Bursts of gamma radiation of varying intensities occur during a storm. The mechanism of their development and its connection with lightning remains largely mysterious. In a new paper, scientists show that stormy gamma-ray bursts are much more common and diverse than previously thought.

Thunder and lightning are just the tip of the iceberg that hides a series of high energy events in the atmosphere during a storm. So, in 1994, NASA’s Compton Observatory satellite, which was observing gamma-ray bursts in space, accidentally recorded a gamma-ray burst coming from Earth.

Further studies confirmed the existence of high-intensity terrestrial gamma-ray bursts (terrestrial gamma ray flashes). In addition, less intense and longer lasting gamma ray radiations are also known (gamma ray shines). The characteristics and mechanism of origin of these phenomena are not fully understood.

Scientists from the EU and the US analyzed data from a flying aircraft laboratory for 2023 that recorded gamma rays during ocean and land storms in the Caribbean and Central America. His research was published in the journal in two articles. Nature.

“Much more happens during thunderstorms than you can imagine,” said Steve Kammer of Duke University (USA), co-author of both papers, commenting on the study.

In general, the mechanism of formation of gamma radiation during storms is known. Initially, an electrostatic charge arises inside the suspension of water, hail and ice, forming a cloud. Positively charged particles stay at the top, negatively charged particles fall down. A strong electric field emerges, accelerating the electrons present there. They accidentally come into contact with air molecules and destroy high-energy electrons from them. And they’re knocking out more and more. The process takes on an avalanche-like character, creating a mass of secondary particles, including gamma quantum.

Scientists used NASA’s ER-2 laboratory, converted from the Cold War U2 spy plane, for the research. The machine soars above storm clouds, flying twice as high as civilian ships. It has high speed, allowing you to move quickly by selecting the most promising storm clouds. Researchers flew 10 flights over tropical Florida during the month.

In the first paper, Mykola Ostgaard from the University of Bergen (Norway) and colleagues described a new type of gamma-ray burst, namely scintillation. It consists of pulses lasting about 250 milliseconds, while terrestrial gamma-ray bursts last about half that time. Researchers recorded a total of 24 tremor events during five flights above the storm. 17 of these were accompanied by lightning.

The authors proposed that a pulsating gamma-ray burst begins as a flash, then suddenly increases in intensity and turns into a series of pulses. It is possible for pulsating gamma-ray bursts to trigger some lightning discharges. According to scientists, the flicker is an intermediate link between gamma-ray bursts and terrestrial gamma-ray bursts.

In the second study, scientists led by Martino Marisaldi, also from the University of Bergen, investigated the properties of gamma rays, which are characterized by low intensity. They recorded what happened during the storm, which covered an area of ​​9 thousand square kilometers and lasted for three hours.

It turns out that this type of gamma radiation is not uncommon and takes different forms. In total, nine out of 10 flights recorded more than 500 gamma rays, each lasting 1 to 10 seconds. This is contrary to previous studies that recorded evenly distributed, longer blinks over tens to hundreds of seconds.