Dirty thunderstorm

Volcanic lightning above an eruption of Mount Rinjani.

A dirty thunderstorm (also volcanic lightning) is a weather phenomenon that is related to the production of lightning in a volcanic plume.[1]

A famous image of the phenomenon was photographed by Carlos Gutierrez and occurred in Chile above the Chaiten Volcano.[2] It circulated widely on the internet.

Other instances have been reported above Alaska's Mount Augustine volcano,[3] Iceland's Eyjafjallajökull volcano[4] and Mount Etna in Sicily, Italy.[5]

Causes

A study in the journal Science indicated that electrical charges are generated when rock fragments, ash, and ice particles in a volcanic plume collide and produce static charges, just as ice particles collide in regular thunderstorms.[6]

Volcanic eruptions are sometimes accompanied by flashes of lightning. However, this lightning doesn’t descend from storm clouds in the sky. It is generated within the ash cloud spewing from the volcano, in a process called charge separation.

As the plume started going downwind, it seemed to have a life of its own and produced some 300 more or less normal [lightning bolts] ... The implication is that it has produced more charge than it started with. Otherwise [the plume] couldn't continue to make lightning.

—Martin A. Uman, co-director of the University of Florida Lightning Research program

Volcanic eruptions also release large amounts of water, which may help fuel these thunderstorms.

References

  1. ↑ Simons, Paul (May 8, 2008). "Dirty thunderstorm shoots lightning from volcano". London: Times Online. Retrieved 2009-01-09.
  2. ↑ "Chile Volcano Erupts with Ash and Lightning". National Geographic. May 6, 2008. Retrieved 2009-01-09.
  3. ↑ Handwerk, Brian (February 22, 2007). "Volcanic Lightning Sparked by "Dirty Thunderstorms"". National Geographic. Retrieved 2009-01-09.
  4. ↑ "Iceland Volcano Pictures: Lightning Adds Flash to Ash". National Geographic. April 19, 2010. Retrieved 2010-04-20.
  5. ↑ editor, Ian Sample Science. "Sky lights up over Sicily as Mount Etna's Voragine crater erupts". the Guardian. Retrieved 2015-12-03.
  6. ↑ Perkins, Sid (March 4, 2015). "Flash glass: Lightning inside volcanic ash plumes create glassy spherules". American Association for the Advancement of Science.
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