Mysterious circular ice that rotates in a river

Snow Roller is a mysterious natural phenomenon in which donut shaped snow rolls like a lot of children have played even though there is no oneAlthough I mentioned earlier, this time is also a mysterious natural phenomenon.

This is because some icy ice is formed at the edge of the river when it is cold enough to snow, and because it is far away from the shore, it rotates around. Especially it seems that the name is not attached, but it is a rare phenomenon.

Details are as below.
First of all, it is easy to understand with animation.
VIDEO: Moscow Ice Disk a rarity of nature | The Burlington Free Press | Burlington, Vermont

It goes smoothly like this way. It is like a rotating floor of a merry-go-round and I doubt that it is a mechanical mechanism, but it is a natural phenomenon. This was taken in the suburbs of Moscow.

A clean circular shape.

This is Canada ·Newfoundland islandThings found in.

You can see that the river is formed outside the part where the river curves.

Also, if it is not snowing, only ice is seen so it seems that a clear figure is visible.

This phenomenon seems to be thought that the ice spreads on the river vortex when the flow of the river is slow, and eventually it was formed into a clean circular shape. There seems to be a thing with a diameter of 200 m in Sweden, but it seems difficult to see in the neighborhood because it is impossible unless some conditions are available.

Spinning ice disc phenomenon seen in British river for first time - Telegraph

The Telegram - St. John's, NL: Local News | A perfect circle

in Note,   Video, Posted by logc_nt