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Jump to navigationJump to searchCreated page with 'File:lighterstill.jpgright|frame ==Origin== French, from French dialect (Franco-Provençal) ''lavantse'', ''avalantse'' *[http://en.wi...'
[[File:lighterstill.jpg]][[File:Avalanche_-_Version_3.jpg|right|frame]]
==Origin==
French, from French [[dialect]] (Franco-Provençal) ''lavantse'', ''avalantse''
*[http://en.wikipedia.org/wiki/18th_century 1771]
==Definitions==
*1: a large mass of [http://en.wikipedia.org/wiki/Snow snow], ice, [[earth]], rock, or other [[material]] in swift [[motion]] down a [[mountain]]side or over a precipice
*2: a sudden great or overwhelming rush or [[accumulation]] of something <hit by an avalanche of paperwork>
*3: a cumulative [[process]] in which photons or accelerated charge carriers produce additional photons or charge carriers through collisions (as with [[gas]] [[molecules]])
==Description==
An '''avalanche''' (also called a ''snowslide'' or ''snowslip'') is a rapid [[flow]] of [http://en.wikipedia.org/wiki/Snow snow] down a slope. Avalanches are typically triggered in a starting zone from a [[mechanical]] [[failure]] in the [http://en.wikipedia.org/wiki/Snowpack snowpack] (slab avalanche) when the forces on the snow exceed its [[strength]] but sometimes only with [[gradually]] widening (loose snow avalanche). After [[initiation]], avalanches usually [[accelerate]] rapidly and grow in mass and [[volume]] as they entrain more snow. If the avalanche moves fast enough some of the snow may mix with the [[air]] forming a powder snow avalanche, which is a type of [http://en.wikipedia.org/wiki/Gravity_current gravity current].
Slides of rocks or debris, behaving in a similar way to snow, are also referred to as avalanches (see [http://en.wikipedia.org/wiki/Rockslide rockslide]). The remainder of this article refers to snow avalanches.
The load on the snowpack may be only due to [[gravity]], in which case failure may result either from weakening in the snowpack or increased load due to [[precipitation]]. Avalanches that occur in this way are known as [[spontaneous]] avalanches. Avalanches can also be triggered by other loads such as skiers, snowmobilers, [[animals]] or [[explosives]]. Seismic activity may also trigger failure in the snowpack and avalanches.
Although primarily [[composed]] of flowing snow and air, large avalanches have the capability to entrain ice, rocks, trees, and other [[material]] on the slope, and are distinct from [http://en.wikipedia.org/wiki/Mudflow mudslides], [http://en.wikipedia.org/wiki/Landslide rock slides], and [http://en.wikipedia.org/wiki/Serac serac] collapses on an icefall. Avalanches are not rare or [[random]] events and are endemic to any [[mountain]] range that accumulates a standing snowpack. Avalanches are most common during [[winter]] or [[spring]] but [[glacier]] movements may cause ice and snow avalanches at any time of year. In mountainous terrain, avalanches are among the most serious objective [http://en.wikipedia.org/wiki/Natural_hazard natural hazards] to [[life]] and [[property]], with their destructive capability resulting from their potential to carry enormous [[mass]]es of snow at high [[speeds]].
There is no universally accepted [[classification]] of avalanches—different classifications are useful for [[different]] [[purposes]]. Avalanches can be described by their size, their destructive potential, their initiation mechanism, their [[composition]] and their [[dynamics]].[http://en.wikipedia.org/wiki/Avalanche]
[[Category: Earth Science]]
==Origin==
French, from French [[dialect]] (Franco-Provençal) ''lavantse'', ''avalantse''
*[http://en.wikipedia.org/wiki/18th_century 1771]
==Definitions==
*1: a large mass of [http://en.wikipedia.org/wiki/Snow snow], ice, [[earth]], rock, or other [[material]] in swift [[motion]] down a [[mountain]]side or over a precipice
*2: a sudden great or overwhelming rush or [[accumulation]] of something <hit by an avalanche of paperwork>
*3: a cumulative [[process]] in which photons or accelerated charge carriers produce additional photons or charge carriers through collisions (as with [[gas]] [[molecules]])
==Description==
An '''avalanche''' (also called a ''snowslide'' or ''snowslip'') is a rapid [[flow]] of [http://en.wikipedia.org/wiki/Snow snow] down a slope. Avalanches are typically triggered in a starting zone from a [[mechanical]] [[failure]] in the [http://en.wikipedia.org/wiki/Snowpack snowpack] (slab avalanche) when the forces on the snow exceed its [[strength]] but sometimes only with [[gradually]] widening (loose snow avalanche). After [[initiation]], avalanches usually [[accelerate]] rapidly and grow in mass and [[volume]] as they entrain more snow. If the avalanche moves fast enough some of the snow may mix with the [[air]] forming a powder snow avalanche, which is a type of [http://en.wikipedia.org/wiki/Gravity_current gravity current].
Slides of rocks or debris, behaving in a similar way to snow, are also referred to as avalanches (see [http://en.wikipedia.org/wiki/Rockslide rockslide]). The remainder of this article refers to snow avalanches.
The load on the snowpack may be only due to [[gravity]], in which case failure may result either from weakening in the snowpack or increased load due to [[precipitation]]. Avalanches that occur in this way are known as [[spontaneous]] avalanches. Avalanches can also be triggered by other loads such as skiers, snowmobilers, [[animals]] or [[explosives]]. Seismic activity may also trigger failure in the snowpack and avalanches.
Although primarily [[composed]] of flowing snow and air, large avalanches have the capability to entrain ice, rocks, trees, and other [[material]] on the slope, and are distinct from [http://en.wikipedia.org/wiki/Mudflow mudslides], [http://en.wikipedia.org/wiki/Landslide rock slides], and [http://en.wikipedia.org/wiki/Serac serac] collapses on an icefall. Avalanches are not rare or [[random]] events and are endemic to any [[mountain]] range that accumulates a standing snowpack. Avalanches are most common during [[winter]] or [[spring]] but [[glacier]] movements may cause ice and snow avalanches at any time of year. In mountainous terrain, avalanches are among the most serious objective [http://en.wikipedia.org/wiki/Natural_hazard natural hazards] to [[life]] and [[property]], with their destructive capability resulting from their potential to carry enormous [[mass]]es of snow at high [[speeds]].
There is no universally accepted [[classification]] of avalanches—different classifications are useful for [[different]] [[purposes]]. Avalanches can be described by their size, their destructive potential, their initiation mechanism, their [[composition]] and their [[dynamics]].[http://en.wikipedia.org/wiki/Avalanche]
[[Category: Earth Science]]
