Rare ‘dark lightning’ might briefly touch passengers when flying


Gamma-ray blasts from thunderstorms are the most energetic natural discharges on Earth

CHICAGO — More than electricity can illuminate a thundercloud.

Brilliant bursts of gamma radiation, known as dark lightning or terrestrial gamma-ray flashes, also explode in lightning storms. And on rare occasions, those powerful blasts — the most energetic radiation to naturally arise on Earth — might even strike a passing airplane, researchers reported December 13 at the American Geophysical Union meeting. The zap could briefly expose passengers to unsafe levels of radiation.

First reported in 1994, dark lightning is estimated to flash around the world about a thousand times each day. But scientists have only a hazy understanding of how it initiates. They generally agree dark lightning is sparked by the electric fields generated by thunderstorms and lightning bolts. These fields can spur electrons to velocities approaching the speed of light, amassing breakneck electron avalanches. When the streaming particles smash into airborne atoms, gamma radiation is unleashed.