This raw footage shows a lightning flash scientists triggered by launching a rocket with a trailing spool of Kevlar-coated copper wire into the air. This lightning flash is particularly important because, while not clear from the video, it produced a terrestrial gamma ray flash (TGF), an intense burst of gamma rays from a thunderstorm that can last from tens to hundreds of microseconds. Until their discovery in 1994, scientists believed the kinds of high-energy particles occurring during TGFs could not be produced in Earth’s atmosphere. These particles are normally produced by particle accelerators or astrophysical phenomena. But scientists now know thunderstorms can make TGFs with such high fluxes of gamma rays that they can overwhelm space instruments designed to observe the sun. In addition, TGFs produce beams of electrons and positrons that propagate into space and spiral along Earth's magnetic field lines. It has even been suggested that TGFs could pose a health risk to individuals in aircraft near thunderstorms. Data from this lightning flash is helping researchers understand the connection between lightning and TGFs, which are generally only observed from orbiting satellites. This is only the second TGF ever produced by triggered lightning. The scientists reported their findings in a recent study in the Journal of Geophysical Research Letters: Atmospheres, a journal of the American Geophysical Union. http://onlinelibrary.wiley.com/doi/10.1002/2015JD024426/abstract Video Produced by AGU Music by: E lucevan le stelle pt. 2 by Jeris (c) copyright 2014 Licensed under a Creative Commons Attribution Noncommercial (3.0) license. http://dig.ccmixter.org/files/VJ_Memes/48129 Ft: Darkroom (mactonite) , Dr. Emiliyan Stankov (iestankov)