Outline of features of the climate of Poznań in the second half of the 20th century in the light of average annual values of selected weather elements

Authors:

• Alojzy Woś

Abstract

The changeability of the climatic relationships has recently been considered one of the major issues of climatology. It is frequently believed that we are witnesses to a radical change of the climatic relations. It must not be forgotten, however, that the analysis of the climatic relations evolution is a very complex issue. The analysis of the contemporary: climatic changes involves two aspects: (1) the natural tendency of the climate to change, observed on the Earth since its early days and occurring in cycles and (2) the tendency of the climate to change as a result of the human activity, the intensity of which is difficult to predict (do we already perceive its effects on a global scale?), occurring as a linear trend. Upon investigating the selected parameters of the major weather components in the Poznań of the second half of the 20th century, special attention was paid to their mean annual values versus the extreme values. Groups of years were identified where the annual values of those parameters had been lower or higher than the average characteristic of the entire 50-year period. An attempt was also made to compare the parameters and their trends with the value of the NAO index which to a large extent explains the observed annual values of the analysed weather elements. Consequently, it may be assumed that the fluctuations of the annual values of the parameters under study occurring in Poznań indicate a clear relationship with the circulation factor, which had affected the climatic relationships in the past years.