- Alison Snyder
- Nov 22
Lightning can start nuclear reactions in the sky
Lightning. Photo: 4FR / iStock
Lightning can create fusion reactions in the air around it, according to research published today in the journal Nature. Nuclear reactions were thought to occur in some thunderstorms but the study provides the first conclusive evidence they are happening.
The question: It seems theoretically impossible for lightning to produce nuclear fusion reactions because the fuel for the reactions — a form of hydrogen called deuterium — isn't available in large enough amounts in the atmosphere. The 50,000°F temperature of lightning is also a lot cooler than the 30,000,000°F near the center of the Sun where nuclear fusion occurs. Yet scientists have observed by-products of these reactions being produced from lightning.
How it works: Lightning can emit high-energy bursts known as gamma-ray flashes. (How and when they occur — they are associated with a small fraction of lightning seen around the world each day — is a mystery itself.) The flashes are energetic enough to knock neutrons out of the nuclei of nitrogen and oxygen in the air, creating radioactive versions of them for a short time.
Researchers have seen signatures of neutrons being formed just after a lightning flash before. The new paper reports a second such observation on February 6, 2017 Japan along with detection of the radioactive nitrogen and oxygen produced when neutrons are removed from their nuclei.
"It leaves no possible doubt as to what's going on, and it's a beautiful and thorough analysis," says David Smith, a physicist at the University of California Santa Cruz who studies gamma-rays produced by lightning and wasn't involved in the research.