0 an area of low pressure and cold air that forms near the North or South Pole and is stronger in winter:
There are two polar vortices in the Earth's atmosphere, one overlying each Pole.
Variations in the strength of the polar vortex in the upper stratosphere may influence surface climate.
This year the winter polar vortices have been particularly persistent in the Arctic.
Lower pressure leads to the contraction of the polar vortex, which moves the frontal systems further south.
