Why Is It So Cold? The Polar Vortex, Explained

A massive winter storm on Jan. 2 was followed by very cold temperatures and dangerous wind chills. Photographer: NASA/GSFC/Aqua/MODIS

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January 7, 2014 at 7:22 PM UTC

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"Polar vortex" has taken an uncontested lead in the competition for buzzword of 2014. It's brought Arctic chill to the continental United States, disrupted industries and cities, and most, curiously, turned Donald Trump into a climate realist. Sort of.

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