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.

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polar front [′pō·lər ′frənt]

(meteorology)

The semipermanent, semicontinuous front separating air masses of tropical and polar origin; this is the major front in terms of air mass contrast and susceptibility to cyclonic disturbance.

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Polar Front 

an atmospheric front arising at the boundary between an air mass originating outside the tropical latitudes and one originating within the tropical latitudes, that is, between polar, or cooler, air and tropical air. The polar front in each hemisphere usually consists of several separate branches, each of which is associated with a series of cyclones that develop along it.