“If the polar vortex were to not be around, it would mean either the sun had gone out or the earth had stopped rotating,” Virginia state climatologist Jerry Stenger explained to me. “It is simply a consequence of differential heating on the earth and its rotation that develops this flow around the pole and that’s totally normal.”
It’s hard to pick up a newspaper or watch the TV news this week without seeing some reference to record cold temperatures spiking across the United States, especially in the Upper Midwest and the Great Plains — courtesy of the winter 2019 Northern Hemisphere polar vortex.
“Detroit is colder than parts of Antarctica and I hate everything” (Detroit Free Press )
“77 below zero? Polar vortex yields deadly cold as thousands endure power cuts, travel issues mount in Midwest” (Accuweather )
“Too cold for mail: Polar vortex brings subzero temps to Midwest, prompts USPS to suspend service” (ABC7 Chicago )
“Deadly Polar Vortex Is Making Its Way to New York” (Hudson Valley Post )
“Polar vortex: temperatures to plummet to -40 degrees Celsius as dangerous arctic chill sweeps over US Midwest” (South China Morning Post )
“Bitterly cold, once-in-a-generation temperatures expected in Wisconsin this week” (Milwaukee Journal Sentinel )
“Chicago Weather: It’s So Cold That You Shouldn’t Talk Too Much–Or Breathe” (CBS2 Chicago )
“Life in #Chiberia: It’s so cold in the Midwest, beer is exploding and we’re setting fire to train tracks to keep them running” (USA Today )
“High temperature on Mars warmer than some places in the northern U.S. Tuesday: Temperatures on Mars soar into the 20s” (WSLS )
Colder than Mars? We’ll get to that later.
I visited Jerry Stenger today at his office in the Department of Environmental Sciences at the University of Virginia to talk to him about the polar vortex for this weekend’s episode of The Score.
In this excerpt, he explains just what the polar vortex is:http://bearingdrift.com/wp-content/uploads/Stenger-excerpt.wav 
The term polar vortex has come to the fore in popular information lately.
The polar vortex has always been there. Climatologists refer to it often in general terms as the jet stream, or the circumpolar vortex, or a polar front — all sorts of names. It’s basically the fast flow in the upper atmosphere that circles the pole and it has lots of undulations and waves in it. Sometimes these waves will catch up with one another and amplify or they will subtract from one another. We have long waves — they cover long distance from east to west — and we have short waves, which move through the system much quicker.
In this particular case that we’re coming up to now, we’re seeing a very southerly dip in the polar vortex … and when we have a southerly dip, it brings cold air with it.
The polar vortex is generally considered the dividing line between the cold air toward the pole and the warmer air toward the tropics. Where we see that, there can be a very steep contrast between the two air masses, so what we’re what’s happening now is that we’re getting into the really, really cold air that’s dipping down on us.
As for those temperatures on Mars, listen to The Score this weekend  for the full interview with Jerry Stenger, because I ask him about what scientists are learning about polar vortices on other planets.
Other guests on the next episode of The Score will include economist Bruce Yandle, on the economic consequences of the shutdown, and Nick Sorrentino, co-founder of Against Crony Capitalism — plus more news, reviews, and interviews.