Dark Lightning Radiation That Of A CT Scan For Those Aboard Planes: A Study

Dark lightning isn't always the first thing a person's thinks of when the plane he or she is on heads through a storm. 

The little-understood phenomenon, which amounts to sudden flashes of gamma-rays, was first discovered in 1994 by a NASA spacecraft. Not until 2010 did Joseph Dwyer, a physics professor at the Florida Institute of Technology, realize that it took place at altitudes where airplanes fly.

Since then, scientists have been eager to determine the reach and impact of these blasts of radiation.

The answer, at least for the latter question, may be solved.

"The good news is that the doses are not super scary - it could be worse," Dwyer said at a meeting of the European Geosciences Union in Vienna, according to Discovery News. "It's similar to going to the doctor's office and getting a CT scan."

What remains unknown, however, is how common flashes of dark lightning are. Because they last only last 10 to 100 microseconds, they often go undetected.

"Unless you have gamma-ray detectors on board, no one would think anything of it," co-researcher David Smith explained.

The current belief, he said, is that these flashes take place between 1/100 to 1/1000 as often as regular lightening.

Dwyer theorizes that dark lightning is caused when super-fast electrons collide with atoms inside thunderclouds and create not just gamma-rays, but X-rays as well, that then evoke a powerful chain reaction.

J. Eric Grove of the Naval Research Laboratory in Washington told the Washington Post that while Dwyer's model closely matches the best recent satellite measurements, there is an Italian satellite that shows some thunderstorms may be producing gamma-ray flashes stronger than what his colleague's theory can account for.

Regardless, said Smith, "It's kind of cool that it's been 250 years since Benjamin Franklin's kite experiment, and we've realized there's a different kind of lightning going on that we never knew about."