Image credit: YouTube MLive
Recently, a Michigan man out for a drive noticed something truly spectacular on the Pine River — in the center of the river was a circle of ice that was being spun around by rushing water. Although it might look like the work of crop circle enthusiasts, it’s actually a well documented natural phenomenon. They’re found on fresh water in cold climates, often in North America and Europe, and can be as small as a few inches or as large as 55 feet wide.
What causes this phenomenon is something known as rotational shear.
Accelerating water causes a large chunk of ice to break off and start spinning. As the ice rotates, it glides against other pieces of ice, which can cause the ice to smooth out and become a circular shape.
Physicists published a study on these ice circles in the journal Physical Review E just last year. Their study found that the spinning was not only caused by currents in the water, but also the increasing temperatures in the water, which are causing the disks to melt. You can learn more about that right here.
In the mean time, check out a video of this cool effect below: