SoylentNews is people
SoylentNews
Arthur T Knackerbracket has processed the following story:
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 eye. Ten flights with the plane, NASA’s ER-2 aircraft, captured the shimmer of gamma-ray outbursts over a variety of timescales and intensities, suggesting that the emissions are more complex and more common than previously thought. And the study unveiled a brand-new type 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 was not involved with the research. It’s most important new data in this field for over a decade, he says.
Scientists knew of two main types of thunderstorm gamma-ray emissions. Short, intense blasts called terrestrial gamma-ray flashes are so luminous they can be seen from space, and last for mere fractions of a millisecond (SN: 1/10/23). Then there are longer, dimmer emissions called gamma-ray glows. Scientists spotted both on the flights.
Glows, the scientists found, were unexpectedly 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. 3 Nature.
“It’s astonishing,” says physicist Ningyu Liu of the University of New Hampshire in Durham, who was not involved with the work.
What’s more, the gamma-ray glows weren’t static, as previously thought, but constantly simmered, brightening and dimming repeatedly on timescales of seconds. “Large storms are bubbling. It’s like a boiling pot,” says Østgaard, of the University of Bergen in Norway.
[...] Thunderstorms produce gamma rays when electrons get accelerated in strong electric fields that build up inside the clouds (SN: 3/15/19). These electrons produce more electrons, and so on. When electrons in this avalanche collide with air molecules, gamma rays result. But although this process is well understood, scientists don’t understand the details behind the different types of gamma-ray outbursts, or how they are related.
The newfound flickering gamma-ray flashes could be a missing link between terrestrial gamma-ray flashes and gamma-ray glows, as their brightness and duration fell in between those of the other 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 second paper in Nature.
In addition, many of the flickering gamma-ray flashes were followed by a type of outburst called a narrow bipolar event, which was then followed by lightning. This could mean that the flickering gamma-ray flashes help initiate lightning, a process that is still not understood (SN: 10/21/11).
Gamma rays might also be involved in limiting how strong electric fields can get in thunderclouds, says coauthor Steven Cummer, an electrical engineer at Duke University. That means that “this whole gamma ray–generating process that was interesting and uncommon before, now actually appears to be quite central in all of atmospheric electricity.”
(Score: 2) by VLM on Wednesday October 09, @07:07PM (1 child)
Why airplanes?
Here's my thoughts so far:
Water attenuates gammas, and "really bad stuff" like kills you in minutes can be stopped by "15 or so" feet of water or less dangerous levels can be stopped by a couple inches of water. Stopped not meaning zero but meaning less dangerous than owning a granite countertop, which is easily measurable although harmless.
So I assume this is a weak signal from storms, but then again can't you detect single gamma photons?
The total precipitable water in air is the amount of water in the air. Usually measured in kilograms per meter but you can express it in inches. It's usually not much, even in storms.
So is the reason for aircraft that the signal only comes from top of clouds, or its so weak it's barely detectable on the best days so even raindrops would be enough to attenuate below detectable or they need to survey large areas (why?) or some other reason ?
(Score: 2, Informative) by day of the dalek on Thursday October 10, @07:55AM
It seems like a lot of the articles about gamma rays being produced in thunderstorms comes from outside meteorology journals, but I did find one article: https://journals.ametsoc.org/view/journals/bams/97/4/bams-d-14-00239.1.xml [ametsoc.org]. I haven't read through the entire article, and it's about the terrestrial gamma ray flashes, which are different from what this story is discussing. But I think it does have a possible answer to your question:
The acronym EET refers to enhanced echo tops. TGF is the article's acronym for terrestrial gamma ray flashes. It's basically where weather radar indicates the top of the storm is. The authors of that paper surmise that gamma ray flashes probably also occur at lower altitudes but get attenuated before reaching the detector because the atmosphere is denser at lower altitudes.