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Snow and
Ice
Ice
can refer to any one of the 14 known solid phases of water. However, in
non-scientific contexts, it usually describes ice Ih, which is the most
abundant of these phases in Earth's biosphere. This type of ice is a soft,
delicate, crystalline solid, which can appear transparent or an opaque
bluish-white color depending on the presence of impurities such as air.
The addition of other materials such as soil may further alter appearance.
The most common phase transition to ice Ih occurs when liquid water is
cooled below 0 °C (273.15 K, 32 °F) at standard atmospheric pressure.
However, it can also sublime from a vapor with no intervening liquid phase
such as in the formation of frost. Ice appears in varied forms such as
hail, ice cubes, and glaciers. It plays an important role with many meteorological
phenomena. The ice caps of the polar regions are of significance for the
global climate and particularly the water cycle.
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