Just goes to show, Estonians are show-offs. Even their rivers make perfect circles of ice (article in Latvian, but it’s the visual that’s important).
Video here, I can’t seem to embed it, except like this: .
Early theories of why the disks formed centered on erosion. Ice disks observed in 1987 and 1994 were in the path of flowing river waters. A paper published in 1997 by the Royal Meteorological Society theorized that flowing river water created a whirlpool effect. As the ice spun, researchers theorized, the borders eroded into a circular shape.A study of ice disks performed in March of last year modeled how this wasn’t quite the case.
Published in the journal Physical Review E, researchers from the University of Liege in Belgium found that temperature changes—and not flowing rivers—prompted the spinning. As water warms it becomes less dense, and as it’s cooled by surface ice, a vortex forms.
I was stuck between two songs, but this seems the most obvious choice: