Polar vortex is a phrase you've probably heard a lot, but what does it actually mean?
"I think, sometimes, people sort of misunderstand the polar vortex and they think it's this giant amoeba of cold that sits over the North Pole that just gets dislodged and heads right over Chicago," said Ryan Hanrahan, meteorologist at NBC Connecticut. "That's not really what happens."
Hanrahan said the polar vortex is something that happens every winter. The sun sets over the Arctic Circle, and thanks to months of darkness, temperatures drop.
"Because of the temperature difference between the really cold weather up there and the somewhat milder air down here, you get this jet stream that circles the entire globe around the North Pole," Hanrahan said. "That's what's called the polar vortex."
Hanrahan said the polar vortex stretches from about 30,000 feet above the Earth all the way up into the stratosphere. Meteorologists have used the term for decades, but it went viral last year, for reasons Hanrahan said he still can't figure out.
"We see headlines that just make us cringe," Hanrahan said. "Like, 'Polar Vortex Plunges Toward United States,' things like that. That's not really true. The polar vortex generally stays up near the North Pole," he said. "Sometimes you can get a small piece of it that can break off and influence our weather. The ironic thing is that we get the coldest when the polar vortex actually weakens."
That's because when the vortex gets disrupted, cold air is more likely to move further south than it normally would.
Hanrahan said the cold weather expected later this week in Connecticut is not a result of the polar vortex. For that, you can thank a ridge of high pressure and warmth in Alaska that's nosing up to the North Pole and bringing cold air south.
Here's one more interesting fact: polar vortices aren't unique to Earth. They've been observed throughout our solar system -- on Venus, Mars, and Saturn.
