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Thursday, July 24, 2008

Photo: Volcanic Lightning Sparked by "Dirty Thunderstorms," Study Finds


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A view of the north side of the Mount Augustine volcano in Alaska shows the tall plume of ash generated by an eruption on January 12, 2006.

Using radio waves to study the ash cloud, researchers have made some of the first direct observations of volcanic lightning. Their study reveals two distinct types of this poorly understood phenomenon and suggests it occurs due to "dirty thunderstorm" activity in the plume.

Photograph courtesy Game McGimsey and the U.S. Geological Survey/ Science