WASHINGTON (dpa-AFX) - Researchers using NASA airborne platforms have found a new kind of gamma-ray emission that is shorter in duration than the steady glows and longer than the microsecond bursts. They're calling it a flickering gamma-ray flash. The discovery fills in a missing link in scientists' understanding of thundercloud radiation and provides new insights into the mechanisms that produce lightning.
The insights, in turn, could lead to more accurate lightning risk estimates for people, aircraft, and spacecraft, NASA says.
Researchers from the University of Bergen in Norway led the study in collaboration with scientists from NASA's Marshall Space Flight Center in Huntsville, Alabama, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, the U.S. Naval Research Laboratory, and multiple universities in the U.S., Mexico, Colombia, and Europe. The findings were described in a pair of papers published in Nature.
The international research team made their discovery while flying a battery of detectors aboard a NASA ER-2 research aircraft. In July 2023, the ER-2 set out on a series of 10 flights from MacDill Air Force Base in Tampa, Florida. The plane flew figure-eight flight patterns a few miles above tropical thunderclouds in the Caribbean and Central America, providing unprecedented views of cloud activity.
The researchers said they were surprised to see the flickering fast radiation bursts known as terrestrial gamma-ray flashes.
'They're almost impossible to detect from space,' said co-principal investigator Martino Marisaldi, who is also a University of Bergen space physicist. 'But when you are flying at 20 kilometers [12.5 miles] high, you're so close that you will see them.' The research team found more than 25 of these new flashes, each lasting between 50 to 200 milliseconds.
The abundance of fast bursts and the discovery of intermediate-duration flashes could be among the most important thundercloud discoveries in a decade or more, said University of New Hampshire physicist Joseph Dwyer, who was not involved in the research. 'They're telling us something about how thunderstorms work, which is really important because thunderstorms produce lightning that hurts and kills a lot of people.'
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