Lightning is one of the most incredible natural phenomenons and there’s a lot we don’t know about it. Now, a study at Kyoto University, Japan has found that lightning strikes can set off photonuclear reactions in the atmosphere, and the gamma rays – emitted in lightning – react with the air to produce radioisotopes and even positrons (or, anti-electrons) – the antimatter partner of electrons.
“We already knew that thunderclouds and lightning emit gamma rays, and hypothesized that they would react in some way with the nuclei of environmental elements in the atmosphere,” explains Teruaki Enoto, the lead researchers of the study in a news release.
In 2015, Teruaki Enoto and his team started building a series of small gamma-ray detectors, and installed them across Japan’s western coastal – an ideal location for observing powerful lightning and thunderstorms. But shortly after a while, their research was jeopardized as their funding fell short. So, in order to continue their work as quickly as possible, they asked internet for help explaining the aims of their project.
After a successful crowdfunding campaign, the team then resumed their work. They were able to build more detectors and install them across the northwest coast of Honshu. And then in February, 2017, the team installed four more detectors in the city of Kashiwazaki, Niigata that picked up a large gamma-ray spike immediately after a lightning strike a few hundred meters away.
When they analyzed the data, the researchers found three distinct gamma-ray bursts. The first one lasted less than one millisecond in duration, the second was a gamma-ray afterglow that decayed after a few milliseconds; and the third one was a prolonged emission and it lasted about one minute.
“We could tell that the first burst was from the lightning strike. Through our analysis and calculations, we eventually determined the origins of the second and third emissions as well.” Enoto explains.
The second afterglow was set off due to reaction between lightning and nitrogen in the atmosphere. Lightning – especially the gamma rays – is powerful enough to knock a neutron out of atmospheric nitrogen. The gamma ray afterglow was produced as a result of the reabsorption of this neutron by particles in the atmosphere. The final, prolonged emission was due unstable nitrogen atoms which released positrons that subsequently collided with electrons in annihilation events releasing gamma rays.
“We have this idea that antimatter is something that only exists in science fiction. Who knew that it could be passing right above our heads on a stormy day?” says Enoto. “And we know all this thanks to our supporters who joined us through ‘academist’. We are truly grateful to all.”
There are over ten detectors on the coast of Japan that continually collect data. Now that they have been able to prove lightning can generate nuclear reactions in the atmosphere, Enoto and his team hope to expand their research and unravel the mysteries of lightning.
The study, entitled “Photonuclear Reactions Triggered By Lightning Discharge” has been published in the journal Nature.
[Source: Kyoto University | Image via Shutterstock]