Termiczne Pory Roku na Pomorzu Zachodnim w Stacji Geoekologicznej Zintegrowanego Monitoringu rodowiska Przyrodniczego w Storkowie w Latach 1987-2007

This article analyses the appearance of the thermic seasons of the year in West Pomerania in the Storkowo Geological Station. The interpretation and the description of the results were conducted on the basis of the measures of the daily mean air temperature in the years 1987-2007. The division of the year into six thermic seasons (according to Marecki, Romer and others) was applied with threshold temperature values of 0.0°C, 5.0°C, 15.0°C. Special attention was paid to the extreme dates of their occurrence as well as to their duration in time. The results of the research prove that the dates of the beginning and the end of the thermic seasons in West Pomerania in the Storkowo Geological Station are the same or approximate to the ones characteristic of Pomerania. The climate of the examined territory highly depends on the masses of air flowing over it. Polar mMaritime air coming from the North Atlantic Ocean is most frequently noticed, causing temperature decrease in the summer and warming in the winter. Consequently, this phenomenon leads to the reduction of frost periods and high frost periods. Less frequent arctic air masses - occurring mainly in the winter term - contribute to an abrupt drop of temperature and cause cold weather. The sudden heat radiation from the ground triggers off the formation of ground frost in the autumn and spring periods as well as frost in the winter. Moreover, the climate is influenced by morphological landform and its shaping, i.e., the location of the Station in the northern part of the chain of terminal moraines with exposition susceptible to the influence of oceanic circulation. Hydrologic factors - such as the presence of the Pars ta River and numerous lakes - contribute to the increase of air humidity and therefore the relaxation of thermic interdependency on the examined territory (decrease of the number of very hot days in the summer and very frosty ones in the winter). In addition, very close location to the Baltic Sea significantly modifies the thermic conditions of West Pomerania. Though the analysed territory doesn't abut on the sea, its influence is highly important, which is visible in the Storkowo Station. A delayed beginning of the spring and the summer is due to the freshening effect of maritime air which, in turn, has warming consequences on the examined territory in the autumn period and delays the beginning of this thermic season.