• Poland;
  • cloudiness;
  • cloud types;
  • empirical orthogonal functions


The study concerns research of the most important features of temporal and spatial structure of cloudiness variability in the area of Poland in the period 1971–2000 using the data from 41 synoptic stations. For all the stations the seasonal and annual values of total cloudiness were calculated, as well as the frequency of total cloudiness, cloud base heights and cloudiness in levels. The analysis by means of the empirical orthogonal functions made it possible to establish the dominant modes of the cloudiness variability in Poland. Mean annual and seasonal cloudiness can be described by means of no more than five dominating eigenvectors presenting the crucial role of circulation influence on the local cloudiness field. Copyright © 2008 Royal Meteorological Society