Thermal classification of months, seasons and years in Lublin (1951–2010)

The source material of studies were the values of the mean monthly air temperature in Lublin in the years 1951-2010. Temperatures were measured in the UMCS Meteorological Observatory, located in city centre (Lublin, Plac Litewski). On the basis of monthly values seasonal averages were calculated for the four calendar seasons: spring (March-May), summer (June-August), autumn (September-November) and winter (December-February) and annual averages. Classification of thermal months, seasons and years in Lublin was calculated by applying the method used by Lorenc. Analyzing the impact of changes in the base period for the thermal thresholds of individual categories it can be observed that on the change in the thermal thresholds of each category the change of value of the multi-annual mean had a greater impact than the change of standard deviation. In the last 12 years (1999-2010) the particularly high concentration of months, seasons and years with values exceeding the value of the standardized 60-year average of at least one standard deviation is noticed. In July, August and the summer they were at least 50% and the year classified to the category of cool year was the year 1996