The radiation produced during a lightning storm is more energetic and potentially threatening to aircraft than previously thought, claim researchers in Italy. Studying this radiation in closer detail could help scientists to probe some of the big unanswered questions in the study of thunder storms, such as how lightning is triggered in clouds.
Scientists have known for a long time that the large electric fields and currents produced during thunder storms can also generate X-rays and gamma rays in the vicinity of clouds. But in the early 1990s a rare type of lightning event was discovered that can produce extremely bright, energetic gamma rays – known as terrestrial gamma ray flashes. So far, however, it has been difficult to determine specific details about this phenomenon such where the radiation originates from and its energy range.
Now researchers involved with the Italian Space Agency's AGILE mission have been able to home in on terrestrial gamma ray flashes. Launched in 2007, this satellite is dedicated to observing gamma rays originating from terrestrial and cosmic sources. Its silicon-based gamma ray detector has recently been fitted with new software that enables the satellite to take snapshots of the radiation at sub-millisecond time intervals.
Flash strikes
The AGILE team led by Marco Tavani gathered data collected from 130 terrestrial gamma ray flash events occurring in the past two and a half years. Reporting its findings in Proceedings of the National Academy of Sciences, Tavini's team noted radiation emerging in all directions from the upper atmosphere, covering a wide range of energies. In some cases gamma rays were up to 100 MeV – more than twice as energetic as previous measurements.
You can read the rest of article at:
http://physicsworld.com/cws/article/news/44722
Scientists have known for a long time that the large electric fields and currents produced during thunder storms can also generate X-rays and gamma rays in the vicinity of clouds. But in the early 1990s a rare type of lightning event was discovered that can produce extremely bright, energetic gamma rays – known as terrestrial gamma ray flashes. So far, however, it has been difficult to determine specific details about this phenomenon such where the radiation originates from and its energy range.
Now researchers involved with the Italian Space Agency's AGILE mission have been able to home in on terrestrial gamma ray flashes. Launched in 2007, this satellite is dedicated to observing gamma rays originating from terrestrial and cosmic sources. Its silicon-based gamma ray detector has recently been fitted with new software that enables the satellite to take snapshots of the radiation at sub-millisecond time intervals.
Flash strikes
The AGILE team led by Marco Tavani gathered data collected from 130 terrestrial gamma ray flash events occurring in the past two and a half years. Reporting its findings in Proceedings of the National Academy of Sciences, Tavini's team noted radiation emerging in all directions from the upper atmosphere, covering a wide range of energies. In some cases gamma rays were up to 100 MeV – more than twice as energetic as previous measurements.
You can read the rest of article at:
http://physicsworld.com/cws/article/news/44722
