odditiesoflife:

Rare Ice Disks

Although extremely rare, ice disks, also known as ice circles, do indeed appear naturally from time to time when conditions are perfect. Above are a few examples of people who have been lucky enough to stumble onto one while holding a camera.

Ice discs form on the outer bends in a river where the accelerating water creates a force called ‘rotational shear’, which breaks off a chunk of ice and twists it around. As the disc rotates, it grinds against surrounding ice — smoothing into a circle. A relatively uncommon phenomenon, one of the earliest recordings is of a slowly revolving disc was spotted on the Mianus River and reported in a 1895 edition of Scientific American.

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