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MELBOURNE, Fla. — Scientists have a possible explanation for a phenomenon that sounds like something from a science fiction novel: dark lightning.
Scientists at the Florida Institute of Technology developed a physics-based model of the thunderstorms that produce this invisible and silent gamma ray. Nicknamed "dark lightning," terrestrial gamma-ray flashes emit radiation low enough in the atmosphere that a commercial airliner could fly through it.
Using their model, lightning researcher Joseph Dwyer and his team at Florida Tech found an electrical breakdown caused by the interaction of high-energy electrons and positrons during especially hot lightning storms creates "explosive growth" in the number of the energy particles, and causes the flash of gamma-rays in the form of a bolt.
Previously associated only with collapsing stars, the discovery — and now increased understanding — of gamma rays in our own atmosphere leads to questions about the safety of flying during such storms, and how to prevent it.
"Although airline pilots already do their best to avoid thunderstorms, occasionally aircraft do end up inside electrified storms," Dwyer said. "On rare occasions, according to the model calculation, it may be possible that hundreds of people, without knowing it, may be simultaneously receiving a sizable dose of radiation from dark lightning."
Near the top of the storm, Dwyer found, a dark lightning bolt emits the equivalent of 10 chest x-rays. Near the middle of the storm — about the atmospheric level a plane would fly through — a bolt can deliver radiation equal to a full-body CT scan.
Though it's unknown if a person has ever received a heavy dose of radiation due to flying through dark lightning, the rate of dark lightning's occurrence limits the chance. One dark lightning bolt occurs for about every 1,000 visible lightning flash.
