ИСТИНА

Monitoring of background gamma-radiation (20-400 keV) coming from the atmosphere is produced in Polar Geophysical Institute (PGI). At the present time the same type of detectors are installed at six stations from Barentsburg (arch. Spitsbergen) to the mid-latitudes (Rostov-on-Don). There is one station in Sayan Mountains at 3000 m altitude. A unique and large database of gamma-radiation flux and its variations at different stations for the period 2009-2017 has been accumulated. It is supplemented by measurements carried out at mid-latitude stations in recent years. All measurements are made on the same type of detector, manufactured in PGI. A phenomenon, discovered from the beginning by the authors, is observed on all stations: there is an increase of the gamma-ray background during precipitation. Those increases occur all over the year and sometimes are 60 %. Moreover, as it was established by additional experiments, increases are not related either to radionuclides in the sediments or to radon emission to the surface air layer. They are observed only in the electromagnetic component, which produced in the atmosphere from cosmic rays. Since 2009 there have been registered more than 1000 such events in Apatity, about 400 in Barentsburg. Complex processing of the data has shown that some characteristics of events differ significantly both on the seasons and on the station locations (polar or mid-latitude). Other characteristics are little dependent on the location and the seasons. Consequently, the gamma-ray background increase during precipitation is due to the influence of local meteorological processes on the propagation and generation of secondary cosmic rays in the Earth's atmosphere.