The June 24 eruption of Galunggung had a large ash
cloud with volcanic lightning.
Such spectacular displays occur when electrical discharges are generated
by friction between particles and gases in an expanding eruption
cloud. Volcanic lightning most often occurs during eruptions which have
large ash clouds. A variety of types of lightning bolts are produced by
such conditions including bolts of different widths traveling in different
directions, St. Elmo's Fire (ball
lightning), and small separate sparks. Volcanic lightning is primarily
hazardous to airplanes and to radio transmissions. The lightning bolts
are generally confined to the eruption cloud and crater
area and are not a major threat to people or animals on the ground. However,
volcanic lightning has been known to set forest fires in forested areas
near the volcano crater.