Struktura czasowa usłonecznienia rzeczywistego na Nizinie Szczecińskiej w latach 2000-2004

The aim o f the studies was to characterize time structure of the real sunshine totals in the Szczecin Lowlands and frequency and variability of number of hours with the sun lasting > 4, > 6 and > 10 h in 2000-2004. The largest daily real sunshine total in the Szczecin Lowlands amounting to 6.6 hours occurs in the first ten days of May, whereas the lowest one, 0.8 h, in the third ten day period of December. During the calendar spring (March-May) a 40% larger number of hours with direct sun radiation is observed as compared to that in autumn (Sept. - Nov.). In March, June and September the real sunshine totals before the noon are larger than those in the afternoon, whereas in December there are no distinct differences between them. An average number of days with real sunshine lasting > 4, > 6 and > 10 h is respectively 141, 97 and 14 and its maximum occurs in May. In spring and summer the frequency of days with the above threshold values is approximate and it amounts on average to about 55, 40 and 10% respectively.