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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.