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the amount of the sky covered by clouds. Cloudiness is determined visually. The extent of cloud formation is measured on a 10-point scale, with a value of 0 corresponding to a cloudless sky and 10 to complete cloud cover. The shape of the clouds is determined according to an international cloud classification.
Cloudiness is one of the most important factors characterizing weather and climate. In the winter and at night, cloudiness impedes the decrease in the temperature of the earth’s surface and the layer of air near the ground as a result of the reduction of radiation into outer space. In the summer and in the daytime, cloudiness lessens the heating of the earth’s surface by the sun’s rays, moderating the climate within continents.