Eruption column

ash columnplumeash plumeeruption plumeplumesvolcanic plumesash cloudcloudcolumn collapseeruption cloud
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption.wikipedia
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Volcanic ash

ashash cloudash fall
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. Eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra.
These are typically produced by lava dome collapse or collapse of the eruption column.

Types of volcanic eruptions

volcanic eruptioneruptionvolcanic eruptions
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption.
They range in intensity from the relatively small lava fountains on Hawaii to catastrophic Ultra-Plinian eruption columns more than 30 km high, bigger than the eruption of Mount Vesuvius in 79 that buried Pompeii.

Stratosphere

stratospheric100K feetatmosphere
In the most explosive eruptions, the eruption column may rise over 40 km, penetrating the stratosphere. Eruption columns with heights of over 20-40 km break through the tropopause and inject particulates into the stratosphere.
However, exceptionally energetic convection processes, such as volcanic eruption columns and overshooting tops in severe supercell thunderstorms, may carry convection into the stratosphere on a very local and temporary basis.

Pyroclastic flow

pyroclastic flowspyroclasticash flow
A common occurrence in explosive eruptions is column collapse when the eruption column is or becomes too dense to be lifted high into the sky by air convection, and instead falls down the slopes of the volcano to form pyroclastic flows or surges (although the latter is less dense). If it does happen, then material reaching the bottom of the convective thrust region can no longer be adequately supported by convection and will fall under gravity, forming a pyroclastic flow or surge which can travel down the slopes of a volcano at speeds of over 100-200 kph.
Flows usually consist of two parts: the basal flow hugs the ground and contains larger, coarse boulders and rock fragments, while an extremely hot ash plume lofts above it because of the turbulence between the flow and the overlying air, admixing and heating cold atmospheric air causing expansion and convection.

Cumulonimbus flammagenitus

pyrocumulonimbuspyrocumulonimbus cloudCumulonimbus flammagenitus (cloud)
On some occasions, if the material isn't dense enough to fall, it may create pyrocumulonimbus clouds.
The aerosol of smoke comprising CbFg clouds can persist for weeks, and with that, reduce ground level sunlight in the same manner as the “nuclear winter" effect. A cumulonimbus flammagenitus may often form from the eruption column of a volcano.

Plume (fluid dynamics)

plumeplumesPlume (hydrodynamics)
The volcanic materials form a vertical column or plume that may rise many kilometers into the air above the vent of the volcano.

Mount Pinatubo

Mt. PinatuboPinatubo1991 eruption of Mount Pinatubo
Substantial amounts of stratospheric injection can have global effects: after Mount Pinatubo erupted in 1991, global temperatures dropped by about 0.5 C-change.
A few hours later the same day, massive blasts lasting about half an hour generated big eruption columns, which quickly reached heights of over 19 km and which generated large pyroclastic surges extending up to 4 km from the summit in some river valleys.

Volcano

volcanicvolcanoesvolcanic igneous activity
If it does happen, then material reaching the bottom of the convective thrust region can no longer be adequately supported by convection and will fall under gravity, forming a pyroclastic flow or surge which can travel down the slopes of a volcano at speeds of over 100-200 kph.
Most of the hydrogen chloride (HCl) and hydrogen fluoride (HF) are dissolved in water droplets in the eruption cloud and quickly fall to the ground as acid rain.

Mount Redoubt

Redoubt VolcanoMt. RedoubtMount Redoubt (Alaska)
Similar damage to aircraft occurred due to an eruption column over Redoubt volcano in Alaska in 1989.
Similarly, in 2003, a blowing cloud of snow was mistaken by an employee of the ConocoPhillips Building in Anchorage for an ash plume.

Tephra

pyroclastpyroclasticpyroclastic material
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. Eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra.

Volcanic gas

gasgasesgaseous content
An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption.

Particulates

particulate matterparticulatefine particulate matter
Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change. Eruption columns with heights of over 20-40 km break through the tropopause and inject particulates into the stratosphere.

Global warming

climate changeglobal climate changeanthropogenic climate change
Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change.

Pyroclastic surge

base surgesurgecold surges
A common occurrence in explosive eruptions is column collapse when the eruption column is or becomes too dense to be lifted high into the sky by air convection, and instead falls down the slopes of the volcano to form pyroclastic flows or surges (although the latter is less dense). If it does happen, then material reaching the bottom of the convective thrust region can no longer be adequately supported by convection and will fall under gravity, forming a pyroclastic flow or surge which can travel down the slopes of a volcano at speeds of over 100-200 kph.

Volatiles

volatileicesice
Eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra.

Magma

magmaticmeltmagmas
Eruption columns form in explosive volcanic activity, when the high concentration of volatile materials in the rising magma causes it to be disrupted into fine volcanic ash and coarser tephra.

Convection

convectiveconvection currentsconvection current
The ash and tephra are ejected at speeds of several hundred metres per second, and can rise rapidly to heights of several kilometres, lifted by enormous convection currents.

Gas

gasesgaseousgaseous state
Intrinsic factors include the diameter of the erupting vent, the gas content of the magma, and the velocity at which it is ejected.

Velocity

velocitiesvelocity vectorlinear velocity
Intrinsic factors include the diameter of the erupting vent, the gas content of the magma, and the velocity at which it is ejected.

Troposphere

troposphericdivergencemid-tropospheric
The atmospheric temperature in the troposphere normally decreases by about 6-7 K/km, but small changes in this gradient can have a large effect on the final column height.

Kelvin

KkelvinsKelvin scale
The atmospheric temperature in the troposphere normally decreases by about 6-7 K/km, but small changes in this gradient can have a large effect on the final column height.

Tropopause

at altitudestratospheric stabilitytop of the atmosphere
Eruption columns with heights of over 20-40 km break through the tropopause and inject particulates into the stratosphere.

Precipitation

rainfallhydrometeorannual precipitation
Ashes and aerosols in the troposphere are quickly removed by precipitation, but material injected into the stratosphere is much more slowly dispersed, in the absence of weather systems.

Weather

weather conditionsweather systemselements
Ashes and aerosols in the troposphere are quickly removed by precipitation, but material injected into the stratosphere is much more slowly dispersed, in the absence of weather systems.

Extinction event

mass extinctionmass extinctionsextinction events
The largest eruptions are thought to cause temperature drops down to several degrees, and are potentially the cause of some of the known mass extinctions.