Variations of cosmic ray muon flux during thunderstorms

Variations of the intensity of cosmic ray muons during thunderstorms are investigated. Linear and quadratic coefficients of regression of the muon flux with near-ground electric field are calculated and compared to the experimental data obtained with the Carpet air shower array in the Baksan Valley, North Caucasus. Based on correlations with the near-ground field, estimates are made of regression coefficients with the mean potential difference in the stratosphere, between the effective level of muon production and the ionosphere. It is shown that maximum observable muon effects (variations with amplitudes of 1%) correspond to a mean potential difference in the stratosphere of about 200 MV.