Volume 7: Meteorology and Oceanography
Canadian Meteorology
Mean Pressure (mbs)
January
Mean Pressure (mbs)
March
Mean Pressure (mbs)
May
Mean Pressure (mbs)
July
Mean Pressure (mbs)
September
Mean Pressure (mbs)
November
Mean Temperature (°F)
January
Mean Temperature (°F)
March
Mean Temperature (°F)
May
Mean Temperature (°F)
July
Mean Temperature (°F)
September
Mean Temperature (°F)
November
The Climate of the American Northlands
Some important divisions of
the northlands This diagram shows some of the
devices used in delimiting the Arctic and
sub-Arctic. The sub-Arctic limit shown is that
line north of which less than four calendar months
have a mean temperature of over 50°F (10°C.).
Tree-line follows various sources.
Mean Sea-Level Pressure in
January. (Courtesy H. G. Dorsey, Jr.) The
prevailing low-level flow of air is parallel to
the isobars, its vectorial mean velocity being
greatest where the isobars are closest together.
Hence mean circulation over the Eastern Canadian
Arctic consists of a great, cyclonically-curving
flow of Arctic air passing southward at high
speeds. Over the western Arctic, however, quieter
conditions prevail, and the surface air is locally
derived. In coastal Alaska stormy conditions
prevail, with air derived from the Pacific. The
positions of the European and American Arctic
frontal zones are indicated by the customary
symbol.
Mean Sea-Level Pressure in
January. This diagram is uniform with fig. 2,
except that dashed isobars are shown for the
values midway (i.e. 2.5 mo.) between the standard
isobars, in order to indicate the form of the
gentler pressure gradients typical of summer. Note
the extended form and northern position of the
Siberian-American Arctic frontal zone.
Mean Air Temperature at
ground-level, January (°F.) Note the great cold
over the central Arctic and the warm gulf over the
open water belts in Baffin Bay, Hudson Strait and
Davis Strait. Note also the remarkable contrast in
temperature between coastal Alaska and the
Yukon-Tanana trenches.
Mean Air Temperature at
ground level in July The outstanding
characteristic is the contrast between the cold
eastern Arctic and the warm interior of the
sub-Artic Mackenzie, Yukon and Tanana
Valleys.
The Northward March of
Persistent Spring Thaw The isolines show the dates
on which mean air temperature rises above 32°F.
Note the retarded spring around ice-covered Hudson
Bay.
The Southward March of
persistent frost in fall Note how far south the
freeze-up goes by mid-October in
Ungava-Labrador.
Oceanography of the Arctic
Bathymetric chart of the
arctic seas (after Wüst) and limits of seas
according to the International Hydrographic
Bureau, Special Publication No. 23, second
edition, 1937. 8 Norwegian or Greenland Sea 9
Barents Sea 10 Kara Sea 11 White Sea 12a Laptev or
Nordenskiöol Sea 12b East Siberian Sea 12c Chukchi
Sea 12d Beaufort Sea 12e Northwest Passage 12f
Hudson Bay (not on map) 12g Arctic Ocean on Polar
Sea
Arctic Sea Ice
Air temperature,
°C.
The Uses of Ice
The entire area outside of
the heavy solid line may be called the “Zone of
Approach by Ship”; the area within the “Zone of
Man-and-Dog Travel.” The stippled portion of the
latter is the “Zone of Comparative
Inaccessibility.” The distance between the
isochronic lines is five days’ dog-sledge travel,
or 60 miles. Incidentally the map shows the
superiority of Peary’s position of 1908 over all
others on land as a base for a dash aimed at the
point of latitude 90° N. It is also favorably
situated for an attack on “Pole of
Inaccessibility,” which is only 200 miles farther
away from Peary’s base than the North
Pole.