Among the terms used to describe wintery weather, among the most dreaded is “polar vortex.” The ominous-sounding term sounds like some Earthly black hole trying to kill us with Arctic air. It started appearing in weather forecasts more frequently this decade, especially after the polar vortex of 2014 that froze out Chicago and the Midwest.
Now it’s back. The polar vortex hovering above the Arctic has shattered into three parts, and it’s looking like the central and eastern United States will be for some brutally cold weather in the next week. So what exactly is a polar vortex, and why do we keep hearing about it year after year?
End of January into early February. Cold. Really, really cold. pic.twitter.com/xV5mVkT9PJ
— Eric Fisher (@ericfisher) January 15, 2019
Frigid Cyclones
The term “polar vortex” has been used as far back as 1853, but names for the phenomenon shifted when scientists began to study it in earnest in the 20th century. The term was revised in 1950, when it was called a “circumpolar vortex,” then back to “polar vortex” by 1959. The American Meteorological Society glossary revised the definition in 2000, 2014, and then again in 2015.
The reason these changes keep happening is that the term “polar vortex” actually describes two types of cold weather events. One happens in the troposphere, the lowest layer of the Earth’s atmosphere, while another happens higher up in the stratosphere. Basically it’s a frigid cyclone.
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