Charge distribution in the thundercloud, electron acceleration, and
lightning initiation
Abstract
The comparative analysis of three thunderstorms on Aragats in May 2021
demonstrates that relativistic runaway electron avalanches (RREAs) are
developing in large areas of the thunderous atmosphere. In the active
storm zone, RREAs last tens of seconds to a few minutes, until lightning
flashes terminate electron acceleration. Thus, RREAs development is
paired with lightning activity, creating huge electron fluxes preceding
the development of lightning leaders. If the lightning activity is far
from the detector site, measured particle fluxes (thunderstorm ground
enhancements - TGEs) are smoothly enhanced and decayed when the
atmospheric conditions cannot anymore sustain the electron runaway
process. The TGE has a symmetrical shape and can last up to 10 minutes
and more. The differential energy spectra of electrons and gamma rays
recovered by particle spectrometers are used to estimate the heigh of a
strong accelerating electric field region, which can extend down to tens
meters above the earth’s surface.