Confirmed: Lightning Causes Nuclear Reactions In The Sky

Lightning is nuts. It's a supercharged bolt of electricity extending from the sky to the ground that can kill people. But it can also produce nuclear reactions, according to new research.

Image: Dmitry Kalinin/Flickr

Scientists have long known that thunderstorms can produce high-energy radiation, such as this one from December 2015 that blasted a Japanese beach town with some gamma radiation. But now, another team of researchers in Japan are reporting conclusive evidence of these gamma rays setting off atom-altering reactions like those in a nuclear reactor.

Basically, we previously wrote that scientists "think that high-energy gamma rays interacted with nitrogen in the atmosphere, leading to the production of neutrons", emphasis added. With this new paper, published today in Nature, a team says that they now know this is happening.

Winter thunderstorms are common on the coast of the Sea of Japan, making it a ripe place to study them. These measurements come from a pair of lightning strikes on 6 February 2017, according to the new paper published in Nature, which left a whole lot of radiation in four detectors between 0.5 and 1.7km away. Following the flash came an afterglow of radiation for up to a minute. After analysing the data and the energies of the particles that came out, the researchers felt they'd conclusively observed the results of those gamma rays kicking neutrons off of nitrogen atoms.

This is cool for a lot of reasons. Most notably, you may remember that atoms like carbon and nitrogen get their identity from their number of protons, but they can have varying flavours based on their number of neutrons. This result could "provide a previously unknown channel for generating" rarer "isotopes of carbon, nitrogen and oxygen naturally on Earth," according to the paper.

At least one other researchers found the results convincing. The observations are a "conclusive indication of electron - positron annihilation", an expected byproduct of some of these radioactive decays, "and represents unequivocal evidence that photonuclear reactions can be triggered by thunderstorms," wrote Leonid Babich, a researcher at the Russian Federal Nuclear Center-All Russian Research Institute of Experimental Research, in a Nature commentary.

As you'd expect, there's more work to be done determining just how many of these isotopes lightning creates and what else lightning might create.

But it's pretty nuts that when a thunderstorm rolls by, it's as if the Earth is operating as a temporary nuclear reactor.