Freezing temperatures in the Chicago area are expected to last into next week, and the weather has created some interesting shapes on Lake Michigan.
Users on Twitter shared images of parts of the lake that had frozen into the shape of rings.
In one of the photos, Twitter user Sharan Banagriri captured images in the water off of Loyola Beach at Rogers Park. That part of the lake, which is about ten miles north of downtown Chicago, experienced temperatures in the low 20s that day. The area of Lake Michigan where the images were taken could be seen from a walkway that leads out to a lighthouse.
In other images shared on Twitter, user Ryan Alioto flew a drone above the lake during temperatures that dipped below 20 degrees to capture those images.
These rings are known as "ice pancakes," and are the result of already formed chucks of ice knocking into each other to form the elliptical-shaped disks, according to the National Snow and Ice Data Center
In February last year, Live Science reported on a mysterious phenomenon at the world's deepest lake, located in Russia's Siberia region. Lake Baikal's ice rings are considered very large and can be seen in images shared by NASA. The rings are seen during Siberia's winter and spring months.
Researchers believe that those rings are caused by warm swirling whirlpools of water under the lake's thick ice. Some of the ice rings on that lake have been up to 4 miles in diameter.