What a disaster!! Lightning crackles around a miles-high ash plume above Chile's Puyehue volcano (map) on Saturday. A volcanic lightning storm isn't "unlike a regular old thunderstorm," Martin Uman, a lightning expert at the University of Florida in Gainesville, told National Geographic News in 2010. This is some picture that I took from National GeoraphicPictures: Chile Volcano Plume Explodes With Lightning.

Eruption Sparks Lightning Show
Chilean Volcano Bursts Back to Life After Decades of Dormancy

Pictures: Chile Volcano Plume Explodes With Lightning

The same ingredients are present: water droplets, ice, and possibly hail—all interacting with each other and with particles, in this case ash from the eruptions, to cause electrical charging, Uman said. (See pictures of a volcanic lightning storm in Iceland.)
taken from: http://news.nationalgeographic.com