This image illustrates two different ways that rotation can happen in a volcanic plume.
Click on image for full size
Image Courtesy of the Zina Deretsky/NSF, after Chakraborty et al., Volcanic mesocyclones, Nature, 3/26/09
Tornado-like Rotation is Key to Understanding Volcanic Plumes
News story originally written on March 23, 2009
Scientists have observed that in some volcanic eruptions, a rotating, column of dust and gas forms and causes the volcanic plume to rotate on its axis. This rotation causes the formation of lightning and creates waterspouts or dust devils.
This phenomena has not been seen very much. It was photographed during the 2008 eruption of Mount Chaiten in southern Chile. In addition, scientists have found a paper written by a sea captain in 1811. In the paper, the captain reported that he saw a volcanic vent coming out of the sea that had a plume coming out of it. The plume rotated on the water like a wheel and there were continuous flashes of lightning and a lot of waterspouts.
The scientists that worked on this project think that the rotation of these volcanic plumes is the primary cause of tornadoes, waterspouts, and lightning that have been seen in the plumes. They also think this process is similar to how a strong thunderstorm creates a tornado. The plume contains a column of hot gases and dust topped with an "umbrella."
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