The radiation balance of the earth and the illumination of the sea surface. Solar, terrestrial and atmospheric radiation What proportion of sunlight is absorbed by the earth's surface

The radiation balance of the earth and the illumination of the sea surface. Solar, terrestrial and atmospheric radiation What proportion of sunlight is absorbed by the earth's surface

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1 TASKS Grade 8 Test round 1. The time at each moment of the day is the same at points located on the same meridian, called: A. Belt B. Decree C. Local D. Summer 2. In what geological era did such events as the appearance of mammals and birds occur , the appearance of the first flowering plants, the dominance of gymnosperms and reptiles: A. Archean B. Proterozoic C. Paleozoic D. Mesozoic 3. What proportion of sunlight is absorbed by the Earth's surface: A. 10% B. 30% C. 50% D. 70% 4. Which of the tectonic structures is characterized by a younger age: A. Russian platform B. West Siberian plate B. Aldan shield D. Folded areas of Kamchatka 5. The most salty sea washing the coast of Russia? A. Chernoye B. Japanese C. Baltic G. Azov 6. The Northern Sea Route starts from the port: A. Arkhangelsk B. Murmansk C. St. Petersburg G. Kaliningrad 7. A scientist from Yekaterinburg (IV belt) organized a webinar for his colleagues from other regions Russia Omsk (V-belt), St. Petersburg (II-belt) and Barnaul (VI-belt) at 14:00 Moscow time. For the participant from which city the webinar will start at 18:00 local time: A. From St. Petersburg B. From Yekaterinburg C. From Barnaul D. From Omsk 8. Specify a marine object not located off the coast of Russia: A. Bussol Strait V. Kerch Strait B. Gdansk Bay D. Riga Bay 9. Which of the following cities are located on the Volga River: A. Penza, Tolyatti V. Nizhny Novgorod, Kirov B. Cheboksary, Yoshkar-Ola G. Kazan, Ulyanovsk 10. Choose an answer, in which the listed peoples belong to the same language group: A. Buryats, Kalmyks, Khakasses B. Bashkirs, Chuvashs, Tatars B. Chechens, Ingush, Adyghes D. Mordva, Udmurts, Kumyks 11. What is the origin of such landforms as ozes and kams: A. Tectonic C. Karst B. Glacial D. Eolian 1

2 12. Reserves of this mineral natural resource in Kaliningrad region are estimated at more than 3 billion tons, 281 deposits have been explored. Its extraction is carried out mainly in the Nesterovsky and Polessky districts of the region. Its calorific value reaches 5000 kcal, although since 1982 its use as a fuel has been prohibited by law. This resource is supplied to many European countries. A. Torf B. Amber C. Gas D. Oil shale 13. During one of the speeches learned geographer V.V. Dokuchaev said: “I beg your pardon that I stopped at ... for a little longer than I expected, but this is because the latter is more expensive for Russia than any oil, any coal, more than gold and iron ores; in it is the age-old inexhaustible Russian wealth. What did V.V. Dokuchaev? A. Forest B. Chernozem C. Gas D. Ocean north to south, and in the mountains from the foot to the peaks ”: A. Natural and economic complexes C. Geographical regions B. Natural zones D. Landscapes 15. What natural phenomenon is referred to in I. Ryabtsev’s story “The Steppe Miracle”. “For the second week in the steppe, July, the most burning, the most merciless, ruled. He licked shallow rivers to the bottom, dispersed animals and birds somewhere. Burnt grass crunched underfoot, crumbling into dust; the bare earth was cut with deep cracks in which snakes, lizards and spiders lay. Wherever you look, there are two colors everywhere: ash-yellow and brown. Against this gloomy background, deceptively pleasing to the eye, leafless bushes of camel's thorn, the only plant in which life still flickered, were scattered in aquamarine strokes. Sparkling under the sun, here and there, in sugar-white patches, lies salt that has come out on dead bald patches. This is a beautiful and at the same time a terrible sight» A. Bora B. Fen V. Sukhovey G. Samum 16. Atmospheric whirlwind of huge (hundreds to several thousand kilometers) diameter with low air pressure in the center. Air circulates counterclockwise in the northern hemisphere and clockwise in the southern hemisphere A. Tornado B. Cyclone C. Anticyclone D. Tornado 17. Indicate the answer in which all rivers belong to the same river system A. Don, Voronezh, Oka C. Volga, Kama, Svir B. Amur, Argun, Shilka G. Ob, Irtysh, Khatanga 18. Which natural resource combines the following deposits: Shtokmanovskoye, Medvezhye, Zapolyarnoye, Astrakhanskoye. A. Oil C. Gas B. Hard coal D. Potassium salt 2

3 19. Determine which peninsulas of Russia are characterized by the following climatic features: A. The climate is very cold, sharply continental. The average temperature in January is t minus ºС, and in July º. Spring begins in mid-June, and in August the average daily temperature drops below zero. Precipitation is from 120 to 140 mm per year. The eastern part of the peninsula is completely covered with a glacier. B. The climate is maritime, more severe in the west than in the east. The annual rainfall is from 600 to 1100 mm. The highest parts of the mountains carry modern glaciers. One of the striking features of the climate of the peninsula is strong winds, hurricanes and storms in all areas of the region. In the winter months, winds blowing with a force of over 6 m/s. B. One of the "warmest" regions of the Earth's subarctic belt. In the northern part of the peninsula, it is warmer than in the southern part, which is due to the influence of a warm current. The average temperature in winter is from -9ºС on the coast to -13ºС in the center of the peninsula. The frost-free period lasts an average of 120 days in a narrow coastal strip of land, shortens as you move away from the seas to 60 days, and on the tops of the mountain range the temperature does not drop below 0ºС for less than 40 days a year. 1. Kamchatka Peninsula 2. Kola Peninsula 3. Taimyr Peninsula 20. Which of the following is an example environmental management? A. Creation of forest shelterbelts in the steppe zone B. Drainage of swamps in the upper reaches of rivers C. Transfer of thermal power plants from natural gas to coal D. Longitudinal plowing of slopes 21. Preparing an advertising brochure for a travel company, the artist tried to depict various exotic corners of the globe. Find two artist's mistakes. A. A Peruvian leads a llama B. A Tuareg drives a team of reindeer C. A Thai rides tourists on a yak D. A Hindustani plows a field on a buffalo carrying with it a mass of stones is: A. Landslide B. Flood C. Sel D. Moraine 23. When did the mainland Pangea split? A. 10 million years ago B. 50 million years ago C. 250 million years ago D. 500 million years ago 24. In 1831, the English polar explorer John Ross made a discovery in the Canadian Arctic archipelago, and 10 years later his nephew James Ross reached its antipode in Antarctica. What kind of discovery are you talking about? A. North magnetic pole B. Arctic circle C. South magnetic pole D. North geographic plus 3

4 25. Set the correspondence: the top of the mountain - the country 1. Toubkal A.Andy a. Russia 2. Aconcagua B. Atlas b. USA 3. Elbrus V. Cordillera c. Argentina 4. McKinley D. Caucasus D. Morocco 26. Monsoon rains often cause floods on the rivers: A. Ob, Indigirka B. Rein, Vistula V. Danube, Yenisei G. Yangtze, Amur 27. Which of the countries is located on different continents? A. Kazakhstan C. Egypt B. Turkey; Russia 28. Establish the correspondence of the proposed concepts to various spheres of the Earth 1. Black smokers A. Lithosphere 2. Halo B. Hydrosphere 3. El Niño C. Biosphere 4. Nekton D. Atmosphere 29. Choose a lake with minimal salinity. А. 40.4

5 Grade 8 Analytical Round Task 1. Use the topographic map to complete the task. 1) Determine the scale of the map if the distance from point A to point B is 900 m. Write down the answer in the form of a numerical and named scale 2) Determine the azimuth and direction in which you need to go from the school to the well. What distance must be covered? 3) Determine the amplitude of the absolute heights of the area 4) In what direction does the river flow. Squirrel? 5) Assess which of the sites indicated on the map by numbers 1 and 2 is better to choose for the construction of a wind power plant designed for emergency power supply of a school in the village of Verkhnee. Give at least two reasons. Maximum score 13.5

6 Task 2. Based on the proposed fragments of satellite images, determine the origin of the lake basins. Give examples of the names of lakes or areas of their distribution. Record your answer in the table Space image number Origin of the lake basin Maximum points 10. An example of a lake or area of ​​​​distribution Task 3. Match the definitions with geographical phenomena and name the continents (or parts of the world) on which these phenomena are observed. A. Pororoka B. Mistral V. Kum G. Scrab D. Atoll 1. Thickets of low-growing evergreen xerophytic shrubs in the tropics and subtropics. 2. Ring-shaped coral island in the form of a narrow ridge surrounding a shallow lagoon. 3. A tidal wave moving upstream from the mouth of a river 4. A sandy desert 5. A cold northwest wind blowing on the country's southern coast, called the Côte d'Azur. Record your answers in a table. Phenomenon Definition number Continent or part of the world 6

7 A B C D E Maximum points 10. Task 4. There are cities on earth where in January people do not need fur coats, fur hats and gloves. From the list, select those cities whose residents do not need winter clothes in January. Why are the residents of each of the cities you have chosen so lucky? Luanda, Managua, Cairo, Stockholm, Bucharest Answer: The maximum number of points is 6. Problem 5. The guys - Finns from a small village located near the Arctic Circle, wanted to correspond with schoolchildren from other countries living with them on the same parallel. They sent letters to Russia, Canada, Sweden. Which countries did the guys forget to write to? What means of transport can deliver a letter there? Answer: The maximum number of points is 6. Task 6. Fill in the gaps in geographical description Nizhny Novgorod region. The Nizhny Novgorod region is located in central Russia, on the (1) plain, in natural zones (2), (3), (4). Funnels, caves, lakes (5) origin are widespread in the relief of the region. The area lies within the (6) climatic zone. The main water arteries are four rivers (7, 8, 9, 10) belonging to the basin (11) of the sea. In the north of the region, (12) soils are zonal, and (13) soils are common in the southeast. Most ancient city Nizhny Novgorod region (14) stands on the left bank of the Volga and is famous for folk crafts. And in the city of Semenov, 300-year-old traditions of folk art craft continue (15). The maximum number of points is 15. Answer:


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Solar energy equal to 100% arrives at the upper boundary of the atmosphere.

Ultraviolet radiation, accounting for 3% of 100% of incoming sunlight, for the most part absorbed by the ozone layer in the upper atmosphere.

About 40% of the remaining 97% interacts with clouds - of which 24% is reflected back into space, 2% is absorbed by clouds and 14% is scattered, reaching the earth's surface as scattered radiation.

32% of incoming radiation interacts with water vapor, dust and haze in the atmosphere - 13% of this is absorbed, 7% is reflected back into space and 12% reaches the earth's surface as scattered sunlight (Fig. 6)

Rice. 6. Radiation balance of the Earth

Therefore, out of the initial 100% of solar radiation on the Earth's surface, 2% of direct sunlight and 26% of diffused light reach.

Of this total, 4% is reflected from the earth's surface back to space, and the total reflection to space is 35% of the incident sunlight.

Of the 65% of the light absorbed by the Earth, 3% comes from the upper atmosphere, 15% from the lower atmosphere, and 47% from the Earth's surface - the ocean and land.

In order for the Earth to maintain thermal equilibrium, 47% of all solar energy that passes through the atmosphere and is absorbed by land and sea must be given off by land and sea back into the atmosphere.

The visible part of the spectrum of radiation entering the surface of the ocean and creating illumination consists of solar rays that have passed through the atmosphere (direct radiation) and some of the rays scattered by the atmosphere in all directions, including to the surface of the ocean (diffuse radiation).

The ratio of the energy of these two light fluxes falling on a horizontal landing depends on the height of the Sun - the higher it is above the horizon, the greater the proportion of direct radiation

The illumination of the sea surface under natural conditions also depends on the cloud cover. High and thin clouds cast down a lot of scattered light, due to which the illumination of the sea surface at average heights of the Sun can be even greater than with a cloudless sky. Dense, rain clouds dramatically reduce illumination.

The light rays that create the illumination of the sea surface undergo reflection and refraction at the water-air boundary (Fig. 7) according to the well-known physical law of Snell.

Rice. 7. Reflection and refraction of a beam of light on the surface of the ocean

Thus, all light rays falling on the surface of the sea are partially reflected, refracted and enter the sea.

The ratio between refracted and reflected light fluxes depends on the height of the Sun. At a height of the Sun 0 0, the entire light flux is reflected from the surface of the sea. With an increase in the height of the Sun, the proportion of the light flux penetrating into the water increases, and at a Sun height of 90 0, 98% of the total flux incident on the surface penetrates into the water.

The ratio of the light flux reflected from the surface of the sea to the incident light is called sea ​​surface albedo . Then the albedo of the sea surface at a Sun height of 90 0 will be 2%, and for 0 0 - 100%. The sea surface albedo is different for direct and diffuse light fluxes. The albedo of direct radiation essentially depends on the height of the Sun, the albedo of scattered radiation practically does not depend on the height of the Sun.

LECTURE 2.

SOLAR RADIATION.

Plan:

1. The value of solar radiation for life on Earth.

2. Types of solar radiation.

3. Spectral composition of solar radiation.

4. Absorption and dispersion of radiation.

5.PAR (photosynthetically active radiation).

6. Radiation balance.

1. The main source of energy on Earth for all living things (plants, animals and humans) is the energy of the sun.

The sun is a gas ball with a radius of 695300 km. The radius of the Sun is 109 times greater than the radius of the Earth (equatorial 6378.2 km, polar 6356.8 km). The sun is composed mainly of hydrogen (64%) and helium (32%). The rest account for only 4% of its mass.

Solar energy is the main condition for the existence of the biosphere and one of the main climate-forming factors. Due to the energy of the Sun, air masses in the atmosphere are constantly moving, which ensures the constancy of the gas composition of the atmosphere. Under the action of solar radiation, a huge amount of water evaporates from the surface of reservoirs, soil, plants. Water vapor carried by the wind from the oceans and seas to the continents is the main source of precipitation for land.

Solar energy is an indispensable condition for the existence of green plants, which convert solar energy into high-energy organic substances during photosynthesis.

The growth and development of plants is a process of assimilation and processing of solar energy, therefore, agricultural production is possible only if solar energy reaches the Earth's surface. A Russian scientist wrote: “Give the best cook as much fresh air, sunlight, a whole river of clean water as you like, ask him to prepare sugar, starch, fats and grains from all this, and he will think that you are laughing at him. But what seems absolutely fantastic to a person is accomplished without hindrance in the green leaves of plants under the influence of the energy of the Sun. It is estimated that 1 sq. a meter of leaves per hour produces a gram of sugar. Due to the fact that the Earth is surrounded by a continuous shell of the atmosphere, the sun's rays, before reaching the surface of the earth, pass through the entire thickness of the atmosphere, which partially reflects them, partially scatters, i.e. changes the amount and quality of sunlight entering the earth's surface. Living organisms are sensitive to changes in the intensity of illumination created by solar radiation. Due to different reactions according to the intensity of illumination, all forms of vegetation are divided into light-loving and shade-tolerant. Insufficient illumination in crops causes, for example, a weak differentiation of straw tissues of grain crops. As a result, the strength and elasticity of tissues decrease, which often leads to lodging of crops. In thickened corn crops, due to low illumination by solar radiation, the formation of cobs on plants is weakened.

Solar radiation affects chemical composition agricultural products. For example, the sugar content of beets and fruits, the protein content in wheat grain directly depend on the number sunny days. The amount of oil in the seeds of sunflower, flax also increases with the increase in the arrival of solar radiation.

Illumination of the aerial parts of plants significantly affects the absorption of nutrients by the roots. Under low illumination, the transfer of assimilates to the roots slows down, and as a result, biosynthetic processes occurring in plant cells are inhibited.

Illumination also affects the emergence, spread and development of plant diseases. The period of infection consists of two phases, differing from each other in response to the light factor. The first of them - the actual germination of spores and the penetration of the infectious principle into the tissues of the affected culture - in most cases does not depend on the presence and intensity of light. The second - after the germination of spores - is most active in high light conditions.

The positive effect of light also affects the rate of development of the pathogen in the host plant. This is especially evident in rust fungi. The more light, the shorter the incubation period for wheat line rust, barley yellow rust, flax and bean rust, etc. And this increases the number of generations of the fungus and increases the intensity of the infection. Fertility increases in this pathogen under intense light conditions.

Some diseases develop most actively in low light, which causes weakening of plants and a decrease in their resistance to diseases (causative agents of various kinds of rot, especially vegetable crops).

Duration of lighting and plants. The rhythm of solar radiation (the alternation of the light and dark parts of the day) is the most stable and recurring environmental factor from year to year. As a result of many years of research, physiologists have established the dependence of the transition of plants to generative development on a certain ratio of the length of day and night. In this regard, cultures according to the photoperiodic reaction can be classified into groups: short day the development of which is delayed at a day length of more than 10 hours. A short day encourages flower formation, while a long day prevents it. Such crops include soybeans, rice, millet, sorghum, corn, etc.;

long day until 12-13 o'clock, requiring long-term illumination for their development. Their development accelerates when the day length is about 20 hours. These crops include rye, oats, wheat, flax, peas, spinach, clover, etc.;

neutral with respect to day length, the development of which does not depend on the length of the day, for example, tomato, buckwheat, legumes, rhubarb.

It has been established that the predominance of a certain spectral composition in the radiant flux is necessary for the beginning of flowering of plants. Short-day plants develop faster when the maximum radiation falls on blue-violet rays, and long-day plants - on red ones. The duration of the light part of the day (astronomical length of the day) depends on the time of year and geographical latitude. At the equator, the duration of the day throughout the year is 12 hours ± 30 minutes. When moving from the equator to the poles after the vernal equinox (21.03), the length of the day increases to the north and decreases to the south. After the autumn equinox (23.09) the distribution of day length is reversed. In the Northern Hemisphere, June 22 is the longest day, the duration of which is 24 hours north of the Arctic Circle. The shortest day in the Northern Hemisphere is December 22, and beyond the Arctic Circle in the winter months, the Sun does not rise above the horizon at all. In middle latitudes, for example, in Moscow, the length of the day during the year varies from 7 to 17.5 hours.

2. Types of solar radiation.

Solar radiation consists of three components: direct solar radiation, scattered and total.

DIRECT SOLAR RADIATIONS- radiation coming from the sun into the atmosphere and then to the earth's surface in the form of a beam of parallel rays. Its intensity is measured in calories per cm2 per minute. It depends on the height of the sun and the state of the atmosphere (cloudiness, dust, water vapor). The annual amount of direct solar radiation on the horizontal surface of the territory of the Stavropol Territory is 65-76 kcal/cm2/min. At sea level, with a high position of the Sun (summer, noon) and good transparency, direct solar radiation is 1.5 kcal / cm2 / min. This is the short wavelength part of the spectrum. When the flow of direct solar radiation passes through the atmosphere, it weakens due to absorption (about 15%) and scattering (about 25%) of energy by gases, aerosols, clouds.

The flow of direct solar radiation falling on a horizontal surface is called insolation. S= S sin hois the vertical component of direct solar radiation.

S – amount of heat received by a surface perpendicular to the beam ,

ho – the height of the Sun, i.e. the angle formed by a sunbeam with a horizontal surface .

At the boundary of the atmosphere, the intensity of solar radiation isSo= 1,98 kcal/cm2/min. - according to the international agreement of 1958. It's called the solar constant. This would be at the surface if the atmosphere were absolutely transparent.

Rice. 2.1. The path of the sun's ray in the atmosphere at different heights of the Sun

SCATTERED RADIATIOND – part of the solar radiation as a result of scattering by the atmosphere goes back into space, but a significant part of it enters the Earth in the form of scattered radiation. Maximum scattered radiation + 1 kcal/cm2/min. It is noted in a clear sky, if there are high clouds on it. Under a cloudy sky, the spectrum of scattered radiation is similar to that of the sun. This is the short wavelength part of the spectrum. Wavelength 0.17-4 microns.

TOTAL RADIATIONQ- consists of diffuse and direct radiation to a horizontal surface. Q= S+ D.

The ratio between direct and diffuse radiation in the composition of total radiation depends on the height of the Sun, cloudiness and pollution of the atmosphere, and the height of the surface above sea level. With an increase in the height of the Sun, the fraction of scattered radiation in a cloudless sky decreases. The more transparent the atmosphere and the higher the Sun, the smaller the proportion of scattered radiation. With continuous dense clouds, the total radiation consists entirely of scattered radiation. In winter, due to the reflection of radiation from the snow cover and its secondary scattering in the atmosphere, the proportion of scattered radiation in the composition of the total increases noticeably.

The light and heat received by plants from the Sun is the result of the action of total solar radiation. Therefore, data on the amounts of radiation received by the surface per day, month, growing season, and year are of great importance for agriculture.

reflected solar radiation. Albedo. The total radiation that has reached the earth's surface, partially reflected from it, creates reflected solar radiation (RK), directed from the earth's surface into the atmosphere. The value of reflected radiation largely depends on the properties and condition of the reflecting surface: color, roughness, humidity, etc. The reflectivity of any surface can be characterized by its albedo (Ak), which is understood as the ratio of reflected solar radiation to total. Albedo is usually expressed as a percentage:

Observations show that the albedo of various surfaces varies within relatively narrow limits (10...30%), with the exception of snow and water.

Albedo depends on soil moisture, with the increase of which it decreases, which is important in the process of changing the thermal regime of irrigated fields. Due to the decrease in albedo, when the soil is moistened, the absorbed radiation increases. The albedo of various surfaces has a well-pronounced daily and annual variation, due to the dependence of the albedo on the height of the Sun. The lowest albedo value is observed at around noon hours, and during the year - in summer.

The Earth's own radiation and the counter radiation of the atmosphere. Efficient radiation. Earth's surface as physical body, which has a temperature above absolute zero (-273 ° C), is a source of radiation, which is called the Earth's own radiation (E3). It is directed into the atmosphere and is almost completely absorbed by water vapor, water droplets and carbon dioxide contained in the air. The radiation of the Earth depends on the temperature of its surface.

The atmosphere, absorbing a small amount of solar radiation and almost all the energy emitted by the earth's surface, heats up and, in turn, also radiates energy. About 30% of atmospheric radiation goes into outer space, and about 70% comes to the Earth's surface and is called the counter atmospheric radiation (Ea).

The amount of energy emitted by the atmosphere is directly proportional to its temperature, carbon dioxide content, ozone and cloud cover.

The surface of the Earth absorbs this counter radiation almost entirely (by 90...99%). Thus, it is an important source of heat for the earth's surface in addition to absorbed solar radiation. This influence of the atmosphere on the thermal regime of the Earth is called the greenhouse or greenhouse effect due to the external analogy with the action of glasses in greenhouses and greenhouses. Glass well transmits the sun's rays, which heat the soil and plants, but delays the thermal radiation of the heated soil and plants.

The difference between the own radiation of the Earth's surface and the counter radiation of the atmosphere is called the effective radiation: Eef.

Eef= E3-Ea

On clear and slightly cloudy nights, the effective radiation is much greater than on cloudy nights; therefore, the nightly cooling of the earth's surface is also greater. During the day, it is blocked by absorbed total radiation, as a result of which the surface temperature rises. At the same time, the effective radiation also increases. The earth's surface in middle latitudes loses 70...140 W/m2 due to effective radiation, which is about half of the amount of heat that it receives from the absorption of solar radiation.

3. Spectral composition of radiation.

The sun, as a source of radiation, has a variety of emitted waves. The fluxes of radiant energy along the wavelength are conditionally divided into shortwave (X < 4 мкм) и длинноволновую (А. >4 µm) radiation. The spectrum of solar radiation at the boundary of the earth's atmosphere is practically between the wavelengths of 0.17 and 4 microns, and the terrestrial and atmospheric radiation - from 4 to 120 microns. Consequently, the fluxes of solar radiation (S, D, RK) refer to short-wave radiation, and the radiation of the Earth (£3) and the atmosphere (Ea) - to long-wave radiation.

The spectrum of solar radiation can be divided into three qualitatively different parts: ultraviolet (Y< 0,40 мкм), ви­димую (0,40 мкм < Y < 0.75 µm) and infrared (0.76 µm < Y < 4 µm). Before the ultraviolet part of the spectrum of solar radiation lies X-ray radiation, and beyond the infrared - the radio emission of the Sun. At the upper boundary of the atmosphere, the ultraviolet part of the spectrum accounts for about 7% of the energy of solar radiation, 46% for the visible and 47% for the infrared.

The radiation emitted by the earth and atmosphere is called far infrared radiation.

The biological effect of different types of radiation on plants is different. ultraviolet radiation slows down growth processes, but accelerates the passage of the stages of formation of reproductive organs in plants.

The value of infrared radiation, which is actively absorbed by water in the leaves and stems of plants, is its thermal effect, which significantly affects the growth and development of plants.

far infrared radiation produces only a thermal effect on plants. Its influence on the growth and development of plants is insignificant.

Visible part of the solar spectrum, firstly, creates illumination. Secondly, the so-called physiological radiation (A, = 0.35 ... 0.75 μm), which is absorbed by leaf pigments, almost coincides with the region of visible radiation (partially capturing the region of ultraviolet radiation). Its energy has an important regulatory and energy significance in the life of plants. Within this region of the spectrum, a region of photosynthetically active radiation is distinguished.

4. Absorption and scattering of radiation in the atmosphere.

passing through earth's atmosphere, solar radiation is attenuated due to absorption and scattering by atmospheric gases and aerosols. At the same time, its spectral composition also changes. At different heights of the sun and different heights of the observation point above the earth's surface, the length of the path traveled by the sun's ray in the atmosphere is not the same. With a decrease in altitude, the ultraviolet part of the radiation decreases especially strongly, the visible part decreases somewhat less, and only slightly the infrared part.

The scattering of radiation in the atmosphere occurs mainly as a result of continuous fluctuations (fluctuations) in the density of air at every point in the atmosphere, caused by the formation and destruction of certain "clusters" (clumps) of molecules atmospheric gas. Aerosol particles also scatter solar radiation. The scattering intensity is characterized by the scattering coefficient.

K = add formula.

The intensity of scattering depends on the number of scattering particles per unit volume, on their size and nature, and also on the wavelengths of the scattered radiation itself.

Rays scatter the stronger, the shorter the wavelength. For example, violet rays scatter 14 times more than red ones, which explains the blue color of the sky. As noted above (see Section 2.2), direct solar radiation passing through the atmosphere is partially dissipated. In clean and dry air, the intensity of the molecular scattering coefficient obeys the Rayleigh law:

k= s/Y4 ,

where C is a coefficient depending on the number of gas molecules per unit volume; X is the length of the scattered wave.

Since the far wavelengths of red light are almost twice the wavelengths of violet light, the former are scattered by air molecules 14 times less than the latter. Since the initial energy (before scattering) of violet rays is less than blue and blue, the maximum energy in scattered light (scattered solar radiation) is shifted to blue-blue rays, which determines the blue color of the sky. Thus, diffuse radiation is richer in photosynthetically active rays than direct radiation.

In air containing impurities (small water droplets, ice crystals, dust particles, etc.), scattering is the same for all areas of visible radiation. Therefore, the sky acquires a whitish tint (haze appears). Cloud elements (large droplets and crystals) do not scatter the sun's rays at all, but reflect them diffusely. As a result, clouds illuminated by the Sun are white.

5. PAR (photosynthetically active radiation)

Photosynthetically active radiation. In the process of photosynthesis, not the entire spectrum of solar radiation is used, but only its

part in the wavelength range of 0.38 ... 0.71 microns, - photosynthetically active radiation (PAR).

It is known that visible radiation, perceived by the human eye as white, consists of colored rays: red, orange, yellow, green, blue, indigo and violet.

The assimilation of the energy of solar radiation by plant leaves is selective (selective). The most intense leaves absorb blue-violet (X = 0.48 ... 0.40 microns) and orange-red (X = 0.68 microns) rays, less yellow-green (A. = 0.58 ... 0.50 microns) and far red (A.\u003e 0.69 microns) rays.

At the earth's surface, the maximum energy in the spectrum of direct solar radiation, when the Sun is high, falls on the region of yellow-green rays (the disk of the Sun is yellow). When the Sun is near the horizon, the far red rays have the maximum energy (the solar disk is red). Therefore, the energy of direct sunlight is little involved in the process of photosynthesis.

Since PAR is one of critical factors productivity of agricultural plants, information on the amount of incoming PAR, accounting for its distribution over the territory and in time are of great practical importance.

The PAR intensity can be measured, but this requires special light filters that transmit only waves in the range of 0.38 ... 0.71 microns. There are such devices, but they are not used on the network of actinometric stations, but they measure the intensity of the integral spectrum of solar radiation. The PAR value can be calculated from data on the arrival of direct, diffuse or total radiation using the coefficients proposed by H. G. Tooming and:

Qfar = 0.43 S"+0.57 D);

distribution maps of monthly and annual amounts of Far on the territory of Russia were drawn up.

To characterize the degree of use of PAR by crops, the coefficient is used beneficial use PAR:

KPIfar = (sumQ/ headlights/sumQ/ headlights) 100%,

where sumQ/ headlights- the amount of PAR spent on photosynthesis during the growing season of plants; sumQ/ headlights- the amount of PAR received for crops during this period;

Crops according to their average values ​​of CPIF are divided into groups (according to): usually observed - 0.5 ... 1.5%; good-1.5...3.0; record - 3.5...5.0; theoretically possible - 6.0 ... 8.0%.

6. RADIATION BALANCE OF THE EARTH'S SURFACE

The difference between the incoming and outgoing fluxes of radiant energy is called the radiation balance of the earth's surface (B).

The incoming part of the radiation balance of the earth's surface during the day consists of direct solar and diffuse radiation, as well as atmospheric radiation. The expenditure part of the balance is the radiation of the earth's surface and reflected solar radiation:

B= S / + D+ Ea-E3-Rk

The equation can also be written in another form: B = Q- RK - Eef.

For night time, the radiation balance equation has the following form:

B \u003d Ea - E3, or B \u003d -Eef.

If the input of radiation is greater than the output, then the radiation balance is positive and the active surface* heats up. With a negative balance, it cools. In summer, the radiation balance is positive during the day and negative at night. The zero crossing occurs in the morning approximately 1 hour after sunrise, and in the evening 1-2 hours before sunset.

The annual radiation balance in areas where a stable snow cover is established has negative values ​​in the cold season, and positive values ​​in the warm season.

The radiation balance of the earth's surface significantly affects the distribution of temperature in the soil and the surface layer of the atmosphere, as well as the processes of evaporation and snowmelt, the formation of fog and frost, changes in the properties of air masses (their transformation).

Knowledge of the radiation regime of agricultural land makes it possible to calculate the amount of radiation absorbed by crops and soil depending on the height of the Sun, the structure of crops, and the phase of plant development. Data on the regime are also necessary for evaluating various methods of regulating soil temperature and moisture, evaporation, on which plant growth and development, crop formation, its quantity and quality depend.

Effective agronomic methods of influencing the radiation and, consequently, the thermal regime of the active surface are mulching (covering the soil with a thin layer of peat chips, rotted manure, sawdust, etc.), covering the soil with plastic wrap, and irrigation. All this changes the reflective and absorptive capacity of the active surface.

* Active surface - the surface of soil, water or vegetation, which directly absorbs solar and atmospheric radiation and emits radiation into the atmosphere, thereby regulating the thermal regime of the adjacent layers of air and the underlying layers of soil, water, vegetation.

) , let's turn to Figure 1 - which shows the parallel and sequential advancement of the heat of the Sun to hot brine solar salt pond. As well as the ongoing changes in the values ​​of various types of solar radiation and their total value along the way.

Figure 1 - Histogram of changes in the intensity of solar radiation (energy) on the way to the hot brine of the solar salt pond.

To assess the effectiveness of the active use of various types of solar radiation, we will determine which of the natural, technogenic and operational factors have a positive and which negative effect on the concentration (increase in the flow) of solar radiation into the pond and its accumulation with hot brine.

The Earth and the atmosphere receive from the Sun 1.3∙10 24 cal of heat per year. It is measured by intensity, i.e. the amount of radiant energy (in calories) that comes from the Sun per unit of time to the surface area perpendicular to the sun's rays.

The radiant energy of the Sun reaches the Earth in the form of direct and scattered radiation, i.e. total. It is absorbed by the earth's surface and is not completely converted into heat, part of it is lost in the form of reflected radiation.

Direct and scattered (total), reflected and absorbed radiation belong to the short-wave part of the spectrum. Along with short-wave radiation, long-wave atmospheric radiation (oncoming) enters the earth's surface, in turn, the earth's surface emits long-wave radiation (intrinsic).

Direct solar radiation refers to the main natural factor in the supply of energy to the water surface of a solar salt pond.

Solar radiation arriving at the active surface in the form of a beam of parallel rays emanating directly from the disk of the Sun is called direct solar radiation.

Direct solar radiation belongs to the short-wave part of the spectrum (with wavelengths from 0.17 to 4 microns, in fact, rays with a wavelength of 0.29 microns reach the earth's surface)

The solar spectrum can be divided into three main areas:

Ultraviolet radiation (λ< 0,4 мкм) - 9 % интенсивности.

Shortwave ultraviolet region (λ< 0,29 мкм) практически полностью отсутствует на уровне моря вследствие поглощения О 2 , О 3 , О, N 2 и их ионами.

Near ultraviolet range (0.29 µm<λ < 0,4 мкм) достигает Земли малой долей излучения, но вполне достаточной для загара;

Visible radiation (0.4 µm< λ < 0,7 мкм) - 45 % интенсивности.

The clear atmosphere transmits visible radiation almost completely, and it becomes a “window” open for this type of solar energy to pass to Earth. The presence of aerosols and atmospheric pollution can be the reasons for the significant absorption of radiation in this spectrum;

Infrared radiation (λ> 0.7 µm) - 46% intensity. Near infrared (0.7 µm< < 2,5 мкм). На этот диапазон спектра приходится почти половина интенсивности солнечного излучения. Более 20 % солнечной энергии поглощается в атмосфере, в основном парами воды и СО 2 (диоксидом углерода). Концентрация СО 2 в атмосфере относительно постоянна и составляет 0,03 %, а концентрация паров воды меняется очень сильно - почти до 4 %.

At wavelengths greater than 2.5 microns, weak extraterrestrial radiation is intensely absorbed by CO 2 and water, so that only a small part of this range of solar energy reaches the Earth's surface.

The far infrared range (λ> 12 µm) of solar radiation practically does not reach the Earth.

From the point of view of the use of solar energy on Earth, only radiation in the wavelength range of 0.29 - 2.5 μm should be taken into account

Most of the solar energy outside the atmosphere is in the 0.2 - 4 micron wavelength range, and on the Earth's surface - in the 0.29 - 2.5 micron wavelength range.

Let's see how they redistribute in general , flows of energy that the Sun gives the Earth. Let's take 100 arbitrary units of solar power (1.36 kW/m 2 ) falling on the Earth and follow their paths in the atmosphere. One percent (13.6 W/m2), the short ultraviolet of the solar spectrum, is absorbed by molecules in the exosphere and thermosphere, heating them up. Another three percent (40.8 W / m 2) of the near ultraviolet is absorbed by the ozone of the stratosphere. The infrared tail of the solar spectrum (4% or 54.4 W / m 2) remains in the upper layers of the troposphere containing water vapor (there is practically no water vapor above).

The remaining 92 shares of solar energy (1.25 kW / m 2) fall on the "transparency window" of the atmosphere of 0.29 microns< < 2,5 мкм. Они проникают в плотные приземные слои воздуха. Значительная часть их (45 единиц или 612 Вт/м 2), преимущественно в синей видимой части спектра, рассеиваются воздухом, придавая голубой цвет небу. Прямые солнечные лучи - оставшиеся 47 процентов (639,2 Вт/м 2) начального светового потока - достигают поверхности. Она отражает примерно 7 процентов (95,2 Вт/м 2) из этих 47 % (639,2 Вт/м 2) и этот свет по пути в космос отдает ещё 3 единицы (40,8 Вт/м 2) диффузному рассеянному свету неба. Forty shares of the energy of the sun's rays, and another 8 from the atmosphere (total 48 or 652.8 W / m 2) are absorbed by the Earth's surface, heating the land and ocean.

The light power scattered in the atmosphere (only 48 shares or 652.8 W / m 2) is partially absorbed by it (10 shares or 136 W / m 2), and the rest is distributed between the Earth's surface and space. More goes into outer space than hits the surface, 30 shares (408 W / m 2) up, 8 shares (108.8 W / m 2) down.

It has been described in common, averaged, a picture of the redistribution of solar energy in the Earth's atmosphere. However, it does not allow solving particular problems of using solar energy to meet the needs of a person in a specific area of ​​his residence and work, and here's why.

The Earth's atmosphere better reflects the oblique sun's rays, so the hourly insolation at the equator and at middle latitudes is much greater than at high latitudes.

The values ​​of the height of the Sun (elevations above the horizon) 90, 30, 20, and 12 ⁰ (the air (optical) mass (m) of the atmosphere corresponds to 1, 2, 3, and 5) with a cloudless atmosphere corresponds to an intensity of about 900, 750, 600 and 400 W / m 2 (at 42 ⁰ - m = 1.5, and at 15 ⁰ - m = 4). In reality, the total energy of the incident radiation exceeds the indicated values, since it includes not only the direct component, but also the value of the scattered component of the radiation intensity on the horizontal surface scattered at air masses 1, 2, 3, and 5 under these conditions, respectively, equals 110, 90, 70, and 50 W / m 2 (with a coefficient of 0.3 - 0.7 for the vertical plane, since only half of the sky is visible). In addition, in areas of the sky close to the Sun, there is a "circumsolar halo" in a radius of ≈ 5⁰.

Table 1 shows data on insolation for various regions of the Earth.

Table 1 - Insolation of the direct component by region for a clean atmosphere

Table 1 shows that the daily amount of solar radiation is maximum not at the equator, but near 40 ⁰. A similar fact is also a consequence of the inclination of the earth's axis to the plane of its orbit. During the summer solstice, the Sun in the tropics is almost all day overhead and the daylight hours are 13.5 hours, more than at the equator on the day of the equinox. With increasing latitude, the length of the day increases, and although the intensity of solar radiation decreases, maximum value daytime insolation occurs at a latitude of about 40 ⁰ and remains almost constant (for cloudless sky conditions) up to the Arctic Circle.

It should be emphasized that the data in Table 1 are valid only for a pure atmosphere. Taking into account cloudiness and atmospheric pollution by industrial waste, typical for many countries of the world, the values ​​given in the table should be at least halved. For example, for England in 70 of the XX century, before the start of the struggle for protection environment, the annual amount of solar radiation was only 900 kWh/m 2 instead of 1700 kWh/m 2 .

The first data on the transparency of the atmosphere on Lake Baikal were obtained by V.V. Bufalom in 1964 He showed that the values ​​of direct solar radiation over Baikal are on average 13% higher than in Irkutsk. The average spectral transparency coefficient of the atmosphere in Northern Baikal in summer is 0.949, 0.906, 0.883 for red, green and blue filters, respectively. In summer the atmosphere is more optically unstable than in winter, and this instability varies considerably from the pre-noon hours to the afternoon. Depending on the annual course of attenuation by water vapor and aerosols, their contribution to the total attenuation of solar radiation also changes. Aerosols play the main role in the cold part of the year, and water vapor plays the main role in the warm part of the year. The Baikal Basin and Lake Baikal are distinguished by a relatively high integral transparency of the atmosphere. With an optical mass m = 2, the average values ​​of the transparency coefficient range from 0.73 (in summer) to 0.83 (in winter).

Aerosols significantly reduce the flow of direct solar radiation into the water area of ​​the pond, and they absorb mainly radiation of the visible spectrum, with the wavelength that freely passes through the fresh layer of the pond, and this for the accumulation of solar energy by the pond is of great importance.(A layer of water 1 cm thick is practically opaque to infrared radiation with a wavelength of more than 1 micron). Therefore, water several centimeters thick is used as a heat-shielding filter. For glass, the long-wavelength infrared transmission limit is 2.7 µm.

A large number of dust particles, freely transported across the steppe, also reduces the transparency of the atmosphere.

Electromagnetic radiation is emitted by all heated bodies, and the colder the body, the lower the intensity of the radiation and the further the maximum of its spectrum is shifted to the long-wave region. There is a very simple relation λmax×Τ=c¹[ c¹= 0.2898 cm∙deg. (Vina)], with the help of which it is easy to establish where the maximum radiation of a body with temperature Τ (⁰K) is located. For example, a human body with a temperature of 37 + 273 = 310 ⁰K emits infrared rays with a maximum near the value λmax = 9.3 µm. And the walls, for example, of a solar dryer, with a temperature of 90 ⁰С, will emit infrared rays with a maximum near the value λmax = 8 µm.

Visible solar radiation (0.4 µm< λ < 0,7 мкм) имеет 45 % интенсивности потому, что температура поверхности Солнца 5780 ⁰К.

In its great progress was the transition from an electric incandescent lamp with a carbon filament to a modern lamp with a tungsten filament. The thing is that a carbon filament can be brought to a temperature of 2100 ⁰K, and a tungsten filament - up to 2500 ⁰K. Why are these 400 ⁰K so important? The thing is that the purpose of an incandescent lamp is not to heat, but to give light. Therefore, it is necessary to achieve such a position that the maximum of the curve falls on the visible study. The ideal would be to have a filament that could withstand the temperature of the Sun's surface. But even the transition from 2100 to 2500 ⁰K increases the fraction of energy attributable to visible radiation, from 0.5 to 1.6%.

Everyone can feel the infrared rays emanating from a body heated to only 60 - 70 ⁰С by bringing the palm from below (to eliminate thermal convection).

The arrival of direct solar radiation in the water area of ​​the pond corresponds to its arrival on the horizontal irradiation surface. At the same time, the above shows that the uncertainty quantitative characteristics arrival at a particular point in time, both seasonal and daily. Only the height of the Sun (the optical mass of the atmosphere) is a constant characteristic.

The accumulation of solar radiation by the earth's surface and the pond differ significantly.

The natural surfaces of the Earth have different reflective (absorbing) abilities. Thus, dark surfaces (chernozem, peat bogs) have a low albedo value of about 10%. ( Surface albedo is the ratio of the radiation flux reflected by this surface into the surrounding space to the flux that fell on it).

Light surfaces (white sand) have a large albedo, 35 - 40%. The albedo of grassy surfaces ranges from 15 to 25%. The albedo of the crowns of a deciduous forest in summer is 14 - 17%, coniferous forest- 12 - 15%. The surface albedo decreases with increasing solar altitude.

The albedo of water surfaces is in the range of 3 - 45%, depending on the height of the Sun and the degree of excitement.

With a calm water surface, the albedo depends only on the height of the Sun (Figure 2).

Figure 2 - Dependence of the reflection coefficient of solar radiation for a calm water surface on the height of the Sun.

The entry of solar radiation and its passage through a layer of water has its own characteristics.

In general, the optical properties of water (its solutions) in the visible region of solar radiation are shown in Figure 3.

Ф0 - flux (power) of the incident radiation,

Photr - the flux of radiation reflected by the water surface,

Фabs is the flux of radiation absorbed by the water mass,

Фр - the flux of radiation that has passed through the water mass.

Body reflectance Fotr/Ф0

Absorption coefficient Фabl/Ф0

Transmittance Фpr/Ф0.

Figure 3 - Optical properties water (its solutions) in the visible region of solar radiation

On the flat boundary of two media, air - water, the phenomena of reflection and refraction of light are observed.

When light is reflected, the incident beam, the reflected beam and the perpendicular to the reflecting surface, restored at the point of incidence of the beam, lie in the same plane, and the angle of reflection equal to the angle fall. In the case of refraction, the incident beam, the perpendicular restored at the point of incidence of the beam to the interface between two media, and the refracted beam lie in the same plane. The angle of incidence α and the angle of refraction β (Figure 4) are related sin α /sin β=n2|n1, where n2 is the absolute refractive index of the second medium, n1 - of the first. Since for air n1≈1, the formula will take the form sin α /sin β=n2

Figure 4 - Refraction of rays during the transition from air to water

When the rays go from air into water, they approach the "perpendicular of incidence"; for example, a beam incident on water at an angle to the perpendicular to the surface of the water enters it already at an angle that is less than (Fig. 4a). But when an incident beam, sliding over the surface of the water, falls on the water surface almost at a right angle to the perpendicular, for example, at an angle of 89 ⁰ or less, then it enters the water at an angle less than a straight line, namely at an angle of only 48.5 ⁰. At a greater angle to the perpendicular than 48.5 ⁰, the beam cannot enter the water: this is the “limiting” angle for water (Figure 4, b).

Consequently, rays falling on water at various angles are compressed under water into a rather tight cone with an opening angle of 48.5 ⁰ + 48.5 ⁰ = 97 ⁰ (Fig. 4c).

In addition, the refraction of water depends on its temperature (Table 2), but these changes are not so significant that they cannot be of interest for engineering practice on the topic under consideration.

Table 2 - Refractive indexwater at different temperatures t

n n n

Let us now follow the course of the rays going back (from point P) - from water to air (Figure 5). According to the laws of optics, the paths will be the same, and all the rays contained in the mentioned 97-degree cone will enter the air at different angles, spreading over the entire 180-degree space above the water. Underwater rays that are outside the mentioned angle (97-degree) will not come out from under the water, but will be reflected entirely from its surface, as from a mirror.

Figure 5 - Refraction of rays during the transition from water to air

If n2< n1(вторая среда оптически менее плотная), то α < β. Наибольшему значению β = 90 ⁰ соответствует угол падения α0 , определяемый равенством sinα0=n2/n1. При угле падения α >α0, only the reflected beam exists, there is no refracted beam ( total internal reflection phenomenon).

Any underwater ray that meets the surface of the water at an angle greater than the "limiting" (i.e. greater than 48.5 ⁰) is not refracted, but reflected: it undergoes " total internal reflection". Reflection is called in this case total because all the incident rays are reflected here, while even the best polished silver mirror reflects only a part of the rays incident on it, while absorbing the rest. Water under these conditions is an ideal mirror. In this case, we are talking about visible light. Generally speaking, the refractive index of water, like other substances, depends on the wavelength (this phenomenon is called dispersion). As a consequence of this, the limiting angle at which total internal reflection occurs is not the same for different wavelengths, but for visible light when reflected at the water-air boundary, this angle changes by less than 1⁰.

Due to the fact that at a greater angle to the perpendicular than 48.5⁰, the sunbeam cannot enter the water: this is the “limiting” angle for water (Figure 4, b), then the water mass, in the entire range of values ​​​​of the Sun’s height, does not change so much insignificantly than air - it is always less .

However, since the density of water is 800 times greater than the density of air, the absorption of solar radiation by water will change significantly.

In addition, if light radiation passes through a transparent medium, then the spectrum of such light has some features. Certain lines in it are greatly weakened, i.e. waves of the corresponding wavelength are strongly absorbed by the medium under consideration. Such spectra are called absorption spectra. The form of the absorption spectrum depends on the substance under consideration.

Since the salt solution solar salt pond may contain different concentrations of sodium and magnesium chlorides and their ratios, then it makes no sense to speak unambiguously about absorption spectra. Although research and data on this issue abound.

So, for example, studies carried out in the USSR (Yu. Usmanov) to identify the transmittance of radiation of various wavelengths for water and a solution of magnesium chloride of various concentrations obtained the following results (Figure 6). And B. J. Brinkworth shows a graphical dependence of the absorption of solar radiation and the monochromatic flux density of solar radiation (radiation) depending on the wavelength (Figure 7).

Figure 7 - Absorption of solar radiation in water

Figure 6 - The dependence of the throughput of a solution of magnesium chloride on the concentration

Consequently, the quantitative supply of direct solar radiation to the hot brine of the pond, after entering the water, will depend on: the monochromatic density of the solar radiation (radiation) flux; from the height of the sun. And also from the albedo of the pond surface, from the purity of the upper layer of the solar salt pond, consisting of fresh water, with a thickness of usually 0.1 - 0.3 m, where mixing cannot be suppressed, the composition, concentration and thickness of the solution in the gradient layer (insulating layer with brine concentration increasing downwards), on the purity of water and brine.

Figures 6 and 7 show that water has the highest transmission capacity in the visible region of the solar spectrum. This is a very favorable factor for the passage of solar radiation through the upper fresh layer of the solar salt pond.

Bibliography

1 Osadchiy G.B. Solar energy, its derivatives and technologies for their use (Introduction to RES energy) / G.B. Osadchy. Omsk: IPK Maksheeva E.A., 2010. 572 p.

2 Twydell J. Renewable energy sources / J. Twydell, A . Weir. M.: Energoatomizdat, 1990. 392 p.

3 Duffy J. A. Thermal processes using solar energy / J. A. Duffy, W. A. ​​Beckman. M.: Mir, 1977. 420 p.

4 Climatic resources of Baikal and its basin /N. P. Ladeyshchikov, Novosibirsk, Nauka, 1976, 318p.

5 Pikin S. A. Liquid crystals / S. A. Pikin, L. M. Blinov. M.: Nauka, 1982. 208 p.

6 Kitaygorodsky A. I. Physics for everyone: Photons and nuclei / A. I. Kitaygorodsky. M.: Nauka, 1984. 208 p.

Heat sources. Thermal energy plays a decisive role in the life of the atmosphere. The main source of this energy is the Sun. As for the thermal radiation of the Moon, planets and stars, it is so negligible for the Earth that in practice it cannot be taken into account. Much more thermal energy is provided by the internal heat of the Earth. According to the calculations of geophysicists, a constant influx of heat from the bowels of the Earth increases the temperature of the earth's surface by 0.1. But such an influx of heat is still so small that there is no need to take it into account either. Thus, only the Sun can be considered the only source of thermal energy on the Earth's surface.

Solar radiation. The sun, which has a temperature of the photosphere (radiating surface) of about 6000°, radiates energy into space in all directions. Part of this energy in the form of a huge beam of parallel solar rays hits the Earth. Solar energy that reaches the earth's surface in the form of direct rays from the sun is called direct solar radiation. But not all solar radiation directed to the Earth reaches the earth's surface, since the sun's rays, passing through a powerful layer of the atmosphere, are partially absorbed by it, partially scattered by molecules and suspended particles of air, some of it is reflected by clouds. The portion of solar energy that is dissipated in the atmosphere is called scattered radiation. Scattered solar radiation propagates in the atmosphere and reaches the Earth's surface. We perceive this type of radiation as uniform daylight, when the Sun is completely covered by clouds or has just disappeared below the horizon.

Direct and diffuse solar radiation, reaching the Earth's surface, is not completely absorbed by it. Part of the solar radiation is reflected from the earth's surface back into the atmosphere and is there in the form of a stream of rays, the so-called reflected solar radiation.

The composition of solar radiation is very complex, which is associated with a very high temperature radiating surface of the sun. Conventionally, according to the wavelength, the spectrum of solar radiation is divided into three parts: ultraviolet (η<0,4<μ видимую глазом (η from 0.4μ to 0.76μ) and infrared (η >0.76μ). In addition to the temperature of the solar photosphere, the composition of solar radiation near the earth's surface is also affected by the absorption and scattering of part of the sun's rays as they pass through the air envelope of the Earth. In this regard, the composition of solar radiation at the upper boundary of the atmosphere and near the Earth's surface will be different. Based on theoretical calculations and observations, it has been established that at the boundary of the atmosphere, ultraviolet radiation accounts for 5%, visible rays - 52% and infrared - 43%. At the earth's surface (at a Sun height of 40 °), ultraviolet rays make up only 1%, visible - 40%, and infrared - 59%.

Intensity of solar radiation. Under the intensity of direct solar radiation understand the amount of heat in calories received in 1 minute. from the radiant energy of the Sun by the surface in 1 cm 2, placed perpendicular to the sun.

To measure the intensity of direct solar radiation, special instruments are used - actinometers and pyrheliometers; the amount of scattered radiation is determined by a pyranometer. Automatic recording of the duration of solar radiation action is carried out by actinographs and heliographs. The spectral intensity of solar radiation is determined by a spectrobolograph.

At the boundary of the atmosphere, where the absorbing and scattering effects of the Earth's air envelope are excluded, the intensity of direct solar radiation is approximately 2 feces for 1 cm 2 surfaces in 1 min. This value is called solar constant. The intensity of solar radiation in 2 feces for 1 cm 2 in 1 min. gives such a large amount of heat during the year that it would be enough to melt a layer of ice 35 m thick, if such a layer covered the entire earth's surface.

Numerous measurements of the intensity of solar radiation give reason to believe that the amount of solar energy coming to the upper boundary of the Earth's atmosphere experiences fluctuations in the amount of several percent. Oscillations are periodic and non-periodic, apparently associated with the processes occurring on the Sun itself.

In addition, some change in the intensity of solar radiation occurs during the year due to the fact that the Earth in its annual rotation does not move in a circle, but in an ellipse, in one of the foci of which is the Sun. In this regard, the distance from the Earth to the Sun changes and, consequently, there is a fluctuation in the intensity of solar radiation. The greatest intensity is observed around January 3, when the Earth is closest to the Sun, and the smallest around July 5, when the Earth is at its maximum distance from the Sun.

For this reason, the fluctuation in the intensity of solar radiation is very small and can only be of theoretical interest. (The amount of energy at maximum distance is related to the amount of energy at minimum distance, as 100:107, i.e. the difference is completely negligible.)

Conditions for irradiation of the surface of the globe. Already the spherical shape of the Earth alone leads to the fact that the radiant energy of the Sun is distributed very unevenly on the earth's surface. So, on the days of the spring and autumn equinoxes (March 21 and September 23), only at the equator at noon, the angle of incidence of the rays will be 90 ° (Fig. 30), and as it approaches the poles, it will decrease from 90 to 0 °. In this way,

if at the equator the amount of radiation received is taken as 1, then at the 60th parallel it will be expressed as 0.5, and at the pole it will be equal to 0.

The globe, in addition, has a daily and annual movement, and the earth's axis is inclined to the plane of the orbit by 66 °.5. Due to this inclination, an angle of 23 ° 30 g is formed between the plane of the equator and the plane of the orbit. This circumstance leads to the fact that the angles of incidence of the sun's rays for the same latitudes will vary within 47 ° (23.5 + 23.5) .

Depending on the time of year, not only the angle of incidence of rays changes, but also the duration of illumination. If in tropical countries at all times of the year the duration of day and night is approximately the same, then in polar countries, on the contrary, it is very different. For example, at 70° N. sh. in summer, the Sun does not set for 65 days, at 80 ° N. sh.- 134, and at the pole -186. Because of this, at the North Pole, radiation on the day of the summer solstice (June 22) is 36% more than at the equator. As for the entire summer half-year, the total amount of heat and light received by the pole is only 17% less than at the equator. Thus, in the summertime in polar countries, the duration of illumination largely compensates for the lack of radiation, which is a consequence of the small angle of incidence of the rays. In the winter half of the year, the picture is completely different: the amount of radiation at the same North Pole will be 0. As a result, over the year, the average amount of radiation at the pole is 2.4 less than at the equator. From all that has been said, it follows that the amount of solar energy that the Earth receives by radiation is determined by the angle of incidence of the rays and the duration of exposure.

In the absence of an atmosphere at different latitudes, the earth's surface would receive the following amount of heat per day, expressed in calories per 1 cm 2(see table on page 92).

The distribution of radiation over the earth's surface given in the table is commonly called solar climate. We repeat that we have such a distribution of radiation only at the upper boundary of the atmosphere.


Attenuation of solar radiation in the atmosphere. So far, we have been talking about the conditions for the distribution of solar heat over the earth's surface, without taking into account the atmosphere. Meanwhile, the atmosphere in this case is of great importance. Solar radiation, passing through the atmosphere, experiences dispersion and, in addition, absorption. Both of these processes together attenuate solar radiation to a large extent.

The sun's rays, passing through the atmosphere, first of all experience scattering (diffusion). Scattering is created by the fact that the rays of light, refracting and reflecting from air molecules and particles of solid and liquid bodies in the air, deviate from the direct path to really "spread out".

Scattering greatly attenuates solar radiation. With an increase in the amount of water vapor and especially dust particles, the dispersion increases and the radiation is weakened. In large cities and desert areas, where the dust content of the air is greatest, dispersion weakens the strength of radiation by 30-45%. Thanks to scattering, the daylight is obtained, which illuminates objects, even if the sun's rays do not fall directly on them. Scattering determines the very color of the sky.

Let us now dwell on the ability of the atmosphere to absorb the radiant energy of the Sun. The main gases that make up the atmosphere absorb radiant energy relatively very little. Impurities (water vapor, ozone, carbon dioxide and dust), on the contrary, are distinguished by a high absorption capacity.

In the troposphere, the most significant admixture is water vapor. They absorb especially strongly infrared (long-wave), i.e., predominantly thermal rays. And the more water vapor in the atmosphere, the naturally more and. absorption. The amount of water vapor in the atmosphere is subject to large changes. Under natural conditions, it varies from 0.01 to 4% (by volume).

Ozone is very absorbent. A significant admixture of ozone, as already mentioned, is in the lower layers of the stratosphere (above the tropopause). Ozone absorbs ultraviolet (shortwave) rays almost completely.

Carbon dioxide is also very absorbent. It absorbs mainly long-wave, i.e., predominantly thermal rays.

Dust in the air also absorbs some of the sun's radiation. Heating up under the action of sunlight, it can significantly increase the temperature of the air.

Of the total amount of solar energy coming to Earth, the atmosphere absorbs only about 15%.

The attenuation of solar radiation by scattering and absorption by the atmosphere is very different for different latitudes of the Earth. This difference depends primarily on the angle of incidence of the rays. At the zenith position of the Sun, the rays, falling vertically, cross the atmosphere in the shortest way. As the angle of incidence decreases, the path of the rays lengthens and the attenuation of solar radiation becomes more significant. The latter is clearly seen from the drawing (Fig. 31) and the attached table (in the table, the path of the sun's beam at the zenith position of the Sun is taken as unity).


Depending on the angle of incidence of the rays, not only the number of rays changes, but also their quality. During the period when the Sun is at its zenith (overhead), ultraviolet rays account for 4%,

visible - 44% and infrared - 52%. At the position of the Sun, there are no ultraviolet rays at all at the horizon, visible 28% and infrared 72%.

The complexity of the influence of the atmosphere on solar radiation is aggravated by the fact that its transmission capacity varies greatly depending on the time of year and weather conditions. So, if the sky remained cloudless all the time, then the annual course of the influx of solar radiation at different latitudes could be graphically expressed as follows (Fig. 32) It is clearly seen from the drawing that with a cloudless sky in Moscow in May, June and July solar radiation would produce more than at the equator. Similarly, in the second half of May, in June and the first half of July, more heat would be generated at the North Pole than at the equator and in Moscow. We repeat that this would be the case with a cloudless sky. But in fact, this does not work, because cloud cover significantly weakens solar radiation. Let us give an example shown in the graph (Fig. 33). The graph shows how much solar radiation does not reach the Earth's surface: a significant part of it is retained by the atmosphere and clouds.

However, it must be said that the heat absorbed by the clouds partly goes to warm the atmosphere, and partly indirectly reaches the earth's surface.

The daily and annual course of the intensity of solnight radiation. The intensity of direct solar radiation near the Earth's surface depends on the height of the Sun above the horizon and on the state of the atmosphere (on its dustiness). If. the transparency of the atmosphere during the day was constant, then the maximum intensity of solar radiation would be observed at noon, and the minimum - at sunrise and sunset. In this case, the graph of the course of the daily intensity of solar radiation would be symmetrical with respect to half a day.

The content of dust, water vapor and other impurities in the atmosphere is constantly changing. In this regard, the transparency of the air changes and the symmetry of the graph of the course of the intensity of solar radiation is violated. Often, especially in summer, at midday, when the earth's surface is heated intensely, powerful ascending air currents occur, and the amount of water vapor and dust in the atmosphere increases. This leads to a significant decrease in solar radiation at noon; the maximum intensity of radiation in this case is observed in the pre-noon or afternoon hours. The annual course of the intensity of solar radiation is also associated with changes in the height of the Sun above the horizon during the year and with the state of transparency of the atmosphere in different seasons. In the countries of the northern hemisphere, the greatest height of the Sun above the horizon occurs in the month of June. But at the same time, the greatest dustiness of the atmosphere is also observed. Therefore, the maximum intensity usually occurs not in the middle of summer, but in the spring months, when the Sun rises quite high * above the horizon, and the atmosphere after winter remains relatively clean. To illustrate the annual course of the solar radiation intensity in the northern hemisphere, we present data on the average monthly midday values ​​of the radiation intensity in Pavlovsk.


The amount of heat from solar radiation. The surface of the Earth during the day continuously receives heat from direct and diffuse solar radiation or only from diffuse radiation (in cloudy weather). The daily value of heat is determined on the basis of actinometric observations: by taking into account the amount of direct and diffuse radiation that has entered the earth's surface. Having determined the amount of heat for each day, the amount of heat received by the earth's surface per month or per year is also calculated.

The daily amount of heat received by the earth's surface from solar radiation depends on the intensity of radiation and on the duration of its action during the day. In this regard, the minimum influx of heat occurs in the winter, and the maximum in the summer. In the geographic distribution of total radiation over the globe, its increase is observed with a decrease in the latitude of the area. This position is confirmed by the following table.


The role of direct and diffuse radiation in the annual amount of heat received by the earth's surface at different latitudes of the globe is not the same. At high latitudes, diffuse radiation predominates in the annual heat sum. With a decrease in latitude, the predominant value passes to direct solar radiation. So, for example, in the Tikhaya Bay, diffuse solar radiation provides 70% of the annual amount of heat, and direct radiation only 30%. In Tashkent, on the contrary, direct solar radiation gives 70%, diffused only 30%.

Reflectivity of the Earth. Albedo. As already mentioned, the Earth's surface absorbs only part of the solar energy coming to it in the form of direct and diffuse radiation. The other part is reflected into the atmosphere. The ratio of the amount of solar radiation reflected by a given surface to the amount of radiant energy flux incident on this surface is called albedo. Albedo is expressed as a percentage and characterizes the reflectivity of a given area of ​​the surface.

Albedo depends on the nature of the surface (properties of the soil, the presence of snow, vegetation, water, etc.) and on the angle of incidence of the Sun's rays on the Earth's surface. So, for example, if the rays fall on the earth's surface at an angle of 45 °, then:

From the above examples, it can be seen that the reflectivity of various objects is not the same. It is most near snow and least near water. However, the examples we have taken refer only to those cases where the height of the Sun above the horizon is 45°. As this angle decreases, the reflectivity increases. So, for example, at a height of the Sun at 90 °, water reflects only 2%, at 50 ° - 4%, at 20 ° -12%, at 5 ° - 35-70% (depending on the state of the water surface).

On average, with a cloudless sky, the surface of the globe reflects 8% of solar radiation. In addition, 9% reflects the atmosphere. Thus, the globe as a whole, with a cloudless sky, reflects 17% of the radiant energy of the Sun falling on it. If the sky is covered with clouds, then 78% of the radiation is reflected from them. If we take natural conditions, based on the ratio between a cloudless sky and a sky covered with clouds, which is observed in reality, then the reflectivity of the Earth as a whole is 43%.

Terrestrial and atmospheric radiation. The earth, receiving solar energy, heats up and itself becomes a source of heat radiation into the world space. However, the rays emitted by the earth's surface differ sharply from the sun's rays. The earth emits only long-wave (λ 8-14 μ) invisible infrared (thermal) rays. The energy emitted by the earth's surface is called earth radiation. Earth radiation occurs and. day and night. The intensity of the radiation is greater, the higher the temperature of the radiating body. Terrestrial radiation is determined in the same units as solar radiation, i.e., in calories from 1 cm 2 surfaces in 1 min. Observations have shown that the magnitude of terrestrial radiation is small. Usually it reaches 15-18 hundredths of a calorie. But, acting continuously, it can give a significant thermal effect.

The strongest terrestrial radiation is obtained with a cloudless sky and good transparency of the atmosphere. Cloudiness (especially low clouds) significantly reduces terrestrial radiation and often brings it to zero. Here we can say that the atmosphere, together with the clouds, is a good "blanket" that protects the Earth from excessive cooling. Parts of the atmosphere, like areas of the earth's surface, radiate energy according to their temperature. This energy is called atmospheric radiation. The intensity of atmospheric radiation depends on the temperature of the radiating part of the atmosphere, as well as on the amount of water vapor and carbon dioxide contained in the air. Atmospheric radiation belongs to the group of long-wave radiation. It spreads in the atmosphere in all directions; some of it reaches the earth's surface and is absorbed by it, the other part goes into interplanetary space.

ABOUT income and expenditure of solar energy on Earth. The earth's surface, on the one hand, receives solar energy in the form of direct and diffuse radiation, and on the other hand, loses part of this energy in the form of terrestrial radiation. As a result of the arrival and consumption of solar energy, some result is obtained. In some cases, this result can be positive, in others negative. Let's give examples of both.

January 8. The day is cloudless. For 1 cm 2 the earth's surface received per day 20 feces direct solar radiation and 12 feces scattered radiation; in total, thus received 32 cal. During the same time, due to radiation 1 cm? earth surface lost 202 cal. As a result, in the language of accounting, there is a loss of 170 feces(negative balance).

July 6th The sky is almost cloudless. 630 received from direct solar radiation cal, from scattered radiation 46 cal. In total, therefore, the earth's surface received 1 cm 2 676 cal. 173 lost by terrestrial radiation cal. In the balance sheet profit on 503 feces(balance positive).

From the above examples, among other things, it is quite clear why in temperate latitudes it is cold in winter and warm in summer.

The use of solar radiation for technical and domestic purposes. Solar radiation is an inexhaustible natural source of energy. The magnitude of solar energy on Earth can be judged by the following example: if, for example, we use the heat of solar radiation, which falls on only 1/10 of the area of ​​the USSR, then we can get energy equal to the work of 30 thousand Dneproges.

People have long sought to use the free energy of solar radiation for their needs. To date, many different solar installations have been created that operate on the use of solar radiation and are widely used in industry and to meet the household needs of the population. In the southern regions of the USSR, solar water heaters, boilers, salt water desalination plants, solar dryers (for drying fruit), kitchens, bathhouses, greenhouses, and apparatus for medical purposes operate on the basis of the widespread use of solar radiation in industry and public utilities. Solar radiation is widely used in resorts for the treatment and promotion of people's health.

- A source-

Polovinkin, A.A. Fundamentals of general geography / A.A. Polovinkin.- M.: State Educational and Pedagogical Publishing House of the Ministry of Education of the RSFSR, 1958.- 482 p.

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