From the Hope This Doesn’t Happen Soon at Aso Desk: Volcanic lightning is the production of lightning in a volcanic plume. Electrical charges are generated when rock fragments and ash in a volcanic plume collide and produce static charges. Unlike regular thunderstorms, though, this type of lightning doesn’t descend from storm clouds to the ground; instead, it remains within the plume (first photo) or sometimes follows the plume up from the crater (second - kinda like upside-down lightning). Little is known about this phenomenon as, obviously, up-close study is a tad difficult. Both of these photos are from the recent Shinmoedake eruption (130km south of Kumamoto on the Kagoshima/Miyazaki border). - William