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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.

Why it matters: It's unclear how thunderstorms and lightning work. "How lightning initiates inside thunderstorms is a complete mystery, and how lightning initially moves inside the storms is not at all clear," lightning expert Joseph Dwyer from the University of New Hampshire tells Axios in an email. He says figuring out how some thunderstorms emit huge gamma-ray flashes thought to trigger the reactions "might tell us something interesting about what's going on inside the storms."

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.

What's next: The gamma-ray flashes themselves were too bright for the researchers' instruments to record. Dwyer says having better instrumentation in places where there are lots of thunderstorms and on aircraft flying near storms would be a very important next step to confirm the bursts start the reactions.

Go deeper

Updated 1 hour ago - Politics & Policy

Shooting at Michigan high school leaves 3 dead, 8 wounded

Police cars restrict access to Oxford High School following the shooting in Oxford, Michigan, on Tuesday. Photo: Matthew Hatcher/Getty Images)

A 15-year-old sophomore was arrested after a shooting at a Michigan high school that left three people dead and eight others wounded Wednesday, according to the Oakland County Sheriff's Office.

The latest: Oakland County Sheriff Michael Bouchard said at a briefing Tuesday night that the suspect's father had on Friday bought the 9mm Sig Sauer pistol investigators believe was used in the shooting at Oxford High School. Authorities released the names of the victims late Tuesday.

City Council member Andre Dickens wins Atlanta mayoral race

Atlanta Mayor-elect Andre Dickens in Atlanta, Georgia, late Tuesday. Photo: Paras Griffin/Getty Images

City Council member Andre Dickens won a runoff election Tuesday to become Atlanta's next mayor, soundly beating the council's president Felicia Moore.

The big picture: Dickens was just a few months ago considered to have an outside chance of replacing Mayor Keisha Lance Bottoms, who announced in May that she wouldn't seek a second term.

UN report: Pandemic set to cost global tourism $2 trillion in 2021

A tourist in front of the Eiffel Tower in Paris on Nov. 25. Photo:Chesnot/Getty Images

A new United Nations report warns that global tourism will see only modest revenue gains in 2021 after last year's historic losses amid the COVID-19 pandemic.

Why it matters: Tourism revenues in 2020 fell by more than half from the previous year — a significant blow to the global economy, according to analysis by the UN World Tourism Organization (UNWTO).