polar front

polar front, zone of transition between polar and tropical air masses . Its average position during the winter is at about 30° lat. and during the summer at about 60° lat. In the N Atlantic Ocean, for example, the polar front can often be traced as a continuous line extending over thousands of miles, usually toward the northeast from a point just off the coast of the United States at about 30°N. Most cyclones outside the tropics develop along the polar front from waves caused by the juxtaposition of cold air moving toward the equator and hot air moving toward the poles the earth's rotation gives this air its cyclonic twist. See front .

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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