April 10, 2009
When a volcano erupts, the volcanic plume full of gas and dust rises and then spreads into the shape of an umbrella. Scientists recently discovered that the plume then begins to rotate. This “volcanic mesocyclone” can spawn waterspouts, dust devils or even lightning.
Mount Redoubt in Alaska rumbled for weeks before it finally erupted on March 22 and 23. All that warning gave scientists plenty of time to set up a series of instruments called the Lightning Mapping Array and produce the image above. Scientists hope that by studying lightning from both volcanic eruptions and thunderstorms, they will gain insight into the electrical mechanisms at work in each phenomenon.
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