NASA's Atmospheric Infrared Sounder (AIRS) instrument captures a polar vortex moving from Central Canada into the U.S. Midwest from January 20 through January 29, 2019. The images show air temperatures at 600 millibars, around 2.5 miles (4 kilometers) high in Earth's troposphere. This polar vortex is responsible for surface air temperatures as low as -40 degrees Fahrenheit (also -40 degrees Celsius) and wind chill readings as low as the -50s and -60s Fahrenheit (-46 and -51 Celsius). Animation available at https://photojournal.jpl.nasa.gov/catalog/PIA22823