A recent article in Nature reports that scientists in Japan have confirmed that nuclear reactions occur in lightning strikes. The researchers, led by astrophysicist Teruaki Enoto from Kyoto University, set up radiation detectors close to a thunderstorm on the east coast of Japan and discovered that lightning kicked off a gamma ray flash, then a gamma ray line, which indicates electron-positron annihalation.
From an report in Science Alert:
According to Enoto, the findings show us there’s more going on in thunderstorms than we may tend to imagine.
“Usually people think lightning can interact with electrons in atoms,” he told ScienceAlert.
“The photonuclear reactions indicate that lightning also interacts even with nuclei if gamma rays have sufficiently high energy to knock out neutrons from the nuclei.”
In addition to generating neutrons and positrons, the process observed is also important because it’s only the second time we’ve seen radioactive isotopes being naturally produced in the atmosphere – with the other example being particles produced by cosmic rays.