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Progressing climate change is often reflected in changing biometeorological conditions. The Sudetes Mountains, located in the Polish–Czech border area, are concerned by this phenomenon. The goal of this paper is to evaluate the influence of atmospheric circulation on multiannual changes in biothermal conditions using the UTCI index. In the analysis, data for 1991–2020, from both Polish and Czech meteorological stations, was considered, while the circulation factor was evaluated using the Lityński classification. The research indicated a positive tendency of UTCI values for the majority of circulation types, which consequently contributed to a decrease in the frequency of cold stress categories. In the summits, a decline in the number of days with extreme cold stress was the most characteristic feature, especially under anticyclonic and northern circulation. Tendencies of heat stress occurrence were in most cases statistically insignificant, except for cyclonic and transitional circulation. [ABSTRACT FROM AUTHOR]

The purpose of this article is to present the development of multifaceted research on snow cover conducted by Polish researchers in various parts of the world since the end of the 19th century up to the modern times. The paper describes Polish studies on physical and chemical properties of snow cover, its long-term changes, relationships between snow cover and climate, impact of snow cover on environmental conditions and human activity. This work is also an attempt to show the contribution of Polish snow-related research to the international achievements in this fields. [ABSTRACT FROM AUTHOR]

This paper analyses day-to-day changes of weather types and links these with synoptic situations, i.e. circulation types, air masses and weather fronts. The weather types were classified according to Woś (1999), while a calendar proposed by Niedźwiedź (2013) was used for synoptic situations. Weather records from Kraków were used covering the period 1961-2010. The frequency of all combinations of day-to-day weather type changes was calculated, identified using specific values of air temperature, cloudiness and precipitation. The analysis of the succession and frequency of the day-to-day changes was linked with the synoptic situations accompanying the change. It was found that the thermal weather types were relatively very stable and remained unchanged on the following day in 61.3% of cases, and that the synoptic situation also remained similar. Weather subtypes, identified with just cloudiness and precipitation, but not temperature, displayed much more day-to-day change in terms of frequency and scale. Synoptically it was the air mass change and/or the occurrence of atmospheric fronts, which tended to cause day-to-day weather type changes, while the impact of circulation was not always clear. Particular attention was devoted to sudden weather type changes caused primarily by dramatic air temperature fluctuations. [ABSTRACT FROM AUTHOR]