Cloud maps show the average cloud cover of an area at the time indicated in the map legend, expressed in percent (%) of sky cover. The cloud cover colour scale is usually from white to dark grey. For details, see the scale used for cloud meteograms. For cloud height, the colour scale ranges from white (high clouds) over light-dark grey (medium clouds) to red lines (low clouds). Our standard cloud levels are explained under Standards>Clouds.

The kind of the coverage depends on the type of cloud. Cirrus (veil) - clouds often cover the sky evenly: a coverage of 10% corresponds to isolated cloud strips; veils from starting around 50% cover, and become increasingly dense, so that at 100% coverage the sun is sometimes still visible as pale disk. With Cumulus (heap) clouds, the coverage corresponds usually to the distribution of the clouds: 10% corresponds to the presence of a few heap clouds; at 50% cover the sun is often hidden, and with 80% only few patches of blue sky are visible; 100% coverage are observed only in the proximity or in thunderstorms, and the sunlight can lose 70-98% of its irradiation depending upon cloud density.

Cloud maps can be combined with wind (streamlines), precipitation (colour scale) or other parameters (see examples displayed). See the legend of each map for details.