Ground frost
Encyclopedia
Ground frost refers to the various coverings of ice
produced by the direct deposition
of water vapor
on objects and trees, whose surfaces have a temperature below the freezing point
of water (0 °C, 32 °F).
and hard) is technically not a type of ground frost.
practice was to base the number of days of ground frost on this criterion: a day with a minimum temperature reaching 30 °F (−1 °C), probably because 32 °F (0 °C) was not considered enough cold to cause damage to growing plants. Since 1961 the statistics have referred to the number of days with grass minimum temperature below 0°C. Occasionally, the term ground frost can still be seen, but it means simply a minimum temperature below 0 °C.
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
produced by the direct deposition
Deposition
Deposition or Depose may refer to:* Deposition , taking testimony outside of court* Deposition , molecules settling out of a solution...
of water vapor
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...
on objects and trees, whose surfaces have a temperature below the freezing point
Freezing Point
Freezing Point is a news journal in the People's Republic of China which has been the subject of controversy over its criticism of Communist Party officials and the sympathetic ear it lent to a Chinese historian who had criticized official history textbooks...
of water (0 °C, 32 °F).
Types
The three main types of ground frost are radiation frost (hoar frost), advection frost (advection hoar frost) and evaporation frost. The latter is a rare type which occurs when surface moisture evaporates into drier air causing its temperature at the surface to fall at or under the freezing point of water. Rime (both softSoft rime
Soft rime is a white ice deposition that forms when the water droplets in light freezing fog or mist freeze to the outer surfaces of objects, with calm or light wind...
and hard) is technically not a type of ground frost.
Alternative definition
Ground frost may also refer to the condition when the temperature of the upper layer of the soil falls below the freezing point of water.In England
From 1906 to 1960 the Met OfficeMet Office
The Met Office , is the United Kingdom's national weather service, and a trading fund of the Department for Business, Innovation and Skills...
practice was to base the number of days of ground frost on this criterion: a day with a minimum temperature reaching 30 °F (−1 °C), probably because 32 °F (0 °C) was not considered enough cold to cause damage to growing plants. Since 1961 the statistics have referred to the number of days with grass minimum temperature below 0°C. Occasionally, the term ground frost can still be seen, but it means simply a minimum temperature below 0 °C.