The Windy City is the scene of a natural phenomenon that occurs in a circular way and is currently taking over Lake Michigan. So-called ‘snowcakes’ or circular slabs of ice have begun to appear along the shore of Chicago’s iconic lake. There are plenty of photos and videos of the lake on social media showing hundreds of rounded ice shapes that resemble flat disks on the water.
But what are these ice discs? How are they formed?
They are mainly due to the cold . They only appear when temperatures drop below freezing for several days. Ranging in diameter from 30 centimeters to 3 meters , the ice formations begin as a thin layer of ice on the surface of the water before accumulating into circular disks. If the body of water has a choppy current, loose, disk-shaped ice crystals will form, according to the National Snow and Ice Data Center. The ice normally has “raised edges or ridges on the perimeter”; is what happens when ice discs collide with each other. Thus, once these bodies of water are cold enough, the pieces of ice that have begun to form will collide with each other, forming elliptical-shaped disks with rounded edges.
The US National Snow and Ice Data Center . he recalls that “a distinctive feature of ice for ice pancakes is the raised edges or ridges on the perimeter, caused by the discs crashing into each other with ocean waves.”
In sum, these ice formations are caused by a number of factors, including freezing temperatures, high wave action, and certain wind conditions. Although most often seen around Antarctica, the phenomenon can occasionally delight those who live near the Great Lakes in the US and Canada.
