An ice circle (Image found on Google)
An ice disc, ice circle, or ice pan is a natural phenomenon that occurs in slow moving water in cold climates. Ice circles are thin and circular slabs of ice that rotate slowly in the water. It is believed that they form in eddy currents. Ice discs have most frequently been observed in Scandinavia and North America, but they are occasionally recorded as far south as England and even Wales. They vary in size, but circles with more than 15 metres in diameter have been observed.
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 spotted on the Mianus River (Stamford, USA) and reported in an 1895 edition of Scientific American.
River specialists state that ice pans are "surface slabs of ice that form in the center of a lake or creek, instead of along the water’s edge. As water cools, it releases heat that turns into 'frazil ice' that can cluster together into a pan-shaped formation. If an ice pan accumulates enough frazil ice and the current remains slow, the pan may transform into a 'hanging dam', a heavy block of ice with high ridges low centre.
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 spotted on the Mianus River (Stamford, USA) and reported in an 1895 edition of Scientific American.
River specialists state that ice pans are "surface slabs of ice that form in the center of a lake or creek, instead of along the water’s edge. As water cools, it releases heat that turns into 'frazil ice' that can cluster together into a pan-shaped formation. If an ice pan accumulates enough frazil ice and the current remains slow, the pan may transform into a 'hanging dam', a heavy block of ice with high ridges low centre.
~Ally
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