The Arctic polar vortex
A strong polar vortex configuration in November 2013
A more typical weak polar vortex on January 5, 2014
The polar vortex (alternate names: Arctic cyclone or polar vortice) is a persistent large-scale cyclone located near geographical poles of a planet. On Earth, a polar vortex is usually in the middle and upper troposphere and stratosphere. The cyclone surrounds the polar highs. Polar storms lie in the wake of the polar front. They strengthen in the winter and weaken near summer. These vortexes span usually between 620 to 1,240 miles. They circulate counter-clockwise in the Northern Hemisphere.
Similar to hurricanes, a Coriolis effect causes the rotation of a polar vortex. The Arctic vortex has two main centers: one is over the Baffin Island, the other is over northeastern Siberia.
Images for kids
Low pressure area over Quebec and Maine, part of the northern polar vortex weakening, on the record-setting cold morning of January 21, 1985
Polar vortex and weather impacts due to stratospheric warming
Southern Hemisphere Ozone Concentration, February 22, 2012
Hubble view of the colossal polar cloud on Mars