Earth storms that generate gamma rays

Storm clouds are more than just rain and lightning. Along with visible light emissions, storm clouds can produce intense bursts of gamma rays, the most energetic and potentially dangerous form of electromagnetic radiation, although fortunately they only last millionths of a second. However, clouds can emit gamma rays steadily, although weaker, for seconds or minutes.

Researchers have now discovered a new type of gamma-ray emission that lasts less than steady glows and longer than microsecond bursts. They call it a gamma ray flicker.

The finding could lead to more accurate estimates of the risks that lightning poses to people, planes and spacecraft.

The work has led to two studies, both published at the same time in the academic journal Nature.

The researchers made their discovery during a flight aboard a NASA science plane that was equipped with special detectors.

The researchers expected those detectors to observe some of those microsecond-long flashes, known as terrestrial gamma-ray flashes (TGFs). These flashes, discovered in 1992 by NASA’s Compton Gamma Ray Observatory spacecraft, accompany some lightning. Despite their high intensity and association with visible light rays, few TGFs have been detected in previous aerial surveys.

During the aforementioned flight of a NASA plane, the researchers were successful and captured 130.

However, the flickering flashes of gamma rays were quite a surprise.

Tropical storm with lightning, near the Santa Marta airport in Colombia. (Photo: Oscar van der Velde)

Flashes of this new class are almost impossible to detect from space. But when you fly at 20 kilometers high, you are close enough to their typical emission zone to capture them if they are generated. The research team found more than 25 of these new flashes, each lasting between 50 and 200 milliseconds.

The discovery of flashes of intermediate duration could be among the most important discoveries in recent years about storm clouds.

One of the studies is titled “Flickering gamma-ray flashes, the missing link between gamma glows and TGFs” and its first signatory is Nikolai Ostgaard, from the University of Bergen in Norway.

The other study is titled “Highly dynamic gamma-ray emissions are common in tropical thunderclouds” and its first signatory is Martino Marisaldi, also from the University of Bergen. (Fountain: NCYT by Amazings)