A circumpolar vortex, or simply polar vortex, is a large region of cold, rotating air that encircles both of Earth's polar regions. Polar vortices also exist on other rotating, low-obliquity planetary bodies.

What exactly is the polar vortex?

Polar vortex versus polar jet stream

The Arctic polar vortex is a band of strong westerly winds that forms in the stratosphere between about 10 and 30 miles above the North Pole every winter. The winds enclose a large pool of extremely cold air.

What is a polar vortex and what causes it?

But what exactly is the polar vortex? And what causes it? The polar vortex is an area of low pressure—a wide expanse of swirling cold air—that is parked in polar regions. During winter, the polar vortex at the North Pole expands, sending cold air southward.