From Big Medical Encyclopedia

CLIMATE — the long-term mode of weather inherent to this or that area which is defined by the natural sequence of meteorological processes. Weather is called the condition of weather conditions at present (set of a radiant energy, space radiation, atmospheric pressure, temperature and air humidity, the direction and speed of wind, clouds, fog, rainfall, aero chemical, electric and magnetic phenomena in the atmosphere).

Formation of weather is caused by interaction of all or the most part of these factors and the phenomena, and also features of the spreading Earth's surface (a relief, a vegetable cover, water spaces, etc.). Weather on limited sites of this or that climatic zone is called a microclimate (e.g., the park, the beach, etc.).

Condition of weather and To. in sublayers of the atmosphere is defined by network meteorol, stations. Studying of an upper atmosphere is carried out by means of artificial Earth satellites, radiosondes, spheres pilots and so forth, and also on direct observations from the Earth's surface.

The main lines of climate depend on a number of so-called climate factors: radiation balance of Earth (intensity and an orientation of flows of a radiant energy in the atmosphere, various at different latitudes and at different times years, month or days), circulation of the atmosphere, the hydrosphere and properties of the spreading surface. The radiation balance of Earth is understood as a ratio of arrival to Earth and removals of flows of a radiant energy of the Sun from it and heat energy of Earth. Circulation of the atmosphere — movement of air masses owing to interaction of moving and stationary areas low (cyclones) and high (anti-cyclones) pressure.

In the course of their interaction on limits of the section pressure differences called by atmospheric fronts are created. These fronts are followed by jump meteorol. factors and phenomena. Warm rainy cloudy weather is inherent to a cyclone with the passing warm front; at a cyclone with the passing cold front the broken-off cloudiness, downpours, strong wind are observed. In a zone of an anti-cyclone formation of frontal zones. it is limited, the central part it is characterized by clear or slightly overcast weather, windless or with light breezes.

Atmospheric circulation depends on change of radiation balance of Earth, periodic within a year. During the cold period of year cyclones arise more often over the ocean, anti-cyclones — over the land; the main atmospheric fronts are generally displaced in the summer to the North, in the winter — to the South. These global changes in atmospheric circulation affect also the major properties K. areas.

Atmospheric circulation is defined also physical. structure of the area. With increase in height pressure of air above sea level goes down, the content in it of oxygen decreases, but goes down as well degree of impurity carbonic acid, carbon monoxide and other gases and dust, ionization of air (light negative aeroions prevail) increases, tension of solar radiation with increase in intensity of its short-wave part increases. In this regard the content in air of ozone increases. In mountains of size of direct solar radiation change depending on orientation of their slopes and time of day. The mountainous terrain influences also circulation of the atmosphere and defines this or that type of weather not only in the most mountain district, but also on the adjacent plain: on the windward side of the ridge upflows of air masses with strengthening of cloudiness and loss of rainfall, on lee side — the descending air currents with temperature increase, decrease in cloudiness and reduction of rainfall are formed (hair dryers). Through high mountains the ascending cold flows usually do not pass, flowing round them and creating the conditions of a microclimate in valleys of the rivers and gorges.

Over big water spaces in warm season air temperature in the afternoon below, than over the land, and less heated air directs from water to the coast — day breezes, at night this movement has the opposite direction — night breezes. The same condition of air is observed in warm season between the wood and the field, in mountain valleys, etc. At the increased stability of sublayers of the troposphere over large water basins in summer days increase in hours of sunshine is noted, cloudiness, rainfall increases in the winter, there are heavy winds (napr, districts of the Baltic and White seas, Kamchatka, some districts of the Black Sea coast of the Caucasus), During the cold periods of year open water surfaces at the expense of warm currents cause warming in nearby districts of sushi. Over such spaces and near them air is pure and contains bigger amount of oxygen and is more ionized. High ionization is caused by crushing of water particles a surf about coastal stones — so-called balloelectric effect. The same condition of air is observed at the mountain rivers and falls (see. Aeroionization ). Snow cover in moderate and high latitudes protects the earth from frost penetration, interferes with bystry increase of temperature owing to a big heat input on thawing of snow in the spring. Features of various areas — mountain, seaside, with climate of deserts, etc. — are considered at the direction of patients on resorts (see).

Character of the spreading Earth's surface significantly influences distribution of radiation balance: in a zone of deserts and steppes weather with steady high temperatures forms, in areas with large forests the increased relative humidity of air and more frequent rainfall is noted. In formation of weather the significant role is played by dynamic turbulence of air (the disorder hashing of its warm and cold streams). In the cities and large industrial centers air to a large extent (in comparison with rural districts) is contaminated by dust, smoke, the condensed water vapor which, mixing up with dust, smoke and gases, can turn into city fog (smog) is more intensively formed here; circulation of sublayers of the atmosphere at the same time is weakened. Concentration of heavy positively charged aeroions grows, the amount of oxygen decreases; all this considerably worsens composition of air. In the USSR gardening of the cities, a construction of fountains, coloring of houses in lighter of tone, etc. improve the device of dymoulovitel, treatment facilities, carrying out of many large industrial facilities for city boundaries meteorol, the mode of the city and by that improve it To.; resorts and areas for rest of the population are carefully protected, the legislative order approved security actions, are established zones of sanitary protection (see), the areas promoting preservation in a natural look and air over it, land and underground natural to lay down. factors.

Climate changes without intervention of the person happen only within geological eras, in present period these changes are very insignificant. Nevertheless throughout a span about 50 years on a global scale it is possible to observe some changes K. Tak, in the first half of 20 century warming of climate of the planet was noted a nek-swarm, cyclonic activity and exchange of air masses between low and high latitudes amplified, intensity of circulation of the atmosphere changed. It is suggested that the last depends on change of intensity of flows of short-wave radiation of the Sun. The transformations which are carried out by the person in various areas of Earth (planting of forest strips, drainage and irrigation of the territory) have only partial and relative influence on To. generally due to changes of the hydrothermal modes; at the same time there are corresponding shifts of local weather and other microclimatic indicators of this district.

On climatic division into districts of Earth of the territory with rather homogeneous conditions To. are allocated in belts, zones and areas. On the division into districts offered by B. P. Alisov (1950) and oriented to features of the general circulation of the atmosphere the following main belts are allocated: equatorial To. — within the equatorial area with the lowered atmospheric pressure (a so-called equatorial depression); passatny — on both sides of the equatorial area with the steady mode of east winds over oceans; To. tropical deserts which corresponds To. areas of oceanic trade winds; Mediterranean — with hot summer and in the cool winter with rains; dry subtropics; cold deserts; sea; midlatitudes; monsoonal midlatitudes; subarctic region; Arctic basin; Antarctica.

At climatic division into districts of extensive territories various classifications, including A. A. Grigoriev and M. I. Budyko's classification (1959) are used. The classification scheme of Earth offered by L. S. Berg (1952) considers, except synoptic data, a landscape factor. Geographical belts and zones of Earth are presented on tsvetn, the tab., Art. 464.

Properties K. exert a great influence on a human body; it is carried out by influence of solar radiation, aero volumetric factors, atmospheric pressure, the gigrotermichesky and wind mode, a condition of electric field of Earth, ionization, natural radioactivity, etc.

Influence on a human body of climatic and weather factors, methods of their use in to lay down. - the prof. the purposes, character of various natural irritants, mechanisms excited by them fiziol, reactions and patol of shifts in a human body, and also measures of the prevention patol, reactions studies climatology medical (see), and also its separate sections — klimatopatologiya (see), climatotherapy (see), climatophysiology (see).

Bibliography: Alisov B. P. Climatic areas of foreign countries, M., 1950, bibliogr.; Berg L. S. Fundamentals of climatology, L., 1938; Blyutgen I. Geography of climates, the lane with it., t. 1 — 2, M., 1973; Budyko M. I. Climate and life, L., 1971; Voyeykov A. I. Chosen compositions, t. 1, page 161, M. — L., 1948; To e p p e of N of Century. Fundamentals of climatology, the lane with it., M., 1938; Mezernitskiyp. G. Medical meteorology, Yalta, 1937; The Multivolume management of «Fundamentals of balneology», under the editorship of V. A. Alexandrov, t. 1 — 3, M., 1956 — 1958; The Environment and natural resources of the USSR, under the editorship of I. P. Gerasimov, etc., M., 1963 — 1972; Physical bases of the theory of climate and its modeling, the lane with English, under the editorship of A.S. Monin, L., 1977; Khromov S. P. Meteorology and climatology, L., 1964; Chubukov L. A. Complex climatology, M., 1949; Conrad U. Poliak L. W. Methods in climatology, Cambridge, 1950; G r i s o 1-1 e t H., Guilmet B. et Arlery R. Climatologie (m6thodes et pratiques), P., 1962; P^ guy Ch. P. Pr£cis de climatologie, river, 19§1.

L. A. Chubukov.