Outside in Chicago right now, the air feels like floating ice. Water freezes in midair before it hits the ground. And the entire landscape has such a frozen sharpness that, staring off my front porch this morning, I wouldn’t have been at all surprised to see a polar bear walking down my street.
But just why is windchill plunging in Chicago and the upper Midwest into temperatures as low as -60 degrees? What the heck is a polar vortex, anyway? The New York Times put together a terrific, animated visualization to explain just that. Long story short, every winter brings the earth a constant, swirling cold air around the north pole (a polar vortex) that usually sits atop the planet like a halo. But more frequently–likely because of global warming in the Arctic–that vortex is fracturing. And when it does, little vortexes split off, jetting cold air south, and pulling warm air north.
The New York Times illustrates all of this in a few glanceable graphics, which are equal parts beautiful and informative. (But the graphics are only almost as cool as this picture of Chicago’s subzero Metra line forced to run on tracks of fire.)
Check out the full visual here.