Thunderstorms churn up a ‘boiling pot’ of gamma rays 

Above the cloud tops, thunderstorms throb with a complex, frenetic light show of high-energy radiation.

A view from a retrofitted spy plane soaring at 20 kilometers up revealed storms glowing and flickering in gamma rays, high-energy light invisible to the attention. Ten flights with the plane, NASA’s ER-2 aircraft, captured the shimmer of gamma-ray outbursts over loads of timescales and intensities, suggesting that the emissions are more complex and more common than previously thought. And the study unveiled a brand-new kind of gamma-ray blast the researchers named a flickering gamma-ray flash.

“I’m absolutely awestruck,” says physicist David Smith, of the University of California, Santa Cruz, who became now not involved with the research. It’s most important new data on this field for over a decade, he says.

Scientists knew of two main styles of thunderstorm gamma-ray emissions. Short, intense blasts often which is often often called terrestrial gamma-ray flashes are so luminous they'll perhaps be seen from space, and last for mere fractions of a millisecond (SN: 1/10/23). Then there are longer, dimmer emissions often which is often often called gamma-ray glows. Scientists spotted both on the flights.

Glows, the scientists found, were very well now persistent and prevalent. They continued for hours, covered thousands of square kilometers, and were seen in nine of the plane’s 10 flights, physicist Nikolai Østgaard and colleagues report in the Oct. three Nature.

“It’s astonishing,” says physicist Ningyu Liu of the University of New Hampshire in Durham, who became now not involved with the work.

What’s more, the gamma-ray glows weren’t static, as previously thought, but constantly simmered, brightening and dimming over and over on timescales of seconds. “Large storms are bubbling. It’s like a boiling pot,” says Østgaard, of the University of Bergen in Norway.

Loaded up with sensors to detect gamma rays, radio waves, visible light and more, the aircraft flew over storms in the Caribbean and Central The u.s.a.a.. Cruising at an altitude about twice that of business flights, the plane had a front-row seat to the fireworks. And because the plane became rigged as much as send data to the bottom in real time, researchers may perhaps direct the plane’s pilot to return to regions that were hopping with gamma rays.

The flights also found terrestrial gamma-ray flashes, including many too dim to be seen from satellites in space, the team reported September 7 in in Geophysical Research Letters. That means that previous satellite observations were missing many terrestrial gamma-ray flashes, making them more common than thought.

Thunderstorms produce gamma rays when electrons get accelerated in strong electric fields that build up within the clouds (SN: three/15/19). These electrons produce more electrons, etc. When electrons on this avalanche collide with air molecules, gamma rays result. But though this process is well understood, scientists don’t understand the small print at the back of different styles of gamma-ray outbursts, or how they're related.

The newfound flickering gamma-ray flashes will also be a missing link between terrestrial gamma-ray flashes and gamma-ray glows, as their brightness and duration fell in between those of the opposite two classes. Like high-energy strobe lights, these outbursts consisted of short pulses of gamma rays that repeated over tens to hundreds of milliseconds, the team reported in a 2d paper in Nature.

In an analogous way, among the flickering gamma-ray flashes were followed by a kind of outburst often which is often often called a narrow bipolar event, which became then followed by lightning. This is in a position to from time to time mean that the flickering gamma-ray flashes assist initiate lightning, a process it's still now not understood (SN: 10/21/eleven).

Gamma rays will also be fascinated about limiting how strong electric fields can get in thunderclouds, says coauthor Steven Cummer, an electrical engineer at Duke University. Which means that “this entire gamma ray–generating process that became interesting and uncommon sooner than, now really appears to be kind of central in all of atmospheric electricity.”