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Published August 2015 | public
Journal Article

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

Abstract

Gamma-ray 'glows' are long duration (seconds to tens of minutes) X-ray and gamma-ray emission coming from thunderclouds. Measurements suggest the presence of relativistic runaway electron avalanches (RREA), the same process underlying terrestrial gamma-ray flashes. Here we demonstrate that glows are relatively a common phenomena near the tops of thunderstorms, when compared with events such as terrestrial gamma-ray flashes. Examining the strongest glow measured by the airborne detector for energetic emissions, we show that this glow is measured near the end of a downward RREA, consistent with occurring between the upper positive charge layer and the negative screening layer above it. The glow discharges the upper positive layer by ≥9.6 mA, strong enough to be an important charging mechanism of the storm. For this glow, the gamma-ray flux observed is close to the value at which relativistic feedback processes become important, with an avalanche multiplication factor of 4,500.

Additional Information

© 2015 Macmillan Publishers Limited. Received 19 Aug 2014; Accepted 17 Jun 2015; Published 12 Aug 2015. We thank Jeff Stith, Allan Schanot and Janine Acquino for their collaboration. This research was funded by NSF grants ATM-0619941, AGS-1160226 and AGS-1519236. Author contributions: D.M.S, B.H., B.G., A.L. and F.M.-M. designed, built and tested the instrument. D.M.S, B.H., B.G., A.L., F.M.-M., J.R.D., S.L., M.S. and H.K.R. participated during the 2009 flight campaign. N.A.K. analysed the data, created the instrument mass model and ran simulations propagating the relativistic feedback model through the instrument response. N.A.K. calibrated the instrument. N.A.K., D.M.S. and J.R.D. interpreted the results from the simulations and found the correct normalizations to find final conclusions. N.A.K., D.M.S. and J.R.D. contributed substantial written content for the paper. N.A.K., B.G. and M.S. created the figures. M.S. obtained and analysed the meteorological data. J.R.D. created the model and simulations used for the relativistic feedback model. J.R.D. derived the equations necessary for finding the amount of current due to relativistic free electrons. The authors declare no competing financial interests.

Additional details

Created:
August 20, 2023
Modified:
October 24, 2023