Abstract: Sunshine duration is an important characteristic of the inflow of solar radiation, one of a multitude of factors shaping the climate conditions of a given area. Based on the data from 31 stations from the years 1971–2018, the spatial diversity of the totals of annual and seasonal sunshine duration is presented. In order to analyse the long-term variability of this element, an additional analysis of long heliographic series from five stations in Poland is used. Furthermore, actual and relative sunshine duration and the number of days without sunshine are characterised. The mean annual sunshine duration from all stations was 1,647 h, while the relative one amounted to 37%. The maximum occurred in 2018 and was, respectively, 2,069 h and 46%; the minimum was found in 1980 (1,275 h and 28%). As the latitude increases, the annual totals of sunshine duration, as well as the monthly totals in the summer and the warm half of the year increase. In the winter and the cold half of the year, sunshine duration decreases from the south to the north. The course of the annual totals of sunshine duration in Poland shows changes similar to those occurring in other parts of Europe, with pronounced periods of “global dimming” and “global brightening”. In the years 1971–2018, at all stations there is a statistically significant growing trend in actual and relative sunshine duration, more strongly expressed in the western than the eastern part of the country, and a decrease in the number of days without sunshine. An analysis of long heliographic series confirmed the high multi-annual variability of sunshine duration in Poland and showed the periods of decreases and increases in sunshine duration also at the turn of the nineteenth and twentieth centuries, and in the first half of the twentieth century, although not as pronounced as the periods of “global dimming” and “global brightening”.
Publication Year: 2021
Publication Date: 2021-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 1
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