Cykliczne wahania opadów atmosferycznych w Polsce w latach 1861-1990

The purpose of the paper is to define the cyclical changes of precipitation in six localities in Poland during the period 1861-1990. The cyclical variability of this element of weather was identified with the use of the method of J. Boryczka, consisting in determination and verification of the dense spectra of oscillations - the true periods. Results of the study are in the majority of cases statistically significant. It was shown that precipitation is subject to the several years and a dozen years long cycles, the latter lasting approximately 11 and 12 years, to the cycle of approximately 30 years and the long-term cycles. The long-term cyclicity is the most differentiated within the area of Poland. The precipitation cycles contained in the spectra of oscillations of the consecutive 12-month sums and the sums for the four seasons, as well as for the year as a whole, have been compared with the cycles of solar activity. The comparison implies high similarity of the cycles of precipitation and solar activity. This may be the evidence for the proposition that the changes of solar activity are one of the essential factors determining variation of precipitation in the country. There is especially strong dependence for the approximately 11-year cycles of precipitation and the solar activity (see Table 8, R > 0.6).