What is the Polar Vortex?

Polar Vortex expert sees disruption coming, cold air returning

Nasa Ozone Watch: Polar vortex facts

Understanding Climate Change and the Polar Vortex - Science

Graphic: What is a polar vortex?

What is the Polar Vortex?, Waugh Research Group

Polar vortex on the way: what that means and what you need to know

A Polar Vortex Weakening May Lie Ahead. Here's What That Could

The 'polar vortex' may appear in the US in January

Weather or Not: Polar Vortex

What is the Polar Vortex and how does it affect Central Pa.?