| GAMMA-RAY AND X-RAY events above thunderstorms are the most
puzzling of all high-altitude electrical phenomena. Their existence was
uncovered only recently by one of the instruments on the Compton
Gamma Ray Observatory satellite (below), which showed gamma rays emanating
from the direction of the earth. Gamma rays are usually taken as signatures
of high-energy nuclear or cosmic sources and thus were not expected to
be produced within the earth's atmosphere. In sprites, for example, electrons
rarely reach energies above about 20 electron volts (the energy a single
electron would gain when accelerated by a potential difference of 20 volts),
whereas gamma rays require about one million electron volts. The discrepancy
is the same as the difference between the energy of a chemical explosive
and an atomic bomb. As is the case with blue
jets, gamma-ray events are just now beginning to yield to scientific
scrutiny. Future observations from satellites should help in this quest.
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