What is a Polar Vortex?
If you’ve turned on the news or stepped outside lately, you’re familiar with the record-breaking cold that is blanketing most of North America. In addition to the bomb cyclone battering the northeastern U.S. with ice and snow, the polar vortex will soon push frigid air straight from the arctic tundra into that region. But just what is this weather phenomenon?
Polar vortexes are basically arctic hurricanes or cyclones. NASA defines them as “a whirling and persistent large area of low pressure, found typically over both North and South poles.” A winter phenomenon, vortexes develop as the sun sets over the pole and temperatures cool, and occur in the middle and upper troposphere and the stratosphere (roughly, between six and 31 miles above the Earth’s surface). In the Northern Hemisphere, the vortexes move in a counterclockwise direction. Typically, they dip down over Canada, but according to NBC News, polar vortexes can move into the contiguous U.S. due to warm weather over Greenland or Alaska—which forces denser cold air south—or other weather patterns.
Polar vortexes aren't rare—in fact, arctic winds do sometimes dip down into the eastern U.S.—but sometimes the sheer size of the area affected is much greater than normal.
How Cold Is It?
So cold that frozen sharks are washing up on Cape Cod beaches. It's so cold that animal keepers at the Calgary Zoo in Alberta, Canada decided to bring its group of king penguins indoors for warmth (the species lives on islands north of Antarctica and the birds aren't used to extreme cold.) Even parts of Alabama and other regions in the Deep South are seeing single-digit temperatures and wind chills below zero.
But thankfully, the arctic freeze is not going to stick around forever: Temperatures for most of the U.S. will gradually warm up to average or above-average levels this month.