Krzysztof Bartoszek

Abstract: To determine extreme weather types in Lublin, in the years 1951–2015, the typology of Woś was applied. It provided a basis for the designation of two extreme thermal types: one with hot and one with very frosty weather. Furthermore, a type of weather with intensive precipitation, not included in the original version of the classification, was  analysed. Meteorological data used in the study were obtained from the Meteorological Observatory of the Department of Meteorology and Climatology of the Maria Curie-Skłodowska University in Lublin. The circulation conditions were determined based on the classification of circulation types for the area of Central-Eastern Europe.

In the years 1951–2015 extreme weather types occurred in Lublin for 5 days in a year on average. Days with the hot weather type were recorded most frequently. Their occurrence was favoured by air advection from the southern or eastern sector with a transitional or anticyclonic character. In the analysed multi-annual period an increasing tendency in  he number of such days was observed. The number of days with the very frosty weather type, primarily related to the advection of air masses from the east, decreased. In the case of the number of days with the weather type with intensive precipitation no evident tendency of changes was determined in the analysed period.

The authors investigated days of sultry weather in the Lublin and Nałęczów region from 1966 to 2010. A long-term variability of such days in relation to the three biometeorological indices : the Scharlau’s criterion, the equivalent temperature and the Heat Stress Index (pHSI) was analyzed. Days of sultry weather can occur in the analyzed area from May to October, but a clearly higher frequency is limited to the period from June to August, with a maximum in July. The most uncomfortable bioclimatic conditions were  noticeable in the second half of the day, when air temperatures were highest. The study also showed that the pHSI index has the greatest practical importance because it has been determined on the basis of the human heat balance model and we can also calculate the number of days with various intensity of sultriness. Regardless of the method of calculating biometeorological indices, a significant increase in the risk of dehydration and overheating of the human body was found. The reason is an increasing number of sultry days that occur in long sequences. The upward trend may limit all kinds of physical outdoor activity in the study area.

The objective of the study was the long-term and annual variability of atmospheric circulation indices over the Lublin region in the years 1951–2010. The zonal, meridional and cyclonicity indices were calculated based on the calendar of circulation types over East-Central Poland. Furthermore, the relationships between atmospheric circulation and thermal as well as precipitation conditions in the Lublin region were examined. In winter season, the strongest zonal circulation was noticed in the period from the second half of the 1980s to the end of the 20th century. In the last two decades of the analyzed period, a higher frequency of southern circulation in summer was observed. The characteristic features of atmospheric circulation in the study area include the prevalence of westerly circulation in autumn and winter, and easterly air flow in spring. The zonal circulation had an important role for monthly air temperature both in winter and in summer, whereas meridional air flow in spring and autumn. Compared to the air flow direction, the character of atmospheric circulation, expressed by anticyclonic and cyclonic circulation, had a weak influence on monthly air temperatures. The cyclonicity index most accurately reflects the variability of monthly precipitation totals in the Lublin region