The fusion of flash with ash! Say the words aloud, together, and it sounds impossible – the kind of thing a six-year-old might think up. And yet, volcanic lightning is very real. But how does it happen?
Few phenomena can compete with the raw beauty and devastating power of a raging thunderstorm, save for a particularly violent volcanic eruption. But when these two forces of nature collide, the resulting spectacle can be so sublime as to defy reason.
German photographer Martin Rietze, has been one of the lucky few to capture volcanic lightning on camera. Late last February, when on a visit to Japan's Sakurajima Volcano, he was able to photograph the lightning as the Volcano erupted leading into a better understanding of the formation. He explains how only very big eruptions can generate major thunderbolts like the ones seen in his pictures.
Smaller eruptions tend to be accompanied by more diminutive storms, which can be difficult to spot through thick clouds of ash. What's more, lightning activity is highest during the beginning stages of an eruption, making it all the more challenging to capture on film. Photographing a big volcanic event at any stage is hard enough as it is; if you're not nearby when it happens, says Rietze, "you will always arrive too late."
Volcanic lightning, the researchers hypothesize, 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.