Hexagonal Rime ~ Richard Osborn imaged this rime frost on the morning of 7th December in Nottingham, England. Overnight the temperature fell to an unusual -20 Celsius. ©Richard Osborn, shown with permission.

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Airborne fog and mist droplets do not necessarily freeze in subzero temperatures. In the absence of dust or other seed nuclei they stay liquid - supercooled. When they impact a cold surface they suddenly solidify to form the hard crystalline rime. The rimy hexagonal netting nicely emphasises the hexagonal structure of the tiny crystals it hosts.