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In meteorology
Meteorology

Meteorology is the interdisciplinary scientific study of the Earth's atmosphere that focuses on weather processes and forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century....
, virga is an observable streak or shaft of precipitation
Precipitation (meteorology)

File:MeanMonthlyP.gifIn meteorology, precipitation is any product of the condensation of Atmosphere water vapor that is deposited on the earth's surface....
 that falls from a cloud
Cloud

A cloud is a visible mass of Drop or frozen crystals floating in the Celestial body atmosphere above the surface of the Earth or another planetary body....
 but evaporates before reaching the ground. At high altitudes the precipitation falls mainly as ice
Ice

Ice is a solid phases of matter, usually crystalline solid, of a non-metallic substance that is liquid or gas at room temperature, such as ammonia ice or methane ice....
 crystal
Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions....
s before melting and finally evaporating; this is usually due to compressional heating, because the air pressure
Atmospheric pressure

Atmospheric pressure is sometimes defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere....
 increases closer to the ground.






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Nimbostratus Virga
In meteorology
Meteorology

Meteorology is the interdisciplinary scientific study of the Earth's atmosphere that focuses on weather processes and forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century....
, virga is an observable streak or shaft of precipitation
Precipitation (meteorology)

File:MeanMonthlyP.gifIn meteorology, precipitation is any product of the condensation of Atmosphere water vapor that is deposited on the earth's surface....
 that falls from a cloud
Cloud

A cloud is a visible mass of Drop or frozen crystals floating in the Celestial body atmosphere above the surface of the Earth or another planetary body....
 but evaporates before reaching the ground. At high altitudes the precipitation falls mainly as ice
Ice

Ice is a solid phases of matter, usually crystalline solid, of a non-metallic substance that is liquid or gas at room temperature, such as ammonia ice or methane ice....
 crystal
Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions....
s before melting and finally evaporating; this is usually due to compressional heating, because the air pressure
Atmospheric pressure

Atmospheric pressure is sometimes defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere....
 increases closer to the ground. It is very common in the desert
Désert

?D?sert? is ?milie Simon's debut single, released in October 2002. The song was a huge success both critically and commercially in her homeland....
 and in temperate climates. It is also common in the Southern United States
Southern United States

The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive region in the southeastern and south-central United States....
 during summer.

Virga can cause very interesting weather effects, because as rain is changed from liquid to vapor form, it removes heat from the air due to the high heat of vaporization of water. In some instances, these pockets of colder air can descend rapidly, creating a dry microburst
Microburst

A microburst is a very localized column of sinking air, producing damaging divergent and straight-line winds at the surface that are similar to but distinguishable from tornadoes which generally have convergent damage....
 which can be extremely hazardous to aviation
Aviation

File:Norwegian military Bell 412SP helicopters.jpgAviation refers to activities involving man-made flying devices , including the people, organizations, and regulatory bodies involved with them....
. Conversely, precipitation evaporating at high altitude can compressionally heat as it falls, and result in a gusty downburst
Downburst

A downburst is created by an area of significantly rain-cooled air that, after hitting ground level, spreads out in all directions producing strong winds....
 which may substantially and rapidly warm the surface temperature. This fairly rare phenomenon, a heat burst
Heat burst

A heat burst is a rare atmospheric phenomenon characterised by gusty winds and a rapid increase in temperature and decrease in dew point . Heat bursts typically occur during night-time and are associated with decaying thunderstorms....
, also tends to be of exceedingly dry air.

Virga also has a role in seeding storm cells whereby small particles from one cloud are blown into neighboring supersaturated air and act as nucleation particles for the next thunderhead
Cumulonimbus cloud

Cumulonimbus is a type of cloud that is tall, dense, and involved in thunderstorms and other intense weather. It is a result of atmospheric instability....
 cloud to begin forming.

Virga can produce dramatic and beautiful scenes, especially during a red sunset
Sunset

File:Sunset 2007-1.jpgSunset is the daily disappearance of the sun below the horizon as a result of the Earth's rotation. The atmospheric conditions created by the setting of the sun are also commonly referred to as "a sunset"....
. The red light can be caught by the streamers of falling precipitation, and winds may push the bottom ends of the virga so it falls at an angle, making the clouds appear to have comma
Comma

A comma is a type of punctuation mark .Comma may also refer to:* Comma , a type of interval in music theory* Comma , a species of butterfly...
s attached.

The word virga is derived from Latin meaning twig or branch and a popular backronym
Backronym

A backronym is a reverse Acronym and initialism, a phrase constructed after the fact to make an existing word or words into an acronym.Backronyms may be invented with serious or humorous intent, or may be a type of false or folk etymology....
 in meteorology is "Variable Intensity Rain Gradient Aloft."

Extraterrestrial versions

Sulfuric acid
Sulfuric acid

Sulfuric acid, hydrogen2sulfuroxygen4, is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry....
 rain in the atmosphere of Venus
Atmosphere of Venus

The atmosphere of Venus was discovered in 1761 by Russian polymath Mikhail Lomonosov. It is much denser and hotter than that of Earth. The temperature and pressure at the surface are 740 K and 93 bar, respectively....
 evaporates before reaching the ground due to the immense heat near the surface. Similarly, virga happens on gas giant planets such as Jupiter
Jupiter

Jupiter is the fifth planet from the Sun and the Solar system by size planet within the Solar System. It is two and a half times as massive as all of the other planets in our Solar System combined....
. In September 2008 NASA's Phoenix lander discovered a snow variety of virga falling from Martian clouds.

See also

  • Fall streaks
    Fall streaks

    Sorry, no overview for this topic
  • Aviation safety


External links

  • Alistair B. Fraser and Craig F. Bohren, Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania, 2 November 1992 and 25 January 1993.