Feeling a Chill? Blame the Polar Vortex. And Global Warming.

On Thursday, temperatures on the East Coast are expected to plummet, and some people — fellow journalists and weather broadcasters, we’re looking at you — may start talking about a “polar vortex.”

We thought you might want to know what the polar vortex is, and what it’s not.

(And we wanted to pre-empt the inevitable chatter about climate change that usually crops up when the thermometer drops — “It’s bone-shakingly cold, how could the Earth be warming?” We’ll tell you how.)

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