On the Thompson River in the southern part of British Columbia, Canada, a rare ice disk with a diameter of about 40 m has formed. This short-lived natural phenomenon will last on the water until the next warming.
The disc was first seen near Kamloops town on Sunday, January 19, and immediately attracted attention. Scientists at the University of Laval in Quebec attributed this unusual phenomenon to the effect of moving warm water under the ice on the surface of the river.
The ice circle cannot be called unique: similar formations of the correct shape were previously observed on the Canadian Gaspe Peninsula and in Maine, USA.
Experts attribute this interesting phenomenon to the properties of water. Warm water is less dense than cold water. When the temperature of the water rises, its molecules begin to move upward. If there is a not very dense block of ice on the surface, particles of warm water begin to move around it with the current, creating a vortex that looks like water in a drain hole.
The water vortex pushes the ice cover in a circle, the ice is sharpened precisely along the edge of the vortex. This is because the flow is stronger at the edges and the water is warmer. The result is a fairly dense ice disk that spins in a circle.
Ice circles are relatively rare because the conditions must be ideal: open water, smooth flow of variable temperature and the presence of thin ice.