Volcanoes produce 'dirty' thunderstorms
Mount Augustine's 2006 eruptions produced lightning
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Friday, 23, Feb 2007 11:48
Some of the first direct observations of lightning produced by volcanic eruptions have been made by scientists.
Researchers have been aware of volcanic lightning for the past few decades but it is poorly understood because of few scientific observations of the phenomena.
Scientists at the University of Alaska and Langmuir Laboratories set up mapping stations to capture the eruptions of Mount Augustine in January 2006.
Writing in the Science journal today, they claim that the data showed the first and largest of these eruptions produced a "spectacular lightning sequence".
"The main explosion, and a smaller explosion [about] three minutes earlier, were accompanied by continuous backgrounds of strong, impulsive radiation and by several embedded lightning-like bursts," the authors write.
"The bursts were detected by both measurement stations and originated from the direction of Augustine's summit."
According to the scientists, the electrical activity from Augustine came in two phases. In the first there were numerous apparently disorganised charges resulting in some "simple lightning".
During the second "conventional lightning discharges occurred within the plume cloud produced by the explosion".
The authors conclude that as these explosions also produce large amounts of water and ash they behave as "dirty thunderstorms".