A study of atmospheric processes based on neutron monitor data and Cherenkov counter measurements at high mountain altitude

The cause of the correlation between cloud cover and cosmic ray intensity is still a subject of discussion. The atmospheric transparency is the primary signature of the atmospheric state. The ability to use neutron monitor and Cherenkov telescope data in order to study atmospheric processes is demonstrated. The recently designed lead free neutron monitor at the Basic Environmental Observatory Moussala (42.11N, 23.35E, 2925 m a.s.l.) is described. The possibility to use Cherenkov telescope measurements for estimation of atmospheric transparency is demonstrated on the basis of Monte Carlo simulations and experimental data. The Monte Carlo simulations are carried out with CORSIKA code assuming FLUKA and QGSJET II hadron interaction models. Experimental data from Cherenkov telescope are presented. Several physical mechanisms related to the influence of cosmic rays on the cloud cover, respectively, the atmospheric transparency are widely discussed.