Changes in cloud characteristics on the territory of Russia

Such characteristics of the cloud cover as the frequency of cloudy (8-10/10) and clear (0-2/10) sky are investigated. The analysis of the seasonal frequency of these characteristics revealed some regional features. To be included in the national cloud monitoring system, the normals for the new base period of 1991-2020 for the average amount of total and low-level clouds, the frequency of cases with different sky conditions (clear, semi-cloudy, cloudy) for total and low-level clouds, as well as the frequency of various forms of clouds were calculated. Long-term changes in the frequency of clear and cloudy sky are analyzed, which revealed an almost universal decrease in the frequency of clear sky for the total cloud cover in all seasons. Keywords: total cloud cover, low-level clouds, cloud forms, cloudy sky, clear sky All-R