Definition

A polar vortex is a large-scale cyclone located near either of the geographical poles. Located in the middle and upper troposphere and the stratosphere, they surround the polar highs and lie in the wake of the polar front.

Description

Typical polar vortex configuration (source:NOAA)

The polar vortices are cold-core low-pressure areas that strengthen in the winter and weaken in the summer due to their reliance upon the temperature differential between the equator and the poles. They usually span less than 1,000 kilometres (620 miles) in which the air circulates in a counter-clockwise fashion (in the Northern Hemisphere) due to the Coriolis effect.