Oct 3, 2024 10:34 PM
https://www.eurekalert.org/news-releases/1059558
INTRO: In the 1990s, NASA satellites built to spot high-energy particles coming from supernovas and other celestial-sized objects discovered a surprise — high energy gamma radiation bursts coming from right here on Earth.
While it didn’t take long for researchers to figure out that these radioactive supercharged particles were coming from thunderstorms, how commonly the phenomenon happened remained a mystery. Satellites weren’t built to find gamma radiation coming from Earth, and they had to be in just the right place at just the right time to do so.
After years of making do with platforms not ideal for the task, a group of scientists secured an opportunity to fly a retrofitted U2 spy plane owned by NASA over storms to take a proper look. In two new papers published October 3 in Nature, the team discovered that gamma radiation produced in thunderstorms is far more common than anyone thought and that the dynamics creating the radiation hold a treasure trove of mysteries yet to be solved.
“There is way more going on in thunderstorms than we ever imagined,” said Steve Cummer, the William H. Younger Distinguished Professor of Engineering at Duke University, who was a coauthor on both papers. “As it turns out, essentially all big thunderstorms generate gamma rays all day long in many different forms.”
The general physics behind how thunderstorms create high-energy flashes of gamma radiation is not a mystery. As thunderstorms develop, swirling drafts drive water droplets, hail and ice into a mixture that creates an electric charge much like rubbing a balloon on your shirt. Positively charged particles end up at the top of the storm while negatively charged particles drop to the bottom, creating an enormous electric field that can be as strong as 100 million AA batteries stacked end-to-end.
When other charged particles — such as electrons — find themselves in such a strong field, they accelerate. If they accelerate to high enough speeds and happen to strike an air molecule, they knock off more high-energy electrons. The process cascades until the collisions have enough energy to create nuclear reactions, producing extremely strong and extremely fast flashes of gamma rays, antimatter and other forms of radiation.
But that’s not the end of the thunderstorm gamma radiation story. Aircraft flying close to thunderstorms have also seen a faint glow of gamma radiation coming from clouds. These storms seem to have enough energy to produce a low-level simmering of gamma radiation, but something prevents it from creating an explosive burst like a popping corn kernel.
“A few aircraft campaigns tried to figure out if these phenomena were common or not, but there were mixed results, and several campaigns over the United States didn’t find any gamma radiation at all,” Cummer said. “This project was designed to address these questions once and for all...” (MORE - details)
PAPER: http://dx.doi.org/10.1038/s41586-024-07893-0
https://youtu.be/qFEtaGJ-ZAs
https://www.youtube-nocookie.com/embed/qFEtaGJ-ZAs
INTRO: In the 1990s, NASA satellites built to spot high-energy particles coming from supernovas and other celestial-sized objects discovered a surprise — high energy gamma radiation bursts coming from right here on Earth.
While it didn’t take long for researchers to figure out that these radioactive supercharged particles were coming from thunderstorms, how commonly the phenomenon happened remained a mystery. Satellites weren’t built to find gamma radiation coming from Earth, and they had to be in just the right place at just the right time to do so.
After years of making do with platforms not ideal for the task, a group of scientists secured an opportunity to fly a retrofitted U2 spy plane owned by NASA over storms to take a proper look. In two new papers published October 3 in Nature, the team discovered that gamma radiation produced in thunderstorms is far more common than anyone thought and that the dynamics creating the radiation hold a treasure trove of mysteries yet to be solved.
“There is way more going on in thunderstorms than we ever imagined,” said Steve Cummer, the William H. Younger Distinguished Professor of Engineering at Duke University, who was a coauthor on both papers. “As it turns out, essentially all big thunderstorms generate gamma rays all day long in many different forms.”
The general physics behind how thunderstorms create high-energy flashes of gamma radiation is not a mystery. As thunderstorms develop, swirling drafts drive water droplets, hail and ice into a mixture that creates an electric charge much like rubbing a balloon on your shirt. Positively charged particles end up at the top of the storm while negatively charged particles drop to the bottom, creating an enormous electric field that can be as strong as 100 million AA batteries stacked end-to-end.
When other charged particles — such as electrons — find themselves in such a strong field, they accelerate. If they accelerate to high enough speeds and happen to strike an air molecule, they knock off more high-energy electrons. The process cascades until the collisions have enough energy to create nuclear reactions, producing extremely strong and extremely fast flashes of gamma rays, antimatter and other forms of radiation.
But that’s not the end of the thunderstorm gamma radiation story. Aircraft flying close to thunderstorms have also seen a faint glow of gamma radiation coming from clouds. These storms seem to have enough energy to produce a low-level simmering of gamma radiation, but something prevents it from creating an explosive burst like a popping corn kernel.
“A few aircraft campaigns tried to figure out if these phenomena were common or not, but there were mixed results, and several campaigns over the United States didn’t find any gamma radiation at all,” Cummer said. “This project was designed to address these questions once and for all...” (MORE - details)
PAPER: http://dx.doi.org/10.1038/s41586-024-07893-0
https://youtu.be/qFEtaGJ-ZAs