Blistering cold air from the Arctic plunged southward this winter, breaking U.S. temperature records.
A persistent pattern of winds spins high above the Arctic in winter. The winds, known as the polar vortex, typically blow in a fairly tight circular formation. But in late December 2013 and early January 2014, the winds loosened and frigid Arctic air spilled farther south than usual, deep into the continental United States. Animated video follows.
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