Dirty Thunderstorm, Volcanic Lightning Weather Phenomenon

"As the plume started going downwind, it seemed to have a life of its own and produced some 300 more or less normal (lightning bolts) ... The implication is that it has produced more charge than it started with. Otherwise (the plume) couldn't continue to make lightning." —Martin Uman, co-director of the University of Florida Lightning Research program
Volcanic eruptions also release large amounts of water, which may help fuel these thunderstorms.