Pressures at the poles are consistently high throughout the year. In the northern hemisphere the high pressure area is not centered at the pole, but it is believed to extend from northern Greenland westward across the islands situated in northern part of Canada.
From the reports of explorers of Antarctica the existence of relatively higher pressure near the South Pole is confirmed.
As regards the origin of the cap of high pressure at the Poles, thermal factor seems to be more important than the dynamic factor. Although because of the diurnal rotation of the earth the layers of air at the poles are thinned out, the persistent low temperature makes the polar air cold and heavy.
This gives rise to the caps of high pressure in Polar Regions, the prevailing easterly winds blow out of these caps of high pressure to the sub-polar low-pressure systems.
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In the northern hemisphere these easterly winds are deflected to the right of their original path and become polar north-easterlies, while in the southern hemisphere the polar winds blow as south- easterlies.
It may be pointed out that the extreme cold of Polar Regions makes the work of collection of atmospheric data very difficult.
Thus, the paucity of accurate climatic data about these regions stands in the way of describing the climatic conditions of these extremities with a fair degree of accuracy.