A five year data set of satellite cloud cover observations and a thirty year data set of surface cloud cover observations were compared over Europe. There is good agreement between the general characteristics of these two cloud climatologies. Differences between monthly means (January, April, July and October) of the two data sets were formed in 5" x 5" grid cells. These differences, regarding all grid points and months are less than half of one tenth of sky cover in 46 per cent of all cases.
The defining parameters (a and h) of the Beta distribution were calculated also for the months of January, April, July and October representing the four seasons. On the basis of a and h values, different cloud cover regions were determined over Europe and these were characterized by averaged curves of the Beta probability density functions. These regions correspond well to distinct areas of geographical environments, as well as to the regimes of the general circulation. Thus, the character of cloud conditions within these regions can be expressed in a numerical way by means of a and h parameters. KEY WORDS Comparison of salcllilc and surface observations Bcla distribution Cloud climatological regions 0 196-1 748/88/O40327-I 1S05.50 1988 by the Royal Meteorological Society