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IceIce 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, fragile, 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 (273.15K, 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. An unusual feature of ice frozen at a pressure of one atmosphere is that the solid is some 8% less dense than liquid water. Ice has a density of 0.917 g/cm³ at 0 °C, whereas water has a density of 0.9998 g/cm³ at the same temperature. Liquid water is most dense, essentially 1.00 g/cm³, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal crystals of ice as the temperature drops to 0 °C. (In fact, the word "crystal" derives from Greek word for frost.) This is due to hydrogen bonds forming between the water molecules, which line up molecules less efficiently (in terms of volume) when water is frozen. The result of this is that ice floats on liquid water, an important factor in Earth's climate. Density of ice increases slightly with decreasing temperature (density of ice at -180 °C (93 K) is 0.9340 g/cm³). When ice melts, it absorbs as much heat energy (the heat of fusion) as it would take to heat an equivalent mass of water by 80°C, while its temperature remains a constant 0°C. It is also possible to superheat ice beyond its equilibrium melting point. With the use of ultrafast laser pulses, bulk ice can be heated up to room temperature for a short period without melting it immediately. It is likely that the interior of an ice crystal has a melting point above 0 °C and that the normal melting at 0 °C is just a surface effect. As a naturally occurring crystalline solid, ice is considered a mineral. Everyday ice and snow is hexagonal ice (ice Ih). Subjected to higher pressures and varying temperatures, ice can form in roughly a dozen different phases. Only a little less stable (metastable) than Ih is cubic structure ice (Ic). But cooling Ih causes a different arrangement to form in which the protons move, XI. With both cooling and pressure more types exist, each being created depending on the phase diagram of ice. These are II, III, V, VI, VII, VIII, IX, and X. With care all these types can be recovered at ambient pressure. The types are differentiated by their crystalline structure, ordering and density. There are also two metastable phases of ice under pressure, both fully hydrogen disordered, these are IV and XII. Ice XII was discovered in 1996. As well as crystalline forms solid water can exist in amorphous states as amorphous solid water (ASW), low density amorphous ice (LDA), high density amorphous ice (HDA), very high density amorphous ice (VHDA) and hyperquenched glassy water (HGW). Check out the following recipes that are tagged "Ice":
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