A thin circle of ice was seen spinning on the Middle Fork Snoqualmie River recently.
Photographer Kaylyn Messer captured a beautiful video of the natural occurrence. See the video below and find more images and video from Kaylyn Messer Photography here.
Ice circles are pretty simple, actually.
In a river or stream, there are currents and eddies. In an eddy, water flows in a circular motion because of obstructions, whether they be boulders or just the shape of the stream itself.
If the eddy is persistent, the water in the center of the eddy is more or less “trapped” and is susceptible to freezing.
The freezing will start at the center of the eddy and work out to the edges where, eventually, the water is flowing too fast to freeze. Or, in other cases, it will happen when a sheet of ice breaks off.
This creates a disc of ice that can spin due to the motion of the surrounding rushing water!