The Midwest and Northeast United States have been blanketed by snow and ice in the past week, thanks to a surge of cold air sweeping down from the Arctic.
And here's what the aftermath looked like from above, courtesy of NASA's Earth Observatory. The stunning pic below was captured on January 13 by the agency's Terra satellite, which passes north-to-south across the equator every morning:
And here's a January 10 pic from NASA's Aqua satellite, which passes south-to-north over the equator in the afternoon (taken together, the two can take images of the entire Earth's surface every 1 to 2 days):
Note that the Great Lakes don't freeze over entirely in the winter — unlike ponds — mainly because they're so deep. As of January 14, about 32 percent of the Great Lakes were covered in ice. Lake Eerie, in particular, has a lot of ice after a deep freeze. (Out in Lake Michigan, meanwhile, snow has been falling on top of the ice, acting as a heat insulator and making it slushier — so authorities have been warning people not to go out.)
In a typical winter, up to 30 to 40 percent of the Great Lakes can freeze over by March, with the ice shifting around from place to place with the wind. And occasionally you get really big extremes: In March 2014, thanks to unusually cold weather, a whopping 92.2 percent of the lakes were covered in ice, the second-most on record.