Dear Tom,
I have seen photographs of lightning bolts flashing through giant clouds of ash rising
above erupting volcanoes. Is this trick photography? A lot can be done with computers
these days to alter photographs.
Jack Larsen, Chicago
Dear Jack,
The number of lightning flashes that occur worldwide in any given year is
immense—literally hundreds of millions of them. The annual tally just in the United
States runs at more than 100 million. An overwhelming majority of those bolts are
“standard” lightning flashes associated with thunderstorms, but friction between sand
particles in sandstorms will occasionally generate electric charges sufficient to produce
lightning. Lightning also frequently flashes through ash clouds above erupting
volcanoes for the same reason. The photographs you saw were probably not doctored.
