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Freezing air temperature. Freezing[ 1] or frost occurs when the air temperature falls below the freezing point of water (0 °C, 32 °F, 273 K ). This is usually measured at the height of 1.2 metres above the ground surface. There exist some scales defining several degrees of frost severity (from "slight" to "very severe") but they depend on ...
Most liquids freeze by crystallization, formation of crystalline solid from the uniform liquid. This is a first-order thermodynamic phase transition, which means that as long as solid and liquid coexist, the temperature of the whole system remains very nearly equal to the melting point due to the slow removal of heat when in contact with air, which is a poor heat conductor.
Freezing level. The 0 °C isotherm under normal conditions. The freezing level, or 0 °C (zero-degree) isotherm, represents the altitude in which the temperature is at 0 °C (the freezing point of water) in a free atmosphere (i.e. allowing reflection of the sun by snow, icing conditions, etc.). Any given measure is valid for only a short period ...
Freezing rain develops when falling snow encounters a layer of warm air aloft, typically around the 800 mbar (800 hPa; 80 kPa) level, causing the snow to melt and become rain. As the rain continues to fall, it passes through a layer of subfreezing air just above the surface and cools to a temperature below freezing (0 °C or 32 °F or 273 K).
Flash freezing. In physics and chemistry, flash freezing is the process whereby objects are rapidly frozen. [ 1] This is done by subjecting them to cryogenic temperatures, or it can be done through direct contact with liquid nitrogen at −196 °C (−320.8 °F). It is commonly used in the food industry .
Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar to the formation of dew, except it occurs below the freezing point of water typically without crossing ...
The frost line —also known as frost depth or freezing depth —is most commonly the depth to which the groundwater in soil is expected to freeze. The frost depth depends on the climatic conditions of an area, the heat transfer properties of the soil and adjacent materials, and on nearby heat sources. For example, snow cover and asphalt ...
The density of dry ice increases with decreasing temperature and ranges between about 1.55 and 1.7 g/cm 3 (97 and 106 lb/cu ft) below 195 K (−78 °C; −109 °F). [3] The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than water ice and leaves no residue as it changes state. [4]