Annual Variations of the Galactic Cosmic Ray Intensity and Seasonal Distribution of the Cloudless Days and Cloudless Nights in Abastumani (41.75oN, 42.82oE; Georgia): (1) experimental study and (2) theoretical modeling

TL;DR

This study investigates the relationship between galactic cosmic ray variations and seasonal patterns of cloudless days and nights at Abastumani, combining observational data with theoretical modeling to explore cosmic influences on cloudiness.

Contribution

It presents a combined experimental and theoretical analysis of how galactic cosmic rays may influence seasonal cloud cover variations.

Findings

Maximum cloudless days in August, nights in September.

Geomagnetic disturbances increase cloudless days and nights in specific months.

Cosmic factors potentially influence cloudiness through GCR flux variations.

Abstract

We study a possible relationships between seasonal distributions of the visually observed cloudless days (CD) and cloudless nights (CN) at Abastumani Astrophysical Observatory (41.75N, 42.82E; Georgia) in 1957-1993. The annual variations of monthly numbers of CD and CN have been observed, with maximum in August for CD and in September for CN. During geomagnetic disturbances it is also observed the growth of number of CD in September andMarch (equinoctial months), and for CN, together with September, in June, April and February. We assume that this phenomenon indicates an influence of cosmic factors on cloudiness, as well as the existence of semiannual and possibly shorter-periodicity variations. This cosmic factor can be the manifestation of different rates of the galactic cosmic rays (GCRs) flux variations in CD and CN periods. The influence of GCR flux on ionization of lower atmosphere and variations of density of cloud condensation nuclei also can be connected to the annual and seasonal changes of temperature at Earth surface of this region. To comprehend behaviors of the annual and semi-annual variations of the GCR intensity and their possible relationships with the seasonal distributions of CD and CN we compose and numerically solve two dimensional (2-D) time dependent transport equation including all important processes in the heliosphere. An analysis of experimentally observed and theoretically obtained results have been carried out.