Polar Vortex

A polar vortex (also known as Polar cyclones, polar vortices, Arctic cyclones, sub-polar cyclones, and the circumpolar whirl) is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer. They usually span 1,000–2,000 kilometers (620–1,240 miles) in which the air is circulating in a counter-clockwise fashion (in the northern hemisphere). The reason for the rotation is the same as any other cyclone, the Coriolis effect.

One center lies near Baffin Island and the other over northeast Siberia. In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude. When the polar vortex is strong, the Westerlies increase in strength. When the polar cyclone is weak, the general flow pattern across mid-latitudes buckles and significant cold outbreaks occur. Ozone depletion occurs within the polar vortex, particularly over the Southern Hemisphere, which reaches a maximum in the spring.