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Until recently, when we were talking about gamma rays we did it to refer to nuclear reactions and most extreme phenomena in the universeas supernova explosions or black holes. However, everything changed a couple of decades ago when it was discovered that thunderstorms have the ability to create gamma rays. What we didn’t imagine is that they are, literally, radioactive.
The study. In reality, we are looking at two joint works published in Nature. one of them describes the frequent emission of gamma ray flashes long-lived over large parts of the atmosphere during tropical storms. The second details the recently identified phenomenon, called flickering gamma ray flashes or FGFand reflects on the relationship between flashes and other forms of radiation from storm clouds.
A plane from the Civil War. It was all possible using the high-altitude aerial scientific aircraft NASA ER-2essentially the repurposed U2 spy plane from the Cold War. The ER-2 flies at twice the altitude of a commercial airliner and It has already been used in the Gulf of Mexico on 10 occasions to study tropical storms.
According to the co-author of the study, Professor Steve Cummerfrom Duke University, “several aerial initiatives have been carried out to find out whether these phenomena are common or not, but the results have been mixed and several campaigns over the United States have not detected any gamma radiation. “This project was designed to address these issues once and for all.”
The discovery. As we said at the beginning, gamma ray events in thunderstorms are divided into terrestrial gamma ray flashes (TGF), which last up to 100 microseconds, and gamma ray glows, which can last hundreds of seconds. However, the two papers found that FGFs consist of a kind of radiation, pulses with a duration longer than TFGs (hundreds of milliseconds), and appear to be connected to the longer-lasting glows.
“Many more things happen in thunderstorms than we ever imagined,” Cummer explains.. “It turns out that, in essence, all large thunderstorms generate gamma rays throughout the day in many different ways.” In fact, ER-2 detected gamma ray flares that lasted for hours and covered an area of almost 9,065 square kilometers.
Theory. Basing in the jobsthe team believes that the formation of the lightning bolts is created by free electrons accelerated by the intense electric field within the clouds. As they move upward, they interact with air and water molecules, and these collisions can create reactions that include the formation of antimatter and gamma rays.
For Martino Marisaldia physicist at the University of Bergen and lead author of one of the papers, “FGFs are notably different from both TGFs and glows, but have some characteristics of both. That is why we consider them the missing link between the two phenomena. FGFs do not emit radio signals, but are usually followed, within milliseconds, by radio pulses called Narrow Bipolar Events, which are usually associated with the onset of lightning strikes. Therefore, it is interesting to hypothesize a causal connection between the two phenomena.”
Conclusion. The researchers indicate that the study debunks old theories. For example, rules out other theoretical mechanisms for the initiation of rays, such as cosmic rays and guide rays. In addition, the work lays the foundation to further clarify the relationship between gamma bursts and storm clouds, as well as between lightning and their sources.
Since many of the recently observed gamma flashes occurred without the presence of lightning, it appears that electrified storms themselves are capable of generating gamma rays. A study that completes the certainly complex map of storm clouds, one of those shocking and amazing moments on our planet.
And no, the emission of gamma rays in tropical storms is not dangerous… given the place where they occur. Actually, if you were up there it would be the least of your worries.
Image | The ALOFT team / Mount Visual
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