Frost flower (sea ice)

Frost flowers are ice crystals commonly found growing on young sea ice and thin lake ice in cold, calm conditions. The ice crystals are similar to hoar frost, and are commonly seen to grow in patches around 3–4 cm in diameter. Frost flowers growing on sea ice have extremely high salinities and concentrations of other sea water chemicals and, because of their high surface area, are efficient releasers of these chemicals into the atmosphere.
Formation
Frost flowers are formed on thin sea ice when the atmosphere is much colder than the underlying ice. Typically a temperature difference between the ice surface and the air of at least 15°C is required, though this can be reduced if the air is very humid. In these conditions a layer of supersaturated vapour is found directly above the sea ice, caused by the sublimation of ice into the dry, cold air. As the warmer, wet air meets the overlying cold air it becomes supersaturated and can condense as hoar-frost like...