Geographia Polonica (1996) vol. 67
Thermal characterization of winters in the 20th century in Krakow
Geographia Polonica (1996) vol. 67, pp. 77-88 | 
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Abstract
Based on Krakow's measurement series of air temperature in the 20th century an attempt was made to analyse the winter season by means of some criteria which are important for the thermal conditions which — in turn — influence natural processes and phenomena. The first day with mean daily air temperature <0°C was taken to determine the beginning of a winter and the last such day for the end of winter. The characterization of winters was based on the number of winter days (mean daily air temperature <0°C), the number of frosty days (daily maximum air temperature <0°C), the number of extreme frosty days (daily maximum air temperature <-10°C) and the sums of frost (sums of mean daily air temperature <0°C). Special attention was paid to extreme winters because of their thermal conditions as well as their frequency and variability. It was established that recently observed winters are the mildest in our century and that the concentration of such winters in the 1980s allowed for a link with global warming. The winters in question are inducing environmental changes.
Keywords: winters, extreme winters, air temperature, South Poland, Kraków
[k.piotrowicz@iphils.uj.edu.pl], Institute of Geography and Spatial Management, Jagiellonian University Grodzka 64, 31-044 Kraków, Poland