DYNAMICS OF CLOUDINESS WITHIN THE BOUNDARIES OF VOLYN REGION IN THE PERIOD 2010–2021

Abstract

Problem Statement and Purpose. Under the influence of climate change processes, the dynamics of individual meteorological phenomena within Ukraine and the Volyn region is changing. The cloudiness of the sky is one of such phenomena, however, changes in the dynamics of cloudiness during the last decades in Ukraine have not been studied enough yet, in contrast to changes in the regime of temperature or precipitation. This determines the relevance of this study, devoted to the analysis of sky cloudiness indicators in the Volyn region during 2010–2021 according to the data of six meteorological stations. The purpose of the work: the study of changes in the dynamics of cloudiness indicators within the Volyn region. Tasks of the work: 1) to analyze modern views on the formation and dynamics of clouds; 2) to investigate changes in the dynamics of cloudiness within the Volyn region based on the analysis of archival materials of six meteorological stations: Lutsk, Kovel, Volodymyr, Svityaz, Manevichi, Lyubeshiv for the period 2010–2021; 3) to conduct own observations of cloud cover, to continue compiling the Cloud Atlas; 4) to compare the dynamics of the temperature of the lower base of clouds of different types in the city of Lutsk and in the adjacent suburban area during the year. Data & Methods. In the process of preparing the work, analytical, comparative-evaluation, mathematicalstatistical (when processing weather archives and obtained observation results), graphic methods were used. Typical methods and algorithms of statistical and graphical analysis in the Excel program are applied. Special research methods: method of observation and data collection, instrumental (determining the temperature of the lower base of clouds) and cartographic method. The initial data for the study were archival data of weather stations Lutsk, Manevichi, Kovel, Volodymyr, Svityaz, and Lyubeshiv, located within the Volyn region, as well as the results of own observations of cloudiness and instrumental measurements of physical indicators of clouds in the city of Lutsk. Results. Studies of the main indicators of sky cloudiness for the period 2010–2021 showed that the average annual total cloudiness within the Volyn region decreased by 0.3–1.1 points. This decrease is the largest for Lutsk, the smallest for Kovel. The height of the lower cloud base, on the contrary, increases. This increase is the largest in Lutsk (almost 1300 m). Average monthly cloud cover values were below normal from March to October (the warm period of the year). In November - February, the cloudiness index was somewhat higher than normal. Deviations of the average monthly cloud cover from the climatic norm varied from + 10% to - 35% in individual months of the year. The lowest average annual cloudiness during the period 2010 - 2021 was in Lutsk (5.9 points), the highest - in Kovel (7.1 points). According to the months of the year, at 6 stations and within the region as a whole, there is a decrease in cloud cover in the warm period. In winter, cloudiness is close to the climatic norm or higher. The clearest sky was over Lutsk. The most «cloudy» stations in Volyn are Kovel and Svityaz. Differences in the temperature of the lower cloud base over Lutsk and in the suburban area (Polonka village) were revealed. The temperature of the lower base was higher than the city in 85% of cases, the excess was 0.1 - 70C. The magnitude of this temperature difference depends on the type of clouds, the season, the direction and strength of the wind. It is the largest for periods with calm weather, in summer and winter, for cumulus, cumulus-rain, cirrus, high-cumulus clouds.