Preliminary Results of Searches for Long-Term Microwave Radiation from Thunderstorm Atmosphere at 1.35-cm Wavelength

Abstract—Remote sensing of the Earth is currently being used to measure nonthermal radiation. Here, powerful electromagnetic radiation of the atmosphere, initiated by cosmic rays, in the range from low frequencies to the gamma range, have recently been discovered. Of particular interest is the study of such radiation in the microwave range, where aerospace research technology is well developed. This paper presents the results of joint measurements of microwave and gamma radiation of the atmosphere during thunderstorms in the summer of 2022 in Transbaikalia. The purpose of the study is to search for relatively long-term (up to several minutes) electromagnetic radiation near a frequency of 22.2 GHz on the line of the rotational spectrum of water vapor molecules. It is assumed that such a feature may arise due to the appearance of avalanches of runaway electrons generated by cosmic rays. In this process, in addition to bremsstrahlung gamma radiation, the excitation of the gaseous medium occurs, which can cause its superradiance in the microwave range. In case of strong electrification in fields with intensity higher than 0.284 MV/m, a unique phenomenon may occur—a self-sustaining photonuclear reaction in the lower atmosphere in thunderclouds. During this process, the electromagnetic glow may last from units to tens of minutes. This study has revealed several episodes of an increase in radiation intensity in the microwave range, accompanied by gamma-ray pulses in the thunderstorm atmosphere. The glow detected in the experiment can be explained by local electric discharges with an increase in cloud electrification. Another explanation is the occurrence of a self-sustaining photonuclear reaction creating a large volume of excited gas. Ways to improve the microwave measurement technique for recording high-energy phenomena in the lower atmosphere at a large distance from the measuring equipment, where gamma rays are not recorded, using satellites are discussed.