Dark lightning

Thunderstorms create bolts of lightning, as we all know.   Scientists have recently discovered that they also create bolts of energy that we cannot see:  pulses of radiation–X-rays and Gamma-rays–that are being called “dark lightning.”

From Ivan Amato:

A lightning bolt is one of nature’s most over-the-top phenomena, rarely failing to elicit at least a ping of awe no matter how many times a person has witnessed one. With his iconic kite-and-key experiments in the mid-18th century, Benjamin Franklin showed that lightning is an electrical phenomenon, and since then the general view has been that lightning bolts are big honking sparks no different in kind from the little ones generated by walking in socks across a carpeted room.

But scientists recently discovered something mind-bending about lightning: Sometimes its flashes are invisible, just sudden pulses of unexpectedly powerful radiation. It’s what Joseph Dwyer, a lightning researcher at the Florida Institute of Technology, has termed dark lightning.

Unknown to Franklin but now clear to a growing roster of lightning researchers and astronomers is that along with bright thunderbolts, thunderstorms unleash sprays of X-rays and even intense bursts of gamma rays, a form of radiation normally associated with such cosmic spectacles as collapsing stars. The radiation in these invisible blasts can carry a million times as much energy as the radiation in visible lightning, but that energy dissipates quickly in all directions rather than remaining in a stiletto-like lightning bolt.

Dark lightning appears sometimes to compete with normal lightning as a way for thunderstorms to vent the electrical energy that gets pent up inside their roiling interiors, Dwyer says. Unlike with regular lightning, though, people struck by dark lightning, most likely while flying in an airplane, would not get hurt. But according to Dwyer’s calculations, they might receive in an instant the maximum safe lifetime dose of ionizing radiation — the kind that wreaks the most havoc on the human body. . . .

[Scientists] began measuring radiation of the lightning that thunderstorms routinely emit and discovered something unexpected: the gamma rays and X-rays of dark lightning.

Nuclear explosions and collapsing stars — those are the sorts of extreme events that had been known to spew out gamma rays, not mere thunderstorms.

How is it that some storms produce these unusually strong rays? Dwyer speculates that super-fast electrons — perhaps revved up after being struck by cosmic rays that hit Earth’s atmosphere from deep space — may be the key. The theory is that these energetic electrons collide with atoms inside thunderclouds to create X-rays and gamma rays. These collisions lead to chain reactions that could be the mysterious basis for dark lightning.

via Thunderstorms contain ‘dark lightning,’ invisible pulses of powerful radiation – The Washington Post.