"Triggering lightning at will, at a predetermined place and time, is the old
Promethean dream which seems more related to legend than to science," lightning
expert Pierre Hubert has written. Yet the technique has taught scientists much
about lightning processes and effects. Here, a rocket trailing a thin, grounded
copper wire was launched into a thundercloud, triggering a series of lightning
bolts that followed the path of the wire, which was vaporized in the process
(see smoke-like vapor). Wind has separated the individual bolts.