We've all heard the weather buzzword of the winter: "Polar Vortex". And with another cold snap moving in this term is starting to emerge again. But what exactly does it mean?

While its theatrical-sounding name may have you picturing scenes from "The Day After Tomorrow", the polar vortex is not some kind of formidable storm system nor is it anything new. It's simply a large region of low pressure that continuously sits near the North Pole during the winter. It is caused by - you guessed it - the cold air up there. The term "vortex" simply refers to the counter-clockwise flow of air that flows around this area of low pressure. This wind flow is strongest at the edge of the polar vortex and is what meteorologists refer to as the jet stream.

So why is the polar vortex a big deal? In essence, the strength of this system controls the jet stream which has big effects on our weather. If the polar vortex weakens and breaks into pieces, as it is doing now, the jet stream may buckle and allow low pressure and cold air to sink southward into the United States (you can consider this a piece of the polar vortex as indicated in blue on the map). This is why the Midwest is so cold this week and the East Coast just got hit with a snow storm. Conversely, where the jet stream surges northward, warm air and dry weather are the result. This is why California is experiencing a major drought this winter.

So next time you hear about the polar vortex you don't have to worry about coastal cities becoming encased in ice. It's just old man winter paying us a visit from the north, as he tends to do now and then.



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