Transcripts of Fermi_TGF_Tropical_Storm

Convective storms hold an extraordinary surprise. Under just the right conditions, they fire off some of the highest-energy light naturally found on Earth-- terrestrial gamma-ray flashes, or TGFs. Rising and falling snow and ice particles repeatedly collide, filling the cloud with electrical charge. Once the electric field is strong enough, a current flows and a lightning flash occurs. The flash produces an abrupt reconfiguration of the electric field. In some cases, a surge of electrons rushes toward the upper part of the storm at speeds nearly as fast as light. When deflected by air molecules, these accelerated electrons give off gamma rays, producing a TGF. Data from NASA's Fermi Gamma-ray Space Telescope suggest more than a thousand TGFs occur each day all over the globe. For the first time, improved data link dozens of TGFs to specific tropical weather systems. Tropical storms far from land tend to generate less frequent lightning. Nevertheless, observations show they are surprisingly prolific producers of TGFs. Tropical Storm Manuel made landfall just shy of hurricane strength. As it rapidly weakened, it produced two TGFs within 24 hours. More typically, TGFs are associated with the strengthening phase of a storm. As Typhoon Bolaven rapidly developed in 2012, thunderstorms nearly 500 miles from its center launched a TGF with four distinct pulses. So far, the record-holder for TGFs is the rapidly strengthening tropical wave that later gave birth to Hurricane Julio. It produced four TGFs within 100 minutes. A fifth followed the next day, with nothing further. What scientists learned so far is that weather tropical storms are capable of producing more TGFs, and those events can arise anywhere in the storm. For stronger storms, like hurricanes and typhoons, TGFs are more common in the outer rain bands, which host the highest lightning flash rates in these storms. The findings provide new insights into the relationship between storm intensity, lightning frequency, and TGFs. This adds another important piece to the puzzle of our understanding of TGFs and how they are created in thunderstorms-- the most powerful natural particle accelerators on planet Earth. On-screen text: NASA astrophysics [Beeping] [Beeping]