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. 
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.
- Simons, Paul (May 8, 2008). "Dirty thunderstorm shoots lightning from volcano". London: Times Online. Retrieved 2009-01-09.
- "Chile Volcano Erupts with Ash and Lightning". National Geographic. May 6, 2008. Retrieved 2009-01-09.
- Handwerk, Brian (February 22, 2007). "Volcanic Lightning Sparked by "Dirty Thunderstorms"". National Geographic. Retrieved 2009-01-09.
- "Iceland Volcano Pictures: Lightning Adds Flash to Ash". National Geographic. April 19, 2010. Retrieved 2010-04-20.
- editor, Ian Sample Science. "Sky lights up over Sicily as Mount Etna's Voragine crater erupts". the Guardian. Retrieved 2015-12-03.
- 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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