INSOLATION (Latin. insolatio, from insolare to expose in the sun) — the electromagnetic and corpuscular sunlight reaching the land surface. In narrow sense under And. understand inflow solar radiation (see) on a horizontal surface. Intensity And. is defined by height of the Sun over the horizon depending on the latitude of the place, the period of year, time of day and also cloudiness and transparency of the atmosphere. And. it consists of a straight line And. (i.e. a direct flow of sunshine) and disseminated (i.e. the sunshine reflected from any surfaces or particles of the atmosphere) radiation (see. Actinometry ). Intensity of a straight line And. it is expressed by amount of energy of the sunlight falling in unit of time on unit of the irradiated surface, perpendicular to sunshine. For absolute measurements of a straight line And. use pirgeliometra, for relative — actinometers. And. defines a thermal condition of the land surface, the atmosphere, natural illumination on Earth. Influencing circulation of the atmosphere of Earth and a moisture circulation, And. finally defines a condition of climate on Earth and in its certain districts.
Live organisms specifically use energy of sunlight. So, radiation in a visible range is the cornerstone sight (see). Due to radiant energy in an infrared range the possibility of maintenance of thermal balance with the environment is provided (see. Infrared radiation ). Energy ultraviolet radiation (see) helps a human body with production of vitamin D, promotes pigmental exchange, stimuliruyushche influences life activity of an organism. To some extent energy of solar radiation caused emergence of life on Earth (see. Life ).
Accounting of conditions And. it is necessary in agriculture, town planning, balneology etc. And. is the cornerstone heliations (see).
Bibliography: Galanin N. F. Radiant energy and its hygienic value, page 9, etc., L., 1969, bibliogr.; Parfyonov A. P. Physical remedies and resort factors, L., 1968.
G. V. Margulies.