Dark Lightning Zaps Unknowing Airline Passengers with Radiation During Flight

You may not have seen it, but you may have been exposed to it. Dark lightning, the flashes of gamma rays that occur at altitudes at which aircraft fly, can zap unknowing passengers with radiation during thunderstorms.

Yet how much radiation that passengers and pilots are exposed to has remained a mystery--until now. New research has pinpointed the amount of radiation that dark lightning produces and how much airline personnel may experience.

Researchers first discovered dark lightning about a decade ago. That's when they found that thunderstorms could generate brief but powerful bursts of gamma rays with the ability to blind sensors on satellites hundreds of miles away, according to Discovery News. Yet while they're bright to the satellites, they're barely noticeable to humans. It's unlikely that many people flying have even noticed the faintly purple flashes.

The new study used computer models in order to find out exactly how this dark lightning discharges. More specifically, the physics-based model was able to pinpoint the exposure dose that someone on a plane would likely receive during one of these dark lightning events.

So how much do passengers receive? At the top of thunderstorms at about 40,000 feet, radiation doses are comparable to about 10 X-rays, or the same dose that people receive from natural background sources of radiation over the course of an entire year. In the middle of the storms at about 16,000 feet, radiation doses could be about 10 times larger and comparable to some of the largest doses received during medical procedures--such as a full-body CT scan.

While these doses could be large, though, there's currently no data on exactly how often these storms actually occur. Because the bursts of dark lightning are so brief, they are usually undetected. This makes it more difficult to calculate exactly how often they occur. However, researchers estimate that dark lightning bursts occur anywhere between 1/100^th to 1/1000^th as often as normal lightning bursts.

The new findings could allow researchers to better understand how dark lightning can impact flight personnel that are more likely to be exposed to these types of storms. In addition, it could prompt airlines to develop planes that can better resist this type of radiation. Currently, researchers recommend that pilots do what they already do: avoid major thunderstorms while in flight.

The research was presented at a meeting of the European Geosciences Union in Vienna.