HEAT BALANCE OF THE EARTH
the balance of the Earth, the ratio of the income and consumption of energy (radiant and thermal) on the earth's surface, in the atmosphere and in the Earth-atmosphere system. The main source of energy for the vast majority of physical, chemical, and biological processes in the atmosphere, hydrosphere, and upper layers of the lithosphere is solar radiation; therefore, the distribution and ratio of the components of T. b. characterize its transformations in these shells.
T. b. are private formulations of the law of conservation of energy and are compiled for a section of the Earth's surface (T. b. of the earth's surface); for a vertical column passing through the atmosphere (T. b. atmosphere); for the same column passing through the atmosphere and the upper layers of the lithosphere or the hydrosphere (T. b. the Earth-atmosphere system).
Equation T. b. earth's surface: R + P + F0 + LE 0 is the algebraic sum of energy flows between an element of the earth's surface and the surrounding space. These streams include the radiation balance (or residual radiation) R - the difference between the absorbed short-wave solar radiation and the long-wave effective radiation from the earth's surface. Positive or negative value radiation balance compensated by multiple heat flows. Since the temperature of the earth's surface is usually not equal to the air temperature, a heat flux P arises between the underlying surface and the atmosphere. A similar heat flux F 0 is observed between the earth's surface and deeper layers of the lithosphere or hydrosphere. In this case, the heat flux in the soil is determined by molecular thermal conductivity, while in water bodies, heat transfer, as a rule, has a turbulent character to a greater or lesser extent. The heat flux F 0 between the surface of the reservoir and its deeper layers is numerically equal to the change in the heat content of the reservoir over a given time interval and the heat transfer by currents in the reservoir. Essential value in T. b. the surface of the earth's surface usually has a heat consumption for evaporation LE, which is defined as the product of the mass of evaporated water E and the heat of evaporation L. The value of LE depends on the moistening of the earth's surface, its temperature, air humidity and the intensity of turbulent heat transfer in the surface air layer, which determines the rate of transfer of water steam from the earth's surface to the atmosphere.
Equation T. b. atmosphere has the form: Ra + Lr + P + Fa D W.
T. b. atmosphere is composed of its radiation balance R a ; heat input or output Lr during phase transformations of water in the atmosphere (r is the sum of precipitation); the arrival or consumption of heat P, due to the turbulent heat exchange of the atmosphere with the earth's surface; the arrival or loss of heat F a caused by heat exchange through the vertical walls of the column, which is associated with ordered atmospheric movements and macroturbulence. In addition, in the equation T. b. atmosphere includes a term DW, equal to the change in heat content inside the column.
Equation T. b. systems Earth - atmosphere corresponds to the algebraic sum of the terms of the equations T. b. earth's surface and atmosphere. Components of T. b. the earth's surface and atmosphere for various areas the globe They are determined by meteorological observations (at actinometric stations, at special stations in the sky, and on meteorological satellites of the Earth) or by climatological calculations.
The average latitudinal values of the components of T. b. the earth's surface for the oceans, land and Earth, and T. b. atmospheres are given in tables 1, 2, where the values of the members of T. b. are considered positive if they correspond to the arrival of heat. Since these tables refer to average annual conditions, they do not include terms characterizing changes in the heat content of the atmosphere and upper layers lithosphere, since for these conditions they are close to zero.
For the Earth as a planet, together with the atmosphere, the scheme of T. b. shown in fig. A flux enters the unit surface of the outer boundary of the atmosphere solar radiation, equal to an average of about 250 kcal/cm 2 per year, of which about 167 kcal/cm 2 is absorbed by the Earth (arrow Q s in the figure). The earth's surface reaches short-wave radiation, equal to 126 kcal / cm 2 per year; 18 kcal/cm 2 per year of this amount is reflected, and 108 kcal/cm 2 per year is absorbed by the earth's surface (arrow Q). The atmosphere absorbs 59 kcal / cm 2 per year of short-wave radiation, that is, much less than the earth's surface. The effective long-wave radiation of the Earth's surface is 36 kcal/cm 2 per year (arrow I), so the radiation balance of the earth's surface is 72 kcal/cm 2 per year. The long-wave radiation of the Earth into the world space is equal to 167 kcal/cm 2 per year (arrow Is). Thus, the Earth's surface receives about 72 kcal / cm 2 per year of radiant energy, which is partially spent on the evaporation of water (circle LE) and partially returned to the atmosphere through turbulent heat transfer (arrow P).
Tab. one . - Heat balance of the earth's surface, kcal / cm 2 year
Latitude, degrees
Earth average
70-60 north latitude
0-10 south latitude
Earth as a whole
Data on the components of T. b. are used in the development of many problems of climatology, land hydrology, and oceanology; they are used to substantiate numerical models of climate theory and to empirically test the results of applying these models. Materials about T. b. play an important role in the study of climate change, they are also used in calculations of evaporation from the surface river basins, lakes, seas and oceans, in studies of the energy regime of sea currents, to study snow and ice covers, in plant physiology to study transpiration and photosynthesis, in animal physiology to study the thermal regime of living organisms. Data about T. b. were also used to study geographic zoning in the works of the Soviet geographer A. A. Grigoriev.
Tab. 2. - Heat balance of the atmosphere, kcal/cm2 year
Latitude, degrees
70-60 north latitude
0-10 south latitude
Earth as a whole
Lit.: Atlas of the heat balance of the globe, ed. M. I. Budyko. Moscow, 1963. Budyko M.I., Climate and life, L., 1971; Grigoriev A. A., Patterns of the structure and development of the geographical environment, M., 1966.
M. I. Budyko.
Great Soviet Encyclopedia, TSB. 2012
See also interpretations, synonyms, word meanings and what is EARTH HEAT BALANCE in Russian in dictionaries, encyclopedias and reference books:
- EARTH
AGRICULTURAL PURPOSE - land provided for the needs of agriculture or intended for these ... - EARTH in the Dictionary of Economic Terms:
RECREATIONAL PURPOSE - lands allocated in accordance with the established procedure, intended and used for organized mass recreation and tourism of the population. To them … - EARTH in the Dictionary of Economic Terms:
ENVIRONMENTAL PURPOSE - lands of reserves (with the exception of hunting); prohibited and spawning zones; lands occupied by forests that perform protective functions; other … - EARTH in the Dictionary of Economic Terms:
NATURAL RESERVE FUND - lands of nature reserves, natural monuments, natural (national) and dendrological, botanical gardens. The composition of the Z.p.-z.f. turn on land with … - EARTH in the Dictionary of Economic Terms:
DAMAGE - see DAMAGE TO THE EARTH ... - EARTH in the Dictionary of Economic Terms:
HEALTH PURPOSE - land plots with natural healing factors (mineral springs, deposits of therapeutic mud, climatic and other conditions), favorable ... - EARTH in the Dictionary of Economic Terms:
GENERAL - in cities, towns and rural areas settlements- land used as means of communication (squares, streets, alleys, ... - EARTH in the Dictionary of Economic Terms:
LAND PRICE - see LAND REGULATION PRICE… - EARTH in the Dictionary of Economic Terms:
SETTLEMENTS - see URBAN LAND ... - EARTH in the Dictionary of Economic Terms:
MUNICIPALIZATION - see MUNICIPALIZATION OF THE LAND ... - EARTH in the Dictionary of Economic Terms:
FOREST FUND - lands covered with forest, as well as. not covered with forest, but provided for the needs of forestry and forestry ... - EARTH in the Dictionary of Economic Terms:
HISTORICAL AND CULTURAL PURPOSE - lands on which (and in which) historical and cultural monuments, places of interest are located, including those declared ... - EARTH in the Dictionary of Economic Terms:
RESERVE - all lands not provided for ownership, possession, use and lease. include lands, ownership, possessions… - EARTH in the Dictionary of Economic Terms:
RAILWAY TRANSPORT - federal lands provided free of charge for permanent (unlimited) use to enterprises and institutions of railway transport for the implementation of assigned ... - EARTH in the Dictionary of Economic Terms:
FOR THE NEEDS OF DEFENSE - lands provided for the accommodation and permanent activities of military units, institutions, military educational institutions, enterprises and organizations of the Armed ... - EARTH in the Dictionary of Economic Terms:
URBAN - see URBAN LAND ... - EARTH in the Dictionary of Economic Terms:
WATER FUND - lands occupied by reservoirs, glaciers, swamps, with the exception of the tundra and forest-tundra zones, hydraulic and other water management facilities; a … - BALANCE in the Dictionary of Economic Terms:
LABOR RESOURCES - a balance of the availability and use of labor resources, compiled taking into account their replenishment and disposal, employment, productivity ... - BALANCE in the Dictionary of Economic Terms:
TRADING PASSIVE - see PASSIVE TRADING BALANCE… - BALANCE in the Dictionary of Economic Terms:
TRADING ACTIVE - see ACTIVE TRADING ... - BALANCE in the Dictionary of Economic Terms:
TRADING - see TRADING BALANCE; FOREIGN TRADE … - BALANCE in the Dictionary of Economic Terms:
CURRENT OPERATIONS - a balance showing the state's net exports, equal to the volume of exports of goods and services minus imports, with the addition of net ... - BALANCE in the Dictionary of Economic Terms:
CONSOLIDATED - see CONSOLIDATED BALANCE ... - BALANCE in the Dictionary of Economic Terms:
BALANCE - see BALANCE BALANCE ... - BALANCE in the Dictionary of Economic Terms:
ESTIMATED - see ESTIMATED ... - BALANCE in the Dictionary of Economic Terms:
SEPARATING - see SEPARATING BALANCE ... - BALANCE in the Dictionary of Economic Terms:
WORKING TIME - a balance that characterizes the resources of the working time of employees of the enterprise and their use on different types works. Presented as… - BALANCE in the Dictionary of Economic Terms:
PAYMENT CURRENT see CURRENT BALANCE ... - BALANCE in the Dictionary of Economic Terms:
PAYMENTS FOR CURRENT OPERATIONS - see BALANCE OF PAYMENTS FOR CURRENT OPERATIONS ... - BALANCE in the Dictionary of Economic Terms:
PAYMENT PASSIVE. see PASSIVE BALANCE OF PAYMENTS... - BALANCE in the Dictionary of Economic Terms:
FOREIGN TRADE PAYMENTS - see FOREIGN TRADE BALANCE OF PAYMENTS ... - BALANCE in the Dictionary of Economic Terms:
PAYMENT ACTIVE - see ACTIVE BALANCE OF PAYMENTS ... - BALANCE in the Dictionary of Economic Terms:
PAYMENT - see PAYMENT ... - BALANCE in the Dictionary of Economic Terms:
PAYMENTS FOR CLEARING SETTLEMENTS - the balance of non-cash settlements for payment obligations or mutual claims ... - BALANCE in the Dictionary of Economic Terms:
PASSIVE TRADING (PAYING) - see PASSIVE TRADING (PAYING) ... - BALANCE in the Dictionary of Economic Terms:
FIXED ASSETS - a balance sheet that compares cash fixed assets, taking into account their depreciation and disposal, and newly introduced funds ... - BALANCE in the Dictionary of Economic Terms:
INTER-BRANCH - see INTER-BRANCH ... - BALANCE in the Dictionary of Economic Terms:
MATERIAL - see MATERIAL ... - BALANCE in the Dictionary of Economic Terms:
LIQUIDATION - see LIQUIDATION ... - BALANCE in the Dictionary of Economic Terms:
INCOME AND EXPENSES - a financial balance sheet, in sections of which the sources and amounts of income and expenses are indicated for a certain period ... - BALANCE in big Soviet encyclopedia, TSB:
(French balance, literally - scales, from Latin bilanx - having two weight bowls), 1) balance, balancing. 2) A system of indicators that ... - EARTH
Old Russian regions formed near the old cities. Z., often for a very significant distance from the city, was the property of its inhabitants and always ... - BALANCE in encyclopedic dictionary Brockhaus and Euphron:
Accounting balance. In B.'s accounting, an equilibrium is established between debit and credit, and B.'s account is distinguished incoming, if commercial books are opened, and ... - BALANCE in the Encyclopedic Dictionary:
I a, pl. no, m. 1. The ratio of mutually related indicators of some activity, process. B. production and consumption. and the balance of trade...
The main source of energy for all processes occurring in the biosphere is solar radiation. The atmosphere surrounding the Earth weakly absorbs short-wave radiation from the Sun, which mainly reaches the earth's surface. Some of the solar radiation is absorbed and scattered by the atmosphere. The absorption of incident solar radiation is due to the presence of ozone in the atmosphere, carbon dioxide, water vapor, aerosols.[ ...]
Under the action of the incident solar flux, as a result of its absorption, the earth's surface heats up and becomes a source of long-wave (LW) radiation directed towards the atmosphere. The atmosphere, on the other hand, is also a source of DW radiation directed towards the Earth (the so-called atmospheric counter-radiation). In this case, mutual heat exchange occurs between the earth's surface and the atmosphere. The difference between the HF radiation absorbed by the earth's surface and the effective radiation is called the radiation balance. The transformation of the energy of HF solar radiation when it is absorbed by the earth's surface and the atmosphere, heat exchange between them constitute the heat balance of the Earth.[ ...]
The main feature of the radiation regime of the atmosphere is the greenhouse effect, which lies in the fact that HF radiation mostly reaches the earth's surface, causing it to heat up, and LW radiation from the Earth is delayed by the atmosphere, while reducing the heat transfer of the Earth into space. The atmosphere is a kind of heat-insulating shell that prevents the Earth from cooling. An increase in the percentage of CO2, H20 vapor, aerosols, etc. will enhance the greenhouse effect, which leads to an increase in the average temperature of the lower atmosphere and climate warming. The main source of thermal radiation of the atmosphere is the earth's surface.[ ...]
The intensity of solar radiation absorbed by the earth's surface and the atmosphere is 237 W/m2, of which 157 W/m2 is absorbed by the earth's surface, and 80 W/m2 by the atmosphere. The heat balance of the Earth is presented in general form in Fig. 6.15.[ ...]
The radiation balance of the earth's surface is 105 W/m2, and the effective radiation from it is equal to the difference between the absorbed radiation and the radiation balance and is 52 W/m2. The energy of the radiation balance is spent on the turbulent heat exchange of the Earth with the atmosphere, which is 17 W/m2, and on the process of water evaporation, which is 88 W/m2.[ ...]
The scheme of heat transfer of the atmosphere is shown in fig. 6.16. As can be seen from this diagram, the atmosphere receives thermal energy from three sources: from the Sun, in the form of absorbed HF radiation with an intensity of approximately 80 W/m2; heat from condensation of water vapor coming from the earth's surface and equal to 88 W/m2; turbulent heat exchange between the Earth and the atmosphere (17 W/m2).[ ...]
The sum of heat transfer components (185 W/m) is equal to the heat losses of the atmosphere in the form of DW radiation into outer space. An insignificant part of the incident solar radiation, which is significantly less than the given components of the heat balance, is spent on other processes occurring in the atmosphere.[ ...]
The difference in evaporation from the continents and the surfaces of the seas and oceans is compensated by the processes of mass transfer of water vapor through air currents and the flow of rivers flowing into the water areas of the globe.
The radiation balance is called the income-expenditure of radiant energy absorbed and emitted by the underlying surface, the atmosphere or the earth-atmosphere system for various periods of time (6, p. 328).
The input part of the underlying surface radiation balance R is made up of direct solar and diffuse radiation, as well as atmospheric counterradiation absorbed by the underlying surface. The expenditure part is determined by the loss of heat due to the intrinsic thermal radiation of the underlying surface (6, p. 328).
Radiation balance equation:
R=(Q+q) (1-A)+d-
where Q is the flux (or sum) of direct solar radiation, q is the flux (or sum) of scattered solar radiation, A is the albedo of the underlying surface, is the flux (or sum) of atmospheric counter-radiation, and is the flux (or sum) of the intrinsic thermal radiation of the underlying surface, e is the absorptive capacity of the underlying surface (6, p. 328).
The radiation balance of the earth's surface for the year is positive everywhere on Earth, except for the ice plateaus of Greenland and Antarctica (Fig. 5). This means that the annual influx of absorbed radiation is greater than the effective radiation for the same time. But this does not mean at all that the earth's surface is getting warmer every year. The excess of absorbed radiation over radiation is balanced by the transfer of heat from the earth's surface into the air by thermal conduction and during phase transformations of water (during evaporation from the earth's surface and subsequent condensation in the atmosphere).
Consequently, for the earth's surface there is no radiative equilibrium in the receipt and return of radiation, but there is a thermal equilibrium: the influx of heat to the earth's surface both by radiative and non-radiative ways is equal to its return by the same methods.
Heat balance equation:
where the value of the radiative heat flux is R, the turbulent heat flux between the underlying surface and the atmosphere is P, the heat flux between the underlying surface and the underlying layers is A, and the heat consumption for evaporation (or heat release during condensation) is LE (L is the latent heat of evaporation, E is the rate of evaporation or condensation) (4, p. 7).
In accordance with the arrival and consumption of heat in relation to the underlying surface, the components of the heat balance can have positive or negative values. In a long-term conclusion, the average annual temperature of the upper layers of soil and water of the World Ocean is considered constant. Therefore, the vertical and horizontal heat transfer in the soil and in the World Ocean as a whole can practically be equated to zero.
Thus, in the long-term derivation, the annual heat balance for the land surface and the World Ocean is made up of the radiation balance, heat losses for evaporation, and turbulent heat exchange between the underlying surface and the atmosphere (Figs. 5, 6). For individual parts of the ocean, in addition to the indicated components of the heat balance, it is necessary to take into account the transfer of heat by sea currents.
Rice. 5. The radiation balance of the Earth and the arrival of solar radiation for the year
The difference between absorbed solar radiation and effective radiation is the radiation balance, or residual radiation of the earth's surface (B). The radiation balance, averaged over the entire surface of the Earth, can be written as the formula B = Q * (1 - A) - E eff or B = Q - R k - E eff. Figure 24 shows the approximate percentage of different types of radiation involved in the radiation and heat balance. It is obvious that the surface of the Earth absorbs 47% of all the radiation that has arrived on the planet, and the effective radiation is 18%. Thus, the radiation balance, averaged over the surface of the entire Earth, is positive and amounts to 29%.
Rice. 24. Scheme of radiation and heat balances of the earth's surface (according to K. Ya. Kondratiev)
The distribution of the radiation balance over the earth's surface is highly complex. Knowledge of the patterns of this distribution is extremely important, since under the influence of residual radiation the temperature regime of the underlying surface and the troposphere and the Earth's climate as a whole are formed. Analysis of maps of the radiation balance of the earth's surface for the year (Fig. 25) leads to the following conclusions.
The annual sum of the radiation balance of the Earth's surface is almost everywhere positive, with the exception of the ice plateaus of Antarctica and Greenland. Its annual values zonally and regularly decrease from the equator to the poles in accordance with the main factor - total radiation. Moreover, the difference in the values of the radiation balance between the equator and the poles is more significant than the difference in the values of the total radiation. Therefore, the zonality of the radiation balance is very pronounced.
The next regularity of the radiation balance is its increase during the transition from land to the ocean with discontinuities and mixing of isolines along the coast. This feature is better expressed in the equatorial-tropical latitudes and gradually smoothes out to the polar ones. The greater radiation balance over the oceans is explained by the lower water albedo, especially in the equatorial-tropical latitudes, and the reduced effective radiation due to the lower temperature of the Ocean surface and the significant moisture content of the air and cloudiness. Due to the increased values of the radiation balance and the large area of the Ocean on the planet (71%), it is he who plays the leading role in the thermal regime of the Earth, and the difference in the radiation balance of the oceans and continents determines their constant and deep mutual influence on each other at all latitudes.
Rice. 25. Radiation balance of the earth's surface for the year [MJ / (m 2 X year)] (according to S. P. Khromov and M. A. Petrosyants)
Seasonal changes in the radiation balance in the equatorial-tropical latitudes are small (Fig. 26, 27). This results in small fluctuations in temperature throughout the year. Therefore, the seasons of the year are determined there not by the course of temperatures, but by the annual rainfall regime. In extratropical latitudes, there are qualitative changes in the radiation balance from positive to negative values during the year. In summer, over vast expanses of temperate and partly high latitudes, the values of the radiation balance are significant (for example, in June on land near the Arctic Circle they are the same as in tropical deserts) and its fluctuations in latitudes are relatively small. This is reflected in the temperature regime and, accordingly, in the weakening of the interlatitudinal circulation during this period. In winter, over large expanses, the radiation balance is negative: the line of zero radiation balance of the coldest month passes over the land approximately along 40 ° latitude, over the oceans - along 45 °. Different thermobaric conditions in winter lead to the activation of atmospheric processes in temperate and subtropical latitude zones. The negative radiation balance in winter in temperate and polar latitudes is partly compensated by the influx of heat with air and water masses from the equatorial-tropical latitudes. In contrast to low latitudes in temperate and high latitudes, the seasons of the year are determined primarily by thermal conditions that depend on the radiation balance.
Rice. 26. Radiation balance of the earth's surface for June [in 10 2 MJ / (m 2 x M es.) |
In the mountains of all latitudes, the distribution of the radiation balance is complicated by the influence of height, duration of snow cover, insolation exposure of slopes, cloudiness, etc. In general, despite the increased values of total radiation in the mountains, the radiation balance is lower there due to the albedo of snow and ice, an increase in the proportion of effective radiation and other factors.
The Earth's atmosphere has its own radiation balance. The arrival of radiation into the atmosphere is due to the absorption of both short-wave solar radiation and long-wave terrestrial radiation. Radiation is consumed by the atmosphere with counter radiation, which is completely compensated by terrestrial radiation, and due to outgoing radiation. According to experts, the radiation balance of the atmosphere is negative (-29%).
In general, the radiation balance of the Earth's surface and atmosphere is 0, i.e., the Earth is in a state of radiative equilibrium. However, the excess of radiation on the Earth's surface and its lack in the atmosphere make one ask the question: why, with an excess of radiation, the Earth's surface does not incinerate, and the atmosphere, with its deficiency, does not freeze to a temperature absolute zero? The fact is that between the surface of the Earth and the atmosphere (as well as between the surface and deep layers of the Earth and water) there are non-radiative methods of heat transfer. The first one is molecular thermal conductivity and turbulent heat transfer (H), during which the atmosphere is heated and heat is redistributed in it vertically and horizontally. The deep layers of the earth and water are also heated. The second is active heat exchange, which occurs when water passes from one phase state to another: during evaporation, heat is absorbed, and during condensation and sublimation of water vapor, the latent heat of vaporization (LE) is released.
It is non-radiative methods of heat transfer that balance the radiation balances of the earth's surface and atmosphere, bringing both to zero and preventing overheating of the surface and supercooling of the Earth's atmosphere. The earth's surface loses 24% of radiation as a result of water evaporation (and the atmosphere, respectively, receives the same amount due to subsequent condensation and sublimation of water vapor in the form of clouds and fogs) and 5% of radiation when the atmosphere is heated from the earth's surface. In total, this amounts to the very 29% of radiation that is excessive on the earth's surface and which is lacking in the atmosphere.
Rice. 27. Radiation balance of the earth's surface for December [in 10 2 MJ / (m 2 x M es.)]
Rice. 28. Components of the heat balance of the earth's surface in the daytime (according to S. P. Khromov)
The algebraic sum of all incomes and expenditures of heat on the earth's surface and in the atmosphere is called the heat balance; the radiation balance is thus the most important component of the heat balance. The equation for the heat balance of the earth's surface has the form:
B – LE – P±G = 0,
where B is the radiation balance of the earth's surface, LE is the heat consumption for evaporation (L is the specific heat of evaporation, £ is the mass of evaporated water), P is the turbulent heat exchange between the underlying surface and the atmosphere, G is the heat exchange with the underlying surface (Fig. 28). The loss of surface heat for heating the active layer during the day and summer is almost completely compensated by its return from the depths to the surface at night and in winter, therefore, the average long-term annual temperature of the upper layers of soil and water of the World Ocean is considered constant and G for almost any surface can be considered equal to zero. Therefore, in the long-term conclusion, the annual heat balance of the land surface and the World Ocean is spent on evaporation and heat exchange between the underlying surface and the atmosphere.
The distribution of the heat balance over the Earth's surface is more complex than the radiative one, due to numerous factors affecting it: cloudiness, precipitation, surface heating, etc. At different latitudes, the heat balance values differ from 0 in one direction or another: at high latitudes it negative, and in low - positive. The lack of heat in the northern and southern polar regions is compensated by its transfer from tropical latitudes mainly with the help of ocean currents and air masses, thereby establishing thermal equilibrium between different latitudes of the earth's surface.
The heat balance of the atmosphere is written as follows: –B + LE + P = 0.
It is obvious that the mutually complementary thermal regimes of the Earth's surface and atmosphere balance each other: all solar radiation entering the Earth (100%) is balanced by the loss of Earth's radiation due to reflection (30%) and radiation (70%), therefore, in general, thermal The balance of the Earth, like the radiative one, is equal to 0. The Earth is in radiant and thermal equilibrium, and any violation of it can lead to overheating or cooling of our planet.
The nature of the heat balance and its energy level determine the features and intensity of most of the processes occurring in the geographic envelope, and above all the thermal regime of the troposphere.
By absorbing the radiant energy of the Sun, the Earth itself becomes a source of radiation. However, the radiation of the Sun and the radiation of the Earth are essentially different. Direct, scattered and reflected solar radiation has a wavelength ranging from 0.17 to 2-4 mk, and called shortwave radiation. The heated surface of the earth, in accordance with its temperature, emits radiation mainly in the wavelength range from 2-4 to 40 mk and called longwave. Generally speaking, both solar radiation and earth radiation have wavelengths of all wavelengths. But the bulk of the energy (99.9%) lies in the indicated wavelength range. The difference in the wavelengths of radiation from the Sun and the Earth plays a large role in the thermal regime of the earth's surface.
Thus, being heated by the rays of the Sun, our planet itself becomes a source of radiation. The long-wavelength, or thermal, rays emitted by the earth's surface, directed upwards, depending on the wavelength, either freely leave through the atmosphere, or are delayed by it. It has been established that the radiation of waves with a length of 9-12 mk freely escapes into interstellar space, as a result of which the surface of the earth loses some of its heat.
To solve the problem of the heat balance of the earth's surface and atmosphere, it was necessary to determine how much solar energy enters various regions of the Earth and how much of this energy is converted into other forms.
Attempts to calculate the amount of incoming solar energy on the earth's surface belong to the middle XIXcentury after the first actinometric instruments were created. However, only in the 1940s XXcentury, a broad development of the problem of studying the heat balance began. This was facilitated by the extensive development of the actinometric network of stations in the postwar years, especially in the period of preparation for the International Geophysical Year. In the USSR alone, the number of actinometric stations reached 200 by the beginning of the IGY. At the same time, the scope of observations at these stations was significantly expanded. In addition to measuring the short-wave radiation of the Sun, the radiation balance of the earth's surface was determined, that is, the difference between the absorbed short-wave radiation and the long-wave effective radiation of the underlying surface. At a number of actinometric stations, observations were organized on the temperature and humidity of the air at heights. This made it possible to calculate the heat costs for evaporation and turbulent heat transfer.
In addition to systematic actinometric observations carried out on a network of ground actinometric stations under the same type of program, in last years experimental work is being carried out to study radiation fluxes in the free atmosphere. To this end, systematic measurements of the balance of long-wave radiation at various heights in the troposphere are carried out at a number of stations using special radiosondes. These observations, as well as data on radiation fluxes in the free atmosphere, obtained with the help of free balloons, airplanes, geophysical rockets and artificial Earth satellites, made it possible to study the regime of the heat balance components.
Using the materials of experimental studies and widely applying computational methods, employees of the Main Geophysical Observatory named after. A. I. Voeikova T. G. Berlyand, N. A. Efimova, L. I. Zubenok, L. A. Strokina, K. Ya. Vinnikov and others under the leadership of M. I. Budyko in the early 50s for the first time a series of maps of heat balance components for the entire globe was constructed. This series of maps was first published in 1955. The published Atlas contained maps of the total distribution of solar radiation, radiation balance, heat consumption for evaporation and turbulent heat transfer on average for each month and year. In subsequent years, in connection with the receipt of new data, especially for the IGY period, the data on the components of the heat balance were refined and the new series maps that were published in 1963.
The heat balance of the earth's surface and the atmosphere, taking into account the inflow and release of heat for the Earth-atmosphere system, reflects the law of conservation of energy. To draw up an equation for the heat balance of the Earth - the atmosphere, one should take into account all the heat - received and consumed - on the one hand, by the whole Earth together with the atmosphere, and on the other hand, by the separately underlying surface of the earth (together with the hydrosphere and lithosphere) and the atmosphere. Absorbing the radiant energy of the Sun, the earth's surface loses part of this energy through radiation. The rest is spent on heating this surface and the lower layers of the atmosphere, as well as on evaporation. The heating of the underlying surface is accompanied by heat transfer to the soil, and if the soil is moist, then heat is also consumed for the evaporation of soil moisture.
Thus, the heat balance of the Earth as a whole consists of four components.
Radiation balance ( R). It is determined by the difference between the amount of absorbed short-wave radiation from the Sun and long-wave effective radiation.
Heat transfer in the soil, characterizing the process of heat transfer between the surface and deeper layers of the soil (BUT). This heat transfer depends on the heat capacity and thermal conductivity of the soil.
Turbulent heat transfer between the earth's surface and atmosphere (R). It is determined by the amount of heat that the underlying surface receives or gives off to the atmosphere, depending on the ratio between the temperatures of the underlying surface and the atmosphere.
Heat spent on evaporation( LE). It is determined by the product of the latent heat of vaporization ( L) for evaporation (E).
These components of the heat balance are interconnected by the following relationship:
R= A+ P+ LE
Calculations of the components of the heat balance make it possible to determine how the incoming solar energy is converted on the surface of the earth and in the atmosphere. In middle and high latitudes, the influx of solar radiation is positive in summer and negative in winter. According to calculations south of 39 ° N. sh. The balance of radiant energy is positive throughout the year. At a latitude of about 50° on the European territory of the USSR, the balance is positive from March to November and negative during the three winter months. At a latitude of 80°, a positive radiation balance is observed only in the period May-August.
According to calculations of the Earth's heat balance, the total solar radiation absorbed by the earth's surface as a whole is 43% of the solar radiation arriving at the outer boundary of the atmosphere. The effective radiation from the earth's surface is 15% of this value, the radiation balance is 28%, heat consumption for evaporation is 23%, and turbulent heat transfer is 5%.
Let us now consider some results of the calculation of the heat balance components for the Earth-atmosphere system. Here are four maps: total radiation for the year, radiation balance, heat costs for evaporation and heat costs for heating air by turbulent heat transfer, borrowed from the Atlas of the heat balance of the globe (edited by M. I. Budyko). From the map shown in Figure 10, it follows that the largest annual values of total radiation fall on the arid zones of the Earth. In particular, in the Sahara and Arabian deserts, the total annual radiation exceeds 200 kcal / cm 2, and in high latitudes of both hemispheres it does not exceed 60-80kcal / cm 2.
Figure 11 shows a map of the radiation balance. It is easy to see that at high and middle latitudes the radiation balance increases towards low latitudes, which is associated with an increase in total and absorbed radiation. It is interesting to note that, in contrast to the isolines of the total radiation, the isolines of the radiation balance break when moving from the oceans to the continents, which is associated with the difference in albedo and effective radiation. The latter are less for water surface, therefore, the radiation balance of the oceans exceeds the radiation balance of the continents.
The smallest annual amounts (about 60 kcal / cm 2) are characteristic of regions where cloudiness prevails, as well as in dry regions, where high values of albedo and effective radiation reduce the radiation balance. The largest annual sums of the radiation balance (80-90 kcal / cm 2) are characteristic of low-cloud, but relatively humid tropical forests and savannas, where the arrival of radiation, although significant, the albedo and effective radiation are greater than in the desert regions of the Earth.
The distribution of annual evaporation rates is shown in Figure 12. Heat consumption for evaporation, equal to the product of the evaporation rate and the latent heat of vaporization (LE), is determined mainly by the amount of evaporation, since the latent heat of vaporization under natural conditions varies within small limits and is on average equal to 600 feces per gram of evaporated water.
As follows from the above figure, evaporation from land mainly depends on heat and moisture reserves. Therefore, the maximum annual amounts of evaporation from the land surface (up to 1000 mm) take place in tropical latitudes, where significant thermal
resources are combined with great hydration. However, the oceans are the most important sources of evaporation. Its maximum values here reach 2500-3000 mm. At the same time, the greatest evaporation occurs in areas with relatively high temperatures. surface water, in particular in the zones warm currents(Gulf Stream, Kuro-Sivo, etc.). On the contrary, in the zones of cold currents, the evaporation values are small. In the middle latitudes there is an annual course of evaporation. At the same time, in contrast to land, the maximum evaporation on the oceans is observed in the cold season, when large vertical gradients of air humidity are combined with increased wind speeds.
The turbulent heat exchange of the underlying surface with the atmosphere depends on the radiation and moisture conditions. Therefore, the greatest turbulent heat transfer occurs in those areas of land where a large influx of radiation is combined with dry air. As can be seen from the map of annual values of turbulent heat transfer (Fig. 13), these are desert zones, where its value reaches 60 kcal / cm 2. The values of turbulent heat transfer are small in the high latitudes of both hemispheres, as well as in the oceans. The maximum annual values can be found in the zone of warm sea currents (more than 30 kcal / cm 2 year), where large temperature differences are created between water and air. Therefore, the greatest heat transfer on the oceans occurs in the cold part of the year.
The heat balance of the atmosphere is determined by the absorption of short-wave and corpuscular radiation from the Sun, long-wave radiation, radiant and turbulent heat transfer, heat advection, adiabatic processes, etc. Data on the arrival and consumption of solar heat are used by meteorologists to explain the complex circulation of the atmosphere and hydrosphere, heat and moisture circulation, and many other processes and phenomena occurring in the air and water shells of the Earth.
- Source-
Pogosyan, H.P. Atmosphere of the Earth / Kh.P. Poghosyan [and d.b.]. - M .: Education, 1970. - 318 p.
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