | 0.8 | 11.8 | 45 |
| 260 | 0.8 | 0.5 | 0.6 | 0.5 | 0.7 | 0.9 | 1.2 | 0.9 | 0.7 | 1.1 | 0.7 | 0.6 | 10.3 | … |
| 261 | 0.6 | 0.6 | 0.5 | 0.5 | 0.9 | 1.2 | 1.1 | 1.4 | 1.6 | 1.1 | 1.4 | 0.7 | 11.6 | 27 |
| 262 | 0.5 | 0.6 | 0.5 | 0.5 | 1.0 | 1.8 | 2.2 | 1.8 | 1.7 | 0.9 | 0.8 | 0.7 | 13.0 | 26 |
| 263 | 0.6 | 0.4 | 0.6 | 0.6 | 1.1 | 1.8 | 2.0 | 1.7 | 1.3 | 0.7 | 0.6 | 0.5 | 12.1 | 30 |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.5 | 0.5 | 0.4 | 0.1 | 0.1 | 0.2 | 2.6 | 3 |
| 303 | 1.2 | 0.7 | 0.7 | 0.1 | 0.2 | 0.2 | * | 0.3 | 0.3 | 0.2 | 1.0 | 0.7 | 5.8 | 2 |
| 304 | 0.4 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 1.0 | 1.1 | 1.0 | 1.1 | 1.1 | 0.5 | 9.0 | 50 |
| 305 | 1.6 | 2.5 | 1.8 | 1.6 | 2.8 | 1.0 | 3.4 | 3.7 | 5.4 | 4.1 | 2.3 | 2.2 | 32.4 | 3-4 |
| 306 | 1.0 | 0.7 | 0.3 | 0.5 | 0.2 | 0.6 | 0.2 | 0.7 | 0.5 | 0.6 | 0.8 | 0.8 | 6.9 | 4-6 |
| 307 | 1.1 | 0.6 | 0.6 | 0.3 | 0.5 | 0.5 | 0.6 | 1.4 | 1.3 | 0.8 | 0.8 | 0.9 | 8.7 | 5 |
| 308 | 1.8 | 1.7 | 0.6 | 1.5 | 0.3 | 1.0 | 0.6 | 0.4 | 1.1 | 1.1 | 1.0 | 1.5 | 12.5 | 10 |
| 309 | 0.6 | 0.5 | 0.7 | 0.6 | 1.5 | 1.2 | 2.7 | 2.0 | 1.7 | 1.4 | 1.3 | 1.0 | 15.2 | 8 |
| 310 | 0.2 | 0.9 | 0.7 | 0.2 | 0.7 | 0.6 | 1.3 | 0.6 | 2.4 | 0.5 | 0.8 | 0.4 | 9.3 | 2-3 |
| 312 | 0.2 | 0.3 | 0.1 | 0.1 | 0.3 | 0.4 | 1.0 | 0.7 | 0.8 | 0.6 | 0.4 | 0.3 | 5.1 | 6-8 |
| 313 | 2.1 | 1.8 | 2.4 | 2.0 | 3.9 | 6.7 | 4.1 | 1.8 | 5.6 | 1.8 | 1.3 | 1.7 | 35.4 | 4-5 |
| 314 | 1.4 | 1.7 | 1.7 | 1.2 | 1.7 | 1.4 | 2.2 | 3.1 | 3.3 | 2.5 | 1.9 | 1.5 | 23.5 | 50 |
| 317 | 3.3 | 2.0 | 2.4 | 2.4 | 2.4 | 2.1 | 1.9 | 2.4 | 3.7 | 5.7 | 3.3 | 2.8 | 34.3 | 28 |
| 318 | 3.3 | 2.6 | 3.3 | 2.5 | 3.5 | 3.2 | 3.1 | 3.8 | 5.8 | 5.7 | 4.6 | 3.2 | 44.6 | 50 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 319 | 1.4 | 1.5 | 2.5 | 1.0 | 2.8 | 1.8 | 2.6 | 3.8 | 4.1 | 4.6 | 1.6 | 0.8 | 28.5 | 2-3 |
| 321 | 7.3 | 8.2 | 11.9 | 7.9 | 9.5 | 8.2 | 6.2 | 6.5 | 7.9 | 9.5 | 5.8 | 10.9 | 99.7 | 4-6 |
| 331 | 3.9 | 3.3 | 2.7 | 2.4 | 1.9 | 1.9 | 1.9 | 2.0 | 3.5 | 3.4 | 3.7 | 3.5 | 34.3 | 50 |
| 333 | 7.5 | 6.4 | 6.2 | 5.2 | 5.0 | 5.9 | 5.8 | 7.0 | 10.3 | 8.4 | 8.7 | 9.5 | 85.9 | 10 |
| 334 | 0.6 | 0.7 | 0.5 | 0.4 | 0.7 | 1.4 | 1.4 | 2.3 | 2.0 | 2.5 | 1.8 | 0.9 | 15.3 | 13 |
| 335 | 1.4 | 0.9 | 1.3 | 0.9 | 0.7 | 1.7 | 2.1 | 2.6 | 2.4 | 4.0 | 2.2 | 1.9 | 22.0 | 12 |
| 336 | 5.0 | 2.6 | 3.1 | 3.5 | 2.3 | 2.4 | 3.2 | 3.7 | 3.8 | 5.1 | 3.3 | 4.5 | 25.0 | 12 |
| 337 | 6.9 | 6.7 | 7.7 | 4.5 | 5.6 | 5.4 | 3.8 | 5.9 | 7.7 | 6.0 | 7.5 | 8.7 | 76.4 | 11 |
| 338 | 8.6 | 6.9 | 6.2 | 5.2 | 4.4 | 4.5 | 4.3 | 4.3 | 7.5 | 7.5 | 7.2 | 7.6 | 74.2 | 15 |
| 339 | 1.7 | 0.9 | 0.9 | 0.8 | 0.9 | 1.6 | 2.0 | 2.6 | 2.6 | 2.6 | 2.0 | 2.5 | 21.1 | 10 |
| 340 | 8.6 | 5.4 | 3.8 | 1.9 | 2.3 | 2.6 | 2.3 | 2.7 | 11.9 | 3.9 | 5.4 | 6.8 | 57.6 | 3 |
| 341 | 4.1 | 3.8 | 4.1 | 2.4 | 3.9 | 3.2 | 4.3 | 4.6 | 6.4 | 4.8 | 5.9 | 6.0 | 53.5 | 8 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 360 | 5.0 | 4.5 | 3.3 | 2.6 | 2.6 | 3.4 | 2.9 | 5.6 | 4.3 | 5.6 | 4.0 | 3.9 | 47.7 | 7 |
| 361 | 1.0 | 0.6 | 0.7 | 0.4 | 0.6 | 1.1 | 1.6 | 2.5 | 1.6 | 1.0 | 0.8 | 0.9 | 12.7 | 5 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 0.2 | 0.3 | 0.2 | 0.2 | 0.2 | 0.3 | 0.7 | 1.1 | 0.7 | 0.3 | 0.2 | 0.2 | 4.6 | 1 |
| 401 | 0.2 | 0.1 | 0.1 | 0.1 | 0.2 | 0.4 | 0.8 | 0.6 | 0.7 | 0.3 | 0.2 | 0.1 | 3.8 | 2 |
| 402 | 1.1 | 1.1 | 0.9 | 1.1 | 0.4 | 0.5 | 0.6 | 1.6 | 1.3 | 1.0 | 1.5 | 1.3 | 12.3 | … |
| 403 | 1.3 | 1.2 | 1.1 | 0.9 | 0.5 | 0.5 | 0.7 | 0.8 | 0.9 | 1.2 | 1.0 | 1.6 | 11.7 | 14 |
| 406 | 2.6 | 3.1 | 2.8 | 2.2 | 2.1 | 2.2 | 2.8 | 2.6 | 3.9 | 3.5 | 3.4 | 2.9 | 34.1 | 50 |
| 407 | 1.4 | 1.4 | 1.3 | 0.6 | 0.8 | 1.3 | 1.5 | 1.6 | 2.7 | 1.5 | 1.5 | 1.4 | 17.0 | 10 |
| 408 | 2.7 | 2.6 | 2.1 | 1.6 | 1.4 | 1.5 | 1.8 | 2.1 | 2.4 | 2.5 | 2.5 | 2.6 | 25.8 | … |
| 409 | 4.9 | 4.6 | 3.6 | 2.7 | 2.8 | 2.7 | 2.9 | 3.7 | 5.5 | 5.0 | 5.2 | 4.5 | 48.1 | 50 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular (cont.): | ||||||||||||||
| 410 | 2.1 | 1.9 | 1.4 | 1.1 | 1.1 | 1.2 | 1.5 | 1.9 | 2.6 | 2.6 | 2.7 | 2.0 | 22.1 | 50 |
| 411 | 6.2 | 7.5 | 4.5 | 2.9 | 3.7 | 3.1 | 3.2 | 3.2 | 7.0 | 7.2 | 7.5 | 5.5 | 61.5 | 50 |
| 412 | 2.8 | 2.9 | 2.4 | 1.7 | 2.7 | 2.7 | 2.4 | 2.0 | 4.0 | 4.3 | 3.8 | 2.4 | 34.1 | 50 |
| 413 | 3.0 | 2.7 | 2.2 | 1.7 | 1.6 | 1.5 | 1.7 | 2.1 | 3.7 | 3.5 | 3.7 | 2.8 | 30.2 | 50 |
| 414 | 4.3 | 4.4 | 3.1 | 2.3 | 1.9 | 2.2 | 2.2 | 2.8 | 4.7 | 4.6 | 4.4 | 3.8 | 40.7 | 50 |
| 415 | 0.5 | 0.8 | 0.5 | 0.6 | 1.2 | 1.2 | 2.3 | 1.9 | 1.7 | 1.3 | 1.3 | 0.9 | 14.4 | 18 |
| 417 | 0.3 | 0.3 | 0.3 | 0.3 | 0.5 | 0.7 | 1.0 | 1.8 | 2.0 | 1.5 | 0.8 | 0.4 | 9.9 | … |
| 419 | 0.7 | 0.8 | 0.6 | 0.6 | 0.8 | 1.5 | 2.3 | 1.9 | 1.9 | 1.5 | 1.2 | 0.9 | 14.7 | 50 |
| 420 | 3.5 | 3.0 | 2.5 | 2.2 | 2.5 | 2.5 | 3.0 | 3.3 | 5.1 | 4.6 | 4.7 | 3.2 | 40.1 | 50 |
| 421 | 1.5 | 1.2 | 1.5 | 1.0 | 1.7 | 1.7 | 2.4 | 3.2 | 2.7 | 2.7 | 2.1 | 1.7 | 23.3 | 50 |
| 422 | 1.7 | 1.5 | 1.3 | 1.4 | 1.7 | 2.0 | 2.4 | 2.8 | 2.6 | 2.3 | 2.1 | 1.7 | 23.5 | 30 |
| 423 | 1.5 | 1.1 | 1.0 | 0.9 | 1.1 | 1.3 | 1.8 | 2.1 | 2.2 | 2.2 | 1.9 | 1.3 | 18.4 | 51 |
| 424 | 1.8 | 1.5 | 1.4 | 1.4 | 1.8 | 1.8 | 2.2 | 2.9 | 2.5 | 2.6 | 2.5 | 2.0 | 24.4 | 40 |
| 425 | 0.8 | 0.6 | 0.7 | 0.9 | 1.2 | 2.0 | 2.6 | 2.9 | 2.7 | 1.9 | 1.2 | 0.9 | 18.9 | 25 |
| 426 | 1.1 | 1.0 | 1.0 | 1.3 | 1.8 | 2.3 | 2.3 | 3.3 | 2.4 | 1.9 | 1.6 | 1.2 | 21.2 | 50 |
| 427 | 0.7 | 0.7 | 0.8 | 1.0 | 1.5 | 1.7 | 2.3 | 2.3 | 1.8 | 1.1 | 0.8 | 0.7 | 15.4 | 25 |
| 428 | 0.9 | 0.8 | 0.9 | 0.8 | 1.4 | 2.0 | 2.4 | 2.5 | 2.2 | 1.8 | 1.3 | 1.0 | 18.0 | 45 |
| 429 | 0.5 | 0.3 | 0.4 | 0.6 | 1.0 | 1.7 | 1.8 | 2.0 | 1.9 | 1.3 | 0.8 | 0.6 | 15.4 | 20 |
| Europe, Inland: | ||||||||||||||
| 450 | 0.5 | 0.4 | 0.3 | 0.3 | 0.8 | 1.3 | 2.8 | 2.4 | 1.3 | 0.9 | 0.7 | 0.4 | 12.1 | 32 |
| 451 | 0.7 | 0.5 | 0.4 | 0.5 | 0.7 | 1.6 | 2.0 | 1.9 | 1.8 | 0.9 | 0.9 | 0.5 | 12.4 | 30 |
| 452 | 0.7 | 0.5 | 0.6 | 0.9 | 1.3 | 2.1 | 2.4 | 2.7 | 1.4 | 1.3 | 1.0 | 0.7 | 15.6 | … |
| 453 | 1.1 | 0.9 | 0.9 | 1.2 | 1.4 | 2.3 | 2.5 | 2.6 | 2.1 | 2.0 | 1.6 | 1.2 | 19.8 | 30 |
| 454 | 3.4 | 2.9 | 2.2 | 1.8 | 1.5 | 1.7 | 2.2 | 3.0 | 3.3 | 3.4 | 2.1 | 2.6 | 30.1 | 50 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Inland (cont.): | ||||||||||||||
| 455 | 1.2 | 1.0 | 1.0 | 0.9 | 1.2 | 1.2 | 1.4 | 1.5 | 1.2 | 1.3 | 1.2 | 1.3 | 14.4 | 38 |
| 456 | 1.0 | 0.7 | 0.7 | 0.8 | 1.3 | 1.7 | 2.7 | 2.9 | 2.0 | 1.6 | 1.1 | 0.9 | 17.3 | 51 |
| 457 | 1.6 | 1.2 | 1.3 | 1.3 | 1.7 | 2.6 | 2.6 | 3.2 | 2.7 | 2.4 | 1.9 | 1.7 | 24.3 | 51 |
| 458 | 1.5 | 1.3 | 1.1 | 1.3 | 1.7 | 2.4 | 3.1 | 3.2 | 2.5 | 2.3 | 1.8 | 1.5 | 23.7 | 50 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.5 | 1.0 | 1.5 | 0.9 | 0.3 | 0.1 | 0.1 | 5.1 | 3 |
| 501 | 0.3 | 0.1 | 0.1 | 0.2 | 0.2 | 0.9 | 1.5 | 1.2 | 0.9 | 0.4 | 0.2 | 0.2 | 6.2 | 18 |
| 502 | 0.2 | 0.1 | 0.1 | 0.2 | 0.2 | 0.8 | 1.5 | 2.0 | 0.9 | 0.3 | 0.1 | 0.2 | 6.5 | 19 |
| 503 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.7 | 1.1 | 1.1 | 0.4 | 0.3 | 0.2 | 0.1 | 4.5 | 22 |
| 504 | 0.1 | 0.1 | 0.1 | * | 0.2 | 0.4 | 1.2 | 1.0 | 0.5 | 0.2 | 0.1 | 0.2 | 4.0 | 4 |
| 505 | 0.7 | 0.6 | 0.5 | 0.4 | 0.5 | 0.7 | 1.0 | 1.5 | 1.4 | 1.1 | 0.6 | 0.6 | 9.6 | 24 |
| 506 | 0.3 | 0.2 | 0.2 | 0.2 | 0.3 | 0.8 | 1.1 | 1.3 | 1.3 | 0.8 | 0.4 | 0.4 | 7.3 | 18 |
| 507 | 0.3 | 0.2 | 0.2 | 0.2 | 0.2 | 0.5 | 1.5 | 1.2 | 1.5 | 0.6 | 0.4 | 0.3 | 7.0 | 6 |
| 508 | 0.3 | 0.3 | 0.2 | 0.2 | 0.2 | 0.6 | 0.6 | 1.6 | 1.1 | 0.5 | 0.4 | 0.2 | 6.2 | 13 |
| 509 | 0.4 | 0.2 | 0.2 | 0.2 | 0.5 | 0.9 | 0.9 | 2.0 | 1.7 | 0.6 | 0.3 | 0.3 | 8.3 | 15 |
| 510 | 0.2 | 0.1 | 0.2 | 0.2 | 0.2 | 0.7 | 0.8 | 1.6 | 1.6 | 0.5 | 0.3 | 0.2 | 6.6 | 17 |
| 511 | 0.1 | 0.1 | 0.0 | 0.0 | 0.2 | 0.4 | 0.3 | 1.4 | 0.4 | 0.1 | 0.2 | 0.2 | 3.4 | 2 |
| 512 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 1.3 | 1.2 | 1.1 | 0.8 | 0.2 | 0.2 | 0.1 | 5.4 | 7 |
| 513 | 0.2 | 0.2 | 0.1 | 0.2 | 0.3 | 1.2 | 1.1 | 1.1 | 0.8 | 0.4 | 0.4 | 0.3 | 6.0 | 7 |
| 514 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.4 | 0.6 | 0.6 | 0.4 | 0.2 | 0.1 | 0.1 | 3.0 | 4 |
| 515 | 0.2 | 0.2 | 0.2 | 0.1 | 0.4 | 0.8 | 1.1 | 1.1 | 0.7 | 0.3 | 0.3 | 0.3 | 5.7 | 14 |
| 516 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 1.1 | 0.9 | 0.6 | 0.8 | 0.2 | 0.1 | 0.2 | 4.2 | 3 |
| 517 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.4 | 0.6 | 0.9 | 0.5 | 0.4 | 0.1 | 0.2 | 4.1 | 11 |
| 518 | 0.2 | 0.2 | 0.2 | 0.2 | 0.4 | 0.9 | 1.1 | 1.8 | 1.8 | 0.9 | 0.4 | 0.4 | 8.2 | 9 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 519 | 0.2 | 0.2 | 0.2 | 0.2 | 0.4 | 0.9 | 1.0 | 1.7 | 1.5 | 0.9 | 0.3 | 0.2 | 7.8 | 12 |
| 520 | 0.3 | 0.3 | 0.2 | 0.3 | 0.7 | 1.3 | 1.8 | 2.0 | 1.5 | 0.7 | 0.5 | 0.4 | 10.0 | 30 |
| 521 | 0.3 | 0.2 | 0.3 | 0.4 | 0.8 | 1.9 | 1.3 | 2.3 | 2.0 | 0.6 | 0.4 | 0.3 | 10.7 | 25 |
| 522 | 0.5 | 0.2 | 0.2 | 0.2 | 0.2 | 0.7 | 1.5 | 1.2 | 0.9 | 0.5 | 0.4 | 0.3 | 6.8 | 7 |
| 523 | 0.1 | 0.4 | 0.5 | 0.5 | 0.2 | 0.4 | 0.8 | 1.8 | 0.8 | 0.7 | 0.2 | 0.2 | 6.7 | 3 |
| 524 | 0.2 | 0.2 | 0.2 | 0.2 | 0.3 | 0.3 | 0.9 | 1.1 | 0.7 | 0.4 | 0.2 | 0.1 | 4.9 | 4 |
| 525 | 0.6 | 0.6 | 0.4 | 0.5 | 0.4 | 0.5 | 1.6 | 1.8 | 2.1 | 1.9 | 0.5 | 1.0 | 11.8 | 8 |
| 526 | 0.3 | 0.3 | 0.4 | 0.3 | 0.4 | 0.7 | 1.7 | 1.8 | 1.2 | 1.0 | 0.6 | 0.4 | 9.2 | 16 |
| 527 | 0.3 | 0.3 | 0.2 | 0.2 | 0.4 | 0.9 | 1.3 | 1.6 | 1.1 | 0.5 | 0.3 | 0.4 | 7.5 | 14 |
| 528 | 0.4 | 0.9 | 0.3 | 0.4 | 0.3 | 0.9 | 2.0 | 2.7 | 2.0 | 0.2 | 0.2 | 0.2 | 10.4 | 3 |
| 529 | 0.9 | 0.7 | 0.8 | 0.9 | 0.3 | 0.7 | 1.7 | 1.9 | 2.7 | 1.8 | 1.3 | 0.6 | 14.3 | 4 |
| 530 | 1.1 | 0.2 | 0.6 | 0.6 | 0.5 | 0.7 | 1.6 | 1.5 | 2.6 | 1.8 | 0.5 | 0.8 | 12.5 | 7 |
| 531 | 0.1 | 0.2 | 0.1 | 0.2 | 0.3 | 1.1 | 2.1 | 2.6 | 1.3 | 1.0 | 0.9 | 0.1 | 10.0 | 4 |
| Asia, Inland: | ||||||||||||||
| 550 | 0.4 | 0.6 | 0.3 | 0.9 | 0.5 | 1.4 | 1.8 | 2.7 | 1.5 | 1.2 | 0.7 | 0.4 | 11.8 | 28 |
| 551 | 0.2 | 0.3 | 0.3 | 0.5 | 0.7 | 0.8 | 1.6 | 1.8 | 1.1 | 0.8 | 0.4 | 0.6 | 9.1 | 3 |
| 552 | 0.3 | 0.2 | 0.3 | 0.3 | 0.5 | 1.0 | 1.5 | 1.6 | 1.5 | 0.9 | 0.4 | 0.3 | 8.9 | 18 |
| 553 | 0.2 | 0.2 | 0.2 | 0.2 | 0.4 | 1.5 | 1.5 | 2.5 | 1.9 | 1.0 | 0.5 | 0.2 | 10.1 | 26 |
| 554 | 0.2 | 0.2 | 0.2 | 0.3 | 0.4 | 1.2 | 1.3 | 1.7 | 1.7 | 0.7 | 0.3 | 0.2 | 8.4 | 17 |
| 556 | 0.2 | 0.1 | 0.1 | 0.2 | 0.3 | 0.9 | 1.1 | 1.0 | 0.5 | 0.3 | 0.3 | 0.2 | 5.1 | 31 |
| 557 | 0.4 | 0.2 | 0.3 | 0.2 | 0.4 | 1.2 | 1.4 | 2.4 | 0.8 | 0.6 | 0.4 | 0.2 | 8.4 | 3 |
| 558 | 0.3 | 0.3 | 0.2 | 0.2 | 0.2 | 0.9 | 1.3 | 1.2 | 0.8 | 0.5 | 0.5 | 0.4 | 6.8 | 13 |
| 559 | 0.6 | 0.4 | 0.2 | 0.2 | 0.5 | 0.9 | 2.4 | 1.7 | 1.1 | 0.4 | 0.8 | 0.6 | 9.8 | 10 |
| 560 | 0.5 | 0.3 | 0.4 | 0.6 | 1.5 | 2.2 | 2.5 | 2.0 | 1.5 | 0.9 | 0.6 | 0.5 | 13.5 | 8 |
| Table ^ XV ^ . Mean precipitation (inches) (cont.) ^ ✓ ^ | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 561 | 0.8 | 0.6 | 0.7 | 0.5 | 2.0 | 2.3 | 2.4 | 3.0 | 2.2 | 1.6 | 1.0 | 1.0 | 18.0 | 10 |
| 562 | 0.6 | 0.4 | 0.5 | 0.5 | 1.3 | 2.5 | 2.4 | 3.2 | 1.9 | 1.3 | 0.8 | 0.7 | 16.1 | 28 |
| 563 | 0.5 | 0.4 | 0.4 | 0.6 | 1.0 | 1.6 | 2.0 | 2.3 | 2.0 | 1.1 | 0.8 | 0.6 | 13.2 | 40 |
| 564 | 0.7 | 0.6 | 0.4 | 0.7 | 1.5 | 2.2 | 3.2 | 1.7 | 1.6 | 0.9 | 1.0 | 0.8 | 15.3 | 5 |
| 565 | 0.3 | 0.3 | 0.2 | 0.3 | 0.7 | 1.5 | 1.0 | 1.3 | 1.0 | 0.6 | 0.6 | 0.4 | 8.2 | … |
| 566 | 0.4 | 0.3 | 0.3 | 0.4 | 0.9 | 1.7 | 1.6 | 2.1 | 1.2 | 0.7 | 0.7 | 0.5 | 10.7 | 26 |
| 567 | 0.3 | 0.3 | 0.3 | 0.3 | 0.9 | 1.3 | 1.3 | 1.6 | 1.0 | 0.7 | 0.6 | 0.4 | 9.0 | … |
| 568 | 0.2 | 0.2 | 0.1 | 0.3 | 0.5 | 1.1 | 1.3 | 1.6 | 0.9 | 0.5 | 0.4 | 0.3 | 7.4 | 35 |
| 569 | * | * | * | 0.1 | 0.7 | 1.6 | 1.1 | 1.7 | 0.4 | 0.6 | 0.1 | 0.1 | 6.5 | 1 |
| 570 | 0.1 | 0.2 | 0.1 | 0.3 | 0.4 | 0.8 | 1.2 | 1.4 | 0.8 | 0.3 | 0.2 | 0.2 | 6.1 | 17 |
| 571 | 0.2 | 0.1 | 0.2 | 0.1 | 0.2 | 0.6 | 1.2 | 1.2 | 0.5 | 0.3 | 0.4 | 0.3 | 5.3 | 4 |
| 572 | 0.3 | 0.3 | 0.3 | 0.2 | 0.3 | 0.8 | 1.5 | 1.9 | 1.1 | 0.5 | 0.5 | 0.4 | 7.9 | 21 |
| 573 | 0.6 | 0.6 | 0.6 | 0.7 | 1.5 | 2.3 | 2.9 | 2.7 | 1.7 | 1.3 | 1.1 | 0.9 | 16.9 | 35 |
| 574 | 0.8 | 0.5 | 0.5 | 0.7 | 1.4 | 2.4 | 2.4 | 2.6 | 1.7 | 1.5 | 1.2 | 1.0 | 16.9 | 48 |
| 575 | 0.8 | 0.5 | 0.5 | 0.5 | 1.0 | 1.8 | 2.1 | 2.0 | 1.7 | 1.0 | 1.0 | 1.0 | 13.8 | 18 |
| 576 | 0.7 | 0.4 | 0.5 | 0.7 | 0.9 | 1.7 | 2.5 | 2.1 | 1.5 | 0.9 | 1.1 | 0.9 | 13.8 | 30 |
| 577 | 0.4 | 0.3 | 0.2 | 0.3 | 0.7 | 1.3 | 1.4 | 1.4 | 1.2 | 0.7 | 0.5 | 0.5 | 8.8 | … |
As shown by the data on the average number of days with precipitation
(Table
^
XIV
^
), the monthly frequencies are more uniform in continental
locations and in the more southerly Arctic latitudes. There is a
tendency toward summer maxima at high-latitude continental locations and
toward autumn and winter maxima in the maritime locations near the major
winter storm tracks, particularly over the Norwegian and Barents Seas.
The annual variation of precipitation amounts over the Arctic Basin
presents a somewhat different picture than the annual variation of
precipitation probabilities. Most locations show decided summer maxima,
usually in July or August. However, between the east coast of Greenland
and Novaya Zemlya the averages are greater in winter than in summer.
(See Table
^
XV
^
.)
^
fig. 48 here
^
Diurnal Variation of Precipitation
. - Because of the general absence of
important diurnal insolational effects in winter at the higher latitudes,
no diurnal variation in precipitation is observed during this season over
the pack-ice. In other seasons, however, the probability of precipitation
appears to be greater at night than in daytime, a difference which is
especially great in spring. During the warmer months in the lower Arctic,
and particularly at inland points, it is to be expected that precipitation
will be most frequent during daylight hours when thermal convection is
most pronounced. Specific Arctic data by which to verify this conclusion
are lacking however.
Snowfall
. - Snowfall in Arctic regions is, on the average, very light.
However, heavy snows do occur in the more mountainous regions and also
in the areas under maritime influence near the major winter cyclone paths.
On the plains or steppes of Arctic continental regions, the average annual
snowfall does not often exceed 2 feet. This snowfall, however, does not
result in a uniform snow cover over the interior. The more exposed ridges
and plateaus are free from snow throughout most of the year because they
are swept clean by winds. At the same time, a fairly deep snow cover may
be experienced in valleys and river courses which are more or less protected
from the scouring action of the wind.
^
tables XVI to XVIII here
^
In regions with a more maritime influence, as around Hudson Bay,
Labrador, southern Greenland and Baffin Bay, average snow depths between
5 and 10 feet are common. In these regions the heaviest precipitation of
the year is often recorded in November and December, with the result that
snowfall constitutes a large percentage of the total annual precipitation.
| Table ^ XVI ^ . Mean number of days with snow ^ ✓ ^ | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | |||||||||||||||
| 002 | e | 11 | 11 | 13 | 13 | 19 | 17 | 14 | 14 | 13 | 17 | 9 | 9 | 156 | 2 |
| 003 | e | 2 | 8 | 6 | 6 | 19 | 7 | 4 | 9 | 16 | 13 | 6 | 6 | 102 | 1 |
| 004 | c | 15 | 17 | 15 | 11 | 10 | 3 | 1 | * | 6 | 9 | 15 | 17 | 118 | .. |
| 005 | e | 11 | 12 | 13 | 8 | 8 | 2 | * | * | 3 | 8 | 12 | 11 | 87 | .. |
| 006 | e | 12 | 8 | 7 | 5 | 6 | 7 | 4 | 8 | 9 | 10 | 9 | 8 | 93 | .. |
| 007 | e | 13 | 11 | 8 | 6 | 7 | 9 | 5 | 7 | 14 | 15 | 10 | 12 | 115 | .. |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | a | 2 | 2 | 2 | 3 | 3 | 1 | 2 | 3 | 8 | 9 | 5 | 6 | 46 | 5 |
| 101 | a | 11 | 14 | 13 | 16 | 13 | 6 | .. | 3 | 8 | 18 | 17 | 15 | … | 0-2 |
| 104 | a | 14 | 15 | 15 | 15 | 9 | 1 | 0 | 0 | 2 | 12 | 15 | 17 | 115 | 1-2 |
| 106 | a | 17 | 12 | 14 | 5 | 1 | * | .. | .. | 1 | 7 | 13 | 15 | … | 0-7 |
| Alaska, Inland: | |||||||||||||||
| 153 | a | 5 | 4 | 4 | 2 | 1 | 0 | 0 | 0 | 1 | 6 | 6 | 4 | 33 | 10 |
| 154 | a | 10 | 9 | 9 | 8 | 4 | 0 | 0 | * | 1 | 7 | 11 | 10 | 69 | 10 |
| 155 | a | 8 | 9 | 9 | 6 | 2 | * | 0 | 0 | 2 | 11 | 11 | 10 | 68 | 11 |
| 156 | a | 13 | 9 | 9 | 7 | 3 | 1 | 0 | 0 | 3 | 12 | 13 | 10 | 80 | 10 |
| 157 | a | 10 | 8 | 8 | 7 | 2 | 0 | 0 | * | 2 | 8 | 11 | 10 | 66 | 10 |
| Canada, Coastal and Insular: | |||||||||||||||
| 204 | d | 5 | 3 | 5 | 4 | 6 | 3 | 0 | 1 | 5 | 9 | 8 | 4 | 53 | 5 |
| 206 | b | 6 | 6 | 7 | 6 | 8 | 2 | 0 | 3 | 6 | 8 | 6 | 2 | 60 | 5 |
| 208 | a | 14 | 8 | 19 | 9 | 19 | 7 | 0 | .. | 17 | 24 | 6 | 2 | … | 0-1 |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: (cont.) | |||||||||||||||
| 210 | b | 6 | 3 | 4 | 4 | 7 | 4 | 1 | 0 | 8 | 8 | 4 | 5 | 54 | 5 |
| 211 | b | 6 | 3 | 6 | 6 | 6 | 4 | * | 1 | 7 | 8 | 6 | 5 | 58 | 7 |
| 213 | d | 3 | 1 | 2 | 2 | 2 | * | 0 | * | 2 | 5 | 3 | 3 | 24 | 5 |
| 214 | d | 3 | .. | .. | 11 | 10 | 11 | .. | .. | .. | 9 | .. | 2 | … | 0-1 |
| 216 | b | 8 | 6 | 7 | 5 | 7 | 1 | * | * | 3 | 9 | 10 | 8 | 64 | 10 |
| 217 | d | 2 | .. | 4 | .. | .. | .. | 0 | 0 | .. | .. | .. | 4 | … | .. |
| 221 | b | 6 | 5 | 6 | 8 | 6 | 1 | 0 | 0 | 3 | 8 | 9 | 8 | 60 | 10 |
| 223 | b | 6 | 6 | 6 | 11 | 10 | 6 | * | * | 5 | 11 | 15 | 11 | 87 | 10 |
| 224 | d | 5 | 5 | 5 | 6 | 7 | 2 | * | 0 | 1 | 9 | 8 | 7 | 54 | 6 |
| 226 | d | 6 | 3 | 4 | 7 | 4 | 2 | 0 | 0 | 2 | 7 | 8 | 7 | 51 | 7 |
| 227 | b | 10 | 8 | 11 | 9 | 10 | 4 | 0 | * | 1 | 11 | 14 | 14 | 92 | 10 |
| 228 | b | 5 | 6 | 6 | 5 | 2 | 1 | * | 0 | 1 | 8 | 9 | 8 | 51 | 10 |
| Canada, Inland: | |||||||||||||||
| 250 | b | 4 | 5 | 4 | 4 | 2 | 1 | 0 | * | 4 | 7 | 8 | 5 | 44 | 10 |
| 251 | d | 4 | 4 | 3 | 4 | 3 | 2 | 0 | 1 | 4 | 8 | 3 | 3 | 40 | 9 |
| 252 | b | 8 | 6 | 8 | 2 | * | 0 | 0 | 0 | 1 | 7 | 11 | 10 | 53 | 10 |
| 253 | b | 7 | 7 | 8 | 2 | 1 | 0 | 0 | 0 | 1 | 5 | 11 | 8 | 50 | 5 |
| 254 | b | 7 | 7 | 8 | 6 | 4 | * | 0 | 0 | 2 | 9 | 11 | 7 | 61 | 10 |
| 255 | b | 9 | 7 | 5 | 4 | * | 0 | 0 | 0 | 1 | 8 | 13 | 13 | 60 | 8 |
| 257 | b | 6 | 7 | 7 | 6 | 2 | 0 | 0 | 0 | 1 | 6 | 8 | 6 | 49 | 10 |
| 258 | b | 6 | 5 | 8 | 3 | 1 | 0 | 0 | 0 | * | 5 | 8 | 8 | 44 | 10 |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland: (cont.) | |||||||||||||||
| 259 | b | 8 | 8 | 9 | 4 | 1 | * | 0 | 0 | 1 | 6 | 12 | 9 | 58 | 10 |
| 260 | e | 8 | 8 | 8 | 4 | 0 | 0 | 0 | 0 | 1 | 4 | 8 | 9 | 50 | .. |
| 262 | b | 7 | 6 | 7 | 3 | 1 | 0 | 0 | 0 | 1 | 6 | 9 | 9 | 49 | 10 |
| Greenland, Iceland, Coastal and Insular: | |||||||||||||||
| 304 | c | 4 | 4 | 6 | 5 | 6 | 3 | 1 | 1 | 6 | 10 | 10 | 6 | 63 | .. |
| 307 | c | 7 | 4 | 5 | 3 | 3 | 1 | * | 1 | 3 | 4 | 6 | 6 | 44 | 5 |
| 308 | c | 8 | 8 | 7 | 4 | .. | 1 | * | 0 | 5 | 5 | 5 | 6 | … | 9 |
| 309 | c | 8 | 8 | 7 | 8 | 4 | 1 | * | 0 | 4 | 8 | 11 | 11 | 70 | 13 |
| 314 | d | 8 | 7 | 7 | 6 | 4 | 2 | * | * | 2 | 7 | 7 | 6 | 56 | 26 |
| 317 | c | 13 | 12 | 11 | 9 | 6 | 1 | 0 | * | 3 | 9 | 10 | 11 | 84 | 28 |
| 318 | e | 11 | 9 | 10 | 8 | 5 | 1 | * | * | 2 | 6 | 9 | 10 | 70 | .. |
| 330 | e | 17 | 14 | 12 | 9 | 3 | 1 | * | * | 2 | 3 | 10 | 12 | 87 | 16 |
| 331 | c | 15 | 12 | 9 | 5 | 2 | * | 0 | 0 | 1 | 4 | 8 | 12 | 69 | 19 |
| 332 | e | 12 | 11 | 12 | 8 | 3 | 1 | 0 | 0 | 1 | 5 | 6 | 8 | 67 | 9 |
| 333 | e | 12 | 10 | 8 | 4 | 2 | * | * | 0 | 1 | 3 | 6 | 9 | 55 | 11 |
| 334 | e | 8 | 7 | 7 | 6 | 2 | 1 | 0 | 0 | 1 | 5 | 4 | 5 | 45 | 14 |
| 335 | e | 12 | 10 | 10 | 9 | 3 | 1 | * | * | 1 | 8 | 8 | 10 | 73 | 15 |
| 336 | e | 9 | 9 | 8 | 8 | 2 | * | 0 | * | 1 | 6 | 7 | 8 | 59 | 16 |
| 337 | e | 8 | 6 | 4 | 3 | 1 | 0 | 0 | 0 | * | * | 4 | 5 | 31 | 11 |
| 338 | e | 8 | 5 | 5 | 3 | 1 | * | 0 | 0 | * | 2 | 3 | 5 | 31 | 15 |
| 339 | e | 11 | 8 | 10 | 9 | 3 | 2 | * | 0 | 1 | 6 | 4 | 6 | 60 | 10 |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland, Iceland, Coastal and Insular: (cont.) | |||||||||||||||
| 340 | e | 14 | 12 | 13 | 11 | 5 | 1 | 0 | 0 | 1 | 8 | 7 | 10 | 82 | 14 |
| 341 | e | 9 | 8 | 7 | 6 | 1 | * | 0 | 0 | 0 | 2 | 3 | 6 | 42 | 8 |
| Greenland, Iceland, Inland: | |||||||||||||||
| 360 | e | 10 | 9 | 8 | 3 | 1 | * | 0 | 0 | 0 | 3 | 4 | 5 | 43 | 7 |
| 361 | e | 12 | 10 | 10 | 10 | 4 | 3 | * | 1 | 4 | 10 | 9 | 10 | 83 | 16 |
| Europe, Coastal and Insular: | |||||||||||||||
| 400 | e | 12 | 11 | 8 | 8 | 9 | 7 | 5 | 7 | 11 | 15 | 13 | 11 | 117 | 10 |
| 401 | e | 7 | 7 | 7 | 8 | 11 | 10 | 9 | 13 | 16 | 14 | 10 | 8 | 120 | 1 |
| 406 | a | 12 | 12 | 14 | 12 | 8 | 4 | * | * | 3 | 9 | 11 | 11 | 96 | 12 |
| 408 | a | 16 | 17 | 16 | 12 | 10 | 4 | 0 | * | 3 | 11 | 15 | 17 | 121 | 44 |
| 411 | a | 14 | 15 | 12 | 8 | 4 | 1 | 0 | 0 | 1 | 6 | 11 | 10 | 81 | .. |
| 412 | a | 11 | 11 | 10 | 6 | 3 | * | 0 | 0 | 1 | 5 | 8 | 8 | 63 | 44 |
| 414 | a | 13 | 14 | 13 | 10 | 7 | 1 | 0 | 0 | 2 | 8 | 11 | 11 | 90 | 44 |
| 415 | e | 11 | 12 | 10 | 9 | 9 | 4 | * | * | 3 | 9 | 15 | 15 | 94 | 18 |
| 416 | c | 11 | 12 | 13 | 10 | 5 | 2 | 0 | 0 | 2 | 7 | 9 | 10 | 81 | 10 |
| 417 | e | 24 | 20 | 19 | 17 | 16 | 6 | 0 | 0 | 1 | 12 | 17 | 22 | 154 | .. |
| 420 | a | 12 | 11 | 11 | 7 | 3 | * | 0 | 0 | * | 4 | 8 | 9 | 65 | 44 |
| 421 | a | 11 | 11 | 11 | 6 | 2 | * | 0 | 0 | * | 3 | 7 | 13 | 64 | 36 |
| 423 | a | 15 | 12 | 12 | 7 | 3 | * | 0 | 0 | * | 5 | 10 | 13 | 77 | 27 |
| 424 | e | 17 | 16 | 13 | 7 | 2 | * | 0 | 0 | * | 4 | 10 | 15 | 84 | 36 |
| 425 | e | 14 | 13 | 11 | 8 | 4 | 1 | 0 | 0 | 1 | 7 | 15 | 16 | 91 | 18 |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular: (cont.) | |||||||||||||||
| 426 | e | 20 | 18 | 12 | 7 | 2 | * | 0 | 0 | * | 5 | 13 | 19 | 97 | 18 |
| 428 | e | 8 | 9 | 8 | 4 | 3 | 1 | 0 | 0 | 1 | 6 | 10 | 10 | 60 | 25 |
| 429 | e | 8 | 7 | 5 | 5 | 6 | 2 | 1 | 1 | 3 | 7 | 10 | 7 | 60 | 17 |
| 450 | a | 13 | 11 | 10 | 8 | 5 | 2 | * | * | 3 | 8 | 12 | 12 | 84 | 32 |
| 451 | a | 9 | 8 | 9 | 7 | 6 | 2 | * | * | 2 | 7 | 9 | 7 | 66 | 44 |
| 452 | c | 12 | 9 | 11 | 10 | 6 | 3 | * | 0 | 1 | 8 | 10 | 10 | 80 | .. |
| 454 | c | 15 | 14 | 13 | 9 | 4 | * | 0 | 0 | 1 | 5 | 10 | 13 | 84 | 44 |
| 455 | a | 12 | 10 | 10 | 5 | 2 | * | 0 | 0 | * | 2 | 7 | 11 | 59 | 38 |
| 456 | a | 14 | 12 | 13 | 9 | 4 | 1 | * | 0 | 2 | 8 | 12 | 15 | 90 | 26 |
| 458 | c | 18 | 17 | 15 | 10 | 4 | * | 0 | 0 | 1 | 8 | 16 | 18 | 107 | 35 |
| Asia, Coastal and Insular: | |||||||||||||||
| 500 | e | 10 | 8 | 8 | 10 | 10 | 9 | 4 | 6 | 13 | 13 | 9 | 8 | 108 | 7-8 |
| 501 | e | 12 | 6 | 6 | 8 | 11 | 9 | 4 | 7 | 11 | 14 | 10 | 11 | 107 | 5-6 |
| 502 | e | 13 | 9 | 7 | 11 | 14 | 8 | 7 | 4 | 13 | 14 | 11 | 11 | 122 | 4-5 |
| 503 | e | 6 | 8 | 5 | 4 | 6 | 7 | 4 | 6 | 10 | 13 | 11 | 8 | 88 | 7-8 |
| 505 | e | 16 | 14 | 13 | 12 | 12 | 7 | 1 | 1 | 5 | 12 | 14 | 14 | 121 | 14 |
| 506 | e | 14 | 10 | 9 | 10 | 8 | 5 | * | * | 5 | 13 | 15 | 16 | 106 | 24 |
| 507 | e | 12 | 10 | 11 | 9 | 7 | 5 | 1 | 1 | 8 | 14 | 12 | 13 | 104 | 17 |
| 508 | e | 16 | 14 | 13 | 12 | 10 | 6 | 2 | 1 | 10 | 18 | 17 | 15 | 133 | 5 |
| 509 | e | 19 | 13 | 14 | 13 | 14 | 8 | 0 | 1 | 10 | 18 | 15 | 12 | 136 | 6-7 |
| 510 | e | 12 | 11 | 11 | 10 | 10 | 9 | 9 | 3 | 10 | 17 | 14 | 12 | 122 | 19 |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: (cont.) | |||||||||||||||
| 511 | e | 4 | 5 | 1 | 2 | 8 | 4 | 0 | 2 | 7 | 4 | 10 | 6 | 53 | 2 |
| 512 | e | 20 | 13 | 12 | 11 | 7 | 1 | 0 | 0 | 1 | 6 | 12 | 12 | 95 | 7 |
| 514 | e | 15 | 12 | 14 | 13 | 13 | 2 | 0 | * | 3 | 12 | 14 | 14 | 112 | 11 |
| 515 | e | 4 | 4 | 4 | 2 | 9 | 6 | 2 | 4 | 11 | 7 | 8 | 6 | 67 | 4 |
| 517 | e | 8 | 7 | 7 | 6 | 8 | 4 | 1 | 5 | 8 | 8 | 7 | 7 | 76 | 9 |
| 518 | e | 13 | 10 | 12 | 11 | 11 | 6 | 1 | * | 6 | 15 | 16 | 16 | 115 | 26 |
| 519 | e | 12 | 11 | 9 | 11 | 12 | 5 | 1 | 1 | 7 | 15 | 14 | 12 | 110 | 22 |
| 520 | e | 8 | 9 | 7 | 7 | 7 | 1 | * | 0 | 3 | 10 | 10 | 9 | 72 | 10 |
| 521 | e | 13 | 9 | 10 | 11 | 11 | 4 | * | * | 4 | 15 | 14 | 10 | 102 | 4 |
| 522 | e | 8 | 9 | 8 | 8 | 6 | 1 | 1 | 4 | 10 | 13 | 10 | 10 | 88 | 4 |
| 523 | e | 11 | 8 | 13 | 10 | 10 | 3 | 4 | 1 | 8 | 13 | 17 | 12 | 110 | 3 |
| 524 | e | 13 | 11 | 14 | 10 | 10 | 0 | 0 | 0 | 2 | 10 | 12 | 10 | 92 | 4 |
| 525 | e | 7 | 6 | 8 | 8 | 5 | 1 | 1 | 1 | 5 | 10 | 11 | 9 | 72 | 7 |
| 526 | e | 8 | 8 | 8 | 7 | 6 | * | 0 | * | 2 | 8 | 10 | 8 | 65 | 13 |
| 527 | e | 9 | 10 | 8 | 7 | 7 | 2 | * | * | 2 | 6 | 9 | 9 | 66 | 14 |
| 529 | a | 12 | 12 | 7 | 8 | 4 | 0 | 0 | 0 | 0 | 2 | 7 | 7 | 69 | 4 |
| 530 | e | 12 | 13 | 15 | 13 | 6 | 0 | 0 | 0 | 0 | 3 | 8 | 12 | 82 | 7 |
| 531 | e | 3 | 3 | 6 | 4 | 4 | * | 0 | * | 0 | 7 | 7 | 3 | 37 | 4 |
| Asia, Inland: | |||||||||||||||
| 550 | e | 22 | .. | 21 | .. | 16 | 7 | 0 | 0 | 10 | 23 | .. | 12 | … | 0-1 |
| 551 | e | 25 | 15 | 8 | 13 | 12 | 7 | 0 | 5 | 8 | 19 | 14 | 16 | 142 | 1 |
| 552 | e | 10 | 7 | 9 | 9 | 8 | 2 | * | 1 | 9 | 16 | 10 | 8 | 89 | .. |
| Table ^ XVI ^ . Mean number of days with snow (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Amt | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland: (cont.) | |||||||||||||||
| 553 | e | 13 | 12 | 12 | 9 | 10 | 5 | * | * | 7 | 19 | 17 | 14 | 118 | 14 |
| 554 | e | 8 | 7 | 9 | 10 | 7 | 5 | 0 | * | 6 | 12 | 13 | 10 | 85 | 4 |
| 556 | e | 7 | 6 | 4 | 4 | 3 | 1 | * | 1 | 4 | 8 | 8 | 8 | 54 | 18 |
| 558 | e | 3 | 5 | 4 | 3 | 1 | 1 | * | 1 | 4 | 8 | 8 | 4 | 42 | 5 |
| 559 | e | 17 | 14 | 10 | 5 | 4 | 1 | * | 1 | 5 | 15 | 18 | 20 | 111 | 9 |
| 560 | e | 10 | 12 | 12 | 10 | 7 | 2 | 0 | * | 3 | 14 | 14 | 13 | 96 | 8 |
| 561 | e | 12 | 7 | 7 | 7 | 5 | 1 | * | 0 | 1 | 8 | 9 | 11 | 667 | 3 |
| 562 | e | 15 | 12 | 13 | 8 | 7 | 1 | * | * | 3 | 12 | 16 | 16 | 104 | 10 |
| 563 | e | 10 | 9 | 10 | 9 | 9 | 4 | * | * | 7 | 16 | 15 | 14 | 103 | 15 |
| 566 | e | 9 | 8 | 6 | 6 | 3 | * | 0 | 0 | 2 | 9 | 10 | 9 | 62 | 16 |
| 567 | e | 12 | 11 | 9 | 7 | 4 | * | 0 | * | 3 | 13 | 15 | 12 | 86 | 12 |
| 568 | e | 9 | 6 | 4 | 4 | 1 | 0 | 0 | 0 | 1 | 10 | 9 | 9 | 53 | 14 |
| 570 | e | 3 | 4 | 5 | 6 | 3 | 0 | 0 | 0 | 2 | 9 | 7 | 3 | 42 | 8 |
| 571 | e | 11 | 2 | 3 | 8 | 6 | 0 | 0 | 0 | 4 | 12 | 12 | 7 | 65 | 0-1 |
| 572 | e | 7 | 7 | 7 | 5 | 4 | * | 0 | * | 3 | 9 | 10 | 8 | 62 | 16 |
| 573 | e | 8 | 6 | 7 | 4 | 2 | * | 0 | 0 | 1 | 6 | 10 | 10 | 54 | 18 |
| 574 | e | 11 | 9 | 9 | 8 | 4 | * | 0 | 0 | 2 | 13 | 15 | 13 | 83 | 21 |
| 575 | e | 17 | 15 | 14 | 9 | 4 | * | 0 | 0 | 3 | 13 | 19 | 18 | 112 | 18 |
| 576 | e | 16 | 14 | 14 | 11 | 6 | * | 0 | * | 5 | 15 | 21 | 18 | 120 | 13 |
| Table ^ XVII. ^ Mean monthly snowfall (inches) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 2.6 | 2.7 | 2.0 | 2.7 | 1.8 | 0.4 | 1.0 | 0.7 | 3.0 | 7.9 | 4.3 | 3.9 | 33.0 | 21-33 |
| 102 | 15.6 | 5.4 | 5.7 | 5.2 | 0.5 | 0.4 | 0.0 | * | 1.4 | 5.2 | 3.5 | 3.8 | 46.7 | 6-11 |
| 104 | 10.8 | 8.9 | 10.2 | 5.1 | 1.3 | 0.2 | 0.0 | * | 0.4 | 3.6 | 8.5 | 10.8 | 59.8 | 29-34 |
| 105 | 0.9 | 0.7 | 0.1 | 0.7 | 0.5 | 0.2 | 1.2 | 0.6 | 1.0 | 1.1 | 0.3 | 0.2 | 7.5 | 2-5 |
| 106 | 12.1 | 8.7 | 7.7 | 2.9 | 0.2 | 0.0 | 0.0 | 0.0 | * | 5.2 | 11.2 | 10.4 | 58.4 | 21-25 |
| Alaska, Inland: | ||||||||||||||
| 152 | 9.4 | 11.3 | 4.5 | 5.1 | 1.8 | 0.0 | 0.0 | 0.0 | * | 7.1 | 11.2 | 11.7 | 62.1 | 6-8 |
| 153 | 7.8 | 6.9 | 3.8 | 1.6 | 0.5 | 0.0 | 0.0 | 0.1 | 1.3 | 7.2 | 7.7 | 5.1 | 42.0 | 21-27 |
| 154 | 7.2 | 4.9 | 8.0 | 3.3 | 0.5 | 0.0 | 0.0 | 0.0 | 0.2 | 3.3 | 5.2 | 9.3 | 41.9 | 16-18 |
| 155 | 10.0 | 9.5 | 8.1 | 2.5 | 0.5 | * | * | 0.0 | 0.9 | 7.6 | 5.8 | 8.6 | 53.5 | 33-37 |
| 156 | 11.7 | 7.2 | 8.1 | 2.7 | 0.4 | * | 0.0 | 0.1 | 0.7 | 6.5 | 7.4 | 8.7 | 53.5 | 31 |
| 157 | 8.4 | 5.4 | 5.5 | 3.6 | 0.5 | * | 0.0 | 0.2 | 1.7 | 8.1 | 9.2 | 10.1 | 52.7 | 28-31 |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | 3.8 | 2.4 | 5.4 | 5.1 | 4.5 | 5.3 | 0.0 | 0.6 | 3.5 | 14.1 | 8.7 | 2.4 | 55.8 | 5 |
| 205 | 1.7 | 4.6 | 1.1 | 1.0 | 0.0 | 0.0 | 0.0 | 0.0 | 4.5 | 7.5 | 7.2 | 0.5 | 28.1 | 3 |
| 206 | 2.3 | 3.2 | 2.5 | 1.2 | 4.0 | 1.4 | 0.0 | 5.3 | 5.5 | 3.8 | 2.2 | 1.2 | 32.6 | 1-4 |
| 210 | 9.7 | 2.1 | 3.7 | 4.5 | 6.2 | 8.7 | 0.1 | * | 17.8 | 17.6 | 10.5 | 3.5 | 84.4 | 4 |
| 211 | 3.9 | 2.3 | 3.9 | 2.7 | 5.3 | 3.5 | 0.1 | 1.6 | 5.7 | 7.0 | 4.3 | 3.9 | 44.2 | 10 |
| 212 | 1.1 | 2.3 | 4.2 | 2.1 | 4.3 | 5.5 | 0.0 | 0.2 | 4.5 | 16.8 | 6.6 | 2.2 | 40.8 | 4 |
| 213 | 2.5 | 0.8 | 0.9 | 2.6 | 3.6 | 0.5 | 0.0 | 0.4 | 1.3 | 5.6 | 4.7 | 3.9 | 26.8 | 5 |
| 214 | 2.4 | 2.3 | 0.8 | 0.4 | 3.8 | 1.5 | 1.0 | * | 1.0 | 11.0 | 8.0 | 1.1 | 33.3 | 5 |
| 215 | 2.2 | … | 1.5 | 3.5 | 5.2 | 0.4 | 0.0 | 0.0 | 4.2 | 3.2 | 1.3 | 2.6 | … | 0-6 |
| 216 | 5.7 | 4.4 | 6.3 | 5.2 | 4.9 | 1.8 | * | 0.2 | 3.9 | 9.9 | 8.4 | 6.3 | 57.0 | 13 |
| 217 | 3.4 | 5.0 | 2.0 | 3.6 | 4.8 | 6.2 | 0.0 | T | 2.5 | 3.9 | 5.8 | 3.6 | 40.8 | 13 |
| Table ^ XVII. ^ Mean monthly snowfall (inches) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: (cont.) | ||||||||||||||
| 221 | 3.5 | 5.5 | 5.0 | 8.8 | 6.1 | 0.8 | 0.0 | * | 1.2 | 9.1 | 8.0 | 9.1 | 57.0 | 20 |
| 222 | 1.7 | 3.8 | 2.4 | 5.1 | 6.3 | 1.6 | 0.0 | 0.0 | 3.4 | 7.2 | 4.6 | 1.3 | 37.4 | 6 |
| 223 | 5.7 | 5.5 | 5.9 | 11.2 | 6.7 | 4.0 | 0.9 | 0.6 | 3.1 | 10.6 | 14.7 | 8.4 | 77.3 | 14 |
| 224 | 7.2 | 7.1 | 4.8 | 10.0 | 5.7 | 2.0 | 0.0 | 0.0 | 1.0 | 12.3 | 9.6 | 4.9 | 64.8 | 6 |
| 225 | 3.0 | 3.4 | 1.7 | 5.4 | 8.8 | 2.3 | 0.0 | 0.0 | 4.1 | 5.2 | 4.3 | 4.8 | 43.0 | 3 |
| 226 | 8.8 | 14.6 | 9.2 | 18.0 | 4.5 | 1.6 | 0.0 | 0.0 | 2.1 | 13.1 | 22.1 | 21.0 | 115.0 | 7 |
| 227 | 10.2 | 11.1 | 9.4 | 8.7 | 9.0 | 3.0 | * | 0.1 | 2.2 | 8.2 | 12.1 | 10.3 | 84.3 | 15 |
| 228 | 4.8 | 6.1 | 8.5 | 7.7 | 1.8 | 1.4 | 0.0 | * | 1.7 | 8.1 | 10.3 | 6.6 | 56.9 | 30 |
| Canada, Inland: | ||||||||||||||
| 250 | 5.8 | 5.3 | 4.3 | 5.0 | 2.4 | 2.2 | * | 0.8 | 3.3 | 7.3 | 8.1 | 4.8 | 49.3 | 20 |
| 251 | 6.0 | 4.7 | 3.9 | 6.2 | 2.7 | 1.2 | 0.0 | * | 3.1 | 8.0 | 6.8 | 6.0 | 48.6 | 28 |
| 252 | 8.7 | 7.0 | 5.1 | 3.5 | 0.6 | 0.1 | 0.0 | * | 1.8 | 7.9 | 11.3 | 10.2 | 56.2 | 41 |
| 253 | 4.5 | 4.3 | 7.1 | 2.7 | 1.2 | 0.0 | 0.0 | 0.0 | 0.5 | 5.0 | 10.8 | 6.3 | 42.4 | 6 |
| 254 | 5.3 | 4.9 | 4.9 | 4.8 | 3.8 | 0.4 | 0.0 | 0.2 | 2.8 | 8.9 | 8.2 | 5.8 | 50.0 | 31 |
| 255 | 11.1 | 7.0 | 6.3 | 4.0 | 0.8 | 0.0 | 0.0 | 0.0 | 0.3 | 9.2 | 15.5 | 13.2 | 67.4 | 9 |
| 256 | 4.6 | 4.9 | 3.5 | 4.1 | 2.5 | 0.2 | 0.0 | 0.1 | 2.8 | 7.0 | 6.1 | 4.5 | 40.3 | 30 |
| 257 | 4.6 | 4.9 | 3.5 | 4.1 | 2.5 | 0.2 | 0.0 | 0.1 | 2.8 | 7.0 | 6.1 | 4.5 | 40.3 | 31 |
| 258 | 7.2 | 7.0 | 4.8 | 5.8 | 4.1 | * | 0.0 | 0.1 | 0.7 | 8.1 | 8.5 | 8.3 | 54.6 | 42 |
| 259 | 6.2 | 5.4 | 5.3 | 4.9 | 1.8 | 0.3 | 0.0 | 0.1 | 0.5 | 5.0 | 8.4 | 8.0 | 45.6 | 45 |
| 260 | 8.1 | 5.0 | 5.8 | 3.4 | 0.2 | * | 0.0 | 0.0 | 0.1 | 2.3 | 6.9 | 5.9 | 37.7 | .. |
| 261 | 6.3 | 5.6 | 5.3 | 2.9 | 1.2 | 0.5 | 0.0 | 0.0 | 1.8 | 6.8 | 14.2 | 7.3 | 51.9 | 27 |
| 262 | 5.4 | 6.0 | 4.9 | 4.1 | 1.3 | 0.1 | 0.0 | * | 0.8 | 4.7 | 8.3 | 6.7 | 42.3 | 26 |
| 263 | 6.1 | 3.7 | 5.9 | 3.1 | 1.0 | 0.1 | 0.0 | 0.0 | 0.5 | 3.0 | 5.1 | 5.2 | 33.7 | 30 |
| Table ^ XVII. ^ Mean monthly snowfall (inches) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland, Iceland, Coastal and Insular: | ||||||||||||||
| 302 | 0.6 | 0.5 | 1.5 | 2.3 | 1.1 | 0.8 | 0.0 | 0.0 | 2.2 | 1.5 | 2.5 | 1.9 | 14.9 | 3 |
| 331 | 3.0 | 3.4 | 1.7 | 0.8 | 0.2 | 0.0 | 0.0 | 0.0 | * | 0.5 | 1.4 | 2.1 | 13.1 | 15 |
| Europe, Coastal and Insular: | ||||||||||||||
| 425 | 8.4 | 6.7 | 8.3 | 8.6 | 5.0 | 0.8 | 0.0 | 0.1 | 1.2 | 5.8 | 8.6 | 8.4 | 60.1 | .. |
| Table ^ XVIII ^ Mean snow depth (inches) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 8 | 7 | 8 | 6 | 3 | * | 0 | * | 1 | 3 | 5 | 6 | 8 | |
| 101 | 1 | 2 | 4 | 9 | 5 | 1 | 0 | 0 | * | 2 | 3 | 1 | 1 | |
| 104 | 3 | 13 | 16 | 11 | 4 | 0 | 0 | 0 | * | * | 2 | 6 | 11 | |
| 105 | 6 | 8 | 7 | 7 | 1 | * | 0 | 0 | 0 | 3 | 8 | 10 | 1-4 | |
| Alaska, Inland: | ||||||||||||||
| 153 | 18 | 26 | 23 | 3 | 0 | 0 | 0 | 0 | * | 7 | 13 | 16 | 10 | |
| 156 | 18 | 17 | 20 | 11 | 1 | 0 | 0 | 0 | * | 1 | 4 | 11 | 14 | |
| Canada, Coastal and Insular: | ||||||||||||||
| 214 | 13 | 22 | 15 | 24 | 24 | 16 | 2 | * | * | 9 | 16 | 18 | 2-3 | |
| 216 | 3 | 4 | 6 | 6 | 3 | 2 | * | * | 4 | 8 | 6 | 3 | 7 | |
| 223 | 16 | 15 | 19 | 14 | 7 | 0 | 0 | 0 | 0 | 3 | 6 | 11 | 8 | |
| 226 | 13 | 15 | 16 | 13 | 4 | 0 | 0 | 0 | 1 | 8 | 10 | 13 | 3 | |
| 227 | 5 | 8 | 16 | * | 0 | 0 | 0 | 0 | 0 | * | 7 | 5 | 8 | |
| Canada, Inland: | ||||||||||||||
| 252 | 23 | 25 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 9 | 13 | 10 | |
| 254 | 18 | 20 | 19 | 14 | 0 | 0 | 0 | 0 | * | 5 | 11 | 20 | 2-21 | |
| 263 | 20 | 19 | 17 | 0 | 0 | 0 | 0 | 0 | 3 | 13 | 15 | 20 | 10 | |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 302 | 3 | 1 | 1 | 2 | 1 | * | 0 | 0 | * | * | 1 | 2 | 2-3 | |
| 305 | 19 | 19 | 21 | 19 | 12 | * | 0 | 0 | * | 2 | 8 | 16 | 3-5 | |
| 308 | 24 | 25 | 28 | 40 | 39 | 8 | * | 0 | * | 5 | 11 | 22 | .. | |
| 310 | 8 | 8 | 11 | 10 | 7 | * | 0 | 0 | * | 1 | 6 | 11 | 2-3 | |
| 312 | 3 | 2 | 2 | 2 | * | * | 0 | * | * | 1 | 3 | 3 | 5-7 | |
| 317 | 11 | 10 | 12 | 14 | 9 | 3 | * | 0 | * | 5 | 12 | 10 | 3 | |
| 318 | 6 | 8 | 13 | 11 | 2 | * | * | 0 | * | 1 | 3 | 5 | 3-5 | |
| 319 | 2 | 3 | 4 | 2 | * | * | 0 | 0 | * | 1 | 2 | 1 | 3-7 | |
| 321 | 36 | 33 | 60 | 65 | 44 | 6 | * | * | * | 3 | 6 | 20 | 3-5 |
| Table ^ XVIII ^ Mean snow depth (inches) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular: (cont.) | ||||||||||||||
| 330 | 4 | 4 | 4 | 2 | 1 | 0 | 0 | 0 | 0 | 2 | 3 | 4 | 11 | |
| 331 | 4 | 2 | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 2 | 10 | |
| Greenland and Iceland, Inland: | ||||||||||||||
| 361 | 18 | 19 | 21 | 15 | 7 | 1 | 0 | 0 | 1 | 5 | 11 | 8 | 11 | |
| Europe, Coastal and Insular: | ||||||||||||||
| 408 | 21 | 28 | 34 | 30 | 14 | * | 0 | 0 | * | 1 | 5 | 15 | .. | |
| 411 | 9 | 13 | 17 | 4 | 1 | 0 | 0 | 0 | 0 | * | 4 | 9 | .. | |
| 415 | 16 | 22 | 25 | 23 | 8 | 0 | 0 | 0 | 0 | 2 | 5 | 10 | .. | |
| 424 | 12 | 16 | 12 | * | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 7 | 20 | |
| 425 | 12 | 16 | 18 | 10 | * | 0 | 0 | 0 | 0 | * | 4 | 8 | .. | |
| 428 | 18 | 24 | 27 | 11 | * | 0 | 0 | 0 | 0 | * | 4 | 11 | 4 | |
| Europe, Inland: | ||||||||||||||
| 451 | 12 | 15 | 16 | 13 | 2 | 0 | 0 | 0 | 0 | 1 | 6 | 11 | .. | |
| 452 | 19 | 25 | 28 | 23 | 6 | 0 | 0 | 0 | 0 | * | 7 | 15 | .. | |
| 454 | 3 | 5 | 4 | 1 | * | 0 | 0 | 0 | 0 | * | 1 | 2 | 15 | |
| 455 | 10 | 12 | 11 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 5 | 25 | |
| 457 | 16 | 19 | 15 | 1 | 0 | 0 | 0 | 0 | 0 | 2 | 3 | 9 | 36 | |
| 458 | 16 | 21 | 20 | 4 | 0 | 0 | 0 | 0 | 0 | 1 | 4 | 11 | 18 | |
| Asia, Coastal and Insular: | ||||||||||||||
| 503 | 7 | 7 | 8 | 8 | 8 | 5 | * | 0 | 1 | 3 | 5 | 6 | 7 | |
| 506 | 10 | 11 | 13 | 12 | 11 | 3 | 0 | 0 | 0 | 1 | 3 | 8 | .. | |
| 508 | 11 | 12 | 12 | 13 | 15 | 8 | 0 | 0 | * | 3 | 6 | 8 | 6 | |
| 510 | 16 | 21 | 25 | 29 | 27 | 9 | 0 | 0 | 0 | 4 | 11 | 14 | 18 |
| Table ^ XVIII ^ Mean snow depth (inches) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular: (cont.) | ||||||||||||||
| 513 | 2 | 1 | 5 | 6 | .. | 0 | 0 | 0 | 0 | 5 | 5 | 3 | 3 | |
| 515 | 18 | 21 | 23 | 24 | 24 | 3 | 0 | 0 | 1 | 6 | 10 | 15 | .. | |
| 517 | 8 | 12 | 12 | 9 | 10 | 4 | 0 | 0 | 0 | 2 | 6 | 3 | 11 | |
| 518 | 7 | 8 | 11 | 13 | 12 | 2 | 0 | 0 | 0 | 1 | 3 | 6 | 26 | |
| 519 | 5 | 5 | 4 | 5 | 4 | * | 0 | 0 | 0 | 1 | 4 | 4 | 22 | |
| 522 | 13 | 17 | 19 | 19 | 12 | * | 0 | 0 | * | 3 | 9 | 12 | .. | |
| 523 | 9 | 10 | 12 | 14 | 14 | 5 | 0 | 0 | 0 | 2 | 5 | 6 | 6 | |
| 526 | 13 | 18 | 22 | 25 | 13 | .. | 0 | 0 | 0 | 2 | 4 | 9 | 3-4 | |
| 527 | 13 | 18 | 20 | 22 | 18 | 2 | 0 | 0 | * | 2 | 5 | 9 | .. | |
| Asia, Inland: | ||||||||||||||
| 552 | 4 | 5 | 4 | 8 | 6 | 0 | 0 | 0 | 1 | 3 | 4 | 4 | .. | |
| 554 | 44 | 50 | 58 | 6 | * | 0 | 0 | 0 | 0 | 5 | 25 | 36 | .. | |
| 556 | 9 | 11 | 11 | 11 | 4 | 0 | 0 | 0 | 0 | 3 | 6 | 8 | 6 | |
| 558 | 15 | 18 | 19 | 16 | 8 | * | 0 | 0 | * | 4 | 9 | 13 | .. | |
| 559 | 15 | 17 | 19 | 19 | 7 | 0 | 0 | 0 | * | 2 | 7 | 12 | .. | |
| 562 | 20 | 27 | 32 | 27 | 8 | .. | 0 | 0 | * | 1 | 5 | 12 | 11 | |
| 563 | 38 | 41 | 40 | 33 | 27 | .. | 0 | 0 | 0 | 2 | 10 | 23 | 3 | |
| 566 | 11 | 13 | 12 | 6 | 0 | 0 | 0 | 0 | * | 1 | 7 | 9 | .. | |
| 568 | 10 | 13 | 15 | 8 | 0 | 0 | 0 | 0 | * | 1 | 4 | 6 | .. | |
| 572 | 33 | 38 | 44 | 48 | 40 | .. | 0 | 0 | 0 | 3 | 14 | 26 | 6 | |
| 573 | 20 | 25 | 28 | 13 | 1 | 0 | 0 | 0 | 0 | 1 | 5 | 12 | 9 | |
| 575 | 14 | 17 | 17 | 7 | * | 0 | 0 | 0 | 0 | 1 | 5 | 10 | .. | |
| 576 | 23 | 24 | 24 | 19 | 1 | 0 | 0 | 0 | 0 | 3 | 11 | 17 | 8 |
It is to be noted that the water equivalent of Arctic snow is often
considerable. With the low winter temperatures which occur in the Arctic,
the precipitated snow (plus hoarfrost) is most often in the form of small
ice spicules which form so compact a mass that 2 inches of the snow may
be equivalent to 1 inch of liquid water. The average density of snow
cover over the Arctic Basin area is least at the beginning of winter and
increases to its maximum value in spring (average densities of snow cover
are of the order of 0.30 to 0.45).
^
fig. 49 here
^
Snow depths probably reach a maximum in March or April over much
of the Arctic. In some of the more maritime regions which experience
heavy snows, the maximum snow depth may not be reached until May. Over
some of the drier continental portions of the Arctic, on the other hand,
the period of maximum snow depth may occur as early as February.
The snow cover disappears at some time during spring or summer
everywhere in the Arctic except at elevations above the permanent snow
line and in local protected locations nearer sea level. Near the Pole
the snow begins to melt in June, and by the end of July the snow cover is
almost gone. The Russian North Polar Expedition (1937), for example,
reported that it was difficult in late July to find enough
snow to use as ballast for the tents
^
[
5
]
^
.
The average thickness of snow cover by months for selected
Siberian
^
arctic
^
locations is given in Table
^
XVIII
^
. Comparing these data with
the data on monthly snowfall (Table
^
XVII
^
), it is seen that the thickness
of the snow cover is not completely determined by snowfall alone. Other
factors such as melting, drifting, evaporation and the accretion of rime,
etc., serve to alter the relationship. Topographical conditions also
exert their influence on the snow depths, since larger amounts of
snowfall occur on windward slopes than in leeward locations. This effect
is particularly noticeable in Greenland where the data show considerably
less accretion in the eastern portions than is observed at western
stations in the same latitude. The amount of accretion in the border
regions of the Greenland Ice Cap must also decrease sharply from south to
north, as is evidenced by the comparatively higher elevation of the
permanent snow line in the north (1400 m) compared to the south — a
difference which exists in spite of the temperature decrease toward the
north.
Thunderstorms
. - Thunderstorms have never been recorded over the Arctic
pack-ice but they do occur infrequently at coastal and inland locations
above the Arctic Circle. In Jakobshaven 3 thunderstorms were experienced
in the course of 62 years. In all Arctic regions their frequency
increases rapidly toward the south. For example, Ivigtut has had 24
thunderstorms in 45 years of record; Nanortalik, 77 in 42 years. At
inland locations in more southerly Arctic latitudes, thunderstorms are
fairly frequent and probably occur at least several times each year. at
some inland stations the average annual number is as high as 9 (as at
Fairbanks). Thunderstorms have been recorded in all months
^
[
43
]
^
but their
occurrence is most probable in July and August.
HUMIDITY
Some of the facts concerning humidity conditions within the Arctic
have already been discussed in the section on the composition of the
atmosphere. There it was emphasized that a clear distinction must be
made between humidity as expressed in terms of the actual moisture
content (by vapor pressure, specific humidity, or mixing ratio) and as
expressed in terms of the degree of saturation (by relative humidity or
by saturation deficit). In the latter case a further distinction must
be made between the expression of relative humidity in terms of percent
of saturation with respect to ice and its expression in terms of
saturation with respect to water. (See Table II.) For example, the
observations on the
Fram
^
[
28
]
^
over the pack-ice during February 1894
gave a mean temperature for the month of −32.1°F. and a mean relative
humidity with respect to ice of 129 percent. The corresponding relative
humidity computed with respect to water for the same month is only 92
percent.
It should be mentioned that humidity computations at low
temperatures in the Arctic are highly questionable partly because of
the importance of small instrumental or observational errors at these
temperatures and also because of the difficulty in obtaining a sample
unaffected by a local source of moisture (such as the observer himself).
As a very generalized statement for the entire Arctic it can be said
that it is essentially a region of high relative humidities but, because
of low temperatures, it is also a region which presents very small absolute
amounts of atmospheric moisture. Relative humidities average generally
between 75 and 100 percent, even over continental areas, except where
foehn (dynamical heating) effects are persistent. Over glaciers, elevated
snowfields, and the pack-ice, however, the relative humidities with respect
to ice are frequently above 100 percent. From 150 observations on about
120 different days in the winters of 1923-24 and 1924-25, Mal^mgren
[
26
]
^
found that over the Polar Sea in winter the relative humidity always
remains near 100 percent. The smallest observed value was 83 percent and
the greatest, 122 percent. In 77 percent of all cases the relative
humidity with respect to ice was between 93 and 107 percent. During
summer the relative humidities were lower over the Polar Sea but even
in July the average (with respect to a water surface) was 95 percent.
^Malm^gren
^
[
26
]
^
points out that in calm weather over the pack-ice
there exists a sharp decrease in relative humidity from the surface
upward due to the presence of the surface temperature inversion. When
the wind blows, however, the mixing processes bring air of higher
temperature, i.e., lower relative humidity, down to the ice. For this
reason the surface humidity decrease as the wind speed increases and
becomes progressively lower as the wind extends the mixing to greater
altitudes. Changes in cloudiness have a similar effect. Under clear
sky conditions (in winter), the increased radiative loss of heat from
the ice lowers the surface air temperature with a resulting increase in
relative humidity. The relations between relative humidity (with respect
to ice) and temperature, wind speed, and cloudiness in winter as found
by Malmgren
^
[
26
]
^
are as follows:
| Wind Speed (mph) | 1.3 | 4.5 | 8.9 | 13.2 | 20.6 |
| Relative Humidity (%) | 105.7 | 103.2 | 101.1 | 98.7 | 96.5 |
| Temperature (°F.) | 10.4 | –0.6 | –8.9 | –17.9 | –25.2 | –35.9 |
| Relative Humidity (%) | 97.1 | 98.1 | 98.9 | 101.1 | 103.2 | 103.9 |
| Cloudiness (0-10) | 0.9 | 3.9 | 7.2 | 9.9 | ||
| Relative Humidity (%) | 104.3 | 101.6 | 99.2 | 97.9 |
When a marked surface temperature inversion is present, the humidity
usually decreases from a maximum at the surface to a value between 50 and
60 percent at the top of the inversion. Above the inversion the humidity
remains fairly constant with altitude unless warm, moist air is being
advected aloft from lower latitudes, in which case a marked maximum in
humidity may occur even at altitudes of 15,000 or 20,000 feet.
The only circumstances that allow low relative humidities to occur
in the Arctic are offered by strong offshore or downslope winds such as
occur at the foot of a glacier or a mountain range. An example of the
lowering of humidity during periods of offshore (downslope) winds is
given by the following average relative humidity data for Foka Bay,
Novaya Zemlya:
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | |
| Onshore wind | … | 82.0 | 92.1 | 92.2 | 92.4 | 93.8 | 94.1 | 94.2 | 91.9 | 83.3 | 83.3 | 84.8 | 91.0 |
| Offshore wind | … | 79.8 | 81.5 | 87.1 | 78.5 | 81.3 | 83.5 | 82.2 | 82.9 | 77.6 | 74.7 | 74.6 | 79.5 |
Annual Variation of Humidity
. — In most inland Arctic regions the
annual variation of relative humidity follows very closely the annual
variation in temperature as would be expected on the basis of the
functional dependence of relative humidity upon air temperature. Inland,
the maximum humidity values are found in winter and the minima, in summer.
In the more maritime regions, the reverse is generally true. In Greenland,
however, the interior ice locations show summer maxima and the coastal
regions, winter maxima. This circumstance can be accounted for by the ^
tables XIX to XXI here
^
fact that the free air at 8,000 to 10,000 feet is exceedingly dry in
winter compared to its state in summer. On the northern coasts of
Greenland, however, the prevailing downslope winds of summer give
humidities which are lower than those recorded during winter when the
katabatic circulation from the Ice Cap is at its weakest.
| Table ^ XIX ^ . Mean relative humidity (%) by seasons at continental and coastal stations | |||||
|---|---|---|---|---|---|
| Continental Stations | Coastal Stations | ||||
| Station | Summer | Winter | Station | Summer | Winter |
| Fairbanks | 48 | 78 | Nome | 83 | 76 |
| Chesterfield | 87 | 92 | Barrow | 87 | 81 |
| Meanook | 74 | 85 | Coppermine | 81 | 73 |
| Hopes Advance | 85 | 89 | “Fram” | 94 | 82 |
| Olekminsk | 67 | 80 | “Maud” | 96 | 78 |
| Verkhoyansk | 60 | 72 | “Sedov” Foka Bay | 91 | 80 |
| West Station* | 83 | 76 | Danmarkshavn** | 79 | 84 |
| Eismitte* | 86 | 79 | Angmagssalik** | 73 | 82 |
| Table ^ XX ^ . Mean relative humidity (%) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 002 | 81 | 85 | .. | .. | .. | .. | .. | .. | .. | .. | 80 | 81 | .. | .. |
| 003 | 74 | 75 | 75 | 80 | 87 | 93 | 96 | 96 | 93 | 85 | 79 | 75 | 84 | 2 |
| 004 | 84 | 83 | 81 | 82 | 82 | 86 | 90 | 86 | 83 | 82 | 81 | 83 | 84 | .. |
| 005 | 86 | 83 | 80 | 82 | 84 | 88 | 85 | 83 | 84 | 82 | 85 | 86 | 84 | .. |
| 007 | 89 | 84 | 83 | 89 | 88 | 93 | 96 | 96 | 93 | 88 | 88 | 86 | 89 | 5-6 |
| 008 | 76 | .. | .. | .. | .. | .. | 95 | 94 | 86 | 79 | 77 | 75 | .. | 0-1 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 84 | 80 | 80 | 80 | 84 | 87 | 86 | 88 | 88 | 86 | 83 | 80 | 84 | 2 |
| Alaska, Inland: | ||||||||||||||
| 156 | 81 | 76 | 62 | 55 | 53 | 56 | 63 | 69 | 67 | 74 | 81 | 82 | 68 | 9 |
| 157 | 92 | 85 | 81 | 67 | 56 | 61 | 65 | 76 | 77 | 80 | 86 | 91 | 76 | 1-2 |
| Canada, Coastal and Insular: | ||||||||||||||
| 201 | .. | .. | .. | .. | 79 | 79 | 80 | 79 | 84 | 83 | .. | .. | .. | .. |
| 204 | 85 | 84 | 87 | 86 | 90 | 89 | 86 | 87 | 86 | 84 | 88 | 86 | 87 | 2-5 |
| 211 | .. | .. | .. | .. | 83 | 77 | 79 | 83 | 83 | 82 | .. | .. | .. | 4 |
| 216 | .. | .. | .. | .. | .. | 89 | 90 | 92 | 93 | 93 | .. | .. | .. | 2-3 |
| 221 | .. | .. | .. | .. | .. | 90 | 84 | 85 | 89 | .. | .. | .. | .. | 5 |
| Canada, Inland: | ||||||||||||||
| 250 | .. | .. | .. | .. | .. | 73 | 76 | 85 | 85 | .. | .. | .. | .. | 5 |
| 252 | .. | .. | .. | .. | 67 | 69 | 76 | 81 | 86 | .. | .. | .. | .. | 5 |
| 253 | 90 | 84 | 78 | 65 | 56 | 64 | 64 | 69 | 75 | 79 | 88 | 91 | 75 | 5 |
| 255 | 93 | 89 | 76 | 70 | 61 | 65 | 66 | 68 | 75 | 78 | 88 | 91 | 77 | 4 |
| 256 | 90 | 84 | 83 | 73 | 67 | 61 | 64 | 71 | 80 | 85 | 93 | 89 | 78 | 3 |
| Table ^ XX ^ . Mean relative Humidity (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland, (cont.): | ||||||||||||||
| 258 | 83 | 83 | 76 | 67 | 62 | 59 | 62 | 65 | 71 | 82 | 87 | 80 | 73 | 4 |
| 260 | .. | .. | .. | .. | 80 | 68 | 71 | 74 | 80 | 90 | .. | .. | .. | 5 |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 303 | 84 | 81 | 88 | 78 | 80 | 80 | 80 | 76 | 70 | 74 | 86 | 87 | 80 | 2 |
| 304 | 73 | 74 | 72 | 78 | 87 | 86 | 82 | 81 | 85 | 89 | 84 | 78 | 75 | 24 |
| 306 | .. | .. | .. | .. | 72 | 73 | 69 | 68 | 69 | .. | .. | .. | .. | 5 |
| 314 | 89 | 89 | 89 | 89 | 88 | 84 | 87 | 87 | 86 | 88 | 90 | 88 | 88 | 7 |
| 317 | 83 | 82 | 81 | 79 | 77 | 74 | 73 | 72 | 73 | 80 | 80 | 81 | 77 | 35 |
| 320 | 75 | 76 | 74 | 72 | 72 | 73 | 76 | 78 | 76 | 75 | 74 | 75 | 75 | 16 |
| 331 | 81 | 80 | 80 | 74 | 70 | 75 | 75 | 74 | 74 | 78 | 81 | 81 | 77 | 3 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 351 | 80 | 77 | 78 | 81 | 86 | 84 | 88 | 84 | 84 | 80 | 79 | 78 | 82 | 1 |
| Europe, Coastal and Insular: | ||||||||||||||
| 403 | 81 | 80 | 80 | 77 | 76 | 82 | 81 | 83 | 82 | 80 | 79 | 82 | 80 | .. |
| 408 | 82 | 81 | 81 | 82 | 82 | 83 | 84 | 85 | 85 | 85 | 85 | 83 | 83 | 15 |
| 412 | 68 | 69 | 71 | 70 | 68 | 71 | 74 | 73 | 75 | 76 | 73 | 69 | 71 | 18 |
| 414 | 77 | 76 | 74 | 71 | 69 | 71 | 74 | 80 | 80 | 80 | 80 | 78 | 75 | 18 |
| 415 | 86 | 85 | 80 | 75 | 71 | 70 | 75 | 80 | 83 | 86 | 88 | 88 | 81 | 24 |
| 420 | 75 | 73 | 73 | 69 | 60 | 74 | 76 | 75 | 76 | 75 | 76 | 74 | 74 | 18 |
| 421 | 83 | 84 | 81 | 71 | 62 | 61 | 67 | 73 | 66 | 81 | 87 | 88 | 76 | 7 |
| 423 | 86 | 85 | 83 | 77 | 64 | 65 | 61 | 73 | 78 | 88 | 91 | 87 | 78 | 7 |
| 424 | 87 | 87 | 82 | 78 | 71 | 72 | 73 | 80 | 83 | 86 | 88 | 89 | 81 | 26 |
| 425 | 88 | 87 | 83 | 81 | 75 | 73 | 80 | 86 | 88 | 88 | 90 | 90 | 84 | 21 |
| Table ^ XX ^ . Mean relative humidity (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular, (cont.): | ||||||||||||||
| 426 | 86 | 85 | 79 | 71 | 63 | 63 | 67 | 74 | 79 | 82 | 86 | 87 | 77 | 25 |
| 428 | 88 | 87 | 83 | 76 | 73 | 68 | 74 | 86 | 85 | 87 | 90 | 89 | 82 | 25 |
| 429 | 87 | 85 | 81 | 75 | 72 | 69 | 73 | 80 | 85 | 87 | 89 | 88 | 81 | 25 |
| Europe, Inland: | ||||||||||||||
| 450 | 85 | 85 | 84 | 74 | 67 | 63 | 63 | 73 | 77 | 83 | 88 | 87 | 77 | 7 |
| 454 | 73 | 70 | 70 | 65 | 65 | 66 | 70 | 72 | 77 | 78 | 75 | 76 | 72 | 18 |
| 455 | 79 | 81 | 78 | 68 | 55 | 55 | 61 | 71 | 73 | 82 | 86 | 84 | 73 | 7 |
| 456 | 90 | 87 | 79 | 70 | 61 | 56 | 63 | 72 | 76 | 85 | 90 | 92 | 77 | 7 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 87 | 84 | 90 | 88 | 88 | 92 | 93 | 92 | 90 | 86 | 87 | 88 | 90 | 7-8 |
| 501 | 82 | 80 | 80 | 84 | 86 | 90 | 90 | 91 | 90 | 87 | 82 | 82 | 85 | 5-6 |
| 502 | 85 | 82 | 82 | 73 | 71 | 70 | 72 | 73 | 80 | 81 | 82 | 85 | 78 | 8 |
| 503 | 86 | 85 | 82 | 84 | 86 | 90 | 90 | 94 | 90 | 87 | 84 | 82 | 87 | 7-8 |
| 507 | 80 | 82 | 80 | 80 | 78 | 78 | 79 | 80 | 82 | 81 | 82 | 82 | 80 | 17 |
| 508 | 85 | 84 | 83 | 86 | 87 | 92 | 92 | 91 | 91 | 90 | 88 | 86 | 88 | 6 |
| 509 | 88 | 87 | 84 | 87 | 89 | 88 | 81 | 87 | 90 | 90 | 87 | 84 | 87 | 6-7 |
| 510 | 89 | 88 | 85 | 88 | 88 | 91 | 90 | 90 | 89 | 88 | 88 | 86 | 88 | 19 |
| 511 | 85 | 85 | 86 | 87 | 89 | 92 | 92 | 90 | 90 | 88 | 87 | 84 | 87 | 2 |
| 513 | 81 | 83 | 80 | 80 | 78 | 77 | 76 | 77 | 82 | 80 | 82 | 79 | 80 | .. |
| 515 | 81 | 82 | 86 | 86 | 88 | 85 | 78 | 84 | 89 | 90 | 87 | 85 | 85 | 6 |
| 518 | 89 | 89 | 86 | 87 | 89 | 90 | 87 | 90 | 88 | 88 | 89 | 85 | 89 | 26 |
| 519 | 87 | 88 | 84 | 84 | 88 | 89 | 88 | 92 | 90 | 90 | 89 | 86 | 88 | 22 |
| 520 | 86 | 90 | 88 | 84 | 83 | 81 | 78 | 82 | 88 | 91 | 87 | 88 | 85 | 4-8 |
| 522 | 80 | 78 | 79 | 70 | 72 | 67 | 69 | 80 | 82 | 87 | 84 | 79 | 77 | 1 |
| Table ^ XX ^ . Mean relative humidity (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland: | ||||||||||||||
| 553 | 84 | 81 | 81 | 82 | 85 | 83 | 74 | 82 | 85 | 89 | 84 | 82 | 83 | 18 |
| 554 | 79 | 72 | 74 | 79 | 79 | 73 | 71 | 81 | 87 | 84 | 80 | 75 | 78 | 2 |
| 556 | 72 | 71 | 67 | 60 | 55 | 53 | 59 | 69 | 75 | 77 | 76 | 74 | 67 | 9 |
| 558 | 78 | 78 | 76 | 71 | 70 | 65 | 68 | 78 | 78 | 83 | 84 | 82 | 76 | 6 |
| 562 | 81 | 80 | 75 | 70 | 67 | 69 | 71 | 77 | 82 | 82 | 83 | 81 | 77 | 10 |
| 566 | 81 | 80 | 73 | 67 | 61 | 64 | 64 | 72 | 75 | 76 | 81 | 80 | 73 | 7-15 |
| 567 | 81 | 81 | 72 | 62 | 60 | 60 | 61 | 69 | 74 | 80 | 83 | 79 | 72 | 12 |
| 573 | 84 | 80 | 73 | 67 | 63 | 64 | 66 | 77 | 77 | 81 | 85 | 89 | 76 | 9 |
| Table ^ XXI ^ . Average vapor pressure (mbs) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | ||||||||||||||
| 003 | 0.3* | 0.3* | 0.4* | 0.8* | 2.0* | 5.2 | 5.9 | 6.0 | 4.2 | 1.8 | 0.6* | 0.3* | … | 1-2 |
| 007 | 1.5 | 1.2 | 0.7 | 1.3 | 2.9 | 5.2 | 6.0 | 6.1 | 5.5 | 3.3 | 1.7 | 1.3 | 3.1 | 5-6 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 2.2 | 1.9 | 1.1 | 1.9 | 3.2 | 5.1 | 6.4 | 6.7 | 5.6 | 4.0 | 2.7 | 2.1 | 3.6 | 7-8 |
| 501 | 1.2 | 1.1 | 0.7 | 1.3 | 2.8 | 5.6 | 7.2 | 6.9 | 5.9 | 2.9 | 1.5 | 1.1 | 3.2 | 5-6 |
| 503 | 1.1 | 1.1 | 0.7 | 1.1 | 2.7 | 5.1 | 6.5 | 6.1 | 5.2 | 2.7 | 1.5 | 0.9 | 2.9 | 7-8 |
| 507 | 2.1 | 1.7 | 1.2 | 2.1 | 3.5 | 5.2 | 7.1 | 7.6 | 5.9 | 4.3 | 3.2 | 2.4 | 3.9 | 17 |
| 508 | 1.7 | 1.3 | 0.8 | 1.7 | 3.5 | 5.2 | 7.5 | 8.0 | 6.5 | 4.0 | 2.4 | 1.9 | 3.7 | 6 |
| 509 | 1.5 | 1.1 | 0.9 | 1.7 | 3.9 | 6.3 | 9.1 | 9.3 | 6.8 | 3.7 | 1.9 | 1.3 | 4.0 | 6-7 |
| 510 | 1.3 | 1.3 | 0.9 | 1.7 | 3.2 | 5.7 | 7.5 | 7.9 | 6.4 | 3.5 | 1.9 | 1.3 | 3.6 | 19 |
| 518 | 2.4 | 1.9 | 1.7 | 2.4 | 4.5 | 5.9 | 8.4 | 9.3 | 7.5 | 4.9 | 3.7 | 2.7 | 4.7 | 26 |
| 519 | 2.0 | 1.3 | 1.5 | 2.1 | 4.4 | 5.7 | 8.8 | 9.3 | 7.3 | 4.5 | 2.9 | 2.1 | 4.4 | 22 |
| Asia, Inland: | ||||||||||||||
| 553 | 1.2 | 1.2 | 1.2 | 1.9 | 3.5 | 6.7 | 10.3 | 9.9 | 7.1 | 3.5 | 1.5 | 1.1 | 4.4 | 18 |
Data concerning the annual course of vapor pressure over the Arctic
are not available in any regional detail. However, the values nearly
everywhere should be lowest in winter (0.1 to 0.4 mb near sea level) and
highest in July or August (4.0 to 6.5 mb near sea level). These values
are approximately of the same order of magnitude as the saturation vapor
pressures at the observed seasonal temperatures. (See page .)
Diurnal Variation of Humidity
. Table
^
XXII
^
shows the diurnal variation
of relative humidity as observed on the
Fram
in South Ellesmere Land.
Average humidity is highest between midnight and 0400h and lowest between
noon and 1600h in all months except January, when the diurnal maxima and
minima are reversed. The January reversal in humidity appears to correspond
to a similar reversal in the diurnal temperature variation during this month
at most stations on the Arctic Ocean and in the Canadian Archipelago.
Sverdrup
^
[
43
]
^
found the diurnal variation in humidity to be very small
over the pack-ice but the hours of maxima and minima appear to correspond
quite closely to those recorded at the coast by the
Fram
.
| Table ^ XXII ^ . Diurnal range in relative humidity (%) in South Ellesmere Land, 1898-1902 | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hour | 2h | 4h | 6h | 8h | 10h | 12h | 14h | 16h | 18h | 20h | 22h | 24h | Ra.* |
| Jan | 83.0 | 83.0 | 83.4 | 83.1 | 83.1 | 83.3 | 83.3 | 83.7 | 83.6 | 83.3 | 83.1 | 83.1 | 0.7 |
| Feb | 85.1 | 84.8 | 84.3 | 84.4 | 84.3 | 84.0 | 83.8 | 83.7 | 84.6 | 84.8 | 84.8 | 84.4 | 1.4 |
| Mar | 80.6 | 81.0 | 80.9 | 80.6 | 80.6 | 79.3 | 79.0 | 79.6 | 79.7 | 80.3 | 80.3 | 80.1 | 2.0 |
| Apr | 83.5 | 83.0 | 82.5 | 81.0 | 79.5 | 78.6 | 78.5 | 78.4 | 79.2 | 81.2 | 82.8 | 83.4 | 5.1 |
| May | 82.1 | 81.3 | 79.6 | 78.7 | 77.4 | 76.1 | 76.3 | 76.8 | 77.8 | 79.0 | 80.2 | 81.4 | 6.0 |
| Jun | 82.2 | 81.9 | 80.8 | 79.4 | 78.2 | 76.8 | 78.2 | 75.9 | 77.4 | 78.5 | 79.9 | 82.0 | 6.3 |
| Jul | 84.4 | 84.4 | 84.6 | 83.4 | 82.4 | 80.5 | 79.1 | 79.1 | 79.7 | 81.3 | 82.6 | 84.1 | 5.7 |
| Aug | 89.3 | 89.4 | 89.1 | 89.3 | 86.9 | 85.2 | 84.3 | 82.6 | 85.2 | 86.4 | 88.0 | 88.7 | 6.8 |
| Sep | 86.3 | 86.7 | 85.2 | 84.0 | 83.3 | 83.0 | 83.0 | 83.6 | 85.8 | 86.4 | 85.7 | 86.3 | 3.7 |
| Oct | 82.3 | 81.7 | 81.5 | 80.6 | 81.2 | 80.0 | 80.5 | 80.2 | 82.5 | 82.3 | 82.8 | 83.0 | 3.0 |
| Nov | 81.7 | 81.4 | 81.7 | 81.4 | 81.9 | 81.2 | 80.6 | 80.9 | 80.5 | 80.8 | 81.1 | 81.2 | 1.4 |
| Dec | 84.1 | 84.3 | 83.8 | 83.8 | 84.0 | 83.4 | 83.3 | 83.2 | 83.8 | 83.6 | 83.6 | 84.2 | 1.1 |
Sverdrup also found that the vapor pressure in the surface air over
the pack-ice has a regular diurnal variation in all months in which the
relative humidity varies regularly but that the phase is reversed. (See
Fig.
^
50
^
.) The maximum vapor pressure occurs at the hour of minimum
relative humidity and the minimum vapor pressure occurs near midnight ^
fig. 50 here
^
when the relative humidity is at its maximum.
^table xxiii here^
Non-Periodic Variations in Humidity
. While the annual and diurnal variations
in the actual moisture content of the atmosphere are quite considerable over
the Arctic, the corresponding variations in relative humidity are very
slight. The principal variations in relative humidity appear to be non–
periodic in nature and the result of several causative factors. In some
coastal areas and in regions which exhibit a local diversity in the character
of the land surface, large changes in humidity can accompany rapid changes
in wind direction. This is particularly true during summer along the coasts
of the Polar Sea, where a sudden change in the wind from an offshore to an
onshore direction will produce an immediate rise in relative humidity. This
change is primarily caused by the sudden change in temperature (see page )
rather than by any large difference in the actual moisture content between
104
offshore and onshore winds. Large variations in relative humidity can
also occur with increases in the wind to speeds which are sufficient to
break down the surface temperature inversion or upon the initiation of
winds which exhibit a considerable dynamical heating because they possess
a large downslope component.
| Table XXIII. Diurnal variation of relative humidity (%) (with respect to water) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Station | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Ayon Island (69°52′N., 167°52′E.) | ||||||||||
| Mean | 82.8 | 86.9 | 83.7 | 86.0 | 84.2 | |||||
| Max. | 83.9 | 88.7 | 89.0 | 86.7 | 84.5 | |||||
| Hour of Max. | 0100 | 0200 | 0400 | 1900 | 0800 | |||||
| Min. | 81.2 | 84.8 | 79.1 | 85.5 | 84.0 | |||||
| Hour of Min. | 1500 | 1600 | 1200 | 1200 | 0100 | |||||
| Amplitude | 2.72 | 3.84 | 8.95 | 1.20 | 0.56 | |||||
| Cape Serdze Kamen (66°53′N., 188°22′E.) | ||||||||||
| Mean | 79.4 | 84.5 | 86.4 | 91.1* | 90.7 | 86.6 | 83.0 | |||
| Max. | 80.0 | 86.6 | 91.1 | 93.1* | 92.1 | 89.0 | 84.5 | |||
| Hour of Max. | 0700 | 0200 | 2400 | 0100* | 2200 | 0400 | 2400 | |||
| Min. | 78.4 | 82.2 | 81.7 | 89.3* | 88.8 | 84.7 | 81.8 | |||
| Hour of Min. | 1200 | 1300 | 1100 | 1000* | 1500 | 1300 | 0700 | |||
| Amplitude | 1.59 | 4.45 | 9.39 | 3.80* | 3.31 | 4.31 | 2.75 | |||
| Pack Ice 1922 (Approx. 71°N., 185°E.) | ||||||||||
| Mean | 95.0 | 95.4 | 84.5 | |||||||
| Max. | 97.0 | 96.1 | 85.2 | |||||||
| Hour of Max. | 2300 | 0800 | 1500 | |||||||
| Min. | 91.3 | 91.7 | 84.1 | |||||||
| Hour of Min. | 1500 | 1400 | 2300 | |||||||
| Amplitude | 5.66 | 1.35 | 1.12 |
| Table XXIII. Diurnal variation of relative humidity (%) (with respect to water) (cont.) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Station | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Pack ice 1923 (Approx. 75.5°N., 165°E.) | ||||||||||
| Mean | 95.5 | 97.0 | 97.3 | 91.1 | 86.0 | |||||
| Max. | 97.7 | 98.3 | 98.2 | 91.5 | 86.3 | |||||
| Hour of Max. | 0200 | 0100 | 0600 | 2000 | 0300 | |||||
| Min. | 93.5 | 95.7 | 95.8 | 90.1 | 85.7 | |||||
| Hour of Min. | 1600 | 0900 | 1300 | 1400 | 1100 | |||||
| Amplitude | 4.17 | 2.60 | 2.38 | 1.40 | 0.63 | |||||
| Pack Ice 1924 (Approx. 76.5°N., 145°E.) | ||||||||||
| Mean | 81.8 | 91.3 | 94.7 | |||||||
| Max. | 83.4 | 92.7 | 96.1 | |||||||
| Hour of Max. | 0200 | 0100 | 2300 | |||||||
| Min. | 79.7 | 89.7 | 92.5 | |||||||
| Hour of Min. | 1300 | 1400 | 1100 | |||||||
| Amplitude | 2.73 | 3.06 | 3.60 |
At lower latitudes in the Arctic the changes in air mass accompanying
frontal passages are probably the most important among the several factors
which account for rapid and sizeable changes in the atmospheric moisture
content. Such changes in air mass are reflected in the observations by
corresponding changes in both the specific humidity (vapor pressure) and
the relative humidity terms.
CLOUDINESS AND CEILINGS
The general character of cloud cover over the Arctic differs
considerably from that considered typical for most temperate regions.
The uniform and contourless stratus clouds which are by far the most
frequent type observed give to the Arctic its reputation for a dull and
monotonous appearance. Over the Arctic Ocean during summer the low
stratus type of cloud constitutes from 70 to 80 percent of all clouds
observed. In winter and spring they are not so frequent, but they still
constitute from 45 to 60 percent of all cloud types present. Along the
coast in more southerly locations, the stratus clouds are proportionately
less frequent. In these regions the cloud decks tend to be more often
broken up by convective currents, with a resulting increase in the
proportion of stratocumulus cloud reported.
Sverdrup
^
[
43
]
^
has shown that there is no direct relation between
air temperature and the occurrence of stratus over the maritime Arctic
regions. However, he does show that the occurrence of low stratus is
closely associated with the presence of a surface temperature inversion.
Along the coasts of the Arctic Ocean in summer the surface inversion
exists only when there is an onshore wind, but with offshore winds and
when the temperature is high at the ground, the temperature decreases
regularly with altitude. Conditions are then unfavorable for the
formation of low cloud. These processes probably account for the
secondary minimum in cloudiness that is observable during one or more
of the summer months at a number of Arctic coastal stations (see Table
^
XXIV
^
).
^
table XXIV here
^
Over nearly all of the Arctic cloudiness is most extensive in summer
and autumn and least extensive in winter and spring. Over the Arctic
Ocean during summer the low stratus overcast may persist for weeks at a
time without once offering a glimpse of blue sky or upper cloud. Days
with clear sky occur rarely if ever. It is significant to note that
average sky conditions computed from observations on both the
Fram
and
the
Maud
indicate that no clear days (cloudiness, 2-tenths or less) are
to be expected during any of the months from June through August.
^
tables XXV to XXVII here
^
The Arctic Ocean proper and those adjacent coastal regions with a
preponderance of onshore winds show a maximum cloud cover in midsummer.
Those localities more often subject to offshore winds present a maximum
105
106
107 110 115 119 122
108 111 116 123 127 131 137 140 144
38 109 112 117 120 124 128 175 176 177 178 180 181
107 110 115 119 122
108 111 116 123 127 131 137 140 144
38 109 112 117 120 124 128 175 176 177 178 180 181
113
114 118
107 110 115 119 122
108 111 116 123 127 131 137 140 144
38 109 112 117 120 124 128 175 176 177 178 180 181
114 118
107 110 115 119 122
38 109 112 117 120 124 128 175 176 177 178 180 181
121
107 110 115 119 122
108 111 116 123 127 131 137 140 144
38 109 112 117 120 124 128 175 176 177 178 180 181
125
126
108 111 116 123 127 131 137 140 144
38 109 112 117 120 124 128 175 176 177 178 180 181
129
130
108 111 116 123 127 131 137 140 144
132 136 139 143 147
133 150 154 156 158 162 169 173
134 159
135 138 145
132 136 139 143 147
108 111 116 123 127 131 137 140 144
135 138 145
132 136 139 143 147
108 111 116 123 127 131 137 140 144
141
142 146 151
132 136 139 143 147
108 111 116 123 127 131 137 140 144
135 138 145
142 146 151
132 136 139 143 147
148
149 153
133 150 154 156 158 162 169 173
142 146 151
152
149 153
133 150 154 156 158 162 169 173
155 157 161 165 167 171
133 150 154 156 158 162 169 173
155 157 161 165 167 171
133 150 154 156 158 162 169 173
134 159
160 163
155 157 161 165 167 171
133 150 154 156 158 162 169 173
160 163
164 166 170
155 157 161 165 167 171
164 166 170
155 157 161 165 167 171
168 172
133 150 154 156 158 162 169 173
164 166 170
155 157 161 165 167 171
168 172
133 150 154 156 158 162 169 173
cloudiness in early autumn, with a secondary maximum in early summer
immediately preceding the summer minimum of stratus just described.
The cause of the double maximum is therefore obvious. At more southerly
coastal locations nearer the winter storm tracks (as over northern
Scandinavian areas), the annual variation in cloudiness is less than is
true for the Arctic generally and some stations show maxima during one
of the winter months.
| Table ^ XXIV ^ . Mean monthly cloudiness (%) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | ||||||||||||||
| 002 | 36 | 41 | 56 | 48 | 76 | 87 | 91 | 85 | 91 | 63 | 39 | 36 | 62 | 2⅓ |
| 003 | 36 | 42 | 34 | 47 | 73 | 85 | 88 | 88 | 82 | 80 | 51 | 40 | 62 | 2 |
| 004 | 84 | 83 | 79 | 83 | 82 | 84 | 90 | 85 | 81 | 83 | 83 | 81 | 83 | … |
| 005 | 82 | 80 | 82 | 86 | 90 | 89 | 87 | 89 | 90 | 86 | 86 | 81 | 86 | 4 |
| 006 | 60 | 69 | 52 | 56 | 82 | 82 | 84 | 88 | 89 | 83 | 62 | 49 | 71 | 4 |
| 007 | 68 | 62 | 50 | 64 | 90 | 95 | 88 | 92 | 95 | 82 | 74 | 65 | 78 | 5 |
| 008 | 53 | .. | .. | .. | .. | .. | 82 | 82 | 80 | 65 | 50 | 57 | .. | 0-1 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 47 | 57 | 53 | 53 | 80 | 80 | 83 | 97 | 90 | 91 | 70 | 60 | 70 | 2½ |
| 102 | 53 | 53 | 57 | 57 | 70 | 67 | 73 | 87 | 73 | 77 | 53 | 63 | 63 | 2½ |
| 104 | 54 | 52 | 50 | 64 | 62 | 62 | 79 | 75 | 68 | 70 | 52 | 58 | 62 | 10 |
| 105 | 52 | 53 | 49 | 50 | 69 | 63 | 66 | 75 | 72 | 69 | 61 | 50 | 61 | 10 |
| 106 | 70 | 60 | 50 | 63 | 83 | 70 | 70 | 77 | 80 | 87 | 70 | 67 | 67 | 8 |
| Alaska, Inland: | ||||||||||||||
| 150 | 53 | 47 | 70 | 57 | 67 | 70 | 70 | 87 | 73 | 70 | 53 | 70 | 63 | 2½ |
| 151 | 63 | 53 | 67 | 57 | 80 | 77 | 73 | 87 | 87 | 87 | 80 | 80 | 73 | 2 |
| 152 | 40 | 47 | 70 | 40 | 60 | 57 | 53 | 73 | 77 | 70 | 47 | 43 | 57 | 2 |
| 153 | 44 | 43 | 42 | 37 | 40 | 41 | 45 | 52 | 57 | 60 | 50 | 40 | 46 | 10 |
| 154 | 60 | 47 | 57 | 77 | 80 | 80 | 87 | 83 | 80 | 77 | 63 | 70 | 70 | 2½ |
| 156 | 63 | 53 | 60 | 60 | 70 | 70 | 70 | 73 | 80 | 80 | 57 | 60 | 63 | 7 |
| 157 | 48 | 50 | 54 | 56 | 61 | 56 | 62 | 68 | 72 | 66 | 57 | 48 | 58 | 10 |
| Canada, Coastal and Insular: | ||||||||||||||
| 201 | 34 | 28 | 50 | 35 | 60 | 66 | 70 | 78 | 63 | 44 | 28 | 36 | 49 | 2 |
| 202 | 20 | 41 | 34 | 45 | 62 | 66 | 62 | 78 | 81 | 57 | 33 | 33 | 51 | 2-5 |
| Table ^ XXIV ^ . Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Canada, Coastal and Insular (cont.): | ||||||||||||||
| 204 | 39 | 42 | 50 | 54 | 60 | 72 | 62 | 76 | 78 | 70 | 56 | 34 | 58 | 3 |
| 213 | 36 | 36 | 40 | 30 | 48 | 58 | 48 | 60 | 70 | 76 | 52 | 30 | 49 | 5 |
| 216 | 46 | 46 | 45 | 53 | 62 | 58 | 58 | 74 | 78 | 68 | 56 | 47 | 58 | 6 |
| 217 | 30 | 26 | 29 | 36 | 74 | 58 | 48 | 82 | 79 | 67 | 40 | .. | .. | 1 |
| 218 | 32 | 25 | 27 | 42 | 68 | 69 | 58 | 68 | 83 | 68 | 56 | 27 | 52 | 2 |
| 220 | 50 | 55 | 64 | 62 | 70 | 82 | 80 | 78 | 84 | 71 | 74 | 58 | 69 | … |
| 223 | 49 | 48 | 55 | 66 | 81 | 76 | 60 | 68 | 79 | 85 | 76 | 52 | 66 | 8-11 |
| 224 | 48 | 50 | 48 | 57 | 67 | 68 | 64 | 51 | 64 | 70 | 65 | 51 | 59 | 2 |
| 226 | 36 | 44 | 26 | 50 | 64 | 56 | 62 | 65 | 63 | 66 | 40 | 53 | 53 | 2 |
| 227 | 68 | 63 | 68 | 74 | 80 | 74 | 70 | 67 | 74 | 79 | 85 | 76 | 73 | 6 |
| 228 | 45 | 52 | 38 | 53 | 56 | 52 | 50 | 48 | 59 | 68 | 56 | 50 | 52 | 5 |
| Canada, Inland: | ||||||||||||||
| 250 | 41 | 42 | 43 | 44 | 45 | 51 | 60 | 74 | 70 | 67 | 58 | 49 | 54 | 8 |
| 252 | 57 | 49 | 44 | 48 | 49 | 53 | 58 | 58 | 59 | 63 | 62 | 63 | 55 | 15 |
| 253 | 70 | 70 | 75 | 57 | 66 | 76 | 86 | 65 | 78 | 69 | 81 | 71 | 71 | … |
| 254 | 44 | 44 | 38 | 44 | 46 | 42 | 43 | 51 | 63 | 64 | 53 | 41 | 48 | … |
| 257 | 37 | 34 | 38 | 46 | 48 | 49 | 56 | 62 | 62 | 70 | 58 | 46 | 50 | 4 |
| 259 | 52 | 47 | 49 | 45 | 54 | 50 | 45 | 44 | 66 | 67 | 62 | 47 | 52 | 18 |
| 260 | 43 | 47 | 39 | 41 | 50 | 41 | 58 | 56 | 66 | 73 | 67 | 51 | 53 | … |
| Greenland, Iceland, Coastal and Insular: | ||||||||||||||
| 301 | 37 | 46 | 62 | 42 | .. | 66 | 69 | 65 | 68 | 59 | 60 | 36 | 62 | 5 |
| 302 | 47 | 47 | 40 | 57 | 63 | 60 | 70 | 60 | 67 | 67 | 63 | 43 | 57 | 2 |
| 303 | 63 | 44 | 50 | 32 | 43 | 52 | 51 | 48 | 48 | 46 | 56 | 54 | 49 | … |
| Table ^ XXIV ^ . Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Greenland, Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 304 | 49 | 45 | 47 | 54 | 66 | 72 | 66 | 68 | 68 | 70 | 71 | 62 | 62 | 31 |
| 307 | 42 | 48 | 50 | 41 | 50 | 64 | 60 | 65 | 56 | 49 | 56 | 49 | 52 | … |
| 308 | 59 | 71 | 50 | 68 | 53 | 58 | 51 | 55 | 51 | 54 | 53 | 62 | 57 | … |
| 310* | 73 | 68 | 67 | 71 | 71 | 71 | 69 | 71 | 72 | 73 | 76 | 76 | 71 | 15 |
| 314 | 75 | 72 | 69 | 70 | 68 | 69 | 66 | 70 | 70 | 69 | 68 | 67 | 69 | 31 |
| 317 | 67 | 61 | 61 | 61 | 63 | 62 | 56 | 54 | 63 | 68 | 67 | 66 | 62 | 30 |
| 318 | 64 | 63 | 59 | 58 | 60 | 61 | 59 | 62 | 62 | 61 | 58 | 58 | 61 | 29 |
| 320 | 68 | 68 | 64 | 62 | 64 | 66 | 64 | 68 | 64 | 63 | 64 | 64 | 65 | 2 |
| 330 | 73 | 74 | 70 | 70 | 60 | 63 | 68 | 72 | 74 | 72 | 72 | 71 | 70 | 16 |
| 331 | 67 | 68 | 71 | 62 | 65 | 71 | 72 | 72 | 66 | 67 | 66 | 67 | 68 | 10 |
| 332 | 78 | 78 | 76 | 77 | 74 | 78 | 81 | 86 | 80 | 72 | 70 | 79 | 77 | 9 |
| 333 | 76 | 73 | 74 | 72 | 78 | 74 | 78 | 75 | 79 | 68 | 74 | 76 | 75 | 11 |
| 334 | 73 | 70 | 71 | 71 | 66 | 66 | 73 | 73 | 70 | 77 | 77 | 74 | 72 | 14 |
| 335 | 68 | 64 | 64 | 70 | 64 | 71 | 76 | 80 | 74 | 76 | 69 | 66 | 70 | … |
| 336 | 75 | 74 | 75 | 74 | 70 | 72 | 74 | 79 | 75 | 79 | 72 | 72 | 74 | 20 |
| 337 | 67 | 67 | 66 | 67 | 74 | 72 | 78 | 75 | 74 | 62 | 69 | 66 | 70 | 11 |
| 339 | 85 | 80 | 84 | 84 | 80 | 82 | 85 | 83 | 83 | 86 | 84 | 82 | 83 | 10 |
| 340 | 66 | 67 | 69 | 69 | 71 | 69 | 75 | 76 | 72 | 72 | 66 | 65 | 70 | 18 |
| 341 | 71 | 70 | 79 | 72 | 71 | 68 | 82 | 69 | 76 | 73 | 75 | 67 | 73 | 8 |
| Greenland, Iceland, Inland: | ||||||||||||||
| 351 | 66 | 49 | 54 | 60 | 61 | 54 | 77 | 60 | 53 | 54 | 52 | 57 | 58 | 1 |
| 360 | 73 | 70 | 70 | 76 | 79 | 74 | 78 | 80 | 78 | 75 | 75 | 74 | 75 | 7 |
| 361 | 75 | 71 | 72 | 75 | 68 | 70 | 74 | 79 | 75 | 81 | 74 | 73 | 74 | 15 |
| Table ^ XXIV ^ . Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 70 | 67 | 61 | 71 | 86 | 85 | 87 | 92 | 92 | 90 | 73 | 64 | 78 | 10 |
| 401 | 64 | 56 | 52 | 76 | 87 | 91 | 91 | 96 | 82 | 85 | 67 | 72 | 77 | 4 |
| 403 | 62 | 59 | 58 | 56 | 66 | 75 | 70 | 73 | 76 | 72 | 61 | 59 | 66 | 14 |
| 406 | 70 | 73 | 73 | 74 | 75 | 73 | 69 | 69 | 77 | 73 | 74 | 65 | 72 | … |
| 407 | 70 | 70 | 75 | 74 | 77 | 74 | 68 | 73 | 82 | 75 | 74 | 69 | 73 | 10 |
| 408 | 76 | 74 | 72 | 71 | 76 | 74 | 72 | 75 | 77 | 77 | 80 | 77 | 75 | 44 |
| 410 | 78 | 76 | 72 | 68 | 68 | 69 | 71 | 69 | 75 | 75 | 77 | 76 | 73 | … |
| 412 | 65 | 63 | 58 | 55 | 58 | 59 | 61 | 59 | 67 | 66 | 65 | 59 | 61 | 44 |
| 414 | 65 | 64 | 60 | 62 | 68 | 68 | 66 | 67 | 76 | 70 | 70 | 60 | 66 | … |
| 415 | 70 | 70 | 60 | 69 | 72 | 68 | 75 | 77 | 77 | 81 | 77 | 76 | 73 | 10 |
| 417 | 82 | 77 | 73 | 81 | 89 | 83 | 80 | 83 | 84 | 86 | 86 | 85 | 82 | 7 |
| 420 | 72 | 71 | 68 | 65 | 66 | 68 | 70 | 70 | 75 | 71 | 71 | 68 | 70 | … |
| 421 | 62 | 60 | 59 | 56 | 55 | 50 | 53 | 68 | 61 | 63 | 60 | 69 | 59 | 20 |
| 423 | 66 | 62 | 55 | 54 | 61 | 55 | 57 | 62 | 63 | 68 | 70 | 71 | 62 | 20 |
| 424 | 80 | 75 | 67 | 64 | 58 | 55 | 53 | 62 | 63 | 74 | 81 | 83 | 68 | … |
| 425 | 73 | 70 | 67 | 68 | 75 | 66 | 64 | 72 | 75 | 77 | 82 | 75 | 72 | 21 |
| 426 | 84 | 78 | 68 | 62 | 60 | 60 | 61 | 64 | 69 | 79 | 83 | 88 | 71 | 10 |
| 428 | 88 | 87 | 83 | 76 | 73 | 68 | 74 | 80 | 85 | 87 | 90 | 89 | 82 | 25 |
| 429 | 79 | 82 | 73 | 75 | 79 | 69 | 73 | 78 | 82 | 85 | 86 | 78 | 78 | 13 |
| Europe, Inland: | ||||||||||||||
| 450 | 62 | 57 | 54 | 56 | 68 | 64 | 68 | 72 | 69 | 68 | 66 | 67 | 64 | … |
| 451 | 66 | 63 | 61 | 64 | 70 | 66 | 66 | 71 | 73 | 71 | 70 | 66 | 67 | 44 |
| 453 | 76 | 65 | 61 | 71 | 67 | 66 | 67 | 70 | 71 | 80 | 79 | 76 | 71 | 9 |
| Table ^ XXIV ^ . Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Europe, Inland (cont.): | ||||||||||||||
| 454 | 77 | 76 | 73 | 71 | 73 | 73 | 77 | 79 | 79 | 77 | 77 | 75 | 76 | 44 |
| 455 | 66 | 62 | 56 | 54 | 52 | 52 | 55 | 56 | 56 | 63 | 66 | 69 | 59 | … |
| 456 | 66 | 59 | 59 | 59 | 63 | 60 | 65 | 68 | 69 | 72 | 71 | 70 | 65 | 20 |
| 457 | 76 | 70 | 60 | 59 | 55 | 56 | 53 | 61 | 62 | 75 | 82 | 81 | 66 | 36 |
| 458 | 76 | 71 | 64 | 62 | 61 | 63 | 59 | 66 | 70 | 78 | 84 | 82 | 70 | 35 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 63 | 61 | 63 | 77 | 89 | 91 | 85 | 89 | 91 | 92 | 81 | 69 | 79 | 8 |
| 501 | 57 | 47 | 46 | 62 | 81 | 88 | 80 | 89 | 89 | 80 | 58 | 62 | 70 | 5 |
| 502 | 58 | 53 | 60 | 59 | 81 | 84 | 80 | 94 | 88 | 78 | 58 | 57 | 70 | 4 |
| 503 | 57 | 60 | 46 | 63 | 86 | 87 | 86 | 93 | 90 | 85 | 64 | 55 | 73 | 7 |
| 504** | 30 | 45 | 34 | 62 | 71 | 85 | 84 | 95 | 90 | 81 | 66 | 44 | 66 | 2½ |
| 505 | 80 | 77 | 71 | 73 | 82 | 76 | 75 | 81 | 84 | 82 | 83 | 75 | 78 | 14 |
| 506 | 76 | 68 | 61 | 70 | 82 | 81 | 71 | 80 | 83 | 85 | 81 | 74 | 76 | 14 |
| 507 | 69 | 69 | 65 | 68 | 80 | 75 | 70 | 78 | 82 | 83 | 80 | 72 | 74 | 16 |
| 508 | 68 | 64 | 60 | 67 | 86 | 82 | 79 | 90 | 90 | 88 | 80 | 70 | 77 | 6 |
| 509 | 71 | 66 | 61 | 68 | 86 | 84 | 79 | 92 | 88 | 85 | 72 | 62 | 76 | 7 |
| 510 | 65 | 69 | 59 | 70 | 85 | 91 | 81 | 90 | 88 | 85 | 75 | 64 | 77 | 18 |
| 511 | 40 | 36 | 32 | 53 | 77 | 80 | 76 | 85 | 90 | 72 | 60 | 51 | 63 | 1½ |
| 513 | 40 | 48 | 43 | 53 | 66 | 71 | 73 | 79 | 78 | 70 | 55 | 50 | 60 | 7 |
| 515 | 34 | 36 | 33 | 36 | 65 | 76 | 68 | 78 | 85 | 73 | 60 | 46 | 58 | 9 |
| 517 | 55 | 58 | 50 | 54 | 79 | 74 | 72 | 79 | 81 | 74 | 67 | 64 | 67 | 9 |
| 518 | 74 | 67 | 66 | 72 | 88 | 83 | 76 | 82 | 88 | 87 | 87 | 79 | 79 | 26 |
| 519 | 69 | 64 | 57 | 69 | 84 | 80 | 68 | 81 | 86 | 86 | 88 | 80 | 76 | 22 |
| Table ^ XXIV. ^ Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 520 | 63 | 65 | 59 | 62 | 72 | 75 | 68 | 75 | 79 | 80 | 70 | 67 | 70 | 33 |
| 521 | 64 | 59 | 59 | 68 | 84 | 78 | 72 | 79 | 81 | 83 | 76 | 66 | 72 | 13 |
| 522 | 47 | 43 | 40 | 46 | 54 | 53 | 61 | 70 | 73 | 65 | 65 | 51 | 56 | 3-6 |
| 523 | 57 | 69 | 68 | 60 | 77 | 84 | 80 | 86 | 91 | 83 | 78 | 75 | 76 | 3 |
| 525 | 53 | 64 | 61 | 74 | 86 | 74 | 77 | 82 | 85 | 79 | 78 | 63 | 73 | 10 |
| 526 | 55 | 53 | 53 | 64 | 68 | 73 | 76 | 72 | 67 | 70 | 64 | 56 | 64 | 14 |
| 527 | 52 | 63 | 54 | 55 | 68 | 69 | 75 | 74 | 72 | 71 | 65 | 60 | 65 | 14 |
| 531 | 64 | 59 | 62 | 53 | 73 | 77 | 79 | 67 | 56 | 64 | 68 | 62 | 65 | 4 |
| Asia, Inland: | ||||||||||||||
| 551 | 42 | 54 | 49 | 64 | 80 | 74 | 74 | 77 | 81 | 79 | 55 | 48 | 65 | 3 |
| 552 | 60 | 46 | 56 | 63 | 68 | 75 | 79 | 79 | 81 | 90 | 73 | 59 | 69 | 12 |
| 553 | 64 | 66 | 65 | 64 | 77 | 80 | 70 | 83 | 84 | 86 | 71 | 62 | 73 | 18 |
| 554 | 65 | 70 | 59 | 69 | 75 | 81 | 70 | 75 | 85 | 82 | 72 | 65 | 72 | 17 |
| 555 | 71 | 58 | 68 | 58 | 67 | 75 | 64 | 74 | 80 | 85 | 76 | 56 | 69 | 4 |
| 556 | 34 | 31 | 33 | 48 | 61 | 64 | 64 | 66 | 66 | 64 | 46 | 39 | 51 | 33 |
| 557 | 52 | 54 | 29 | 36 | 40 | 64 | 64 | 68 | 74 | 71 | 65 | 48 | 55 | 4 |
| 558 | 40 | 42 | 32 | 34 | 51 | 57 | 62 | 72 | 70 | 68 | 54 | 48 | 53 | 9 |
| 559 | 53 | 48 | 44 | 52 | 63 | 65 | 61 | 75 | 74 | 71 | 62 | 56 | 60 | 10 |
| 560 | 67 | 54 | 52 | 51 | 67 | 62 | 58 | 65 | 69 | 70 | 65 | 62 | 62 | 11 |
| 561 | 55 | 49 | 43 | 47 | 60 | 58 | 55 | 61 | 67 | 69 | 68 | 61 | 58 | 9 |
| 562 | 66 | 59 | 54 | 58 | 70 | 69 | 62 | 68 | 72 | 80 | 72 | 69 | 67 | 24 |
| 563 | 63 | 60 | 58 | 59 | 68 | 68 | 63 | 70 | 79 | 81 | 70 | 63 | 67 | 46 |
| 564 | 59 | 64 | 63 | 67 | 75 | 75 | 73 | 76 | 77 | 81 | 72 | 62 | 70 | 5 |
| 565 | 61 | 51 | 58 | 67 | 79 | 60 | 50 | 53 | 67 | 78 | 69 | 70 | 64 | 13 |
| 566 | 56 | 60 | 49 | 53 | 68 | 65 | 58 | 63 | 70 | 74 | 63 | 68 | 63 | 23 |
| Table ^ XXIV. ^ Mean monthly cloudiness (%) (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Inland (cont.): | ||||||||||||||
| 567 | 66 | 63 | 56 | 65 | 72 | 71 | 67 | 69 | 75 | 79 | 70 | 63 | 68 | 25 |
| 568 | 52 | 45 | 37 | 49 | 59 | 56 | 56 | 60 | 63 | 73 | 61 | 56 | 56 | 30 |
| 569 | 34 | 41 | 41 | 57 | 69 | 63 | 50 | 67 | 69 | 68 | 54 | 34 | 54 | 1 |
| 570 | 23 | 20 | 24 | 34 | 46 | 38 | 36 | 42 | 48 | 59 | 42 | 22 | 36 | 16 |
| 572 | 53 | 54 | 50 | 56 | 67 | 65 | 68 | 71 | 71 | 72 | 65 | 56 | 62 | 21 |
| 573 | 64 | 65 | 58 | 56 | 61 | 65 | 60 | 62 | 67 | 71 | 76 | 71 | 65 | 9 |
| 574 | 67 | 58 | 57 | 56 | 65 | 64 | 58 | 64 | 63 | 78 | 75 | 65 | 64 | 20 |
| 575 | 61 | 57 | 60 | 64 | 68 | 63 | 62 | 65 | 71 | 76 | 75 | 65 | 66 | 18 |
| 576 | 73 | 64 | 58 | 63 | 67 | 67 | 68 | 68 | 74 | 75 | 79 | 77 | 69 | 13 |
| Table ^ XXV. ^ Mean number of clear days | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | |||||||||||||||
| 002 | g | 14 | 12 | 9 | 8 | 7 | 0 | 0 | 0 | 0 | 4 | 11 | 15 | 80 | 2 1/2 |
| 003 | g | 14 | 9 | 12 | 10 | 2 | 0 | 0 | 0 | 1 | 1 | 7 | 9 | 65 | 2 |
| 004 | g | * | * | 1 | 0 | * | * | * | * | 0 | * | * | * | 2 | … |
| 005 | c | 1 | 1 | 1 | 1 | * | 1 | * | * | * | 0 | 0 | 1 | 6 | … |
| 006 | c | 6 | 2 | 7 | 6 | 1 | 2 | 2 | 1 | 1 | 1 | 6 | 9 | 43 | 4 |
| 117 | c | 5 | 3 | 8 | 5 | * | 0 | 1 | 1 | 0 | * | 2 | 5 | 31 | 5 |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | g | 17 | 18 | 18 | 14 | 7 | 9 | 8 | 4 | 4 | 6 | 12 | 13 | 130 | 10 |
| 102 | g | 15 | 13 | 15 | 12 | 12 | 13 | 7 | 6 | 7 | 8 | 11 | 12 | 132 | 11-13 |
| 104 | g | 10 | 11 | 12 | 9 | 9 | 8 | 5 | 4 | 6 | 7 | 10 | 11 | 102 | 19 |
| 105 | g | 13 | 8 | 7 | 4 | 5 | 8 | 3 | 4 | 3 | 2 | 2 | 2 | 61 | 2-4 |
| 106 | g | 9 | 8 | 10 | 9 | 7 | 8 | 6 | 4 | 6 | 6 | 7 | 9 | 89 | 24-26 |
| Alaska, Inland: | |||||||||||||||
| 152 | g | 15 | 14 | 18 | 16 | 12 | 10 | 4 | 5 | 6 | 7 | 15 | 15 | 137 | 8-10 |
| 153 | g | 15 | 16 | 17 | 18 | 15 | 15 | 15 | 11 | 10 | 9 | 10 | 13 | 164 | 10 |
| 154 | g | 11 | 10 | 12 | 9 | 6 | 9 | 4 | 5 | 5 | 7 | 11 | 11 | 100 | 18-19 |
| 156 | g | 10 | 9 | 11 | 10 | 4 | 4 | 5 | 3 | 4 | 5 | 8 | 11 | 84 | 10 |
| 157 | g | 12 | 10 | 10 | 10 | 6 | 8 | 7 | 6 | 5 | 7 | 8 | 12 | 101 | 10 |
| Canada, Coastal and Insular: | |||||||||||||||
| 201 | c | 16 | 14 | 8 | 12 | 5 | 4 | 4 | 1 | 4 | 12 | 17 | 16 | 113 | 2 |
| 202 | c | 20 | 11 | 13 | 9 | 6 | 5 | 6 | 1 | 1 | 7 | 15 | 14 | 108 | 3 |
| 204 | c | 16 | 13 | 13 | 9 | 8 | 6 | 8 | 4 | 3 | 7 | 11 | 18 | 117 | 3-5 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Canada, Coastal and Insular (cont.): | |||||||||||||||
| 213 | c | 17 | 21 | 20 | 20 | 15 | 13 | 14 | 6 | 6 | 7 | 12 | 16 | 168 | 3-5 |
| 220 | g | 14 | 16 | 16 | 8 | 4 | 4 | 6 | 2 | 0 | 2 | 5 | 10 | 87 | 2 |
| 223 | g | 11 | 12 | 12 | 6 | 5 | 4 | 9 | 6 | 3 | 3 | 5 | 14 | 90 | 5-7 |
| 224 | g | 15 | 18 | 19 | 10 | 5 | 5 | 6 | 10 | 4 | 6 | 7 | 12 | 116 | 4-5 |
| 226 | c | 13 | 18 | 17 | 15 | 7 | 6 | 6 | 7 | 4 | 9 | 7 | 18 | 125 | 2 |
| 227 | c | 11 | 7 | 7 | 6 | 4 | 6 | 6 | 10 | 4 | 5 | 6 | 8 | 80 | 2-5 |
| Canada, Inland: | |||||||||||||||
| 250 | c | 16 | 13 | 20 | 13 | 10 | 12 | 8 | 6 | 4 | 7 | 13 | 15 | 136 | 2-4 |
| Greenland and Iceland, Coastal and Insular: | |||||||||||||||
| 301 | g | 13 | 10 | 3 | .. | .. | 4 | 4 | 2 | 2 | 4 | 5 | 9 | .. | 0-3 |
| 302 | g | 12 | 11 | 16 | 11 | 8 | 9 | 6 | 10 | 6 | 7 | 8 | 15 | 119 | 2 |
| 304 | g | 9 | 10 | 10 | 8 | 5 | 3 | 5 | 5 | 4 | 3 | 3 | 6 | 71 | 31 |
| 307 | g | 12 | 10 | 9 | 11 | 8 | 5 | 6 | 4 | 4 | 9 | 4 | 11 | 93 | … |
| 308 | g | 7 | 2 | 8 | 7 | 7 | 6 | 7 | 5 | 7 | 7 | 8 | 7 | 78 | 19 |
| 310** | g | 1 | 2 | 2 | 1 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 2 | 18 | 15 |
| 314 | g | 1 | 1 | 2 | 2 | 3 | 2 | 2 | 2 | 2 | 3 | 2 | 2 | 24 | 31 |
| 317 | g | 4 | 4 | 5 | 6 | 6 | 6 | 6 | 8 | 6 | 4 | 4 | 5 | 64 | 30 |
| 318 | g | 5 | 7 | 7 | 9 | 9 | 7 | 8 | 7 | 7 | 7 | 7 | 7 | 87 | 28 |
| 320 | g | 2 | 2 | 4 | 3 | 4 | 2 | 3 | 2 | 3 | 4 | 4 | 3 | 35 | 19 |
| 330 | g | 2 | 2 | 3 | 2 | 5 | 4 | 4 | 3 | 2 | 2 | 2 | 3 | 32 | 16 |
| 331 | g | 2 | 2 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 1 | 2 | 2 | 20 | 16 |
| 332 | g | 1 | 1 | 1 | 1 | 2 | 1 | 1 | * | 1 | * | 1 | * | 10 | 16 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Greenland and Iceland, Coastal and Insular (cont.) | |||||||||||||||
| 333 | g | 1 | 2 | 2 | 2 | 11 | 1 | 1 | 1 | 2 | 2 | 1 | 1 | 16 | 11 |
| 334 | g | 1 | 1 | 2 | 1 | 2 | 2 | 1 | 1 | 1 | * | * | 1 | 13 | 14 |
| 335 | g | 3 | 4 | 4 | 3 | 5 | 3 | 2 | 1 | 2 | 3 | 3 | 3 | 34 | 15 |
| 336 | g | 1 | 1 | 1 | 2 | 3 | 2 | 1 | 1 | 1 | 1 | 2 | 1 | 17 | 16 |
| 337 | g | 3 | 2 | 3 | 3 | 1 | 2 | 1 | * | 1 | 2 | 2 | 2 | 22 | 11 |
| 339 | g | * | 1 | 1 | 1 | * | * | * | 0 | * | * | * | 1 | 4 | 10 |
| 340 | g | 4 | 3 | 2 | 3 | 3 | 3 | 1 | 1 | 1 | 1 | 3 | 4 | 30 | 14 |
| 341 | g | 7 | 3 | 2 | 3 | 4 | 4 | 1 | 4 | 2 | 2 | 2 | 5 | 39 | 8 |
| Greenland and Iceland, Inland: | |||||||||||||||
| 360 | g | 4 | 3 | 1 | 2 | 1 | 2 | 2 | 1 | 1 | 3 | 2 | 2 | 24 | 7 |
| 361 | g | 1 | 1 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | * | 1 | 1 | 15 | 16 |
| Europe, Coastal and Insular: | |||||||||||||||
| 400 | c | 3 | 3 | 6 | 3 | 1 | 1 | 1 | * | 0 | * | 3 | 6 | 28 | 10 |
| 401 | c | 4 | 5 | 7 | 2 | 1 | 1 | 1 | 0 | 0 | 0 | 2 | 8 | 30 | 4 |
| 403 | c | 6 | 6 | 7 | 7 | 4 | 3 | 3 | 2 | 2 | 3 | 6 | 7 | 56 | … |
| 406 | a | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 1 | 2 | 2 | 4 | 35 | 12 |
| 407 | c | 1 | 1 | 1 | 1 | 1 | 1 | 3 | 2 | 0 | 1 | 1 | 2 | 15 | 10 |
| 408 | a | 2 | 2 | 3 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 0 | 22 | 29 |
| 412 | a | 3 | 5 | 5 | 4 | 5 | 6 | 5 | 3 | 3 | 4 | 3 | 4 | 50 | 28 |
| 414 | c | 5 | 4 | 6 | 5 | 5 | 5 | 5 | 4 | 3 | 4 | 4 | 7 | 57 | 25 |
| 415 | c | 1 | 1 | 3 | 2 | 1 | 2 | 1 | * | * | 1 | 1 | 1 | 14 | 18 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Europe, Coastal and Insular (cont.): | |||||||||||||||
| 417 | c | 1 | 2 | 1 | 1 | 0 | 1 | 2 | 0 | 1 | 0 | 0 | 1 | 10 | 7 |
| 420 | c | 4 | 5 | 5 | 5 | 5 | 5 | 4 | 3 | 2 | 3 | 3 | 3 | 47 | 27 |
| 421 | c | 11 | 7 | 8 | 10 | 12 | 11 | 10 | 7 | 10 | 6 | 6 | 5 | 103 | 8 |
| 423 | c | 4 | 5 | 6 | 5 | 4 | 5 | 6 | 4 | 4 | 4 | 2 | 3 | 52 | 8 |
| 424 | c | 2 | 2 | 5 | 4 | 5 | 5 | 5 | 3 | 3 | 2 | 2 | 2 | 40 | 36 |
| 425 | c | 4 | 3 | 5 | 5 | 3 | 4 | 3 | 1 | 3 | 2 | 2 | 2 | 35 | 13 |
| 426 | c | 2 | 2 | 4 | 5 | 4 | 4 | 4 | 2 | 3 | 2 | 1 | 1 | 33 | 18 |
| 428 | c | 1 | 2 | 3 | 3 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 19 | 18 |
| 429 | c | 4 | 2 | 3 | 3 | 1 | 3 | 2 | 1 | 1 | 1 | 1 | 2 | 21 | 13 |
| Europe, Inland: | |||||||||||||||
| 450 | c | 5 | 4 | 5 | 6 | 4 | 2 | 3 | 4 | 2 | 4 | 2 | 4 | 45 | 8 |
| 451 | a | 3 | 3 | 4 | 3 | 2 | 3 | 3 | 2 | 1 | 2 | 2 | 3 | 31 | 18 |
| 453 | c | 3 | 3 | 4 | 3 | 3 | 3 | 2 | 2 | 1 | 1 | 1 | 2 | 28 | 9 |
| 454 | c | 2 | 2 | 3 | 3 | 2 | 2 | 1 | 1 | 1 | 2 | 2 | 2 | 23 | 31 |
| 455 | c | 7 | 6 | 6 | 9 | 10 | 8 | 8 | 5 | 6 | 5 | 4 | 2 | 76 | 8 |
| 456 | c | 5 | 4 | 5 | 5 | 5 | 4 | 5 | 4 | 3 | 3 | 3 | 4 | 50 | 8 |
| 457 | c | 3 | 3 | 6 | 6 | 5 | 5 | 5 | 4 | 4 | 2 | 1 | 2 | 46 | 36 |
| 458 | c | 2 | 3 | 5 | 5 | 3 | 3 | 4 | 3 | 2 | 2 | 1 | 1 | 34 | 35 |
| Asia, Coastal and Insular: | |||||||||||||||
| 500 | c | 4 | 3 | 4 | 2 | * | * | 2 | 1 | * | * | 2 | 4 | 21 | 8 |
| 501 | c | 7 | 7 | 9 | 5 | 2 | * | 2 | 1 | * | 2 | 7 | 5 | 46 | 5 |
| 502 | c | 8 | 6 | 6 | 6 | 1 | 1 | 2 | 1 | * | 2 | 5 | 6 | 43 | 4 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 503 | c | 7 | 4 | 8 | 5 | 1 | * | 1 | 0 | 1 | 1 | 5 | 7 | 40 | 7 |
| 505 | b | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 1 | 0 | 1 | 3 | 2 | 24 | 13 |
| 506 | c | 3 | 4 | 5 | 2 | 1 | 2 | 3 | 1 | 0 | 1 | 1 | 2 | 25 | 14 |
| 507 | c | 3 | 3 | 3 | 4 | 2 | 3 | 3 | 2 | 1 | 1 | 1 | 2 | 26 | 16 |
| 508 | c | 3 | 3 | 5 | 3 | 1 | 1 | 2 | * | * | 1 | 1 | 3 | 23 | 6 |
| 509 | c | 4 | 3 | 5 | 3 | * | 1 | 1 | 0 | * | 1 | 2 | 6 | 26 | 7 |
| 510 | c | 5 | 4 | 5 | 4 | 1 | * | 2 | * | * | 1 | 2 | 5 | 29 | 18 |
| 511 | c | 15 | 15 | 17 | 11 | 5 | 4 | 5 | 2 | 2 | 6 | 7 | 13 | 102 | 2-3 |
| 512 | g | 6 | 7 | 12 | 10 | 6 | 4 | 7 | 5 | 2 | 4 | 5 | 13 | 81 | 2-3 |
| 513 | c | 13 | 8 | 12 | 8 | 4 | 3 | 2 | 1 | 2 | 3 | 6 | 7 | 69 | 4 |
| 514 | c | 11 | 12 | 14 | 10 | 6 | 4 | 5 | 2 | 3 | 2 | 8 | 10 | 86 | 11 |
| 515 | c | 17 | 14 | 15 | 13 | 4 | 2 | 4 | 2 | 1 | 3 | 7 | 11 | 93 | 5 |
| 516 | c | 16 | 11 | 9 | 12 | 7 | 7 | 6 | 5 | 3 | 6 | 9 | 8 | 98 | 4 |
| 517 | c | 6 | 4 | 6 | 5 | 2 | 2 | 1 | 0 | 1 | 1 | 2 | 4 | 34 | 9 |
| 518 | c | 3 | 4 | 4 | 3 | 0 | 1 | 2 | 1 | * | 1 | 1 | 3 | 21 | 26 |
| 519 | c | 3 | 4 | 6 | 3 | 1 | 1 | 3 | 1 | 0 | * | 2 | 3 | 27 | 22 |
| 520 | g | 4 | 3 | 4 | 3 | 2 | 2 | 3 | 2 | 1 | 1 | 2 | 4 | 31 | 10 |
| 521 | c | 4 | 4 | 6 | 3 | 1 | 2 | 2 | 1 | * | 1 | 2 | 5 | 33 | 13 |
| 522 | c | 10 | 9 | 11 | 9 | 7 | 5 | 5 | 2 | 3 | 3 | 3 | 8 | 75 | 4 |
| 523 | c | 8 | 6 | 7 | 6 | 2 | 2 | 2 | 1 | 1 | 1 | 2 | 3 | 41 | 3 |
| 525 | c | 6 | 6 | 5 | 2 | 1 | 1 | 2 | 1 | 1 | 2 | 2 | 5 | 34 | 8 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 526 | c | 7 | 6 | 8 | 4 | 3 | 2 | 1 | 2 | 3 | 3 | 4 | 6 | 48 | 13 |
| 527 | c | 8 | 17 | 10 | 12 | 7 | 10 | 5 | 6 | 4 | 12 | 11 | 11 | 110 | 4 |
| 531 | c | 3 | 3 | 4 | 6 | 1 | 1 | 1 | 3 | 5 | 5 | 2 | 2 | 35 | 4 |
| Asia, Inland: | |||||||||||||||
| 551 | d | 3 | 9 | 18 | 7 | 7 | 3 | 4 | 1 | 3 | 5 | 8 | 12 | 81 | 2 |
| 552 | c | 11 | 12 | 12 | 10 | 8 | 5 | 5 | 6 | 4 | 3 | 7 | 11 | 94 | 20 |
| 553 | c | 6 | 5 | 5 | 4 | 2 | 1 | 3 | 1 | 1 | 2 | 4 | 7 | 40 | 18 |
| 554 | c | 11 | 4 | 13 | 6 | 5 | 2 | 4 | 6 | 1 | 3 | 6 | 11 | 72 | 3 |
| 555 | g | 2 | 6 | 4 | 8 | 6 | 1 | 4 | 2 | 1 | 1 | 3 | 7 | 45 | 4 |
| 556 | c | 12 | 11 | 12 | 9 | 4 | 2 | 3 | 2 | 3 | 5 | 9 | 9 | 81 | 8 |
| 557 | c | 10 | 6 | 8 | 7 | 4 | 3 | 1 | 2 | 2 | 3 | 4 | 6 | 56 | 14 |
| 558 | c | 14 | 11 | 13 | 15 | 8 | 5 | 5 | 2 | 3 | 4 | 8 | 10 | 98 | 9 |
| 559 | c | 6 | 7 | 7 | 5 | 1 | 5 | 3 | * | 2 | 2 | 3 | 3 | 44 | 4 |
| 560 | c | 10 | 10 | 11 | 9 | 7 | 4 | 6 | 5 | 5 | 7 | 9 | 10 | 93 | 8 |
| 561 | d | 8 | 9 | 12 | 9 | 8 | 9 | 9 | 7 | 5 | 6 | 8 | 9 | 99 | 6 |
| 562 | c | 5 | 3 | 5 | 6 | 3 | 2 | 3 | 3 | 1 | 2 | 3 | 3 | 39 | … |
| 563 | c | 6 | 6 | 7 | 7 | 4 | 3 | 3 | 3 | 2 | 2 | 5 | 6 | 54 | 11 |
| 566 | c | 5 | 1 | 4 | 4 | 1 | 2 | 5 | 3 | 2 | 1 | 3 | 4 | 35 | 8 |
| 567 | c | 5 | 5 | 9 | 6 | 3 | 2 | 2 | 3 | 3 | 2 | 4 | 8 | 50 | 11 |
| 568 | c | 10 | 9 | 14 | 9 | 5 | 5 | 5 | 5 | 5 | 3 | 6 | 7 | 86 | 24 |
| 570 | c | 19 | 19 | 17 | 14 | 7 | 11 | 10 | 11 | 9 | 6 | 8 | 17 | 148 | 8 |
| Table ^ XXV. ^ Mean number of clear days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Inland (cont.): | |||||||||||||||
| 572 | c | 9 | 8 | 9 | 7 | 4 | 3 | 2 | 3 | 2 | 4 | 5 | 6 | 53 | 10 |
| 573 | c | 9 | 11 | 13 | 11 | 8 | 7 | 8 | 7 | 7 | 6 | 7 | 7 | 101 | 9 |
| 574 | d | 9 | 13 | 11 | 9 | 6 | 9 | 10 | 7 | 5 | 5 | 5 | 6 | 95 | 6 |
| 575 | c | 6 | 6 | 6 | 4 | 3 | 3 | 4 | 3 | 2 | 2 | 3 | 5 | 47 | 18 |
| 576 | c | 3 | 3 | 6 | 4 | 3 | 3 | 3 | 2 | 2 | 3 | 1 | 2 | 35 | 13 |
| Table ^ XXVI. ^ Mean number of partly cloudy days | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | |||||||||||||||
| 002 | g | 9 | 10 | 8 | 13 | 6 | 4 | 4 | 7 | 3 | 15 | 13 | 10 | 102 | 2 1/2 |
| 003 | g | 13 | 13 | 16 | 12 | 13 | 14 | 9 | 5 | 9 | 23 | 19 | 18 | 164 | 2 |
| 004 | g | 10 | 8 | 13 | 10 | 13 | 9 | 7 | 9 | 11 | 11 | 11 | 13 | 125 | … |
| 005 | c | 13 | 11 | 12 | 9 | 7 | 7 | 8 | 8 | 5 | 11 | 12 | 13 | 116 | … |
| 006 | c | 16 | 17 | 16 | 15 | 11 | 8 | 7 | 8 | 6 | 10 | 14 | 14 | 144 | 4 |
| 007 | c | 12 | 16 | 16 | 13 | 6 | 4 | 6 | 3 | 3 | 7 | 13 | 12 | 109 | 5 |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | g | 4 | 4 | 5 | 5 | 5 | 7 | 7 | 6 | 5 | 6 | 5 | 5 | 64 | 10 |
| 102 | g | 5 | 5 | 6 | 7 | 9 | 8 | 5 | 7 | 8 | 7 | 5 | 5 | 77 | 11-13 |
| 104 | g | 7 | 6 | 6 | 7 | 10 | 9 | 7 | 8 | 8 | 8 | 6 | 5 | 87 | 19 |
| 105 | g | 5 | 5 | 5 | 4 | 4 | 6 | 4 | 4 | 5 | 6 | 8 | 9 | 67 | 2-4 |
| 106 | g | 8 | 7 | 7 | 8 | 11 | 10 | 9 | 9 | 9 | 9 | 7 | 7 | 101 | 24-26 |
| Alaska, Inland: | |||||||||||||||
| 152 | g | 6 | 6 | 5 | 7 | 11 | 13 | 13 | 10 | 8 | 7 | 4 | 6 | 95 | 8-10 |
| 153 | g | 5 | 3 | 5 | 5 | 8 | 8 | 8 | 8 | 7 | 4 | 5 | 5 | 71 | 10 |
| 154 | g | 6 | 5 | 7 | 7 | 9 | 8 | 6 | 7 | 7 | 7 | 6 | 6 | 81 | 18-19 |
| 156 | g | 6 | 6 | 7 | 9 | 11 | 14 | 9 | 6 | 7 | 6 | 6 | 6 | 96 | 10 |
| 157 | g | 4 | 4 | 6 | 5 | 7 | 6 | 6 | 5 | 5 | 4 | 5 | 5 | 62 | 10 |
| Canada, Coastal and Insular: | |||||||||||||||
| 201 | d | 11 | 12 | 17 | 15 | 14 | 11 | 19 | 14 | 15 | 12 | 10 | 11 | 151 | 2 |
| 202 | d | 9 | 11 | 15 | 15 | 11 | 11 | 11 | 11 | 11 | 13 | 12 | 13 | 143 | 3 |
| 204 | d | 4 | 6 | 7 | 9 | 9 | 8 | 9 | 6 | 7 | 6 | 5 | 4 | 79 | 3-5 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Canada, Coastal and Insular (cont.): | |||||||||||||||
| 213 | d | 3 | 3 | 5 | 3 | 5 | 4 | 4 | 6 | 5 | 4 | 4 | 5 | 52 | 3-5 |
| 218 | d | 12 | 12 | 14 | 14 | 13 | 10 | 17 | 16 | 10 | 16 | 13 | 20 | 167 | 2 |
| 223 | d | 10 | 6 | 7 | 8 | 5 | 5 | 7 | 6 | 6 | 6 | 5 | 7 | 76 | 5-7 |
| 224 | d | 4 | 3 | 2 | 5 | 5 | 4 | 5 | 8 | 4 | 5 | 5 | 3 | 52 | 4-5 |
| 226 | d | 6 | 6 | 4 | 5 | 7 | 8 | 7 | 8 | 4 | 5 | 7 | 5 | 71 | 2 |
| 227 | d | 8 | 7 | 8 | 7 | 6 | 5 | 7 | 7 | 6 | 6 | 4 | 7 | 77 | 2-5 |
| Canada, Inland: | |||||||||||||||
| 250 | d | 4 | 5 | 4 | 4 | 8 | 6 | 9 | 8 | 6 | 4 | 2 | 5 | 61 | 2-4 |
| Greenland and Iceland, Coastal and Insular: | |||||||||||||||
| 301 | g | 12 | 12 | 3 | .. | .. | 11 | 17 | 14 | 16 | 17 | 14 | 18 | .. | 1-3 |
| 302 | g | 5 | 5 | 5 | 3 | 4 | 5 | 5 | 4 | 7 | 6 | 4 | 4 | 57 | 2 |
| 304 | g | 13 | 11 | 13 | 12 | 12 | 11 | 12 | 11 | 11 | 13 | 13 | 12 | 144 | 31 |
| 307 | g | 11 | 10 | 14 | 14 | 14 | 13 | 13 | 17 | 20 | 14 | 20 | 10 | 170 | … |
| 308 | g | 12 | 12 | 14 | 13 | 13 | 14 | 15 | 19 | 15 | 14 | 12 | 11 | 164 | 19 |
| 310* | g | 16 | 14 | 16 | 16 | 15 | 14 | 16 | 16 | 16 | 16 | 14 | 12 | 181 | 15 |
| 314 | g | 15 | 15 | 16 | 16 | 15 | 16 | 17 | 15 | 15 | 14 | 15 | 17 | 186 | 31 |
| 317 | g | 14 | 13 | 14 | 13 | 13 | 13 | 16 | 14 | 14 | 14 | 13 | 14 | 165 | 30 |
| 318 | g | 13 | 9 | 12 | 10 | 12 | 12 | 11 | 11 | 12 | 11 | 11 | 14 | 138 | 28 |
| 320 | g | 16 | 15 | 15 | 16 | 17 | 17 | 17 | 16 | 16 | 15 | 14 | 18 | 192 | 19 |
| 330 | g | 14 | 12 | 13 | 15 | 15 | 15 | 13 | 12 | 13 | 14 | 13 | 13 | 163 | 16 |
| 331 | g | 15 | 12 | 14 | 13 | 17 | 15 | 14 | 15 | 16 | 19 | 15 | 15 | 100 | 16 |
| 332 | g | 13 | 11 | 13 | 11 | 15 | 13 | 10 | 10 | 11 | 12 | 12 | 15 | 146 | 16 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Greenland and Iceland, Coastal and Insular (cont.): | |||||||||||||||
| 333 | g | 12 | 11 | 12 | 12 | 14 | 14 | 12 | 13 | 11 | 15 | 15 | 13 | 154 | 11 |
| 334 | g | 16 | 16 | 15 | 17 | 18 | 16 | 15 | 17 | 17 | 16 | 16 | 16 | 194 | 14 |
| 335 | g | 14 | 13 | 13 | 12 | 13 | 12 | 12 | 11 | 11 | 11 | 13 | 15 | 151 | 15 |
| 336 | g | 16 | 14 | 12 | 12 | 14 | 13 | 14 | 11 | 13 | 11 | 14 | 16 | 157 | 16 |
| 337 | g | 15 | 15 | 15 | 15 | 15 | 14 | 13 | 14 | 13 | 16 | 15 | 14 | 174 | 11 |
| 339 | g | 10 | 10 | 9 | 8 | 13 | 12 | 9 | 12 | 11 | 10 | 10 | 12 | 125 | 10 |
| 340 | g | 15 | 13 | 15 | 12 | 13 | 13 | 14 | 14 | 15 | 15 | 15 | 15 | 169 | 14 |
| 341 | g | 8 | 11 | 9 | 11 | 11 | 11 | 9 | 10 | 11 | 12 | 11 | 10 | 124 | 8 |
| Greenland and Iceland, Inland: | |||||||||||||||
| 360 | g | 9 | 10 | 13 | 10 | 10 | 13 | 11 | 11 | 11 | 11 | 12 | 13 | 134 | 7 |
| 361 | g | 15 | 16 | 15 | 13 | 16 | 15 | 15 | 13 | 15 | 13 | 15 | 17 | 178 | 16 |
| Europe, Coastal and Insular: | |||||||||||||||
| 400 | d | 13 | 13 | 13 | 13 | 7 | 7 | 7 | 5 | 5 | 8 | 11 | 12 | 114 | 10 |
| 401 | d | 16 | 14 | 17 | 12 | 6 | 4 | 5 | 4 | 6 | 10 | 16 | 14 | 124 | 4 |
| 403 | d | 12 | 10 | 13 | 13 | 14 | 10 | 12 | 12 | 12 | 12 | 12 | 13 | 145 | … |
| 406 | a | 13 | 10 | 11 | 10 | 10 | 10 | 11 | 12 | 12 | 13 | 12 | 14 | 138 | 12 |
| 407 | d | 17 | 16 | 14 | 14 | 13 | 14 | 15 | 14 | 12 | 16 | 15 | 17 | 177 | 10 |
| 408 | a | 13 | 13 | 14 | 13 | 11 | 12 | 13 | 12 | 14 | 13 | 12 | 12 | 152 | 29 |
| 412 | a | 14 | 11 | 14 | 15 | 16 | 14 | 14 | 16 | 13 | 14 | 12 | 13 | 166 | 28 |
| 414 | d | 12 | 11 | 12 | 11 | 12 | 11 | 13 | 14 | 11 | 13 | 13 | 12 | 145 | 25 |
| 415 | d | 14 | 13 | 16 | 13 | 12 | 14 | 13 | 14 | 13 | 12 | 12 | 13 | 160 | 18 |
| 417 | d | 12 | 10 | 17 | 11 | 7 | 9 | 27 | 9 | 9 | 10 | 9 | 9 | 139 | 7 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Europe, Coastal and Insular (cont.): | |||||||||||||||
| 420 | d | 13 | 11 | 13 | 13 | 14 | 14 | 15 | 14 | 13 | 14 | 12 | 13 | 158 | 27 |
| 421 | d | 10 | 10 | 11 | 11 | 14 | 14 | 17 | 16 | 14 | 12 | 11 | 8 | 148 | 8 |
| 423 | d | 13 | 9 | 12 | 15 | 17 | 15 | 17 | 15 | 12 | 9 | 10 | 8 | 152 | 8 |
| 424 | g | 9 | 10 | 12 | 14 | 17 | 17 | 19 | 18 | 17 | 12 | 8 | 7 | 160 | 36 |
| 425 | d | 12 | 11 | 15 | 14 | 15 | 17 | 16 | 16 | 13 | 12 | 11 | 11 | 163 | 13 |
| 426 | d | 10 | 9 | 14 | 13 | 16 | 17 | 16 | 18 | 15 | 11 | 8 | 8 | 154 | 18 |
| 428 | d | 10 | 10 | 14 | 13 | 16 | 15 | 16 | 14 | 11 | 10 | 8 | 10 | 147 | 18 |
| 429 | d | 8 | 9 | 13 | 10 | 12 | 14 | 14 | 14 | 11 | 9 | 10 | 10 | 132 | 13 |
| Europe, Inland: | |||||||||||||||
| 450 | d | 16 | 14 | 15 | 15 | 13 | 12 | 15 | 10 | 12 | 11 | 11 | 10 | 154 | 8 |
| 451 | a | 16 | 14 | 16 | 15 | 12 | 13 | 15 | 12 | 15 | 11 | 13 | 14 | 166 | 18 |
| 453 | d | 11 | 14 | 15 | 12 | 16 | 15 | 18 | 16 | 16 | 10 | 10 | 12 | 165 | 9 |
| 454 | d | 11 | 11 | 14 | 12 | 14 | 13 | 12 | 12 | 11 | 13 | 11 | 13 | 146 | 31 |
| 455 | g | 11 | 9 | 11 | 12 | 15 | 15 | 17 | 16 | 17 | 9 | 10 | 9 | 151 | 8 |
| 456 | d | 14 | 11 | 14 | 12 | 14 | 12 | 14 | 14 | 13 | 10 | 11 | 8 | 147 | 8 |
| 457 | d | 10 | 11 | 13 | 13 | 18 | 17 | 19 | 17 | 16 | 12 | 9 | 9 | 164 | 36 |
| 458 | d | 12 | 10 | 13 | 13 | 18 | 17 | 19 | 16 | 15 | 10 | 8 | 10 | 161 | 35 |
| Asia, Coastal and Insular: | |||||||||||||||
| 500 | d | 15 | 16 | 17 | 11 | 7 | 6 | 7 | 5 | 5 | 8 | 9 | 12 | 119 | 8 |
| 501 | d | 14 | 16 | 16 | 15 | 10 | 8 | 8 | 5 | 6 | 11 | 13 | 15 | 138 | 5 |
| 502 | d | 12 | 15 | 19 | 14 | 10 | 8 | 9 | 3 | 7 | 10 | 15 | 16 | 141 | 4 |
| 503 | d | 13 | 15 | 17 | 13 | 8 | 8 | 7 | 5 | 5 | 9 | 13 | 15 | 129 | 7 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 505 | b | 12 | 10 | 14 | 14 | 9 | 11 | 13 | 11 | 9 | 11 | 9 | 13 | 136 | 13 |
| 506 | d | 11 | 12 | 15 | 14 | 10 | 9 | 12 | 12 | 8 | 7 | 7 | 10 | 127 | 14 |
| 507 | d | 14 | 13 | 17 | 12 | 11 | 11 | 13 | 10 | 10 | 12 | 12 | 15 | 150 | 16 |
| 508 | d | 14 | 14 | 15 | 15 | 9 | 10 | 10 | 7 | 6 | 8 | 12 | 15 | 136 | 6 |
| 509 | d | 11 | 12 | 15 | 14 | 9 | 8 | 12 | 6 | 7 | 9 | 13 | 14 | 131 | 7 |
| 510 | d | 12 | 11 | 16 | 11 | 8 | 6 | 8 | 6 | 7 | 9 | 12 | 13 | 119 | 18 |
| 511 | d | 4 | 3 | 5 | 3 | 3 | 4 | 2 | 4 | 3 | 4 | 4 | 6 | 45 | 2-3 |
| 512 | g | 2 | 3 | 3 | 4 | 3 | 3 | 3 | 2 | 4 | 4 | 6 | 4 | 41 | 2-3 |
| 513 | d | 4 | 3 | 4 | 4 | 4 | 6 | 6 | 4 | 5 | 5 | 5 | 5 | 55 | 7 |
| 514 | d | 3 | 2 | 3 | 4 | 3 | 2 | 3 | 2 | 2 | 2 | 2 | 3 | 30 | 11 |
| 515 | d | 9 | 9 | 13 | 12 | 13 | 12 | 12 | 8 | 5 | 10 | 9 | 11 | 123 | 5 |
| 516 | d | 9 | 6 | 8 | 6 | 9 | 8 | 6 | 4 | 3 | 5 | 5 | 5 | 77 | 4 |
| 517 | d | 18 | 18 | 18 | 16 | 11 | 13 | 16 | 14 | 14 | 15 | 17 | 17 | 187 | 9 |
| 518 | d | 12 | 12 | 15 | 12 | 8 | 9 | 12 | 10 | 7 | 7 | 8 | 9 | 123 | 26 |
| 519 | d | 14 | 14 | 17 | 15 | 9 | 10 | 15 | 12 | 10 | 9 | 10 | 13 | 149 | 22 |
| 520 | g | 12 | 12 | 16 | 13 | 10 | 11 | 14 | 15 | 13 | 12 | 12 | 12 | 152 | 10 |
| 521 | d | 17 | 16 | 16 | 14 | 9 | 11 | 15 | 12 | 13 | 9 | 11 | 15 | 156 | 13 |
| 522 | d | 14 | 14 | 17 | 14 | 16 | 19 | 16 | 16 | 12 | 15 | 17 | 15 | 185 | 4 |
| 523 | d | 15 | 12 | 11 | 10 | 11 | 9 | 10 | 8 | 6 | 10 | 12 | 14 | 128 | 3 |
| 525 | c | 15 | 11 | 16 | 12 | 10 | 16 | 11 | 11 | 8 | 10 | 8 | 14 | 142 | … |
| 526 | c | 15 | 12 | 13 | 15 | 13 | 14 | 13 | 17 | 15 | 14 | 16 | 17 | 174 | 13 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 527 | e | 3 | 1 | 2 | 2 | 4 | 3 | 2 | 2 | 5 | 3 | 1 | 1 | 28 | 4 |
| 531 | a | 10 | 6 | 8 | 6 | 9 | 8 | 6 | 4 | 3 | 5 | 6 | 6 | 77 | 4 |
| Asia Inland: | |||||||||||||||
| 551 | c | 11 | 4 | 4 | 6 | 6 | 3 | 7 | 5 | 6 | 5 | 5 | 2 | 64 | 2 |
| 552 | d | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 4 | 4 | 2 | 4 | 4 | 51 | 20 |
| 553 | d | 12 | 10 | 14 | 15 | 11 | 11 | 14 | 9 | 9 | 6 | 10 | 11 | 133 | 18 |
| 554 | d | 13 | 7 | 9 | 10 | 9 | 12 | 12 | 10 | 8 | 9 | 11 | 13 | 123 | 3 |
| 555 | g | 14 | 12 | 13 | 12 | 11 | 13 | 17 | 14 | 10 | 7 | 10 | 14 | 147 | 4 |
| 556 | d | 15 | 13 | 15 | 13 | 16 | 15 | 17 | 15 | 14 | 14 | 14 | 16 | 177 | 8 |
| 557 | c | 11 | 9 | 12 | 13 | 13 | 14 | 14 | 13 | 14 | 13 | 14 | 13 | 154 | 14 |
| 558 | c | 11 | 11 | 14 | 10 | 14 | 16 | 15 | 13 | 12 | 14 | 12 | 15 | 157 | 9 |
| 559 | d | 18 | 13 | 19 | 18 | 15 | 14 | 18 | 12 | 12 | 17 | 17 | 15 | 188 | 4 |
| 560 | e | 4 | 2 | 4 | 4 | 4 | 7 | 8 | 6 | 5 | 4 | 4 | 3 | 55 | 8 |
| 561 | f | 2 | 1 | 2 | 3 | 3 | 4 | 4 | 2 | 2 | 1 | 2 | 2 | 28 | 6 |
| 562 | d | 12 | 16 | 17 | 16 | 17 | 18 | 19 | 19 | 14 | 13 | 12 | 13 | 188 | … |
| 563 | d | 13 | 11 | 14 | 13 | 13 | 15 | 18 | 14 | 12 | 9 | 10 | 12 | 154 | 11 |
| 566 | d | 13 | 17 | 19 | 17 | 15 | 17 | 17 | 16 | 13 | 14 | 12 | 15 | 185 | 8 |
| 567 | d | 20 | 15 | 15 | 14 | 17 | 17 | 20 | 17 | 14 | 13 | 14 | 18 | 194 | 11 |
| 568 | d | 14 | 13 | 14 | 15 | 18 | 19 | 19 | 17 | 16 | 16 | 16 | 15 | 192 | 24 |
| Table ^ XXVI. ^ Mean number of partly cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Inland (cont.): | |||||||||||||||
| 570 | c | 11 | 8 | 12 | 12 | 20 | 16 | 18 | 16 | 14 | 15 | 15 | 10 | 167 | 16 |
| 572 | g | 12 | 10 | 13 | 14 | 13 | 17 | 17 | 15 | 13 | 12 | 13 | 13 | 162 | 10 |
| 573 | e | 4 | 3 | 2 | 5 | 5 | 7 | 8 | 7 | 6 | 3 | 3 | 3 | 56 | 9 |
| 574 | f | 1 | 0 | 2 | 2 | 3 | 3 | 3 | 2 | 1 | 1 | 0 | 2 | 20 | 6 |
| 575 | c | 13 | 13 | 14 | 15 | 16 | 17 | 17 | 16 | 14 | 11 | 10 | 12 | 168 | 18 |
| 576 | c | 12 | 14 | 15 | 16 | 17 | 17 | 18 | 17 | 14 | 12 | 12 | 11 | 172 | 13 |
| Table ^ XXVII. ^ Mean number of cloudy days | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Oceanic: | |||||||||||||||
| 002 | g | 8 | 6 | 14 | 9 | 18 | 26 | 27 | 24 | 27 | 12 | 6 | 6 | 183 | 2 1/2 |
| 003 | g | 4 | 6 | 3 | 8 | 16 | 16 | 22 | 26 | 20 | 7 | 4 | 14 | 136 | 2 |
| 004 | g | 21 | 20 | 18 | 20 | 18 | 21 | 24 | 22 | 19 | 20 | 19 | 18 | 238 | … |
| 005 | c | 17 | 16 | 18 | 20 | 24 | 22 | 23 | 23 | 25 | 20 | 18 | 17 | 243 | … |
| 006 | c | 9 | 9 | 8 | 9 | 19 | 20 | 22 | 22 | 23 | 20 | 10 | 8 | 178 | 4 |
| 007 | c | 14 | 9 | 7 | 12 | 25 | 26 | 24 | 27 | 27 | 24 | 15 | 14 | 225 | 5 |
| Alaska, Coastal and Insular: | |||||||||||||||
| 100 | g | 10 | 6 | 8 | 11 | 19 | 14 | 16 | 21 | 21 | 19 | 13 | 13 | 171 | 10 |
| 102 | g | 11 | 10 | 10 | 11 | 10 | 9 | 19 | 18 | 14 | 15 | 14 | 14 | 156 | 11-13 |
| 104 | g | 14 | 11 | 13 | 14 | 12 | 13 | 19 | 19 | 16 | 16 | 14 | 15 | 176 | 19 |
| 105 | g | 13 | 15 | 18 | 22 | 22 | 16 | 24 | 22 | 22 | 22 | 20 | 20 | 237 | 2-4 |
| 106 | g | 14 | 13 | 14 | 13 | 14 | 12 | 16 | 18 | 16 | 16 | 16 | 15 | 177 | 24-26 |
| Alaska, Inland: | |||||||||||||||
| 152 | g | 10 | 8 | 9 | 7 | 8 | 7 | 15 | 16 | 16 | 17 | 10 | 10 | 134 | 8-10 |
| 153 | g | 11 | 9 | 9 | 7 | 8 | 7 | 8 | 12 | 13 | 18 | 15 | 13 | 130 | 10 |
| 154 | g | 14 | 13 | 12 | 13 | 16 | 13 | 21 | 19 | 19 | 17 | 14 | 14 | 185 | 18-19 |
| 156 | g | 15 | 13 | 13 | 11 | 16 | 12 | 17 | 22 | 19 | 20 | 16 | 14 | 188 | 10 |
| 157 | g | 15 | 14 | 15 | 15 | 18 | 16 | 18 | 20 | 20 | 20 | 17 | 14 | 202 | 10 |
| Canada, Coastal and Insular: | |||||||||||||||
| 201 | c | 4 | 2 | 6 | 3 | 12 | 15 | 18 | 16 | 11 | 7 | 3 | 4 | 101 | 2 |
| 202 | c | 2 | 6 | 3 | 6 | 14 | 14 | 14 | 19 | 18 | 11 | 3 | 4 | 114 | 3 |
| 204 | c | 11 | 9 | 12 | 12 | 14 | 16 | 14 | 21 | 20 | 18 | 14 | 10 | 170 | 3-5 |
| 213 | c | 10 | 4 | 6 | 8 | 11 | 13 | 12 | 19 | 19 | 20 | 14 | 9 | 146 | 3-5 |
| Table ^ XXVII. ^ Mean number of cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Canada, Coastal and Insular (cont.): | |||||||||||||||
| 218 | c | 5 | 0 | 1 | 8 | 14 | 16 | 8 | 13 | 20 | 13 | 12 | 1 | 111 | 2 |
| 223 | c | 11 | 10 | 12 | 16 | 22 | 21 | 16 | 18 | 21 | 23 | 20 | 10 | 199 | 5-7 |
| 224 | c | 12 | 8 | 10 | 15 | 21 | 20 | 21 | 13 | 23 | 21 | 18 | 16 | 198 | 4-5 |
| 226 | c | 13 | 5 | 9 | 10 | 17 | 17 | 19 | 16 | 22 | 17 | 16 | 9 | 169 | 2 |
| 227 | c | 12 | 14 | 16 | 17 | 21 | 19 | 18 | 15 | 20 | 20 | 20 | 17 | 208 | 2-5 |
| Canada, Inland: | |||||||||||||||
| 250 | c | 11 | 10 | 9 | 13 | 13 | 13 | 15 | 17 | 20 | 20 | 16 | 11 | 168 | 2-4 |
| Greenland and Iceland, Coastal and Insular: | |||||||||||||||
| 301 | g | 6 | 6 | 22 | .. | .. | 15 | 10 | 15 | 12 | 10 | 11 | 4 | … | 1-2 |
| 302 | g | 14 | 12 | 10 | 16 | 19 | 16 | 20 | 17 | 17 | 18 | 18 | 12 | 189 | 2 |
| 304 | g | 9 | 7 | 8 | 10 | 14 | 16 | 14 | 15 | 15 | 15 | 14 | 13 | 150 | 31 |
| 307 | g | 8 | 8 | 8 | 5 | 9 | 12 | 12 | 10 | 6 | 8 | 6 | 10 | 102 | … |
| 308 | g | 12 | 14 | 9 | 10 | 11 | 10 | 9 | 7 | 8 | 10 | 10 | 13 | 123 | 19 |
| 310* | g | 14 | 12 | 13 | 13 | 14 | 14 | 13 | 14 | 13 | 14 | 15 | 17 | 166 | 15 |
| 314 | g | 15 | 12 | 13 | 12 | 13 | 12 | 12 | 14 | 13 | 14 | 13 | 12 | 155 | 31 |
| 317 | g | 13 | 17 | 12 | 11 | 12 | 11 | 9 | 9 | 10 | 13 | 13 | 12 | 136 | 30 |
| 318 | g | 13 | 12 | 12 | 11 | 10 | 11 | 12 | 13 | 11 | 13 | 12 | 10 | 140 | 28 |
| 320 | g | 13 | 11 | 12 | 11 | 10 | 11 | 11 | 13 | 11 | 12 | 12 | 11 | 138 | 19 |
| 330 | g | 15 | 14 | 15 | 13 | 11 | 11 | 14 | 16 | 15 | 15 | 15 | 15 | 170 | 16 |
| 331 | g | 14 | 14 | 15 | 15 | 12 | 14 | 15 | 15 | 13 | 11 | 13 | 14 | 165 | 16 |
| 332 | g | 17 | 16 | 17 | 18 | 14 | 16 | 20 | 21 | 18 | 19 | 17 | 16 | 209 | 16 |
| 333 | g | 18 | 15 | 17 | 16 | 17 | 15 | 18 | 17 | 17 | 14 | 14 | 17 | 195 | 11 |
| Table ^ XXVII. ^ Mean number of cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Greenland and Iceland, Coastal and Insular (cont.): | |||||||||||||||
| 334 | g | 14 | 11 | 14 | 12 | 11 | 12 | 15 | 13 | 12 | 15 | 14 | 14 | 158 | 14 |
| 335 | g | 14 | 11 | 14 | 15 | 13 | 15 | 17 | 19 | 17 | 17 | 14 | 13 | 180 | 15 |
| 336 | g | 14 | 13 | 18 | 16 | 14 | 15 | 16 | 19 | 16 | 19 | 14 | 14 | 191 | 16 |
| 337 | g | 13 | 11 | 13 | 12 | 15 | 14 | 17 | 17 | 16 | 13 | 13 | 15 | 169 | 11 |
| 339 | g | 21 | 17 | 21 | 21 | 18 | 18 | 22 | 19 | 19 | 21 | 20 | 19 | 236 | 10 |
| 340 | g | 12 | 12 | 14 | 15 | 15 | 14 | 16 | 16 | 14 | 15 | 12 | 12 | 166 | 14 |
| 341 | g | 16 | 14 | 20 | 16 | 16 | 15 | 21 | 17 | 17 | 17 | 17 | 16 | 202 | 8 |
| Greenland and Iceland, Inland: | |||||||||||||||
| 360 | g | 18 | 15 | 17 | 18 | 20 | 15 | 18 | 19 | 18 | 17 | 16 | 16 | 207 | 7 |
| 361 | g | 15 | 11 | 14 | 15 | 13 | 13 | 15 | 17 | 14 | 18 | 14 | 13 | 172 | 16 |
| Europe, Coastal and Insular: | |||||||||||||||
| 400 | c | 15 | 12 | 12 | 14 | 23 | 22 | 23 | 26 | 25 | 23 | 16 | 13 | 225 | 10 |
| 401 | c | 11 | 9 | 7 | 16 | 24 | 25 | 25 | 27 | 24 | 19 | 14 | 9 | 208 | 4 |
| 403 | c | 13 | 12 | 11 | 10 | 13 | 17 | 16 | 17 | 16 | 16 | 12 | 11 | 164 | … |
| 406 | a | 15 | 15 | 17 | 17 | 18 | 17 | 16 | 15 | 17 | 16 | 26 | 13 | 202 | 12 |
| 407 | c | 13 | 11 | 16 | 15 | 17 | 15 | 13 | 15 | 18 | 14 | 14 | 12 | 173 | 10 |
| 408 | a | 16 | 13 | 14 | 15 | 18 | 16 | 16 | 17 | 15 | 17 | 17 | 17 | 191 | 29 |
| 412 | a | 14 | 12 | 12 | 11 | 10 | 10 | 12 | 12 | 14 | 13 | 15 | 14 | 149 | 28 |
| 414 | c | 14 | 13 | 13 | 14 | 14 | 14 | 13 | 13 | 16 | 14 | 13 | 12 | 163 | 25 |
| 415 | c | 16 | 14 | 12 | 15 | 18 | 15 | 17 | 16 | 17 | 18 | 18 | 17 | 191 | 18 |
| 417 | c | 18 | 16 | 13 | 18 | 24 | 20 | 2 | 22 | 20 | 21 | 21 | 21 | 216 | 7 |
| 420 | c | 15 | 12 | 13 | 12 | 12 | 11 | 12 | 14 | 15 | 14 | 15 | 15 | 160 | 27 |
| Table ^ XXVII. ^ Mean number of cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Europe, Coastal and Insular (cont.): | |||||||||||||||
| 421 | c | 10 | 11 | 12 | 9 | 5 | 5 | 4 | 8 | 6 | 13 | 13 | 18 | 114 | 8 |
| 423 | c | 14 | 14 | 13 | 10 | 10 | 10 | 8 | 12 | 14 | 18 | 18 | 20 | 161 | 8 |
| 424 | c | 20 | 16 | 14 | 12 | 9 | 8 | 7 | 10 | 10 | 17 | 20 | 22 | 165 | 36 |
| 425 | c | 16 | 14 | 11 | 12 | 13 | 9 | 12 | 14 | 14 | 17 | 17 | 18 | 168 | 13 |
| 426 | c | 20 | 17 | 13 | 12 | 11 | 10 | 11 | 11 | 12 | 19 | 20 | 22 | 178 | 18 |
| 428 | c | 20 | 16 | 14 | 14 | 14 | 12 | 14 | 16 | 18 | 20 | 21 | 20 | 199 | 18 |
| 429 | c | 20 | 18 | 16 | 17 | 18 | 14 | 14 | 17 | 19 | 21 | 20 | 19 | 212 | 13 |
| Europe, Inland: | |||||||||||||||
| 450 | c | 10 | 10 | 11 | 9 | 14 | 16 | 13 | 17 | 16 | 16 | 17 | 17 | 166 | 8 |
| 451 | a | 12 | 11 | 11 | 12 | 17 | 14 | 13 | 17 | 14 | 18 | 15 | 14 | 168 | 18 |
| 453 | c | 17 | 11 | 12 | 15 | 12 | 12 | 11 | 13 | 13 | 20 | 19 | 17 | 172 | 9 |
| 454 | c | 18 | 15 | 14 | 15 | 15 | 15 | 17 | 19 | 18 | 17 | 17 | 16 | 196 | 31 |
| 455 | c | 13 | 13 | 14 | 9 | 6 | 7 | 6 | 10 | 7 | 17 | 16 | 20 | 138 | 8 |
| 456 | c | 12 | 13 | 12 | 13 | 12 | 14 | 12 | 13 | 13 | 14 | 18 | 16 | 162 | 8 |
| 457 | c | 18 | 14 | 12 | 11 | 8 | 8 | 7 | 10 | 10 | 17 | 20 | 20 | 155 | 36 |
| 458 | c | 17 | 15 | 13 | 12 | 10 | 10 | 8 | 12 | 13 | 19 | 21 | 20 | 170 | 35 |
| Asia, Coastal and Insular: | |||||||||||||||
| 500 | c | 12 | 9 | 10 | 17 | 24 | 24 | 22 | 25 | 25 | 23 | 19 | 15 | 225 | 8 |
| 501 | c | 10 | 5 | 6 | 10 | 19 | 22 | 21 | 25 | 24 | 18 | 10 | 11 | 181 | 5 |
| 502 | c | 11 | 7 | 6 | 10 | 20 | 21 | 20 | 27 | 23 | 19 | 10 | 9 | 181 | 4 |
| 503 | c | 11 | 9 | 6 | 12 | 22 | 22 | 23 | 26 | 24 | 21 | 12 | 9 | 196 | 7 |
| 505 | b | 17 | 16 | 15 | 14 | 20 | 16 | 15 | 19 | 21 | 19 | 18 | 15 | 205 | 13 |
| Table ^ XXVII ^ . Mean number of cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Coastal and Insular (cont.): | |||||||||||||||
| 506 | c | 17 | 12 | 11 | 14 | 20 | 19 | 16 | 18 | 22 | 23 | 22 | 19 | 213 | 14 |
| 507 | c | 14 | 12 | 11 | 14 | 18 | 16 | 15 | 19 | 19 | 18 | 17 | 14 | 189 | 16 |
| 508 | c | 14 | 11 | 11 | 12 | 21 | 19 | 19 | 24 | 24 | 22 | 17 | 13 | 206 | 6 |
| 509 | c | 16 | 13 | 11 | 13 | 22 | 21 | 18 | 25 | 23 | 21 | 15 | 11 | 208 | 7 |
| 510 | c | 14 | 13 | 10 | 15 | 22 | 24 | 21 | 25 | 23 | 21 | 16 | 13 | 217 | 18 |
| 511 | c | 12 | 10 | 9 | 16 | 23 | 24 | 24 | 25 | 25 | 21 | 19 | 12 | 218 | 2-3 |
| 512 | g | 23 | 18 | 16 | 16 | 22 | 23 | 21 | 24 | 24 | 23 | 19 | 14 | 243 | 2-3 |
| 513 | c | 10 | 12 | 11 | 14 | 19 | 19 | 20 | 23 | 21 | 19 | 24 | 13 | 95 | 7 |
| 514 | c | 17 | 14 | 15 | 16 | 22 | 24 | 24 | 27 | 25 | 27 | 20 | 18 | 249 | 11 |
| 515 | c | 5 | 5 | 3 | 5 | 14 | 16 | 15 | 21 | 24 | 18 | 14 | 9 | 149 | 5 |
| 516 | b | 6 | 11 | 14 | 12 | 15 | 15 | 19 | 22 | 24 | 20 | 16 | 18 | 190 | 4 |
| 517 | c | 7 | 6 | 7 | 9 | 18 | 15 | 14 | 17 | 15 | 15 | 11 | 10 | 144 | 9 |
| 518 | c | 16 | 12 | 12 | 15 | 23 | 20 | 17 | 20 | 23 | 23 | 21 | 19 | 221 | 26 |
| 519 | c | 14 | 10 | 8 | 12 | 21 | 19 | 13 | 18 | 20 | 22 | 18 | 15 | 189 | 22 |
| 520 | g | 15 | 13 | 11 | 14 | 19 | 7 | 14 | 14 | 16 | 18 | 16 | 15 | 182 | 10 |
| 521 | c | 10 | 8 | 9 | 13 | 21 | 17 | 14 | 18 | 17 | 21 | 17 | 11 | 176 | 13 |
| 522 | c | 7 | 5 | 3 | 7 | 8 | 6 | 10 | 13 | 15 | 13 | 10 | 8 | 105 | 4 |
| 523 | c | 8 | 10 | 13 | 14 | 18 | 19 | 19 | 22 | 23 | 20 | 16 | 14 | 196 | 3 |
| 525 | b | 10 | 11 | 10 | 16 | 20 | 13 | 18 | 19 | 21 | 19 | 20 | 12 | 189 | 8 |
| 526 | b | 10 | 10 | 10 | 11 | 14 | 14 | 17 | 13 | 12 | 14 | 11 | 8 | 143 | 13 |
| 527 | d | 21 | 10 | 20 | 16 | 21 | 17 | 23 | 23 | 22 | 16 | 18 | 20 | 227 | 4 |
| 531 | c | 12 | 8 | 11 | 8 | 16 | 16 | 17 | 13 | 10 | 13 | 12 | 9 | 144 | 4 |
| Table ^ XXVII ^ . Mean number of cloudy days (cont.) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec | |
| Asia, Inland: | |||||||||||||||
| 551 | b | 17 | 15 | 8 | 17 | 18 | 24 | 20 | 25 | 21 | 21 | 17 | 17 | 220 | … |
| 552 | c | 16 | 12 | 14 | 15 | 18 | 20 | 21 | 21 | 22 | 26 | 19 | 16 | 220 | 20 |
| 553 | c | 13 | 13 | 12 | 11 | 18 | 18 | 14 | 21 | 20 | 23 | 16 | 13 | 192 | 18 |
| 554 | c | 7 | 11 | 9 | 14 | 17 | 16 | 15 | 15 | 21 | 19 | 13 | 7 | 170 | 3 |
| 555 | g | 15 | 10 | 14 | 10 | 14 | 16 | 10 | 15 | 19 | 23 | 17 | 10 | 173 | 4 |
| 556 | c | 4 | 4 | 4 | 8 | 11 | 13 | 11 | 14 | 13 | 12 | 7 | 6 | 107 | 8 |
| 557 | b | 10 | 13 | 11 | 10 | 14 | 13 | 16 | 16 | 14 | 14 | 12 | 12 | 155 | 14 |
| 558 | b | 6 | 6 | 4 | 5 | 9 | 9 | 11 | 16 | 15 | 13 | 10 | 3 | 110 | 9 |
| 559 | c | 7 | 8 | 5 | 7 | 5 | 11 | 10 | 19 | 16 | 12 | 10 | 13 | 133 | 4 |
| 560 | d | 17 | 16 | 16 | 17 | 20 | 19 | 17 | 20 | 20 | 20 | 17 | 18 | 217 | 8 |
| 561 | d | 21 | 18 | 17 | 18 | 20 | 17 | 18 | 22 | 23 | 24 | 20 | 20 | 238 | 6 |
| 562 | c | 14 | 9 | 9 | 8 | 11 | 10 | 9 | 9 | 15 | 16 | 15 | 15 | 138 | … |
| 563 | c | 12 | 11 | 10 | 10 | 14 | 12 | 10 | 14 | 16 | 20 | 15 | 13 | 157 | … |
| 566 | c | 13 | 10 | 8 | 9 | 15 | 11 | 9 | 12 | 15 | 16 | 15 | 12 | 145 | 8 |
| 567 | c | 6 | 8 | 7 | 10 | 12 | 11 | 9 | 11 | 13 | 16 | 12 | 6 | 121 | 11 |
| 568 | c | 7 | 6 | 3 | 6 | 8 | 6 | 7 | 9 | 9 | 12 | 8 | 9 | 90 | 24 |
| 570 | b | 1 | 1 | 2 | 4 | 4 | 3 | 3 | 4 | 7 | 10 | 7 | 4 | 50 | 8 |
| 572 | g | 20 | 10 | 9 | 9 | 4 | 10 | 12 | 13 | 15 | 15 | 12 | 12 | 141 | 10 |
| 573 | d | 18 | 14 | 16 | 14 | 18 | 16 | 15 | 17 | 17 | 22 | 20 | 21 | 208 | 9 |
| 574 | d | 21 | 15 | 18 | 19 | 22 | 18 | 18 | 22 | 24 | 25 | 25 | 23 | 250 | 6 |
| 575 | b | 12 | 9 | 11 | 11 | 12 | 10 | 10 | 12 | 14 | 18 | 17 | 14 | 150 | 18 |
| 576 | b | 16 | 11 | 10 | 10 | 11 | 10 | 10 | 12 | 14 | 16 | 17 | 18 | 158 | 13 |
^
figs. 51 and 52 here
^
At the more northerly locations the average amount of cloud cover
is relatively small in winter and also during the early spring, the
latter period being the most favorable for air operations within the
Arctic. The average cloud cover during winter is about 4-tenths over
the pack-ice and from 2- to 3-tenths at northerly land stations. These
figures are to be compared with summer averages of about 9- and 8-tenths,
respectively.
During the winter and early spring months the proportion of high
clouds increases but the stratiform types still predominate. The
cumuliform types of cloud are exceedingly rare anywhere over the Arctic
Ocean and are infrequent elsewhere except over interior Arctic locations
during summer. The excessive cloudiness prevalent during the warmer
months does not affect temperatures as significantly as might be expected
from experiences in lower latitudes. In the Arctic insolation is not
affected as much by clouds as in locations farther south, partly because
the layers of clouds in the Arctic are thinner than in lower latitudes
and partly because the incoming radiation is doubly reflected from snow–
covered ground and clouds. On account of the relatively strong insolation
on overcast days, the diurnal temperature range is much greater than on
corresponding overcast days in lower latitudes. This condition is
particularly true during spring months.
Diurnal Variation of Cloudiness
. — The hourly cloud data available for
a few localities over the Arctic Ocean and adjacent coasts show that
there is an apparent and regionally consistent diurnal variation during
the dark season and in the months when the night is longer than the day.
At this time there appears to be a definite maximum cloudiness during
the day (so-called) and a minimum cloudiness during the night. Simpson
^
[
39
]
^
ascribes this feature to the fact that the observer’s estimate of
cloud cover tends to be too low when the sun is more than 10° below the
horizon. Other observers have subsequently verified Simpson’s conclusion
as to the non-reality of the diurnal variation in Arctic cloudiness during
the winter half-year.
During the summer half-year, when the sun is either continuously
above the horizon or the day is longer than night, the character of the
diurnal variation is regionally complex and appears to change from one
month to the next. Sverdrup
^
[
43
]
^
suggests that the maximum at night
occurs when there is a prevalence of stable fog situations, and that a
daytime maximum is associated with convection currents. The type of
diurnal variation which results depends upon which factor dominates
the local weather.
Cloud Altitudes and Ceilings
. — Cloud heights are lower in the Arctic
than in temperate latitudes. Over the Arctic Ocean and adjacent coasts,
for example, the bases of stratus clouds will be found anywhere between
the surface and 5,000 feet
^
[
43
]
^
but most frequently below 1,500 feet.
The following data from the
Maud
Expedition give the ranges and averages
of ceilings described by the bases of the various cloud types over the
Arctic Basin (as determined from pilot balloon observations):
| Cloud Form | Altitude of Bases (feet) | Greatest Frequency at Altitude (feet) |
| Cirrus | Up to 19,000 | … |
| Cirrostratus | 15,000 to 16,000 | … |
| Cirrocumulus | 15,000 to 16,000 | … |
| Altostratus | 8,000 to 15,000 | 11,500 to 13,000 |
| Altocumulus | 8,000 to 15,000 | About 10,000 |
| Stratocumulus | 1,600 to 8,000 | About 1,600 |
| Fractostratus | 650 to 6,500 | … |
| Stratus | 0 to 5,000 | Below 1,600 |
These data indicate that low ceilings unfavorable for air operations
over the Arctic Basin should be closely associated with the prevalence
of the stratus type of cloud formation. It is difficult to generalize
in similar fashion for inland areas because of the almost inseparable
relation between cloud altitudes and orography. In general, the period
of the greatest frequency of low ceilings will correspond to the period
of most frequent cloud cover, but there are important local exceptions
to this rule.
According to Rigby
^
[
34
]
^
, low ceilings are most frequent nearly
everywhere in the Arctic during summer and early autumn, particularly
over the Kara and Barents Sea areas. Only in the more southerly Arctic
areas, nearer the major winter cyclone tracks, is there a general
reversal of this seasonal pattern.
The vertical extent of cloudiness over the Arctic also averages
considerably less than at the lower latitudes where the atmospheric
moisture content is relatively high and where convective and frontal
activity is more vigorous. The weather reconnaissance flights which
have been conducted by the U. S. Air Force since 1947 show very clearly
that summer is the season of the greatest vertical development of cloud
systems over the Arctic. (See Table
^
XXVIII
^
.) During this season the average
altitude of the tops of the lower cloud layers is of the order of 11,000 ^
table XXVIII here
^
to 12,000 feet, with the higher forms of clouds extending well above
20,000 feet. In late autumn, winter, and early spring, on the other
hand, the tops are normally below 6,000 feet — easily topped by aircraft
cruising at relatively low flight altitudes.
| Table XXVIII. Cloud cover* data from USAF reconnaissance flights July 1948 to June 1949 Route — Fairbanks to Barrow to North Pole to Prince Patrick Island to Aklavik to Fairbanks, or vice versa, depending on winds | ||||||||
|---|---|---|---|---|---|---|---|---|
| Month | Below 18,280 Feet | Above 18,280 Feet | ||||||
| Ovc | Bkn | Sct | Clr | Ovc | Bkn | Sct | Clr | |
| Frequency (%) of Specified Cloud Conditions | ||||||||
| January | 29 | 5 | 7 | 59 | 0 | 0 | 4 | 96 |
| February | 36 | 6 | 8 | 50 | 0 | 0 | 6 | 94 |
| March | 23 | 6 | 8 | 63 | 1 | 4 | 15 | 80 |
| April | 17 | 13 | 19 | 51 | 7 | 5 | 11 | 77 |
| May | 46 | 19 | 12 | 23 | 4 | 2 | 5 | 89 |
| June | 54 | 29 | 17 | 0 | 3 | 7 | 43 | 47 |
| July | 64 | 29 | 6 | 1 | 5 | 4 | 37 | 54 |
| August | 64 | 23 | 7 | 6 | 14 | 4 | 28 | 54 |
| September | 45 | 35 | 16 | 4 | 1 | 4 | 26 | 69 |
| October | 43 | 16 | 14 | 27 | 2 | 1 | 27 | 70 |
| November | 48 | 16 | 13 | 23 | 0 | 0 | 5 | 95 |
| December | 28 | 8 | 14 | 50 | 0 | 1 | 7 | 92 |
The preceding figures apply principally to conditions over the
Arctic Ocean and contiguous coastal areas. In more southerly locations
on the fringes of the true Arctic, the vertical cloud structures are
more nearly typical of those found in temperate regions. At times of
strong convective or frontal activity, the cloud tops in these areas
may often exceed 30,000 feet.
FOG AND VISIBILITY
With the possible exception of blowing snow, fog is the most
important weather factor limiting aviation in the Arctic regions.
Over a large portion of the Arctic seas fog may be expected to occur
on at least 90 days each year, and in many maritime areas the average
number is greater than 160. Fog frequencies are usually much lower
at inland locations, but at some points the annual figure may run
as high as 120 to 130 days. (See Table
^
XXIX
^
.)
^
table XXIX here
^
| Table ^ XXIX ^ . Mean number of days with fog | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 003 | 15 | 8 | 12 | 5 | 17 | 19 | 27 | 27 | 15 | 6 | 7 | 10 | 167 | 2 |
| 004 | 2 | 3 | 3 | 5 | 3 | 6 | 13 | 10 | 6 | 3 | 2 | 2 | 58 | … |
| 005 | 1 | 2 | 3 | 5 | 7 | 9 | 19 | 15 | 12 | 4 | 3 | 1 | 82 | … |
| 006 | 3 | 6 | 7 | 7 | 4 | 6 | 20 | 20 | 13 | 4 | 2 | 1 | 92 | 4 |
| 007 | 2 | 4 | 3 | 4 | 3 | 14 | 26 | 23 | 14 | 5 | 3 | 3 | 105 | 5 |
| Alaska, Coastal and Insular: | ||||||||||||||
| 100 | 5 | 10 | 2 | 5 | 7 | 10 | 15 | 16 | 5 | 3 | 3 | 1 | 83 | 4 |
| 101 | 2 | 1 | 2 | 5 | 6 | 12 | 14 | 6 | 6 | 4 | * | 1 | 59 | 2 |
| 102 | 1 | 2 | 3 | 3 | 3 | 4 | 2 | 2 | 2 | 1 | 1 | 1 | 25 | 9-10 |
| 103 | 2 | 3 | 5 | 10 | 10 | 16 | 15 | 7 | 5 | 2 | 1 | 1 | 77 | 1-3 |
| 104 | 5 | 5 | 5 | 4 | 5 | 11 | 8 | 6 | 4 | 4 | 3 | 7 | 67 | 8 |
| 105 | 2 | 3 | 3 | 5 | 9 | 12 | 15 | 12 | 5 | 4 | 3 | 4 | 76 | 6-7 |
| 106 | * | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | * | 1 | 1 | 3 | 6-7 |
| Alaska, Inland: | ||||||||||||||
| 150 | 1 | 2 | 1 | * | 1 | 1 | 1 | 2 | 2 | 1 | 1 | * | 14 | 4-5 |
| 151 | 13 | 13 | 8 | 10 | 6 | 6 | 8 | 10 | 7 | 5 | 7 | 12 | 105 | 2-3 |
| 152 | 1 | 1 | 2 | 1 | 1 | * | 1 | 3 | 3 | 1 | 1 | 1 | 16 | 6-7 |
| 153 | 4 | 4 | 1 | 0 | * | 0 | * | * | 2 | 2 | 2 | 4 | 20 | 5-10 |
| 154 | 2 | 1 | 3 | 2 | 4 | 2 | 5 | 7 | 6 | 3 | 2 | 3 | 40 | 7-8 |
| 155 | 1 | 1 | 0 | * | 0 | * | * | 1 | 1 | 1 | * | * | 5 | 10 |
| 156 | 17 | 11 | 12 | 1 | 1 | 1 | 2 | 4 | 3 | 7 | 6 | 13 | 78 | 8-9 |
| 157 | 1 | 1 | * | 0 | * | 0 | * | * | 2 | * | * | 1 | 6 | 7-10 |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Coastal and Insular: | ||||||||||||||
| 204 | 0 | 1 | 0 | * | * | 1 | 2 | 2 | 1 | 1 | * | 1 | 7 | 6-7 |
| 205 | 0 | 0 | * | 0 | 0 | 1 | 2 | 1 | 10 | 2 | 0 | 0 | 16 | 1-3 |
| 206 | 4 | 1 | 0 | 1 | 0 | 1 | 10 | 12 | 13 | 1 | 2 | 1 | 44 | 1-3 |
| 210 | 1 | 2 | 1 | 2 | * | 1 | 6 | 7 | 1 | 1 | 1 | 1 | 26 | 3-4 |
| 211 | 0 | 0 | 1 | * | * | 1 | 4 | 8 | 2 | 1 | 1 | 0 | 22 | 3-4 |
| 212 | 00 | 1 | 0 | 1 | 1 | 3 | 5 | 2 | 2 | 0 | 1 | 0 | 16 | 3 |
| 213 | 1 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 14 | 14-18 |
| 214 | 1 | 1 | * | 1 | * | 2 | 3 | 4 | 1 | 1 | 1 | 1 | 16 | 2-3 |
| 215 | * | * | * | 1 | 3 | 6 | 7 | 6 | 3 | * | * | 0 | 26 | 7-10 |
| 216 | * | 1 | * | 1 | 2 | 1 | 2 | 3 | 1 | 1 | * | * | 12 | 10-11 |
| 217 | 1 | 1 | * | 1 | 2 | 2 | 2 | 3 | 2 | 1 | 1 | 1 | 17 | 4-8 |
| 221 | * | 1 | 1 | 1 | 2 | 2 | 3 | 4 | 2 | 1 | 1 | 1 | 17 | 20 |
| 222 | 2 | 3 | 2 | 1 | 1 | 2 | 4 | 4 | 3 | 5 | 4 | 2 | 34 | 2½ |
| 223 | * | 1 | 1 | 1 | 2 | 7 | 9 | 9 | 6 | 1 | * | 0 | 37 | 12-13 |
| 224 | 1 | 1 | * | 1 | 1 | 2 | 3 | 2 | 3 | 1 | 1 | 1 | 16 | 16-17 |
| 225 | 1 | 2 | 2 | * | 1 | 2 | 3 | 3 | 3 | 1 | 1 | 1 | 20 | 5 |
| 226 | * | * | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ** | 0 | * | 8 | 10-12 |
| 228 | 4 | 3 | 3 | 2 | 2 | 3 | 6 | 7 | 4 | 2 | 2 | 4 | 42 | 2½ |
| Canada, Inland: | ||||||||||||||
| 250 | 1 | 1 | * | 0 | * | * | 1 | * | 1 | 1 | * | 1 | 5 | 11-16 |
| 251 | 6 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 1 | 2 | 1 | 15 | 1-5 |
| 254 | 2 | 2 | 1 | 1 | * | * | * | 1 | 2 | 2 | 2 | 2 | 16 | 17-21 |
| 256 | * | 1 | * | * | * | * | * | * | * | 1 | 1 | * | 3 | 1½ |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Canada, Inland (cont.): | ||||||||||||||
| 259 | 1 | 1 | 1 | * | 1 | * | * | * | 1 | 1 | 2 | 1 | 9 | 1½ |
| 261 | 0 | 0 | 0 | * | 0 | 0 | * | 0 | 0 | * | 1 | * | 1 | 1 |
| Greenland and Iceland, Coastal and Insular: | ||||||||||||||
| 301 | 1 | 0 | 3 | 2 | .. | 6 | 7 | 11 | 5 | 3 | 1 | 1 | .. | 5 |
| 304 | 2 | 1 | 1 | 2 | 5 | 9 | 11 | 7 | 2 | 1 | * | 1 | 42 | 31 |
| 306 | 7 | 5 | 8 | 9 | 10 | 13 | 10 | 5 | 3 | 2 | 2 | 2 | 76 | 5 |
| 307 | 0 | 1 | 1 | 1 | 2 | 6 | 6 | 7 | 4 | 0 | .. | .. | .. | .. |
| 308 | 4 | 6 | 6 | 8 | 15 | 14 | 11 | 8 | 9 | 5 | 4 | 6 | 96 | 11 |
| 309 | 9 | 9 | 11 | 12 | 15 | 15 | 17 | 17 | 8 | 8 | 3 | 5 | 125 | .. |
| 311 | 1 | * | 0 | 2 | 3 | 5 | 5 | 5 | 2 | * | 0 | 1 | 24 | 6 |
| 314 | 1 | 1 | 2 | 4 | 8 | 11 | 14 | 14 | 8 | 2 | 1 | 1 | 67 | 31 |
| 315 | 3 | 2 | 9 | 4 | 9 | 9 | 11 | 6 | 6 | 9 | 4 | 6 | 78 | 5 |
| 316 | 8 | 5 | 14 | 18 | 26 | 23 | 28 | 26 | 26 | 3 | 8 | 10 | 195 | 25 |
| 317 | 1 | 1 | 2 | 4 | 9 | 11 | 11 | 9 | 5 | 3 | 2 | 1 | 59 | 30 |
| 318 | * | * | 1 | 1 | 1 | 3 | 5 | 6 | 3 | 1 | * | * | 21 | 28 |
| 330 | 1 | 1 | 1 | 2 | 2 | 1 | 1 | 1 | 1 | * | 1 | 1 | 12 | 16 |
| 331 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 18 | 16 |
| 332 | 2 | 2 | 2 | 1 | 6 | 5 | 10 | 9 | 4 | 2 | 1 | 2 | 46 | 9 |
| 333 | 1 | 2 | 3 | 4 | 7 | 7 | 8 | 7 | 5 | 2 | 3 | 2 | 51 | 11 |
| 334 | * | 1 | 2 | 2 | 5 | 5 | 9 | 6 | 3 | * | 1 | 1 | 35 | 14 |
| 335 | 1 | * | 1 | 2 | 4 | 5 | 8 | 6 | 3 | 2 | * | 1 | 34 | 15 |
| 336 | * | * | 1 | 1 | 2 | 2 | 3 | 3 | 2 | 1 | 1 | 1 | 17 | 16 |
| 337 | * | * | 1 | * | * | 1 | 1 | * | * | * | * | * | 4 | 11 |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Greenland and Iceland, Coastal and Insular (cont.): | ||||||||||||||
| 339 | 1 | * | 2 | 1 | 4 | 4 | 5 | 3 | 2 | * | 1 | * | 23 | 10 |
| 340 | 1 | 1 | 2 | 1 | 2 | 3 | 5 | 3 | 2 | 1 | 1 | * | 23 | 14 |
| 341 | 1 | 1 | 2 | 2 | 4 | 5 | 10 | 7 | 4 | 2 | 2 | 1 | 41 | 8 |
| Greenland and Iceland, Inland: | ||||||||||||||
| 351 | 15 | 14 | 4 | 1 | 6 | 1 | 2 | 13 | 15 | 26 | 16 | 20 | 133 | 1 |
| 360 | * | 1 | 1 | 1 | * | 1 | 1 | * | 1 | 1 | 1 | 1 | 9 | 7 |
| 361 | 2 | 1 | 1 | 1 | 2 | 2 | 4 | 2 | 2 | 2 | 2 | 1 | 20 | 16 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 6 | 7 | 9 | 9 | 9 | 10 | 15 | 16 | 6 | 5 | 4 | 5 | 100 | 10 |
| 401 | 2 | * | 4 | 8 | 5 | 13 | 24 | 24 | 14 | 5 | 2 | 2 | 104 | 4 |
| 403 | * | 1 | * | * | * | 3 | 4 | 3 | 1 | 1 | 0 | 0 | 13 | 7 |
| 405 | 2 | 5 | 4 | 5 | 3 | 2 | 11 | 3 | 5 | 1 | 1 | 2 | 44 | 9 |
| 406 | 0 | 0 | 0 | * | 1 | 3 | 6 | 5 | 1 | * | 0 | 0 | 16 | 12 |
| 407 | * | 0 | 0 | 0 | * | * | 2 | 1 | 1 | 0 | * | * | 4 | 10 |
| 408 | * | * | 0 | * | 1 | 3 | 7 | 5 | 1 | * | * | * | 17 | 44 |
| 410 | * | 1 | * | 1 | 3 | 4 | 5 | 2 | 2 | 1 | * | * | 19 | .. |
| 412 | * | * | 0 | * | * | * | 1 | * | * | * | 0 | * | 1 | 44 |
| 414 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 1 | 1 | 1 | 14 | 46 |
| 415 | 1 | * | * | * | 1 | 1 | 3 | 4 | 2 | 1 | 2 | 1 | 16 | 10 |
| 417 | 2 | 3 | 3 | 5 | 6 | 12 | 14 | 12 | 5 | 3 | 4 | 2 | 71 | .. |
| 420 | * | * | 1 | 1 | 2 | 3 | 3 | 2 | 1 | 1 | * | * | 14 | 44 |
| 421 | 2 | 2 | 3 | 4 | 3 | 2 | 2 | 3 | 4 | 5 | 3 | 2 | 35 | 50 |
| 422 | 1 | 1 | 1 | 2 | 1 | 1 | * | 1 | 2 | 2 | 2 | 1 | 14 | 14 |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Europe, Coastal and Insular (cont.): | ||||||||||||||
| 423 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 2 | 3 | 3 | 2 | 23 | 50 |
| 424 | 9 | 8 | 9 | 8 | 4 | 2 | 2 | 2 | 7 | 10 | 8 | 8 | 77 | 36 |
| 425 | 1 | 1 | 2 | 1 | 2 | 1 | 2 | 3 | 2 | 2 | 1 | 1 | 17 | 10 |
| 426 | 3 | 4 | 4 | 4 | 2 | 1 | 1 | 3 | 7 | 6 | 5 | 5 | 46 | 10 |
| 428 | 3 | 3 | 3 | 2 | 1 | * | 1 | 2 | 2 | 4 | 3 | 3 | 27 | 10 |
| 429 | * | * | 0 | 0 | * | 0 | * | 1 | 1 | 1 | 0 | 0 | 3 | 7 |
| Europe, Inland: | ||||||||||||||
| 450 | 4 | 3 | 3 | 2 | 2 | 0 | 0 | 1 | 2 | 5 | 5 | 4 | 31 | 50 |
| 451 | 5 | 2 | 1 | * | * | * | * | 1 | 2 | 2 | 3 | 2 | 16 | 44 |
| 453 | 3 | 3 | 2 | 2 | 1 | 1 | 2 | 7 | 6 | 6 | 7 | 5 | 45 | 10 |
| 454 | 3 | 2 | 2 | 2 | 2 | 1 | 2 | 3 | 5 | 6 | 4 | 4 | 36 | 44 |
| 455 | 5 | 3 | 2 | 1 | 0 | 0 | 0 | 2 | 5 | 5 | 4 | 4 | 31 | 50 |
| 456 | 4 | 3 | 2 | 2 | 2 | 1 | 2 | 3 | 4 | 6 | 5 | 5 | 39 | 50 |
| 457 | 2 | 2 | 2 | 2 | 1 | 1 | * | 2 | 4 | 5 | 3 | 2 | 26 | 35 |
| 458 | 2 | 2 | 2 | 1 | 1 | * | * | 1 | 3 | 2 | 2 | 1 | 17 | 35 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 1 | 2 | 3 | 4 | 5 | 12 | 17 | 17 | 10 | 3 | 1 | 1 | 76 | 8 |
| 501 | 4 | 3 | 4 | 3 | 7 | 14 | 19 | 18 | 8 | 4 | 1 | 1 | 86 | 5 |
| 502 | 4 | 5 | 6 | 6 | 6 | 9 | 13 | 16 | 6 | 8 | 4 | 3 | 85 | 4 |
| 503 | 2 | 4 | 7 | 7 | 6 | 11 | 21 | 21 | 11 | 5 | 4 | 1 | 99 | 7 |
| 505 | 2 | 3 | 2 | 2 | 4 | 8 | 12 | 11 | 8 | 5 | 3 | 2 | 62 | 14 |
| 506 | 6 | 5 | 7 | 6 | 9 | 15 | 17 | 16 | 11 | 5 | 3 | 4 | 106 | 14 |
| 507 | 2 | 2 | 2 | 1 | 3 | 4 | 6 | 6 | 5 | 3 | 2 | 2 | 39 | 16 |
| 508 | 5 | 8 | 8 | 6 | 6 | 15 | 18 | 12 | 8 | 6 | 4 | 5 | 101 | 6 |
| 509 | 6 | 4 | 3 | 5 | 8 | 9 | 8 | 8 | 8 | 6 | 4 | 3 | 73 | 7 |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Coastal and Insular (cont.): | ||||||||||||||
| 510 | 3 | 6 | 6 | 6 | 5 | 14 | 17 | 15 | 8 | 6 | 4 | 4 | 94 | 18 |
| 512 | 3 | 3 | 3 | 5 | 5 | 14 | 12 | 8 | 5 | 4 | 2 | 1 | 65 | 7 |
| 513 | 3 | 1 | * | 2 | 4 | 6 | 4 | 8 | 2 | 1 | 2 | 2 | 35 | 4 |
| 514 | 4 | 7 | 8 | 8 | 8 | 15 | 18 | 15 | 6 | 3 | 3 | 6 | 101 | 10 |
| 515 | 0 | 0 | 0 | 1 | 3 | 2 | * | 2 | * | 2 | 2 | 0 | 11 | 5 |
| 516 | 2 | 1 | 3 | 3 | 10 | 16 | 21 | 23 | 10 | 3 | 2 | 2 | 95 | 3 |
| 517 | 2 | 2 | 3 | 5 | 7 | 12 | 14 | 14 | 6 | 3 | 4 | 3 | 75 | 10 |
| 518 | 4 | 5 | 6 | 7 | 10 | 14 | 16 | 14 | 8 | 7 | 5 | 4 | 99 | 26 |
| 519 | 2 | 2 | 3 | 4 | 7 | 15 | 14 | 16 | 8 | 6 | 2 | 2 | 80 | 22 |
| 520 | 0 | 1 | * | 1 | 1 | * | 1 | 2 | 4 | 3 | * | * | 14 | 9 |
| 521 | 3 | 2 | 4 | 4 | 5 | 7 | 5 | 6 | 5 | 5 | 3 | 2 | 51 | 13 |
| 522 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | * | 6 | 5 |
| 523 | 5 | 2 | 4 | 4 | 10 | 14 | 16 | 15 | 10 | 3 | 5 | 3 | 91 | 3 |
| 524 | 1 | 1 | 4 | 6 | 11 | 10 | 13 | 9 | 9 | 10 | 4 | 3 | 81 | 4 |
| 525 | 5 | 5 | 6 | 5 | 8 | 14 | 17 | 13 | 11 | 4 | 4 | 3 | 95 | 8 |
| 526 | 1 | * | * | 1 | 2 | 6 | 7 | 7 | 3 | 1 | * | 1 | 29 | 14 |
| 527 | 2 | 2 | 1 | 2 | 5 | 7 | 3 | 2 | 1 | 1 | 2 | 1 | 29 | 14 |
| 529 | 1 | 2 | 1 | 3 | 4 | 10 | 10 | 12 | 3 | 1 | 1 | 1 | 49 | 3 |
| 530 | 5 | 2 | 4 | 7 | 5 | 8 | 12 | 10 | 8 | 6 | 3 | 7 | 77 | 5 |
| 531 | 0 | 0 | 0 | 1 | 5 | 9 | 12 | 9 | 4 | 1 | 0 | 0 | 41 | 4 |
| Asia, Inland: | ||||||||||||||
| 550 | 2 | 2 | 1 | 1 | 2 | 4 | 3 | 6 | 4 | 4 | 4 | 3 | 35 | 5 |
| 551 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 2 | 1 | 1 | 0 | 0 | 5 | 2 |
| 552 | 10 | 12 | 7 | 6 | 4 | 7 | 6 | 6 | 9 | 13 | 9 | 11 | 100 | 8 |
| Table ^ XXIX ^ . Mean number of days with fog (cont.) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Asia, Inland (cont.): | ||||||||||||||
| 553 | 7 | 4 | 5 | 7 | 7 | 4 | 3 | 5 | 5 | 8 | 7 | 4 | 66 | 18 |
| 554 | 4 | 2 | 3 | 1 | 3 | 6 | 2 | 1 | 3 | 3 | 4 | 3 | 32 | 4 |
| 555 | 5 | 4 | 2 | 0 | 1 | 2 | 4 | 3 | 4 | 5 | 2 | 6 | 38 | 3 |
| 556 | 3 | 2 | 1 | * | 1 | * | 1 | 5 | 4 | 1 | 2 | 4 | 24 | 9 |
| 558 | 3 | 2 | 1 | * | 1 | * | 1 | 3 | 2 | 2 | 1 | 2 | 18 | 8 |
| 559 | 0 | 1 | * | 0 | 0 | 0 | 1 | 4 | 2 | 1 | 1 | * | 10 | 4 |
| 560 | 2 | 1 | 1 | 1 | 1 | * | * | 1 | 2 | 2 | 1 | 2 | 12 | 8 |
| 561 | 0 | 0 | 0 | 0 | * | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 2 | 5 |
| 562 | 0 | * | * | * | 1 | * | * | 1 | 2 | 1 | * | 0 | 6 | 10 |
| 563 | * | * | * | 0 | 1 | * | * | * | 1 | 1 | 1 | 2 | 6 | 7 |
| 566 | 7 | 2 | 1 | * | 0 | * | 1 | 3 | 2 | 1 | 1 | 4 | 22 | 8 |
| 567 | 4 | 2 | 1 | * | * | * | * | 1 | 1 | 1 | 1 | 5 | 16 | 10 |
| 568 | 12 | 7 | 1 | * | 0 | * | * | 1 | 2 | 2 | 2 | 10 | 38 | 25 |
| 570 | 0 | 0 | * | * | * | 1 | 2 | 3 | 3 | 1 | 0 | 0 | 10 | 7 |
| 572 | 0 | * | 0 | * | 1 | * | * | 1 | 1 | 1 | 1 | 0 | 5 | 14 |
| 573 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 3 | 3 | 4 | 2 | 3 | 23 | 9 |
| 574 | 2 | 1 | * | 0 | * | * | 1 | 3 | 3 | * | * | * | 10 | 9 |
| 575 | 2 | * | * | 0 | 1 | 1 | 4 | 6 | 6 | 1 | * | 2 | 23 | 11 |
| 576 | 8 | 3 | * | * | * | * | 1 | 1 | 1 | 1 | 1 | 7 | 23 | 11 |
It is quite probable that the frequency of fog over the Arctic
Ocean decreases from the coasts toward the Pole. According to
Stefansson
^
[41]
^
, the zone of most frequent fog formation is a belt
parallel to the coast line of the Polar Sea. This belt does not
extend more than twenty or thirty miles seaward or more than a
corresponding distance inland. However, regional comparisons
concerning the number of days with fog are somewhat unreliable,
partly because the observations have been made at a variety of hours
and partly because fog has not always been recorded in accordance with
international procedures. For these reasons, and for the additional
reason that fog is essentially a phenomenon governed by local rather
than regional factors, caution should be exercised in attempting to ^
table XXX here
^
distinguish small regional and areal differences in the frequencies
of fog occurrence on the basis of the observational materials presented
in the several figures and tables. The data, however, are probably
entirely adequate for purposes of noting in time differences in fog
occurrence at the locations for which data are available and for
pointing out the large and more important regional differences in
prevalence of the phenomenon.
| Table XXX. Prevailing wind direction during fog occurrence | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Yrs Rec |
| Oceanic: | |||||||||||||
| 006 | SW | SW | E | N | SW | S | NW | NW | S | W | SE | SW | 5-6 |
| E | E | ||||||||||||
| Asia, Coastal and Insular: | |||||||||||||
| 500 | SE | SE | SE | NW | NW | NW | NW | NW | SE | NW | W | SE | 7-8 |
| SW | |||||||||||||
| 503 | E | W | E | SW | NE | E | E | E | W | NE | E | E | 7-8 |
| S | |||||||||||||
| SW | |||||||||||||
| 506 | S | S | S | NE | NE | NE | NE | NE | SW | SW | SW | SE | 20 |
| 507 | NE | E | NE | NE | NE | NE | SE | E | NE | SE | NE | NE | 17 |
| E | E | SE | |||||||||||
| 510 | S | S | S | S | S | N | N | NE | S | S | S | S | 19 |
| 512 | W | SW | W | NE | E | E | N | E | E | SW | SW | SW | .. |
| 517 | .. | .. | .. | .. | .. | E | E | E | NE | .. | .. | .. | .. |
| 518 | S | S | S | SW | SW | SW | N | SW | SW | SW | S | S | 26 |
| 523 | .. | .. | .. | .. | .. | SE | SE | SE | SE | .. | .. | .. | .. |
| 525 | .. | .. | .. | .. | .. | N | N | N | N | .. | .. | .. | .. |
| 530 | .. | .. | .. | .. | .. | SE | SE | SE | SE | .. | .. | .. | .. |
| Asia, Inland: | |||||||||||||
| 552 | SW | SW | SW | N | N | SW | N | SW | SW | SW | SW | SW | .. |
Fog Types
. - Four types of fog are of common occurrence in the Arctic.
The most common type is an advection fog formed primarily during
warmer months when relatively warm, moist air moves over a cold surface.
A further condition is the existence of a surface temperature inversion
which serves to retard turbulent dissipation of the fog. The areas
which are most favorable for the formation of this type of summer fog
are the open waters of the Kara, Laptev, East Siberian, and Chukchi
Seas. Fifteen to twenty days per month with fog is a normal condition
for these areas during the summer. Because of the influx of warm
water from the Gulf Stream system, this type of fog is less frequent
over the Barents and Norwegian Seas. The frequency of the summer
advection fogs decreases rapidly from the coast line inland and
diminishes less rapidly over the pack-ice.
The second type of fog of importance in the Arctic is the
radiation fog of winter. These fogs form readily under a sharp
surface temperature inversion during very cold weather and are
caused by reduction in temperature of the moist surface air by
contact with the radiationally-cooled ground or ice surface. Because
the heat conduction from subsurface layers is larger over oceanic ice
than over land or snow surfaces, the radiational cooling is more
effective in producing fog over coastal and inland points than over
the ice of the Arctic Ocean.
According to Petterssen
/
^
[
31
]
^
/
, the fogs are also less frequent
over snow surfaces than over snow-free regions because of the
depression of the saturation vapor pressure over ice. Even when the
air is clear and calm so that radiational cooling is most rapid,
fogs do not easily form over cold snowfields. The following fog
data obtained on the
Maud
Expedition
^
(
^
Sverdrup
/
^
[
43
]
^
/
^
)
^
show that there
is a conspicuous minimum in fog frequencies between the temperatures
of +5° and −13°:
The minimum in fog probability in the temperature range +5° to −22°
appears to be associated with the vapor pressure depression which
is noted to be at a maximum in the temperature ranges +5° to −15°
(see Table II). The data also show a secondary maximum probability
in the temperature range −22° to −31°. This appears to be associated
with the prevalence of ice fog, which is to be discussed in succeeding
paragraphs.
| Temperature | 41° | 41° | 32° | 23° | 14° | 5° | 4° |
| to | to | to | to | to | to | ||
| Interval (°F.) | 32° | 23° | 14° | 5° | −4° | −13° | |
| Probability of dense through light fog (mist) | 0.114 | 0.317 | 0.224 | 0.110 | 0.061 | 0.027 | 0.020 |
| Temperature | −13° | −22° | −31° | 40° | |||
| to | to | to | |||||
| Interval (°F.) | −22° | −31° | −40° | ||||
| Probability of dense through light fog (mist) | 0.046 | 0.095 | 0.076 | 0.210 |
Because radiation fog is essentially a surface phenomenon, the
fog layers are usually shallow. They are also of light density, since
they tend to occur at the lowest temperatures when the quantity of
water vapor available for condensation is of necessity low. They
occur most frequently along river bottoms open to cold air drainage
and where there is sluggish air movement. They appear to be most
common in the lower Lena River Valley in Siberia and the lower
Mackenzie River Valley in North America. They are also quite frequent
in the Yukon Valley and in the valleys of the principal northward–
flowing rivers of Siberia, as well as over the pack-ice during cold
weather.
The third type of fog, one of minor importance, is “steam fog”
or “Arctic smoke.” These fogs occur over open water which is subject
to invasion by very cold air. They occur only when the contrast
between air temperature and water temperature is very great. Under
such conditions the rate of evaporation from the water surface remains
relatively high, but the capacity of the surface air to hold moisture
is limited by its low temperature. As a result, the excess moisture
quickly condenses into fog, giving a “steaming” appearance to the water
surface. These fogs occur most frequently over rivers, unfrozen lakes,
open leads or polynias in the Arctic ice, and over coastal waters
which are adjacent to a local cold-air source. Such “steam” fogs are
generally shallow and are quickly dissipated by wind. However, they
may be sufficiently dense at times to obscure coastal landmarks and
landing strips adjacent to open water. Over the Arctic Ocean they
serve the very important purpose of advising the traveler of the
presence of open water.
Similar to the “steam” fogs are the “animal” or “human” fogs
which are possible at Arctic temperatures of −40° F. or below. At
such temperatures the small amount of moisture given off by humans
or animals is sufficient to cause light fog in the immediate vicinity.
Persistent fog, however, occurs only under calm, or nearly calm,
conditions. At times such fog may be sufficiently dense to obscure
a herd of reindeer or caribou or a dog team. The effect probably
also adds to the frequency and density of fog within villages and
towns of the Arctic under very cold and calm conditions.
The fourth type of fog, ice fog, is classified as a separate
form because of its composition rather than because is possesses
unique processes of formation. Ice fog is formed when temperatures
are low enough to cause direct atmospheric sublimation of moisture
in the form of ice crystals rather than in the form of sub-cooled
water droplets as in ordinary radiation or advection fogs. This
type of fog is particularly prevalent in and near inhabited areas
where there is a local source of moisture and where local combustion
products supply an abundance of condensation nuclei. The fog layers
vary in thickness from 50 to 500 feet and, while vertical visibilities
are usually good, horizontal visibility may be reduced to zero in
some cases. Ice fog which is dense enough and persistent enough to
seriously affect aircraft operations rarely occurs with temperatures
above −20°F. and with wind speeds in excess of 3 mph. This type of
fog is prevalent at all interior Arctic installations and at coastal
areas under distinct continental influence.
Annual Variation of Fog
. - While there is a tendency for Arctic
locations to show a maximum frequency of fog in summer, autumn, or
late spring, almost any month of the year will be represented as a
maximum month at some Arctic point. Inland areas which show a
preponderance of the radiation type of fog tend to present maxima
during one of the cooler months and particularly during autumn.
Maritime locations most frequently affected by advection fogs present
decided summer maxima.
At higher elevations, as on the Greenland Ice Cap and in the
Alaskan mountains, fog is most often simply surface-lying cloud. This
fact is attested by the parallel curves shown when frequencies of days
with precipitation and days with fog are plotted together. In such
locations the period of maximum fogginess then merely coincides with
the period of maximum frontal activity. An example of such a fog–
precipitation regime is given by the following data for West Station
located at a moderate elevation (3,130 feet) on the edge of the
Greenland Ice Cap:
West Station (Lat. 71°11′ N.; Long. 51°07′ W.)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | |
| No. days with | |||||||||||||
| Precipitation | 13 | 19 | 11 | 12 | 9 | 6 | 4 | 15 | 8 | 10 | 10 | 13 | 130 |
| Fog | 11 | 16 | 13 | 11 | 7 | 4 | 3 | 15 | 5 | 12 | 10 | 16 | 123 |
Diurnal Variation of Fog
. - During the summer months over the Arctic
Ocean and adjacent coasts the probability of fog is much greater in
the night hours than during the early afternoon. This tendency is
shown clearly by the following data obtained on the
Maud
Expedition
during the months of June through August:
| Local Hour | 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 |
| Probability of Fog | 0.36 | 0.37 | 0.33 | 0.27 | 0.22 | 0.19 | 0.18 | 0.19 | 0.22 | 0.24 | 0.28 | 0.32 |
The
Maud
data also show a somewhat similar diurnal variation in fog
frequencies during the colder months, but Sverdrup
/
^
[
43
]
^
/
assumes that
this variation is largely spurious and suggests that darkness has, to
some extent, influenced the accuracy of the fog observations.
Data from inland Arctic stations show a diurnal variation in
fog similar to that noted over the maritime Arctic regions, with a
definite tendency for the phenomenon to occur more frequently in the
early morning than at noon or in the evening. It is common practice
in these regions to limit aviation activities during early morning
hours because of the prevalence of visibility-restricting fog.
Other Visibility-Reducing Factors
. - During the warmer months in the
Arctic, fog is the most important visibility-reducing factor. During
the winter months, however, blowing snow is the most common cause of
reduced visibilities, particularly in the more unprotected continental
and insular locations. Observations at Coppermine recorded by the
Canadian Polar Year Expedition
/
^
[
7
]
^
/
show that there were 79 hours
during the winter (1932-33) when blowing snow reduced the visibility
to 1,000 yards or less. At Chesterfield Inlet, blowing snow was
reported on 99 days from October to May inclusive. During November
1949, Pt. Barrow, Alaska, reported 265 hours with blowing snow, and
in December of the same year, Barter Island, Alaska, reported 241
^
table XXXI here
^
such hours. Other Arctic Alaskan stations show monthly averages of 65
to 120 hours during the winter season. Conditions over interior
Greenland and portions of Siberia are probably much more severe. The
frequency and severity of blowing snow is, of course, related directly
to the frequency of high winds and the presence of new or powdery snow
cover.
| Table XXIX. Mean number of days with blowing snow | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Station | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann | Yrs Rec |
| Oceanic: | ||||||||||||||
| 006 | 9 | 6 | 11 | 8 | 9 | 5 | 0 | 0 | 4 | 8 | 8 | 8 | 75 | 5-6 |
| 007 | 13 | 11 | 15 | 14 | 15 | 5 | 0 | * | 3 | 12 | 11 | 11 | 110 | 5-6 |
| Europe, Coastal and Insular: | ||||||||||||||
| 400 | 9 | 10 | 15 | 13 | 10 | 1 | * | * | 4 | 10 | 8 | 11 | 94 | 10 |
| Asia, Coastal and Insular: | ||||||||||||||
| 500 | 12 | 12 | 16 | 16 | 12 | 4 | 0 | 0 | 2 | 8 | 11 | 10 | 103 | 7-8 |
| 501 | 11 | 13 | 13 | 12 | 11 | 3 | 0 | 0 | 2 | 9 | 6 | 11 | 89 | 5-6 |
| 502 | 14 | 13 | 15 | 18 | 15 | 4 | 0 | 0 | 2 | 8 | 11 | 9 | 107 | 4-5 |
| 503 | 18 | 14 | 19 | 16 | 18 | 9 | 0 | 1 | 7 | 14 | 16 | 18 | 150 | 7-8 |
| 507 | 11 | 10 | 11 | 11 | 9 | 1 | 0 | 0 | 1 | 6 | 10 | 11 | 82 | 17 |
| 508 | 11 | 9 | 11 | 14 | 14 | 3 | * | 0 | * | 7 | 10 | 12 | 91 | 6 |
| 509 | 16 | 15 | 16 | 17 | 12 | 1 | 0 | 0 | 1 | 6 | 13 | 11 | 108 | 6-7 |
| 510 | 13 | 15 | 16 | 18 | 14 | 3 | 0 | 0 | 2 | 12 | 13 | 14 | 120 | 19 |
| 518 | 12 | 13 | 16 | 13 | 9 | * | 0 | 0 | 0 | 3 | 8 | 13 | 88 | 26 |
| 519 | 8 | 8 | 10 | 8 | 4 | * | 0 | 0 | * | 3 | 6 | 4 | 51 | 22 |
The best visibility conditions in the Arctic occur in April and
May when the summer fogs are not yet manifest, and when the slight
ice-crystal turbidity is not so frequent as in winter
[
^
42
^
]
.
From the preceding discussion it is apparent that the Arctic is
not a region of consistently good visibilities. At first glance it
might appear that such a statement is in disagreement with the one
previously made (on page ___) to the effect that Arctic air masses
are characterized by exceptionally good visibilities (because of low
values of turbidity). Actually, the two conclusions are not in dis–
agreement. Arctic visibilities can be described as either poor or
very good depending upon whether or not hydrometeors are present in
the surface atmosphere. Such a statement implies that moderate visi–
bilities are comparatively rare in the Arctic. This latter conclusion
is verified for at least one Arctic area by Hovmøller
[
^
20
^
]
who points
out that visibilities in the range 1 to 12 miles are rare along the
northeastern coasts of Greenland, i.e., the greatest number of visibili–
ties are either less than 1 mile or greater t
^
h
^
an 12 miles.
SUNSHINE, ILLUMINATION
The duration of sunshine has seldom been included among the
records of Arctic observations. Over the Arctic Ocean such data
are available only from the
Maud
Expedition
[
^
43
^
]
. These obser–
vations show that during March and April the duration of sunshine,
both in actual hours and in percent of possible sunshine hours, is
greater over the Arctic Ocean than over any region in southern Europe.
The values are much less during summer, however.
Duration of Sunshine over the Arctic Ocean (from the
Maud
)
| Mar | Apr | May | Jun | Jul | Aug | |
| Hours | 204 | 309 | 269 | 98 | 117 | 70 |
| % of possible hours | 69 | 64 | 38 | 14 | 16 | 14 |
During the year 1932-33, records of sunshine were obtained by
the Canadian North Polar Year Expeditions to Coppermine, Chesterfield
Inlet, and Capes Hopes Advance. Here, the greatest number of hours
of sunshine and also the greatest percentage of possible sunshine were
recorded during July and August when the duration of sunshine amounted
to 40 or 50 percent of the total possible. The minimum was reached in
December when less than 10 percent of the possible was recorded.
In Arctic regions the quality of light is often a more practical
consideration than is the duration of sunlight or darkness. The
amount of light reflected from the snow surfaces is much greater than
in lower latitudes because of the lower angle of incidence of the
sun’s rays. As a result, the useful illumination is much greater
than under similar conditions of sunlight in lower latitudes. One
disadvantage, however, is that the light reflected from the snow surface
may be so intense as to obliterate definitive shadows. The resulting
lack of contrast may make it impossible to distinguish outlines of
terrain features or even of fairly large surface objects at close
range. Dark mountains may be seen for great distances, while a
crevasse immediately ahead of the traveler may be unseen. Moreover,
because of the high reflectivity of the snow cover, the danger of
severe sunburn is more likely than in southern latitudes, and snow
glasses are a necessary part of the equipment of every Arctic
traveler.
In winter, however, the high reflectivity of the snow cover
is a valuable asset. Pilots have reported that the light of a half–
moon over a snow-bounded airfield is sufficient for landing purposes.
Most surface activities can be carried on under moonlight conditions
in the Arctic and the light of the stars alone is sufficient for some
purposes. It is only during periods of heavy overcast that the Arctic
darkness begins to approach the darkness of temperate latitudes.
The total illumination throughout the year is greatest over the
Arctic pack-ice and the Greenland Ice Cap and least over open water
surfaces in winter and over snow-free land areas in summer.
Fig. 53 here
| Table XXXII. Locations of Arctic weather stations | |||||
|---|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N | Longitude ° ′ | Elevation (ft.) | |
| Oceanic: | |||||
| 001 | “Sedov” (Drifting Ship) (1939) | Jan | 84 55 | 124 12 E | Sea level |
| Feb | 85 55 | 119 26 | |||
| Mar | 86 24 | 110 05 | |||
| Apr | 86 13 | 89 32 | |||
| May | 85 45 | 78 27 | |||
| Jun | 85 50 | 68 08 | |||
| Jul | 85 33 | 62 13 | |||
| Aug | 86 11 | 54 46 | |||
| Sep | 86 05 | 37 59 | |||
| Oct | 84 49 | 25 54 | |||
| Nov | 84 09 | 13 31 | |||
| Dec | 82 35 | 81 15 | |||
| 002 | “Fram” (Drifting Ship) (1893-1896) | Mean Position 82° 42′ N., 89° 36′ E | Sea level | ||
| 003 | “Maud” (Drifting Ship) (1922-1924) | Mean Position 74° 36′ N., 164° 00′ E. | Sea level | ||
| 004 | Jay Mayen | 70 59 | 08 20 W. | 76 | |
| 005 | Bear Island | 74 28 | 19 17 E. | 133 | |
| 006 | Ostrov Domashnii | 79 30 | 91 08 | 10 | |
| 007 | Ostrov Uedineniia | 77 30 | 82 12 | 30 | |
| 008 | Papanin North Polar Expedition (Drifting Ice) (1937-1938) | Jan | 77 00 | 10 W. | Sea level |
| Feb | 73 00 | 17 | |||
| Mar | .. | .. | |||
| Table XXXII. Locations of Arctic weather stations (cont.) | |||||
|---|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N | Longitude ° ′ | Elevation (ft.) | |
| Oceanic: (cont.): | |||||
| 008 (cont.) | Papanin North Polar Expedition (Drifting Ice) (cont.) | Apr | .. | .. | |
| May | 89 20 | 60 W. | |||
| Jun | 88 50 | 10 | |||
| Jul | 88 20 | 05 | |||
| Aug | 87 30 | 00 | |||
| Sep | 86 20 | 00 | |||
| Oct | 84 40 | 05 E. | |||
| Nov | 83 30 | 05 W. | |||
| Dec | 81 30 | 07 | |||
| 009 | Foka Bay | 76 00 | 60 12 E. | Sea level | |
| Alaska, Coastal and Insular: | |||||
| 100 | Barrow | 71 18 | 156 47 W. | 13 | |
| 101 | Point Hope | 68 20 | 166 48 | 19 | |
| 102 | Kotzebue | 66 52 | 162 38 | 11 | |
| 103 | Wales | 65 36 | 168 04 | 3 | |
| 104 | Nome | 64 30 | 165 24 | 17 | |
| 105 | Gambell | 63 51 | 171 36 | 30 | |
| 106 | Anchorage | 61 13 | 149 52 | 118 | |
| Alaska, Inland: | |||||
| 150 | Shungnak | 66 55 | 157 05 W. | 142 | |
| 151 | Umiat | 69 26 | 151 50 | .. | |
| 152 | Wiseman | 67 26 | 150 13 | 675 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N | Longitude ° ′ | Elevation (ft.) |
| Alaska, Inland (cont.): | ||||
| 153 | Fort Yukon | 66 34 | 148 18 W. | 417 |
| 154 | Bethel | 60 48 | 161 45 | 35 |
| 155 | Tanana | 65 10 | 152 06 | 220 |
| 156 | Fairbanks | 64 51 | 147 43 | 440 |
| 157 | Eagle | 64 46 | 141 12 | 804 |
| Canada, Coastal and Insular: | ||||
| 200 | Lady Franklin Bay | 82 00 | 63 06 W. | .. |
| 201 | Fort Conger | 81 44 | 64 45 | .. |
| 202 | Ellesmere Land | 76 36 | 87 06 | .. |
| 203 | Goose Fiord | 76 44 | 88 39 | .. |
| 204 | Craig Harbor | 76 12 | 79 35 | 12 |
| 205 | Bache Peninsula | 79 10 | 76 45 | 10 |
| 206 | Holman Island | 70 30 | 117 38 | 30 |
| 207 | Banks Strait | 73 48 | 114 54 | .. |
| 208 | Winter Harbor | 74 47 | 110 48 | .. |
| 209 | Barrow Strait | 74 06 | 93 34 | .. |
| 210 | Fort Ross | 72 02 | 94 03 | 50 |
| 211 | Arctic Bay | 73 16 | 84 17 | 36 |
| 212 | Dundas Harbor | 74 34 | 82 10 | 18 |
| 213 | Pond Inlet | 72 43 | 78 30 | 13 |
| 214 | Clyde | 70 20 | 68 30 | 26 |
| 215 | Herschel Island | 69 30 | 139 15 | .. |
| 216 | Coppermine | 67 49 | 115 10 | 13 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N | Longitude ° ′ | Elevation (ft.) |
| Canada, Coastal and Insular (cont.): | ||||
| 217 | Cambridge Bay | 69 05 | 105 00 W. | 15 |
| 218 | King William Land | 68 37 | 95 53 | .. |
| 219 | Foxe Channel | 67 12 | 84 42 | .. |
| 220 | Cumberland Sound | 66 30 | 67 06 | .. |
| 221 | Chesterfield Inlet | 63 20 | 90 43 | 13 |
| 222 | Coral Harbor | 64 11 | 83 21 | 193 |
| 223 | Nottingham Island | 63 07 | 77 56 | 54 |
| 224 | Lake Harbor | 62 50 | 69 55 | 54 |
| 225 | Upper Frobishcher Bay | 63 45 | 68 32 | 54 |
| 226 | Pangnirtung | 66 09 | 65 30 | 50 |
| 227 | Resolution Island | 61 18 | 64 53 | 127 |
| 228 | Churchill | 58 47 | 94 11 | 44 |
| Canada, Inland: | ||||
| 250 | Aklavik | 68 14 | 134 50 | 25 |
| 251 | Fort McPherson | 66 58 | 134 55 | .. |
| 252 | Dawson | 64 04 | 139 29 | 1,062 |
| 253 | Whitehorse | 60 43 | 135 05 | 2,289 |
| 254 | Fort Good Hope | 66 15 | 128 38 | 214 |
| 255 | Watson Lake | 60 07 | 128 48 | 2,248 |
| 256 | Norman Wells | 65 17 | 126 47 | 290 |
| 257 | Fort Norman | 64 54 | 125 40 | .. |
| 258 | Fort Simpson | 61 52 | 121 13 | 572 |
| 259 | Hay River | 60 51 | 115 58 | .. |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude (ft.) | Elevation (ft.) |
| Canada, Inland (cont.): | ||||
| 260 | Yellowknife | 62 28 | 114 27 W. | 660 |
| 261 | Fort Resolution | 61 10 | 114 00 | .. |
| 262 | For Smith | 60 00 | 111 52 | 680 |
| 263 | Fort Vermilion | 58 23 | 115 59 | .. |
| Greenland and Iceland, Coastal and Insular: | ||||
| 300 | Robeson Channel | 82 00 | 63 42 W. | Sea level |
| 301 | Inglefield Bay | 77 20 | 67 30 | Sea level |
| 302 | Thule | 76 34 | 68 48 | 129 |
| 303 | Danmarkshavn | 76 46 | 18 45 | 20 |
| 304 | Upernivik | 73 47 | 56 09 | 59 |
| 305 | Marrak | 70 30 | 54 15 | 136 |
| 306 | Umanak | 70 41 | 52 09 | .. |
| 307 | Myggbukta | 73 30 | 21 35 | 13 |
| 308 | Scoresbysund | 70 28 | 21 58 | 56 |
| 309 | Gothavn | 69 14 | 53 31 | 36 |
| 310 | Edgesminde | 68 43 | 52 50 | 106 |
| 311 | Holstensborg | 66 56 | 53 39 | 89 |
| 312 | Sondrestromfjord | 66 30 | 52 15 | 190 |
| 313 | Cruncher Island | 66 02 | 53 33 | 51 |
| 314 | Godthaab | 64 11 | 51 45 | 66 |
| 315 | Skjoldungen | 63 21 | 41 39 | 297 |
| 316 | Atterbury Dome | 65 20 | 40 18 | 1,186 |
| 317 | Angmagssalik | 65 30 | 37 33 | 95 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Greenland and Iceland, Coastal and Insular (cont.): | ||||
| 318 | Ivigtut | 61 12 | 48 10 W. | 82 |
| 319 | Narsaq Point | 60 54 | 46 00 | 95 |
| 320 | Nanortalik | 60 10 | 45 17 | 23 |
| 321 | Prince Christian Sound | 60 03 | 43 12 | 250 |
| 330 | Lambavtn | 65 30 | 24 06 | 5 |
| 331 | Reykjavik | 64 09 | 21 57 | 167 |
| 332 | Kollsa | 65 21 | 21 11 | 39 |
| 333 | Vik | 63 25 | 19 01 | 20 |
| 334 | Grimsey | 66 30 | 18 01 | 72 |
| 335 | Husavik | 66 02 | 17 21 | .. |
| 336 | Akureyri | 65 41 | 18 05 | 23 |
| 337 | Fagurholsmyru | 63 54 | 16 37 | 131 |
| 338 | Holar | 64 18 | 15 11 | .. |
| 339 | Hofn | 66 02 | 14 48 | 20 |
| 340 | Seydisfjorder | 65 16 | 14 00 | 26 |
| 341 | Vattarnes | 64 56 | 13 41 | 66 |
| Greenland and Iceland, Inland: | ||||
| 350 | Watkins Ice Station | 67 03 | 41 49 W. | 8,200 |
| 351 | Eismitte | 70 54 | 40 42 | 9,938 |
| 360 | Haell | 64 04 | 20 13 | 427 |
| 361 | Grimsstadhir | 65 36 | 16 12 | 1,247 |
| Europe, Coastal and Insular: | ||||
| 400 | Bukhta Tikhaya | 80 19 | 52 48 E. | 20 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Europe, Coastal and Insular (cont.): | ||||
| 401 | Ostrov Rodol’fa | 81 48 | 57 57 E. | 157 |
| 402 | Quade Hook | 78 57 | 12 30 | 33 |
| 403 | Green Harbor | 78 02 | 14 15 | 36 |
| 404 | Storo | 76 30 | 16 30 | .. |
| 405 | Mossel Bay | 79 54 | 16 27 | .. |
| 406 | Gjesvaer | 71 06 | 25 22 | 20 |
| 407 | Kistrand | 70 28 | 25 15 | 5 |
| 408 | Vardo | 70 22 | 31 06 | 39 |
| 409 | Nordoyan | 64 48 | 10 33 | 102 |
| 410 | Skomvaer | 67 30 | 11 54 | 65 |
| 411 | Svolvaer | 68 14 | 14 37 | 3 |
| 412 | Bodo | 67 17 | 14 26 | 56 |
| 413 | Andenes | 67 20 | 16 08 | 23 |
| 414 | Tromso | 69 39 | 18 57 | 335 |
| 415 | Kola | 68 53 | 33 01 | 23 |
| 416 | Swayatoi Nos | 68 09 | 39 49 | 246 |
| 417 | Kolquev Island | 68 46 | 48 18 | 22 |
| 418 | Pusstoserssk | 67 35 | 52 11 | 39 |
| 419 | Kirkenes | 62 02 | 04 59 | 135 |
| 420 | Bronnoysund | 65 28 | 12 12 | 17 |
| 421 | Harnösand | 62 38 | 17 57 | 29 |
| 422 | Vaasa | 63 05 | 21 37 | 30 |
| 423 | Haparanda | 65 50 | 24 09 | 13 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Europe, Coastal and Insular (cont.): | ||||
| 424 | Helsingfors | 60 10 | 24 57 E. | 39 |
| 425 | Kem | 64 57 | 34 39 | 30 |
| 426 | Leningrad | 59 56 | 30 16 | 20 |
| 427 | Solovets | 65 01 | 35 45 | 56 |
| 428 | Archangel | 64 28 | 40 31 | 20 |
| 429 | Mezen | 65 50 | 44 16 | 66 |
| Europe, Inland: | ||||
| 450 | Karesuando | 68 26 | 22 30 | 1,091 |
| 451 | Karasjok | 69 28 | 25 31 | 443 |
| 452 | Inari | 68 57 | 26 49 | 502 |
| 453 | Sodankyla | 67 22 | 26 39 | 591 |
| 454 | Trondheim | 63 26 | 10 25 | 210 |
| 455 | Falun | 60 37 | 15 38 | 399 |
| 456 | Stenselle | 65 04 | 17 11 | 1,076 |
| 457 | Jyvaskyla | 62 14 | 25 44 | 387 |
| 458 | Kajaani | 64 13 | 27 46 | 479 |
| 459 | Ust Ssyssolssk | 61 40 | 50 51 | 332 |
| 460 | Ust Zylma | 65 27 | 52 10 | 220 |
| Asia, Coastal and Insular: | ||||
| 500 | Mys Zhelaniia | 76 57 | 68 34 | 26 |
| 501 | Mys Sterlegova | 75 25 | 88 54 | 33 |
| 502 | Ust’e R. Taimyry | 76 12 | 99 04 | 30 |
| 503 | Mys Cheliuskina | 77 43 | 104 17 | 16 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Asia, Coastal and Insular (cont.): | ||||
| 504 | Ostrov Kotel’nyy | 76 02 | 138 06 E. | .. |
| 505 | Malye Karmakuly | 72 23 | 52 44 | 52 |
| 506 | Ostrov Vaigach | 70 24 | 58 48 | 36 |
| 507 | Matochkin Shar | 73 16 | 56 24 | 59 |
| 508 | Ostrov Belyi | 73 20 | 70 02 | 20 |
| 509 | Gydo-Yamo | 70 55 | 79 33 | 26 |
| 510 | Ostrov Diksona | 73 30 | 80 24 | 66 |
| 511 | Ostrov Sagastyr’ | 73 23 | 126 36 | 16 |
| 512 | Tiksi Bay | 71 35 | 128 56 | 33 |
| 513 | Kazach’ye | 70 45 | 136 16 | 56 |
| 514 | Shalaurova | 73 11 | 143 14 | 26 |
| 515 | Russkoye Ust’ye | 71 00 | 149 05 | 6 |
| 516 | Mys Medvezhiy | 69 38 | 162 24 | .. |
| 517 | Wrangell Island | 70 58 | 178 33 W. | 10 |
| 518 | Yugorski Shar | 69 49 | 60 46 E. | 43 |
| 519 | Mare-Sale | 69 43 | 66 48 | 56 |
| 520 | Obdorsk | 66 35 | 66 31 | 86 |
| 521 | Novy Port | 67 42 | 72 57 | 16 |
| 522 | Wizhne-Kolymsk | 68 32 | 160 59 | 16 |
| 523 | Mys Shmidta | 68 55 | 179 29 W. | 30 |
| 524 | Mys Van Karem | 67 28 | 175 17 | .. |
| 525 | Uelen | 66 10 | 169 50 | 23 |
| 526 | Gizhiga | 62 03 | 160 30 E. | 33 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Asia, Coastal and Insular (cont.): | ||||
| 527 | Anadyr’ | 64 45 | 177 35 E. | 16 |
| 528 | Zaliv Kresta | 66 10 | 178 59 W. | 13 |
| 529 | Providence Bay | 64 24 | 173 13 | 13 |
| 530 | Lawrence Bay | 65 35 | 170 40 | Sea level |
| 531 | Ola | 59 33 | 151 13 E. | 16 |
| Asia, Inland: | ||||
| 550 | Volochanka | 70 58 | 94 30 E. | .. |
| 551 | Khatanga | 72 00 | 102 09 | 230 |
| 552 | Bulun | 70 40 | 127 12 | 115 |
| 553 | Ust ‘Yeniseiskii Port | 69 40 | 84 24 | 20 |
| 554 | Dudinka | 69 24 | 86 04 | 66 |
| 555 | Igarka | 67 30 | 86 50 | .. |
| 556 | Verkhoyansk | 67 35 | 133 30 | 400 |
| 557 | Abyy | 68 26 | 145 11 | 59 |
| 558 | Sredne-Kolymsk | 67 27 | 153 34 | 98 |
| 559 | Rodchevo | 66 18 | 152 44 | 33 |
| 560 | Berezovo | 63 56 | 65 04 | 138 |
| 561 | Samorova | 60 58 | 69 04 | 544 |
| 562 | Surgut | 61 17 | 75 20 | 135 |
| 563 | Turukhansk | 65 55 | 87 38 | 13 |
| 564 | Taimba | 60 19 | 98 55 | 551 |
| 565 | El’gyay | 62 29 | 117 31 | 443 |
| 566 | Olekminsk | 60 24 | 120 24 | 499 |
| Table XXXII. Locations of Arctic weather stations (cont.) | ||||
|---|---|---|---|---|
| Station Number | Station Name | Latitude ° ′ N. | Longitude ° ′ | Elevation (ft.) |
| Asia, Inland (cont.): | ||||
| 567 | Viliusk | 63 45 | 121 35 | 394 |
| 568 | Yakutsk | 62 01 | 129 43 | 354 |
| 569 | Semenowskij Rodnik | 64 00 | 132 00 | 3,346 |
| 570 | Ust’-Maya | 60 25 | 134 29 | 581 |
| 571 | Olmyaken | 63 28 | 142 30 | 2,625 |
| 572 | Markovo | 64 41 | 170 25 | 85 |
| 573 | Tobolsk | 58 12 | 68 14 | 355 |
| 574 | Yeniseysk | 58 27 | 92 10 | 256 |
| 575 | Kirensk | 57 47 | 108 07 | 865 |
| 576 | Blagoveshchensk Priisk | 58 10 | 114 17 | 1,608 |
| 577 | Bur | 58 57 | 106 31 | 1,414 |
THE METEOROLOGY OF THE ARCTIC
INFORMATION ON DIAGRAMS
| Figs. 1-3 | Supplied. |
| Fig. 4 | Same as Fig. 18 (p. 90) in Haurwitz and Austin: “Climatology.” Copyright by McGraw-Hill, New York |
| Figs. 5-12 | Supplied. |
| Fig. 13 | Upper figure same as Fig. 351, p. 623, and lower figure same as Fig. 357, p. 625 in Meddelelser om Gronland, Bd. 75, 1930. |
| Fig. 14 | Supplied. |
| Fig. 15 | Same as Tafel X at p. 252 in “Danmark Expeditionen til Gronlands Nordostkyst 1906-1908. |
| Figs. 16-17 | To be found in Scoresby, Wm., Transactions of the Royal Soc. of Edinburgh. Vol. 9. pp. 299-305. |
| Fig. 18 | Same as Fig. 89 (p. 160) in S. Petterssen: Weather Analysis and Forecasting, Copyright by McGraw-Hill, New York. |
| Fig. 19 | Same as Fig. 90 in book referred to under Fig. 18. |
| Fig. 20 | Same as Fig. 124 (p. 269) in book referred to under Fig. 18. |
| Fig. 21 | Same as Fig. 126 (p. 271) in book referred to under Fig. 18. |
| Fig. 22 | Same as Fig. 128 (p. 273) in book referred to under Fig. 18. |
| Figs. 23-28 | Supplied. |
1. Baur, F. “Das Klima der bisher erforschten Teile der Arktis.” Arktis, No. 2, Gotha, 1929.
2. Bedient, H. A. Unpublished Report. Air Weather Service, Washington, D. C., 1950.
3. Bergeron, T., Geofys. Pub., Vol. 5, No. 6, Oslo, 1928.
4. Bogolepow, M. Met Zeitschr. Vol. 49, No. 7, p. 258-261. 1932.
5. Brontman, L. “On the Top of the World.” Victor Gollancz Ltd. London, 1938.
6. Canadian Dept. of Marine and Fisheries. “Report of the Meteoro– logical Services of Canada for the Year Ending December 31, 1908.” Otto^a^wa, 1912.
7. Canadian Dept. of Transport. “Canadian Polar Year Expedition, 1932-1933. Meteorology.” Vol. I. Ott o^a^wa, 1940.
8. Carmichael, H. and Dymond, E. G. Proc. Roy. Soc. Ser. A. Math. and Phys. Sci., Vol. 171, pp. 345-359. London, 1939.
9. Collinson, Sir Richard. “Journal of the Enterprise,” p. 176.
10. Craig, R. A. Am. Met. Soc. Monographs, Vol. 1, No. 2. Boston, Mass., 1950.
11. Dobson, G.M.D., Proc. Roy. Soc. London, A, 129, 1930; A, 185, 1946; A, 110, 1926; A, 114, 1929.
12. Dorsey, N. G. “Meteorological Characteristics of Northern Arctic America.” (unpublished). Mass. Inst. of Tech., 1949.
13. Dzerdzerjevski, B. L. “Circulation Schemes in the Troposphere over the Central Arctic.” Inst. of Theoretical Geoph. Moscow and Leningrad. 1945.
14. Flohn, H. Polarforschung, Ser. II, 17(1-2): pp. 143-149. Kiel, 1947.
15. Gutenberg, B. Bul. Am. Met. Soc., Vol. 20, pp. 192-201.
16. Hann, J. and Suring, R., “Lehrbuch der Meteorologie,” p. 180, Leipzig, 1937.
17. Haurwitz, B. and Austin, J. M., “Climatology,” McGraw-Hill, New York, 1944.
18. Helmholtz, H. von. Met. Zeitschr. Bd. 5, pp. 329-340. 1888.
19. Holz, R. S. “Pole Vaulting for Weather.” Unpublished. Air Weather Service, Washington, D. C., 1950.
20. Hovm o ^ ö ^ ller, E. Meddelelser om Gr o ^ ö ^ nland, Bd. 144, No. 1, Appendix 1. 1947.
21. International Meteorological Organization, Publication No. 62, Lausanne, 1948.
22. Kaye, G.W.C. and Evans, E.J., Nature, Jan. 1939.
23. Koch, J. P. and Wegener, A., Meddelelser om Gr o ^ ö ^ nland, Vol. 75, pp. 405-676.
24. K o ^ ö ^ ppen, W., “Die Klimate der Erde”, Berlin, 1923.
25. K o ^ ö ^ ppen, W. “Klimakunde von Russland.” Handbuch der Klimatologie, Band III, Teil N. Berlin, 1939.
26. Malmgren, F. Geofys. Pub., Vol. 4, No. 6. Oslo, 1926.
27. Meteorological Division, Dep. of Transport, “Meteorology of the Canadian Arctic”, Toronto, 1944.
28. Mohn, H. “Meteorology.” The Norwegian North Polar Exp. 1893-1896. Vol. VI. Christiania, 1905.
29. Mohn, H. “Report on the Scientific Results of the Second Nor– wegian Arctic Expedition in the Fram. 1898-1902.” Christiania, 1907.
30. Namias, J. and Smith, K. “Normal Distribution of Pressure at 10,000 feet over the Northern Hemisphere.” U. S. Weather Bureau, Washington, D. C., 1944.
31. Petterssen, S., “Weather Analysis and Forecasting,” McGraw-Hill, New York, 1940.
32. Petterssen, S. Proceedings of the Centenary Celebrations, Roy. Met. Soc., London, 1950.
33. Phillips, W., Unpublished report on flying hazards at Alaskan air– fields. Air Weather Service, Washington, D. C., 1951.
34. Rigby, M. “Climatology of the Arctic Regions.” Parts I-III. Air Weather Service, Washington, D. C., 1946.
35. Roberts, B., The Polar Record, Vol. 4, No. 27.
36. Rothwell, P., J. of Acoust. Soc. of Am., Vol. 19, pp. 205-221.
37. Saby, S. and Nyborg, W. L., J. of Acoust. Soc. of Am., Vol. 18, pp. 316-322.
38. Scoresby, W., Trans. Roy. Soc. of Edinburgh, Vol. 9, pp. 299-305. 1821.
39. Simpson, G. C. “Meteorology.” British Antarctic Exp., 1910-1913. Vol. I. Discussion. Calcutta, 1919.
40. Sorge, E., Geog. Journ. Roy. Geog. Soc., Vol. 81; 333-352. 1933.
41. Stefansson, V. “The Friendly Arctic.” New York, 1943.
42. Sverdrup, H. U., Petersen, H. and Loewe, F., “Klima des Kanadischen Arkipels und Gr o ^ ö ^ nlands.” Handbuck^ h ^ der Klimatologie, edited by K o ^ ö ^ ppen and Geiger. Vol. II, Part K. 1935.
43. Sverdrup, H. U. “Meteorology, Part I, Discussion.” The Norwegian North Polar Expedition with the Maud. Scientific Results, Vol. II. Bergen, 1933.
44. Sverdrup, H. U. “Meteorology, Part II, Tables.” The Norwegian North Polar Expedition with the Maud. Scientific Results, Vol. II. Bergen, 1933.
45. Tikhomirova, E. I. “Klimaticheskii Ocherk Karskogo Maria” (Climatic Outline of the Kara Sea). Trans. Arctic Sci. Res. Inst. U. S. S. R. Vol. 187. Moscow, Leningrad, 1946.
46. T o ^ ö ^ nsberg, E. and Langlo Olsen, K. L., Geofys. Pub., Vol. 13, No. 12, Oslo, 1944.
47. U. S. Weather Bureau, “Normal Weather Maps,” Washington, 1944.
48. U. S. Weather Bureau and Air Weather Service. “Upper Air Wind Normals for the Northern Hemisphere.” Washington, D. C., 1945, (Unpublished).
49. Vederman, J. and Smith, C. D., Bul. Amer. Met. Soc., Vol. 31, No. 6: 197-205. 1950.
50. Waelchen, K., Zeitschr. f. Geophys., Vol. 10, p. 322.
51. Wegener, A., “Danmark Expeditionen til Gr o ^ ö ^ nlands, Nordostkyst 1906-08,” pp. 127-355.
52. Wegener, A., Medelelser om Gr o ^ ö ^ nland, Vol. 42, p. 561.
53. Wexler, H., Monthly Weather Review, Vol. 64, No. 4, Washington, 1936.
54. Wexler, H., Bul. Amer. Met Soc., Vol. 29. No. 10; 547-550. 1948.
55. Whipple, F. W. Proc e ^ é ^ s Verbaux, Intern. Met. Assoc., Edinborough, 1936.
56. Wiese, W. “Scientific Results of the Arctic Expedition on the Sedov.” Trans. of the Arctic Inst., Vol. 1, 1936.
LEGEND TO DIAGRAMS
| Fig. 1. | The principal climatic zones of the northern hemisphere. Ref. Kőppen ^ [ ^ 24 ^ ] ^ . |
| Fig. 2. | Mean meridional distribution of temperature. Ref. Hann and Sűring ^ [ ^ 16 ^ ] ^ . |
| Fig. 3. | Mean meridional distribution of ozone. Ref. Craig ^ [ ^ 10 ^ ] ^ . the unit of ozone amount is the equivalent height of a column of ozone at standard pressure and temperature. |
| Fig. 4. | Mean meridional distribution of relative humidity. Ref. Haurwitz and Austin ^ [ ^ 17 ^ ] ^ . |
| Fig. 5. | Some typical examples of temperature soundings. Upper diagram: July. Lower diagram: January. Ref. Canadian Meteorological Service ^ [ ^ 27 ^ ] ^ . |
| Fig. 6. | Mean meridional cross-section of temperature (°C) in January. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
| Fig. 7. | Mean meridional cross-section of temperature (°C) in July. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
LEGEND TO DIAGRAMS (cont.)
| Fig. 8. | Mean meridional cross-section of annual variation of temperature (°C.) |
| Fig. 9. | Some examples of temperature inversions in the Arctic. |
| Fig. 10. | Annual variation of temperature inversions. Ref. Sverdrup ^ [ ^ 43 ^ ] ^ . |
| Fig. 11. | Relation between inversion conditions and wind speed and cloudiness. Ref. Canadian Meteorological Service ^ [ ^ 27 ^ ] ^ . |
| Fig. 12. | Diagrammatic representation of sound beams. A: Uniform temperature; B: Normal lapse rate; C: Inversion with sound source below the inversion; D: Inversion with sound source above inversion layer; E: Multiple inversion; F: Influence of wind. |
| Fig. 13. | Superior mirage. Upper picture Gundahl’s Knold (76°43′ N., 32°01′ W.) without optical distortion. Lower picture strong vertical distortion due to inversion layer. Ref. ^ [ ^ 23 ^ ] ^ . |
LEGEND TO DIAGRAMS
(cont.)
| Fig. 14. | Diagramatic representation of looming. Hatched areas indicate twilight or darkness. |
| Fig. 15. | Inferior mirage near Cape Bismark, 1st Oct. 1907. Ref. Wegener ^ [ ^ 51 ^ ] ^ . |
| Fig. 16. | Telescopic appearance of ships, as observed in the Greenland Sea, June 28th, 1820, 73°30′N., 11°10′W. Ref. ^ [ ^ 38 ^ ] ^ . |
| Fig. 17. | Telescopic appearance of east coast of Greenland, at a distance of 35 miles, July 18th, 1820, 71°20′N., 17°30′W. Ref. ^ [ ^ 38 ^ ] ^ . |
| Fig. 18. | Source region of principal air masses in winter. Ref. Patterssen ^ [ ^ 31 ^ ] ^ . |
| Fig. 19. | Source region of principal air masses in summer. Ref. Petterssen ^ [ ^ 31 ^ ] ^ . |
| Fig. 20. | Mean position of main frontal zones in winter. Ref. Petterssen ^ [ ^ 31 ^ ] ^ . |
LEGEND TO DIAGRAMS
(cont.)
| Fig. 21. | Mean position of main frontal zones in summer. Ref. Petterssen ^ [ ^ 31 ^ ] ^ . |
| Fig. 22. | Cross-section through principal frontal zones. Ref. Petterssen ^ [ ^ 31 ^ ] ^ . |
| Fig. 23. | Example of synoptic situation, showing traveling cyclones and anticyclones. |
| Fig. 24. | Mean meridional distribution of percentage frequencies of cyclogenesis (CG), cyclone centers (C), anticyclo– genesis (AG), and anticyclones (A) in squares of 100,000 sq. kilometers. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
| Fig. 25. | Geographical distribution of percentage frequency of cyclones in winter. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
| Fig. 26. | Geographical distribution of percentage frequency of cyclones in summer. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
| Fig. 27. | Geographical distribution of percentage frequency of anticyclones in winter. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
LEGEND TO DIAGRAMS
(cont.)
| Fig. 28. | Geographical distribution of percentage frequency of anticyclones in summer. Ref. Petterssen ^ [ ^ 32 ^ ] ^ . |
| Fig. 29. | Mean surface pressure for January (in mbs.) Ref. Dorsey ^ [ ^ 12 ^ ] ^ . |
| Fig. 30. | Mean surface pressure for April (in mbs.) Ref. Dorsey ^ [ ^ 12 ^ ] ^ . |
| Fig. 31. | Mean surface pressure for July (in mbs.) Ref. Dorsey ^ [ ^ 12 ^ ] ^ . |
| Fig. 32. | Mean surface pressure for October (in mbs.) Ref. Dorsey ^ [ ^ 12 ^ ] ^ . |
| Fig. 33. | Mean altitude of the 700-mb. pressure surface for January (in feet). Revised from Namias and Smith ^ [ ^ 30 ^ ] ^ . |
| Fig. 34. | Mean altitude of the 700-mb. pressure surface for July (in feet). Revised from Namias and Smith ^ [ ^ 30 ^ ] ^ . |
| Fig. 35. | Surface wind roses-Mean distribution of the surface wind by both speed (mph) and direction. Winter. |
LEGEND TO DIAGRAMS
(cont.)
| Fig. 36. | Surface wind roses-Mean distribution of the surface wind by both speed (mph) and direction. Summer. |
| Fig. 37. | Example of diurnal variation of wind speed over the pack-ice and at the coast. Ref. Sverdrup ^ [ ^ 43 ^ ] ^ . |
| Fig. 38. | Mean air flow and upper wind distribution at 3 Km. (10,000 feet) during winter. Long arrows give mean flow pattern. Wind roses showing frequency distribution of various wind directions and speeds have been entered for certain stations, and sector mean winds are given for certain locations. |
| Fig. 39. | Mean air flow and upper wind distribution at 3 Km. (10,000 feet) during summer. Long arrows give mean flow pattern. Wind roses showing frequency distribution of various wind directions and speeds have been entered for certain stations, and vector mean winds are given for certain locations. |
LEGEND TO DIAGRAMS (cont.)
| Figure 40. | Mean air flow and upper wind distribution at 6 Km. (20,000 feet) during winter. Long arrows give mean flow pattern according to (ref. 48). Wind roses showing frequency distribution of various wind directions and speeds have been entered for certain stations, and vector mean winds are given for certain locations (ref. 48). Wind roses near the 40,000-foot level are shown in the inset. |
| Figure 41. | Mean air flow and upper wind distribution at 6 Km. (20,000 feet) during winter. Long arrows give mean flow pattern according to (ref. 48). Wind roses showing frequency distribution of various wind directions and velocities have been entered for certain stations, and vector mean winds are given for certain locations (ref. 48). Wind roses near the 40,000-foot level are shown in the inset. |
LEGEND TO DIAGRAMS (cont.)
| Figure 42. | Frequency distribution of wind according to direction, 3 Km. (10,000 feet) during winter. |
| Figure 43. | Frequency distribution of wind according to direction, 3 Km. (10,000 feet) during summer. |
| Figure. 44. | Mean surface temperature (°F) during January. |
| Figure. 45. | Mean surface temperature (°F) during July. |
| Figure 46. | Mean surface temperature profile along 140 E. meridian (approximately). |
| Figure 47. | Examples of the diurnal variation of temperature at Arctic stations with continental and maritime climate. Ref. Sverdrup ^ [ ^ 43 ^ ] ^ . |
| Figure 48. | Mean precipitation amounts (inches). |
| Figure 49. | Mean snow depth on ground (inches). |
| Figure 50. | Diurnal variation of relative humidity and vapor pressure over the pack-ice. Ref. Sverdrup ^ [ ^ 43 ^ ] ^ . |
| Figure 51. | Mean cloudiness during February (percentage of total cover). |
LEGEND TO DIAGRAMS (cont.)
| Figure 52. | Mean cloudiness during August (percentage of total cover). |
| Figure 53. | Station locator map. |
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