How Does Volcanic Lightning Occur?
Researchers hypothesize that volcanic lightning is the result of charge-separation. As positively charged ejecta makes its way skyward, regions of opposite but separated electrical charges take shape. A lightning bolt is nature’s way of balancing the charge distribution. The same thing is thought to happen in regular-old thunderstorms. But this much is obvious, right? So what makes volcanic lightning different?
One of the most significant studies done to make meaningful observations of volcanic eruptions was published in 2007, after researchers used radio waves to detect a previously unknown type of lightning zapping from the crater of Alaska’s Mount Augustine volcano in 2006.
"During the eruption, there were lots of small lightning (bolts) or big sparks that probably came from the mouth of the crater and entered the (ash) column coming out of the volcano," said study co-author Ronald J. Thomas in a 2007 interview with National Geographic. "We saw a lot of electrical activity during the eruption and even some small flashes going from the top of the volcano up into the cloud. That hasn’t been noticed before."
The observations suggest that the eruption produced a large amount of electric charge, corroborating the 1963 hypothesis – but the newly identified lightning posed an interesting puzzle: where, exactly, do these charges come from? “We’re not sure if it comes out of the volcano or if it is created just afterwards,” Thomas explains. “One of the things we have to find out is what’s generating this charge.”
Source; Image: Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul April 17, 2010. Credit:LUCAS JACKSON (Reuters)