High level of solar radiation. Solar, terrestrial and atmospheric radiation

ATMOSPHERE

Atmosphere. Structure, composition, origin, significance for civil defense. Thermal processes in the atmosphere. Solar radiation, its types, latitudinal distribution and transformation by the earth's surface.

Atmosphere- the air shell of the Earth, held by the force of gravity and participating in the rotation of the planet. The force of gravity keeps the atmosphere close to the Earth's surface. The greatest pressure and density of the atmosphere are observed at the earth's surface, as you rise up, the pressure and density decrease. At an altitude of 18 km, the pressure decreases by a factor of 10, and at an altitude of 80 km, by a factor of 75,000. The lower boundary of the atmosphere is the surface of the Earth, the upper boundary is conventionally assumed to be a height of 1000-1200 km. The mass of the atmosphere is 5.13 x 10 15 tons, and 99% of this amount is contained in the lower layer up to a height of 36 km.

The evidence for the existence of high layers of the atmosphere is as follows:

At an altitude of 22-25 km, mother-of-pearl clouds are located in the atmosphere;

At an altitude of 80 km, noctilucent clouds are visible;

At an altitude of about 100-120 km, burning of meteorites is observed, i.e. here the atmosphere still has sufficient density;

At an altitude of about 220 km, the scattering of light by the gases of the atmosphere begins (the phenomenon of twilight);

Auroras begin at about 1000-1200 km, this phenomenon is explained by the ionization of air by corpuscular streams coming from the sun. A highly rarefied atmosphere extends to an altitude of 20,000 km, it forms the earth's corona, imperceptibly passing into interplanetary gas.

The atmosphere, like the planet as a whole, rotates counterclockwise from west to east. Due to rotation, it acquires the shape of an ellipsoid, i.e. The thickness of the atmosphere near the equator is greater than near the poles. It has a protrusion in the direction opposite to the Sun, this "gas tail" of the Earth, sparse like a comet, has a length of about 120 thousand km. The atmosphere is connected with other geospheres by heat and moisture exchange. The energy of atmospheric processes is the electromagnetic radiation of the sun.

The development of the atmosphere. Since hydrogen and helium are the most common elements in space, they undoubtedly were also part of the protoplanetary gas and dust cloud from which the Earth arose. Due to the very low temperature of this cloud, the very first terrestrial atmosphere could only consist of hydrogen and helium, because. all other elements of the matter from which the cloud was composed were in a solid state. Such an atmosphere is observed in the giant planets, obviously, due to the large attraction of the planets and the distance from the Sun, they retained their primary atmospheres.

Then the heating of the Earth followed: heat was generated by the gravitational contraction of the planet and the decay of radioactive elements inside it. The Earth lost its hydrogen-helium atmosphere and created its own secondary atmosphere from the gases released from its depths (carbon dioxide, ammonia, methane, hydrogen sulfide). According to A.P. Vinogradov (1959), in this atmosphere H 2 O was the most, followed by CO 2 , CO, HCl, HF, H 2 S, N 2 , NH 4 Cl and CH 4 (the composition of modern volcanic gases is approximately the same). V. Sokolov (1959) believed that there were also H 2 and NH 3 here. There was no oxygen, and reducing conditions dominated the atmosphere. Now similar atmospheres are observed on Mars and Venus, they are 95% carbon dioxide.

The next stage in the development of the atmosphere was transitional - from abiogenic to biogenic, from reducing conditions to oxidizing ones. Main constituent parts gas shell of the Earth became N 2 , CO 2 , CO. As side impurities - CH 4, O 2. Oxygen originated from water molecules in the upper atmosphere under the action of ultraviolet rays sun; it could also stand out from those oxides that made up the earth's crust, but the vast majority of it went back to the oxidation of minerals earth's crust or the oxidation of hydrogen and its compounds in the atmosphere.

The last stage in the development of the nitrogen-oxygen atmosphere is associated with the emergence of life on Earth and, with the emergence of the mechanism of photosynthesis. The content of oxygen - biogenic - began to increase. At the same time, the atmosphere almost completely lost carbon dioxide, some of which entered the huge deposits of coal and carbonates.

This is the path from the hydrogen-helium atmosphere to the modern one, in which nitrogen and oxygen now play the main role, and argon and carbon dioxide are present as impurities. Modern nitrogen is also of biogenic origin.

The composition of atmospheric gases.

atmospheric air- a mechanical mixture of gases in which dust and water are contained in suspension. Clean and dry air at sea level is a mixture of several gases, and the ratio between the main constituent gases of the atmosphere - nitrogen (volume concentration 78.08%) and oxygen (20.95%) - is constant. In addition to them, atmospheric air contains argon (0.93%) and carbon dioxide (0.03%). The amount of other gases - neon, helium, methane, krypton, xenon, hydrogen, iodine, carbon monoxide and nitrogen oxides are negligible (less than 0.1%) (Table).

table 2

Gas composition of the atmosphere

In the high layers of the atmosphere, the composition of the air changes under the influence of hard solar radiation, which leads to the disintegration (dissociation) of oxygen molecules into atoms. Atomic oxygen is the main component of the high layers of the atmosphere. Finally, in the most distant layers of the atmosphere from the Earth's surface, the lightest gases, hydrogen and helium, become the main components. A new compound, hydroxyl OH, has been discovered in the upper atmosphere. The presence of this compound explains the formation of water vapor at high altitudes in the atmosphere. Since the bulk of the matter is concentrated at a distance of 20 km from the Earth's surface, changes in the air composition with height do not have a noticeable effect on the overall composition of the atmosphere.

The most important components of the atmosphere are ozone and carbon dioxide. Ozone is triatomic oxygen ( O 3 ), present in the atmosphere from the Earth's surface to an altitude of 70 km. In the surface layers of air, it is formed mainly under the influence of atmospheric electricity and in the process of oxidation of organic substances, and in the higher layers of the atmosphere (stratosphere) - as a result of the action of ultraviolet radiation from the Sun on an oxygen molecule. Most of the ozone is in the stratosphere (for this reason, the stratosphere is often called the ozonosphere). The layer of maximum ozone concentration at an altitude of 20-25 km is called the ozone screen. In general, the ozone layer absorbs about 13% of solar energy. The decrease in ozone concentration over certain areas is called "ozone holes".

Carbon dioxide together with water vapor causes the greenhouse effect of the atmosphere. the greenhouse effect- heating of the inner layers of the atmosphere, due to the ability of the atmosphere to transmit short-wave radiation from the Sun and not to release long-wave radiation from the Earth. If there were twice as much carbon dioxide in the atmosphere, the average temperature of the Earth would reach 18 0 C, now it is 14-15 0 C.

The total weight of atmospheric gases is approximately 4.5·10 15 t. Thus, the "weight" of the atmosphere per unit area, or atmospheric pressure, is approximately 10.3 t/m 2 at sea level.

There are many particulate matter in the air, the diameter of which is fractions of a micron. They are the nuclei of condensation. Without them, the formation of fogs, clouds, and precipitation would be impossible. Particulate matter in the atmosphere is associated with many optical and atmospheric phenomena. The ways they enter the atmosphere are different: volcanic ash, smoke from fuel combustion, plant pollen, microorganisms. AT recent times condensation nuclei are industrial emissions, radioactive decay products.

An important component of the atmosphere is water vapor, its amount in humid equatorial forests reaches 4%, in the polar regions it decreases to 0.2%. Water vapor enters the atmosphere due to evaporation from the surface of the soil and water bodies, as well as transpiration of moisture by plants. Water vapor is a greenhouse gas, and together with carbon dioxide, it traps most of the Earth's long-wave radiation, keeping the planet from cooling.

The atmosphere is not a perfect insulator; it has the ability to conduct electricity due to the action of ionizers - ultraviolet radiation from the sun, cosmic rays, radio radiation active substances. The maximum electrical conductivity is observed at an altitude of 100-150 km. As a result of the combined action of atmospheric ions and charge earth's surface creates an electric field in the atmosphere. In relation to the earth's surface, the atmosphere is positively charged. Allocate the neutrosphere– a layer with a neutral composition (up to 80 km) and ionosphere is the ionized layer.

The structure of the atmosphere.

There are several main layers of the atmosphere. The lower one, adjacent to the earth's surface, is called troposphere(height 8-10 km at the poles, 12 km in temperate latitudes and 16-18 km above the equator). The air temperature gradually decreases with height - by an average of 0.6ºC for every 100 m of ascent, which is noticeably manifested not only in mountainous areas, but also in the highlands of Belarus.

The troposphere contains up to 80% of the total air mass, the main amount of atmospheric impurities and almost all water vapor. It is in this part of the atmosphere at an altitude of 10-12 km that clouds form, thunderstorms, rains and other physical processes occur that shape the weather and determine climatic conditions in different areas of our planet. The lower layer of the troposphere that is directly adjacent to the earth's surface is called ground layer.

The influence of the earth's surface extends to approximately 20 km, and then the air is heated directly by the Sun. Thus, the GO boundary, lying at a height of 20-25 km, is determined, among other things, by the thermal effect of the earth's surface. At this altitude, latitudinal differences in air temperature disappear, and geographic zoning is blurred.

Above starts stratosphere, which extends to a height of 50-55 km from the surface of the ocean or land. This layer of the atmosphere is significantly rarefied, the amount of oxygen and nitrogen decreases, and hydrogen, helium and other light gases increase. The ozone layer formed here absorbs ultraviolet radiation and strongly affects the thermal conditions of the Earth's surface and physical processes in the troposphere. In the lower part of the stratosphere, the air temperature is constant, here is the isothermal layer. Starting from a height of 22 km, the air temperature rises, at the upper boundary of the stratosphere it reaches 0 0 C (the temperature rise is explained by the presence of ozone here, which absorbs solar radiation). In the stratosphere, intense horizontal movement of air occurs. The speed of air flows reaches 300-400 km/h. The stratosphere contains less than 20% of the atmospheric air.

At an altitude of 55-80 km is mesosphere(in this layer, the air temperature decreases with height and drops to –80 0 C near the upper boundary), between 80-800 km is located thermosphere, which is dominated by helium and hydrogen (air temperature rises rapidly with altitude and reaches 1000 0 C at an altitude of 800 km). The mesosphere and thermosphere together form a powerful layer called ionosphere(region of charged particles - ions and electrons).

The uppermost, highly rarefied part of the atmosphere (from 800 to 1200 km) is exosphere. It is dominated by gases in the atomic state, the temperature rises to 2000ºC.

In the life of GO, the atmosphere is of great importance. The atmosphere has a beneficial effect on the Earth's climate, protecting it from excessive cooling and heating. Daily temperature fluctuations on our planet without an atmosphere would reach 200ºC: during the day + 100ºC and above, at night -100ºC. At present, the average air temperature near the Earth's surface is +14ºС. The atmosphere does not allow meteors and hard radiation to reach the Earth. Without the atmosphere, there would be no sound, auroras, clouds, and precipitation.

The climate-forming processes are heat exchange, moisture exchange and circulation of the atmosphere.

Heat transfer in the atmosphere. The heat transfer ensures the thermal regime of the atmosphere and depends on the radiation balance, i.e. heat inflows coming to the earth's surface (in the form of radiant energy) and leaving it (radiant energy absorbed by the Earth is converted into heat).

Solar radiation is the flux of electromagnetic radiation coming from the Sun. At the upper boundary of the atmosphere, the intensity (flux density) solar radiation equal to 8.3 J / (cm 2 / min). The amount of heat that radiates 1 cm 2 of a black surface in 1 minute with perpendicular incidence of sunlight is called solar constant.

The amount of solar radiation received by the Earth depends on:

1. from the distance between the Earth and the Sun. Earth is closest to the Sun in early January, farthest in early July; the difference between these two distances is 5 million km, as a result of which the Earth in the first case receives 3.4% more, and in the second 3.5% less radiation than with the average distance from the Earth to the Sun (in early April and in early October);

2. from the angle of incidence sun rays on the earth's surface, which in turn depends on the geographical latitude, the height of the sun above the horizon (changing during the day and seasons), the nature of the relief of the earth's surface;

3. from the transformation of radiant energy in the atmosphere (scattering, absorption, reflection back into the world space) and on the earth's surface. The average albedo of the Earth is 43%.

About 17% of all radiation is absorbed; ozone, oxygen, nitrogen absorb mainly short-wave ultraviolet rays, water vapor and carbon dioxide - long-wave infrared radiation. The atmosphere dissipates 28% of the radiation; 21% goes to the earth's surface, 7% goes into space. That part of the radiation that comes to the earth's surface from the entire firmament is called scattered radiation . The essence of scattering lies in the fact that the particle, absorbing electromagnetic waves, itself becomes a source of light emission and radiates the same waves that fall on it. Air molecules are very small, comparable in size to the wavelength of the blue part of the spectrum. In pure air, molecular scattering predominates, hence the color of the sky is blue. With dusty air, the color of the sky becomes whitish. The color of the sky depends on the content of impurities in the atmosphere. With a high content of water vapor, which scatters red rays, the sky acquires a reddish tint. The phenomena of twilight and white nights are associated with scattered radiation, because After the Sun has set below the horizon, the upper layers of the atmosphere are still illuminated.

The top of the clouds reflects about 24% of the radiation. Consequently, about 31% of all solar radiation entering the upper boundary of the atmosphere comes to the earth's surface in the form of a stream of rays, it is called direct radiation . The sum of direct and diffuse radiation (52%) is called total radiation. The ratio between direct and scattered radiation varies depending on the cloudiness, dustiness of the atmosphere and the height of the Sun. The distribution of total solar radiation over the earth's surface is zonal. The highest total solar radiation of 840-920 kJ/cm 2 per year is observed in the tropical latitudes of the Northern Hemisphere, which is explained by low cloudiness and high air transparency. At the equator, the total radiation decreases to 580-670 kJ/cm 2 per year due to high cloudiness and reduced transparency due to high humidity. In temperate latitudes, the total radiation is 330-500 kJ / cm 2 per year, in polar latitudes - 250 kJ / cm 2 per year, and in Antarctica due to high altitude mainland and a little humidity it is a little more.

The total solar radiation entering the earth's surface is partially reflected back. The ratio of reflected radiation to total, expressed as a percentage, is called albedo. Albedo characterizes the reflectivity of a surface and depends on its color, humidity and other properties.

Freshly fallen snow has the highest reflectivity - up to 90%. Albedo of sands 30-35%, grass - 20%, deciduous forest - 16-27%, coniferous - 6-19%; dry chernozem has an albedo of 14%, wet - 8%. The albedo of the Earth as a planet is taken equal to 35%.

By absorbing radiation, the Earth itself becomes a source of radiation. Thermal radiation of the Earth - terrestrial radiation- is long-wave, because The wavelength depends on the temperature: the higher the temperature of the radiating body, the shorter the wavelength of the rays emitted by it. The radiation of the earth's surface heats the atmosphere and it itself begins to radiate radiation into the world space ( counter radiation of the atmosphere) and to the earth's surface. The counter radiation of the atmosphere is also long-wavelength. Two streams of long-wave radiation meet in the atmosphere - surface radiation (terrestrial radiation) and atmospheric radiation. The difference between them, which determines actual loss heat from the earth's surface is called effective radiation , it is directed to the Cosmos, because more terrestrial radiation. Effective radiation is greater during the day and in summer, because. depends on surface heating. Effective radiation depends on air humidity: the more water vapor or water droplets in the air, the less radiation (therefore, in cloudy weather in winter it is always warmer than in clear weather). In general, for the Earth, the effective radiation is 190 kJ/cm 2 per year (the highest in tropical deserts is 380, the lowest in polar latitudes is 85 kJ/cm 2 per year).

The earth simultaneously receives radiation and gives it away. The difference between the received and spent radiation is called radiation balance, or residual radiation. The arrival of the radiation balance of the surface is the total radiation (Q) and the counter radiation of the atmosphere. Consumption - reflected radiation (R k) and terrestrial radiation. The difference between the terrestrial radiation and the counter radiation of the atmosphere - effective radiation (E eff) has a minus sign and is part of the flow rate in the radiation balance:

R b \u003d Q-E eff -R k

The radiation balance is distributed zonally: it decreases from the equator to the poles. largest radiation balance characteristic of equatorial latitudes and is 330-420 kJ / cm 2 per year, in tropical latitudes it decreases to 250-290 kJ / cm 2 per year (due to an increase in effective radiation), in temperate latitudes the radiation balance decreases to 210-85 kJ / cm 2 per year, in polar latitudes its value approaches zero. The general feature of the radiation balance is that over the oceans at all latitudes the radiation balance is higher by 40-85 kJ/cm2, because the albedo of water and the effective radiation of the ocean are less.

The incoming part of the radiation balance of the atmosphere (R b) consists of effective radiation (E eff) and absorbed solar radiation (R p), the expenditure part is determined by the atmospheric radiation going into space (E a):

R b \u003d E eff - E a + R p

The radiation balance of the atmosphere is negative, while that of the surface is positive. The total radiation balance of the atmosphere and the earth's surface is equal to zero, i.e. The earth is in a state of radiant equilibrium.

Thermal balance is the algebraic sum of the heat fluxes coming to the earth's surface in the form of the radiation balance and leaving it. It consists of the heat balance of the surface and the atmosphere. In the incoming part of the heat balance of the earth's surface is the radiative balance, in the outgoing part - the cost of heat for evaporation, for heating the atmosphere from the Earth, for heating the soil. Heat is also used for photosynthesis. Soil formation, but these costs do not exceed 1%. It should be noted that above the oceans, more heat is spent on evaporation, in tropical latitudes - on heating the atmosphere.

In the heat balance of the atmosphere, the incoming part is the heat released during the condensation of water vapor and transferred from the surface to the atmosphere; the flow rate is the sum of the negative radiation balance. The heat balance of the earth's surface and the atmosphere is zero, i.e. The earth is in a state of thermal equilibrium.

Thermal regime of the earth's surface.

Directly from the sun's rays, the earth's surface is heated, and already from it - the atmosphere. The surface that receives and gives off heat is called active surface . In the temperature regime of the surface, the daily and annual temperature variations are distinguished. The diurnal variation of surface temperatures – change in surface temperature during the day. The daily course of land surface temperatures (dry and devoid of vegetation) is characterized by one maximum at about 13:00 and one minimum before sunrise. Daytime maxima of land surface temperature can reach 80 0 C in the subtropics and about 60 0 C in temperate latitudes.

The difference between the maximum and minimum daily surface temperature is called daily temperature range. The daily temperature amplitude can reach 40 0 ​​С in summer, the smallest amplitude of daily temperatures in winter - up to 10 0 С.

Annual variation of surface temperature - change in the average monthly surface temperature during the year, due to the course of solar radiation and depends on the latitude of the place. In temperate latitudes, the maximum land surface temperatures are observed in July, the minimum - in January; on the ocean, the highs and lows are a month late.

Annual amplitude of surface temperatures equal to the difference between the maximum and minimum average monthly temperatures; increases with increasing latitude of the place, which is explained by the increase in fluctuations in the magnitude of solar radiation. The annual temperature amplitude reaches its greatest values ​​on the continents; on the oceans and sea ​​shores significantly less. The smallest annual temperature amplitude is observed in the equatorial latitudes (2-3 0), the largest - in the subarctic latitudes on the continents (more than 60 0).

Thermal regime of the atmosphere. Atmospheric air is slightly heated by direct sunlight. Because the air shell freely passes the sun's rays. The atmosphere is heated by the underlying surface. Heat is transferred to the atmosphere by convection, advection and condensation of water vapor. The layers of air, heated by the soil, become lighter and rise upwards, while the colder, therefore, heavier air descends. As a result of thermal convection heating of high layers of air. The second heat transfer process is advection– horizontal air transfer. The role of advection is to transfer heat from low to high latitudes; in the winter season, heat is transferred from the oceans to the continents. Water vapor condensation- an important process that transfers heat to high layers of the atmosphere - during evaporation, heat is taken from the evaporating surface, during condensation in the atmosphere, this heat is released.

Temperature decreases with height. The change in air temperature per unit distance is called vertical temperature gradient on average, it is 0.6 0 per 100 m. At the same time, the course of this decrease in different layers of the troposphere is different: 0.3-0.4 0 up to a height of 1.5 km; 0.5-0.6 - between heights of 1.5-6 km; 0.65-0.75 - from 6 to 9 km and 0.5-0.2 - from 9 to 12 km. In the surface layer (2 m thick), the gradients, when converted to 100 m, are hundreds of degrees. In rising air, the temperature changes adiabatically. adiabatic process - the process of changing the air temperature during its vertical movement without heat exchange with the environment (in one mass, without heat exchange with other media).

Exceptions are often observed in the described vertical temperature distribution. It happens that the upper layers of air are warmer than the lower ones adjacent to the ground. This phenomenon is called temperature inversion (increase in temperature with height) . Most often, an inversion is a consequence of a strong cooling of the surface layer of air caused by a strong cooling of the earth's surface on clear, quiet nights, mainly in winter. With a rugged relief, cold air masses slowly flow down the slopes and stagnate in basins, depressions, etc. Inversions can also form when air masses move from warm to cold regions, since when heated air flows onto a cold underlying surface, its lower layers noticeably cool (compression inversion).

Daily and annual variations in air temperature.

The daily course of air temperature is called the change in air temperature during the day - in general, it reflects the course of the temperature of the earth's surface, but the moments of the onset of maxima and minima are somewhat late, the maximum occurs at 14 o'clock, the minimum after sunrise.

Daily amplitude of air temperature (the difference between the maximum and minimum air temperatures during the day) is higher on land than over the ocean; decreases when moving to high latitudes (the greatest in tropical deserts - up to 40 0 ​​C) and increases in places with bare soil. The magnitude of the daily amplitude of air temperature is one of the indicators of the continentality of the climate. In deserts, it is much greater than in areas with a maritime climate.

Annual variation of air temperature (change in average monthly temperature during the year) is determined primarily by the latitude of the place. Annual amplitude of air temperature - the difference between the maximum and minimum average monthly temperatures.

The geographical distribution of air temperature is shown using isotherms - lines connecting points on the map with the same temperature. The distribution of air temperature is zonal; annual isotherms generally have a sublatitudinal strike and correspond to the annual distribution of the radiation balance.

On average for the year, the warmest parallel is 10 0 N.L. with a temperature of 27 0 C is thermal equator. In summer, the thermal equator shifts to 20 0 N, in winter it approaches the equator by 5 0 N. The shift of the thermal equator in SP is explained by the fact that in SP the land area located at low latitudes is larger compared to the SP, and it has higher temperatures during the year.

The bright luminary burns us with hot rays and makes us think about the significance of radiation in our life, its benefits and harms. What is solar radiation? The lesson of school physics invites us to get acquainted with the concept of electromagnetic radiation in general. This term refers to another form of matter - different from matter. This includes both visible light and the spectrum that is not perceived by the eye. That is, x-rays, gamma rays, ultraviolet and infrared.

Electromagnetic waves

In the presence of a source-emitter of radiation, its electromagnetic waves propagate in all directions at the speed of light. These waves, like any other, have certain characteristics. These include the oscillation frequency and wavelength. Any body whose temperature differs from absolute zero has the property to emit radiation.

The sun is the main and most powerful source of radiation near our planet. In turn, the Earth (its atmosphere and surface) itself emits radiation, but in a different range. Observation of the temperature conditions on the planet over long periods of time gave rise to a hypothesis about the balance of the amount of heat received from the Sun and given off into outer space.

Solar radiation: spectral composition

The vast majority (about 99%) of the solar energy in the spectrum lies in the wavelength range from 0.1 to 4 microns. The remaining 1% is longer and shorter rays, including radio waves and x-rays. About half of the radiant energy of the sun falls on the spectrum that we perceive with our eyes, approximately 44% - in infrared radiation, 9% - in ultraviolet. How do we know how solar radiation is divided? The calculation of its distribution is possible thanks to research from space satellites.

There are substances that can enter a special state and emit additional radiation of a different wave range. For example, there is a glow at low temperatures that are not characteristic of the emission of light by a given substance. This type of radiation, called luminescent, does not lend itself to the usual principles of thermal radiation.

The phenomenon of luminescence occurs after the absorption of a certain amount of energy by the substance and the transition to another state (the so-called excited state), which is higher in energy than at the substance's own temperature. Luminescence appears during the reverse transition - from an excited to a familiar state. In nature, we can observe it in the form of night sky glows and aurora.

Our luminary

The energy of the sun's rays is almost the only source of heat for our planet. Its own radiation, coming from its depths to the surface, has an intensity that is about 5 thousand times less. At the same time, visible light - one of the most important factors of life on the planet - is only a part of solar radiation.

The energy of the sun's rays is converted into heat by a smaller part - in the atmosphere, a larger one - on the surface of the Earth. There it is spent on heating water and soil (upper layers), which then give off heat to the air. Being heated, the atmosphere and the earth's surface, in turn, emit infrared rays into space, while cooling.

Solar radiation: definition

The radiation that comes to the surface of our planet directly from the solar disk is commonly referred to as direct solar radiation. The sun spreads it in all directions. Taking into account the huge distance from the Earth to the Sun, direct solar radiation at any point on the earth's surface can be represented as a beam of parallel rays, the source of which is practically in infinity. The area located perpendicular to the rays of sunlight thus receives the greatest amount of it.

Radiation flux density (or irradiance) is a measure of the amount of radiation incident on a particular surface. This is the amount of radiant energy falling per unit time per unit area. This value is measured - energy illumination - in W / m 2. Our Earth, as everyone knows, revolves around the Sun in an ellipsoidal orbit. The sun is at one of the foci of this ellipse. Therefore, every year certain time(early January) the Earth occupies a position closest to the Sun and in another (early July) - farthest from it. In this case, the magnitude of the energy illumination varies in inverse proportion relative to the square of the distance to the sun.

Where does the solar radiation that reaches the Earth go? Its types are determined by many factors. Depending on the geographical latitude, humidity, cloudiness, part of it is dissipated in the atmosphere, part is absorbed, but most still reaches the surface of the planet. In this case, a small amount is reflected, and the main one is absorbed by the earth's surface, under the influence of which it is heated. Scattered solar radiation also partially falls on the earth's surface, is partially absorbed by it and partially reflected. The rest of it goes into outer space.

How is the distribution

Is solar radiation homogeneous? Its types after all "losses" in the atmosphere can differ in their spectral composition. After all, the rays various lengths and dissipated and absorbed differently. On average, about 23% of its initial amount is absorbed by the atmosphere. Approximately 26% of the total flux is converted into diffuse radiation, 2/3 of which then falls on the Earth. In essence, this is a different type of radiation, different from the original. Scattered radiation is sent to Earth not by the disk of the Sun, but by the vault of heaven. It has a different spectral composition.

Absorbs radiation mainly ozone - the visible spectrum, and ultraviolet rays. Infrared radiation is absorbed by carbon dioxide (carbon dioxide), which, by the way, is very small in the atmosphere.

Scattering of radiation, weakening it, occurs for any wavelength of the spectrum. In the process, its particles, falling under electromagnetic influence, redistribute the energy of the incident wave in all directions. That is, the particles serve as point sources of energy.

Daylight

Due to scattering, the light coming from the sun changes color when passing through the layers of the atmosphere. The practical value of scattering is in the creation of daylight. If the Earth were devoid of an atmosphere, illumination would exist only in places where direct or reflected rays of the sun hit the surface. That is, the atmosphere is the source of illumination during the day. Thanks to it, it is light both in places inaccessible to direct rays, and when the sun is hidden behind clouds. It is scattering that gives color to the air - we see the sky blue.

What else influences solar radiation? The turbidity factor should not be discounted either. After all, the weakening of radiation occurs in two ways - the atmosphere itself and water vapor, as well as various impurities. The level of dust increases in summer (as does the content of water vapor in the atmosphere).

Total radiation

It refers to the total amount of radiation falling on the earth's surface, both direct and diffuse. The total solar radiation decreases in cloudy weather.

For this reason, in summer, the total radiation is on average higher before noon than after it. And in the first half of the year - more than in the second.

What happens to the total radiation on the earth's surface? Getting there, it is mostly absorbed by the upper layer of soil or water and turns into heat, part of it is reflected. The degree of reflection depends on the nature of the earth's surface. The indicator expressing the percentage of reflected solar radiation to its total amount falling on the surface is called the surface albedo.

The concept of self-radiation of the earth's surface is understood as long-wave radiation emitted by vegetation, snow cover, upper layers of water and soil. The radiation balance of a surface is the difference between its amount absorbed and emitted.

Effective Radiation

It is proved that the counter radiation is almost always less than the terrestrial one. Because of this, the surface of the earth bears heat loss. The difference between the intrinsic radiation of the surface and the atmospheric radiation is called the effective radiation. This is actually a net loss of energy and, as a result, heat at night.

It also exists during the daytime. But during the day it is partially compensated or even blocked by absorbed radiation. Therefore, the surface of the earth is warmer during the day than at night.

On the geographical distribution of radiation

Solar radiation on Earth is unevenly distributed throughout the year. Its distribution has a zonal character, and the isolines (connecting points of equal values) of the radiation flux are by no means identical to the latitudinal circles. This discrepancy is caused by different levels of cloudiness and transparency of the atmosphere in different regions of the globe.

The total solar radiation during the year has the greatest value in subtropical deserts with a low-cloud atmosphere. It is much less in the forest regions of the equatorial belt. The reason for this is increased cloudiness. This indicator decreases towards both poles. But in the region of the poles it increases again - in the northern hemisphere it is less, in the region of snowy and slightly cloudy Antarctica - more. Above the surface of the oceans, on average, solar radiation is less than over the continents.

Almost everywhere on Earth, the surface has a positive radiation balance, that is, for the same time, the influx of radiation is greater than the effective radiation. The exceptions are the regions of Antarctica and Greenland with their ice plateaus.

Are we facing global warming?

But the above does not mean the annual warming of the earth's surface. The excess of absorbed radiation is compensated by heat leakage from the surface into the atmosphere, which occurs when the water phase changes (evaporation, condensation in the form of clouds).

Thus, there is no radiation equilibrium as such on the Earth's surface. But there is a thermal equilibrium - the inflow and loss of heat is balanced in different ways, including radiation.

Card balance distribution

In the same latitudes of the globe, the radiation balance is greater on the surface of the ocean than over land. This can be explained by the fact that the layer that absorbs radiation in the oceans has a large thickness, while at the same time, the effective radiation there is less due to the cold of the sea surface compared to land.

Significant fluctuations in the amplitude of its distribution are observed in deserts. The balance is lower there due to the high effective radiation in dry air and low cloud cover. To a lesser extent, it is lowered in areas of monsoon climate. In the warm season, the cloudiness there is increased, and the absorbed solar radiation is less than in other regions of the same latitude.

Of course, main factor, on which the average annual solar radiation depends, is the latitude of a particular area. Record "portions" of ultraviolet go to countries located near the equator. This is Northeast Africa, its eastern coast, the Arabian Peninsula, the north and west of Australia, part of the islands of Indonesia, the western coast of South America.

In Europe, Turkey, the south of Spain, Sicily, Sardinia, the islands of Greece, the coast of France (southern part), as well as part of the regions of Italy, Cyprus and Crete take on the largest dose of both light and radiation.

How about us?

Solar total radiation in Russia is distributed, at first glance, unexpectedly. On the territory of our country, oddly enough, it is not the Black Sea resorts that hold the palm. The largest doses of solar radiation fall on the territories bordering China and Severnaya Zemlya. In general, solar radiation in Russia is not particularly intense, which is fully explained by our northern geographic location. The minimum amount of sunlight goes to the northwestern region - St. Petersburg, together with the surrounding areas.

Solar radiation in Russia is inferior to Ukraine. There, the most ultraviolet radiation goes to the Crimea and territories beyond the Danube, in second place are the Carpathians with the southern regions of Ukraine.

The total (both direct and scattered) solar radiation falling on a horizontal surface is given by months in specially designed tables for different territories and is measured in MJ / m 2. For example, solar radiation in Moscow ranges from 31-58 in the winter months to 568-615 in the summer.

About solar insolation

Insolation, or the amount of useful radiation falling on a surface illuminated by the sun, varies greatly in different geographic points. Annual insolation is calculated per square meter in megawatts. For example, in Moscow this value is 1.01, in Arkhangelsk - 0.85, in Astrakhan - 1.38 MW.

When determining it, it is necessary to take into account such factors as the time of year (illuminance and day length are lower in winter), the nature of the terrain (mountains can block the sun), weather conditions characteristic of the area - fog, frequent rains and cloudiness. The light-receiving plane can be oriented vertically, horizontally or obliquely. The amount of insolation, as well as the distribution of solar radiation in Russia, is a data grouped in a table by city and region, indicating the geographical latitude.

1. What is called solar radiation? In what units is it measured? On what does its value depend?

The totality of radiant energy sent by the Sun is called solar radiation, usually it is expressed in calories or joules per square centimeter per minute. Solar radiation is distributed unevenly over the earth. It depends:

From the density and humidity of the air - the higher they are, the less radiation the earth's surface receives;

From the geographical latitude of the area - the amount of radiation increases from the poles to the equator. The amount of direct solar radiation depends on the length of the path that the sun's rays travel through the atmosphere. When the Sun is at its zenith (the angle of incidence of the rays is 90 °), its rays hit the Earth in the shortest way and intensively give off their energy to a small area;

From the annual and daily movement of the Earth - in the middle and high latitudes, the influx of solar radiation varies greatly by season, which is associated with a change in the midday height of the Sun and the length of the day;

From the nature of the earth's surface - the lighter the surface, the more sunlight it reflects.

2. What are the types of solar radiation?

Exist the following types Solar Radiation: Radiation reaching the earth's surface consists of direct and diffuse. Radiation that comes to Earth directly from the Sun in the form of direct sunlight in a cloudless sky is called direct. It carries the greatest amount of heat and light. If our planet had no atmosphere, the earth's surface would receive only direct radiation. However, passing through the atmosphere, about a quarter of the solar radiation is scattered by gas molecules and impurities, deviates from direct way. Some of them reach the Earth's surface, forming scattered solar radiation. Thanks to scattered radiation, light also penetrates into places where direct sunlight (direct radiation) does not penetrate. This radiation creates daylight and gives color to the sky.

3. Why does the inflow of solar radiation change according to the seasons of the year?

Russia, for the most part, is located in temperate latitudes, lying between the tropic and the polar circle, in these latitudes the sun rises and sets every day, but never at its zenith. Due to the fact that the angle of the Earth's inclination does not change during its entire revolution around the Sun, in different seasons the amount of incoming heat in temperate latitudes is different and depends on the angle of the Sun above the horizon. So, at a latitude of 450 max, the angle of incidence of the sun's rays (June 22) is approximately 680, and min (December 22) is approximately 220. The smaller the angle of incidence of the Sun's rays, the less heat they bring, therefore, there are significant seasonal differences in the received solar radiation in different seasons of the year: winter, spring, summer, autumn.

4. Why is it necessary to know the height of the Sun above the horizon?

The height of the Sun above the horizon determines the amount of heat coming to the Earth, so there is a direct relationship between the angle of incidence of the sun's rays and the amount of solar radiation coming to the earth's surface. From the equator to the poles, in general, there is a decrease in the angle of incidence of the sun's rays, and as a result, from the equator to the poles, the amount of solar radiation decreases. Thus, knowing the height of the Sun above the horizon, you can find out the amount of heat coming to the earth's surface.

5. Choose the correct answer. The total amount of radiation reaching the Earth's surface is called: a) absorbed radiation; b) total solar radiation; c) scattered radiation.

6. Choose the correct answer. When moving towards the equator, the amount of total solar radiation: a) increases; b) decreases; c) does not change.

7. Choose the correct answer. The largest indicator of reflected radiation has: a) snow; b) black soil; c) sand; d) water.

8. Do you think it is possible to get a tan on a cloudy summer day?

The total solar radiation consists of two components: diffuse and direct. At the same time, the Sun's rays, independent of their nature, carry ultraviolet, which affects the tan.

9. Using the map in Figure 36, determine the total solar radiation for ten cities in Russia. What conclusion did you draw?

Total radiation in different cities Russia:

Murmansk: 10 kcal/cm2 per year;

Arkhangelsk: 30 kcal/cm2 per year;

Moscow: 40 kcal/cm2 per year;

Perm: 40 kcal/cm2 per year;

Kazan: 40 kcal/cm2 per year;

Chelyabinsk: 40 kcal/cm2 per year;

Saratov: 50 kcal/cm2 per year;

Volgograd: 50 kcal/cm2 per year;

Astrakhan: 50 kcal/cm2 per year;

Rostov-on-Don: more than 50 kcal/cm2 per year;

The general pattern in the distribution of solar radiation is as follows: the closer an object (city) is to the pole, the less solar radiation falls on it (city).

10. Describe how the seasons differ in your area ( natural conditions, people's lives, their occupations). In which season of the year is life most active?

Difficult relief, a large extent from north to south, allow us to distinguish 3 zones in the region, differing both in relief and in climatic characteristics: mountain-forest, forest-steppe and steppe. The climate of the mountain-forest zone is cool and humid. Temperature regime varies depending on the terrain. This zone is characterized by short cool summers and long snowy winters. Permanent snow cover is formed in the period from October 25 to November 5 and it lies until the end of April, and in some years the snow cover remains until May 10-15. The coldest month is January. The average temperature in winter is minus 15-16°C, the absolute minimum is 44-48°C. The warmest month is July with an average air temperature of plus 15-17°C, the absolute maximum air temperature in the summer in this area reached plus 37-38°C The climate of the forest-steppe zone is warm, with fairly cold and snowy winters. The average January temperature is minus 15.5-17.5°C, the absolute minimum air temperature reached minus 42-49°C. The average air temperature in July is plus 18-19°C. The absolute maximum temperature is plus 42.0°C The climate of the steppe zone is very warm and arid. The winter here is cold, with severe frosts, blizzards, which are observed for 40-50 days, causing a strong transfer of snow. The average January temperature is minus 17-18°C. In severe winters, the minimum air temperature drops to minus 44-46°C.

The sun is a source of heat and light, giving strength and health. However, its impact is not always positive. Lack of energy or its excess can upset the natural processes of life and provoke various problems. Many people believe that tanned skin looks much more beautiful than pale, but if you spend a long time under direct rays, you can get a severe burn. Solar radiation is a stream of incoming energy propagating in the form of electromagnetic waves passing through the atmosphere. It is measured by the power of the energy transferred by it per unit surface area (watt / m 2). Knowing how the sun affects a person, you can prevent its negative impact.

What is solar radiation

Many books have been written about the Sun and its energy. The sun is the main source of energy for all physical and geographical phenomena on Earth. One two-billionth of the light penetrates into the upper layers of the planet's atmosphere, while the greater part settles in world space.

Rays of light are the primary sources of other forms of energy. Getting on the surface of the earth and into the water, they form into heat, affect climatic features and weather.

The degree of exposure to light rays on a person depends on the level of radiation, as well as the period spent under the sun. People use many types of waves to their advantage, using x-rays, infrared rays, and ultraviolet light. However, solar waves in their pure form in large quantities can adversely affect human health.

The amount of radiation depends on:

• position of the sun. The largest number exposure occurs in the plains and deserts, where the solstice is quite high, and the weather is cloudless. The polar regions receive the minimum amount of light, since cloud cover absorbs a significant part of the light flux;
• day length. The closer to the equator, the longer the day. It is there that people get more heat;
• atmospheric properties: cloudiness and humidity. At the equator, increased cloudiness and humidity, which is an obstacle to the passage of light. That is why the amount of light flux there is less than in tropical zones.

Distribution

The distribution of sunlight over the earth's surface is uneven and depends on:

• density and humidity of the atmosphere. The larger they are, the less exposure;
• geographic latitude of the area. The amount of light received rises from the poles to the equator;
• the movements of the earth. The amount of radiation varies depending on the time of year;
• characteristics of the earth's surface. A large number of of the light flux is reflected in light surfaces, such as snow. Chernozem reflects the light energy most weakly.

Due to the extent of its territory, the level of radiation in Russia varies considerably. Solar exposure in the northern regions is approximately the same - 810 kWh / m 2 for 365 days, in the south - more than 4100 kWh / m 2.

Quite a few importance is the duration of the hours during which the sun shines. These indicators are diverse in different regions, which is influenced not only by geographical latitude, but also by the presence of mountains. On the map of solar radiation in Russia, it is clearly seen that in some regions it is not advisable to install power lines, since natural light is quite capable of providing residents with electricity and heat.

Kinds

Light streams reach the Earth in various ways. It is on this that the types of solar radiation depend:

• The rays from the sun are called direct radiation.. Their strength depends on the height of the sun above the horizon. The maximum level is observed at 12 noon, the minimum - in the morning and evening. In addition, the impact intensity is related to the time of year: the highest occurs in summer, the lowest in winter. It is characteristic that in the mountains the level of radiation is higher than on flat surfaces. Also polluted air reduces direct light output. The lower the sun above the horizon, the less ultraviolet.
• Reflected radiation is radiation that is reflected by water or the surface of the earth.
• Scattered solar radiation is formed when the light flux is scattered. The blue color of the sky in cloudless weather depends on it.

Absorbed solar radiation depends on the reflectivity of the earth's surface - albedo.

The spectral composition of radiation is diverse:

• colored or visible rays give illumination and have great importance in plant life;
• ultraviolet should penetrate the human body moderately, since its excess or lack can be harmful;
• infrared irradiation gives a feeling of warmth and affects the growth of vegetation.

Total solar radiation is direct and scattered rays penetrating the earth.. In the absence of clouds, at about 12 noon, and also in summer time year it reaches its maximum.

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Vladimir
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How does the impact

Electromagnetic waves are made up of different parts. There are invisible, infrared and visible, ultraviolet rays. Characteristically, radiation fluxes have a different energy structure and affect people in different ways.

The light flux can have a beneficial, healing effect on the condition of the human body. Passing through the visual organs, light regulates metabolism, sleep patterns, and affects the general well-being of a person. In addition, light energy can cause a feeling of warmth. When the skin is irradiated, photochemical reactions occur in the body that contribute to the proper metabolism.

Ultraviolet has a high biological ability, having a wavelength of 290 to 315 nm. These waves synthesize vitamin D in the body, and are also capable of destroying the tuberculosis virus in a few minutes, staphylococcus - within a quarter of an hour, typhoid fever bacilli - in 1 hour.

Characteristically, cloudless weather reduces the duration of emerging epidemics of influenza and other diseases, such as diphtheria, which have the ability to be transmitted by airborne droplets.

The natural forces of the body protect a person from sudden atmospheric fluctuations: air temperature, humidity, pressure. However, sometimes such protection is weakened, which, under the influence of high humidity, together with elevated temperatures, leads to thermal shock.

Exposure to radiation is related to the degree of its penetration into the body. The longer the wavelength, the stronger the radiation. Infrared waves are able to penetrate up to 23 cm under the skin, visible streams - up to 1 cm, ultraviolet - up to 0.5-1 mm.

People receive all types of rays during the activity of the sun, when they stay in open spaces. Light waves allow a person to adapt to the world, which is why in order to ensure comfortable well-being in rooms, it is necessary to create conditions for an optimal level of lighting.

Human impact

The impact of solar radiation on human health is determined various factors. The place of residence of a person, the climate, as well as the amount of time spent under direct rays matter.

With a lack of sun, residents of the Far North, as well as people whose activities are related to working underground, such as miners, experience various life disorders, bone strength decreases, and nervous disorders occur.

Children who receive less light suffer from rickets more often than others. In addition, they are more susceptible to dental diseases, and also have a longer course of tuberculosis.

However, too long exposure to light waves without a periodic change of day and night can be detrimental to health. For example, residents of the Arctic often suffer from irritability, fatigue, insomnia, depression, and decreased ability to work.

Radiation in Russian Federation has less activity than, for example, in Australia.

Thus, people who are under long-term radiation:

• are at high risk of developing skin cancer;
• have an increased tendency to dry skin, which in turn accelerates the aging process and the appearance of pigmentation and early wrinkles;
• may suffer from visual impairment, cataracts, conjunctivitis;
• have a weakened immune system.

Lack of vitamin D in humans is one of the causes of malignant neoplasms, metabolic disorders, which leads to overweight, endocrine disorders, sleep disturbances, physical exhaustion, bad mood.

A person who systematically receives the light of the sun and does not abuse sunbathing, as a rule, does not experience health problems:

• has a stable work of the heart and blood vessels;
• does not suffer from nervous diseases;
• has a good mood;
• has a normal metabolism;
• rarely gets sick.

Thus, only a dosed intake of radiation can positively affect human health.

How to protect yourself

An excess of radiation can provoke overheating of the body, burns, as well as exacerbation of some chronic diseases.. Fans of sunbathing need to take care of the implementation of simple rules:

• sunbathe in open spaces with caution;
• during hot weather, hide in the shade under scattered rays. This is especially true for young children and older people with tuberculosis and heart disease.

It should be remembered that it is necessary to sunbathe in safe time days, and also not to be under the scorching sun for a long time. In addition, you should protect your head from heatstroke by wearing a hat, sunglasses, closed clothing, and using various sunscreens.

Solar radiation in medicine

Light fluxes are actively used in medicine:

• X-rays use the ability of waves to pass through soft tissues and the skeletal system
• the introduction of isotopes allows you to fix their concentration in the internal organs, to detect many pathologies and foci of inflammation;
• radiation therapy can destroy the growth and development of malignant neoplasms.

The properties of waves are successfully used in many physiotherapy devices:

• Devices with infrared radiation are used for heat treatment of internal inflammatory processes, bone diseases, osteochondrosis, rheumatism, due to the ability of waves to restore cellular structures.
• Ultraviolet rays can adversely affect living beings, inhibit plant growth, suppress microorganisms and viruses.

The hygienic value of solar radiation is great. Devices with ultraviolet radiation are used in therapy:

• various injuries of the skin: wounds, burns;
• infections;
• diseases of the oral cavity;
• oncological neoplasms.

In addition, radiation has a positive effect on the human body as a whole: it can give strength, strengthen the immune system, and compensate for the lack of vitamins.

Sunlight is an important source of full human life. Sufficient intake of it leads to a favorable existence of all living beings on the planet. A person cannot reduce the degree of radiation, but he can protect himself from its negative effects.

solar radiation called the flow of radiant energy from the sun going to the surface the globe. The radiant energy of the sun is the primary source of other types of energy. Absorbed by the surface of the earth and water, it turns into thermal energy, and in green plants - into the chemical energy of organic compounds. Solar radiation is the most important climate factor and the main cause of weather changes, since various phenomena occurring in the atmosphere are associated with thermal energy received from the sun.

Solar radiation, or radiant energy, by its nature is a stream of electromagnetic oscillations propagating in a straight line at a speed of 300,000 km / s with a wavelength from 280 nm to 30,000 nm. Radiant energy is emitted in the form of individual particles called quanta, or photons. To measure the length of light waves, nanometers (nm), or microns, millimicrons (0.001 microns) and anstroms (0.1 millimicrons) are used. Distinguish infrared invisible thermal rays with a wavelength of 760 to 2300 nm; visible light rays (red, orange, yellow, green, blue, blue and violet) with a wavelength of 400 (violet) to 759 nm (red); ultraviolet, or chemically invisible, rays with a wavelength of 280 to 390 nm. Rays with a wavelength of less than 280 millimicrons do not reach the earth's surface, due to their absorption by ozone in the high layers of the atmosphere.

At the edge of the atmosphere, the spectral composition of the sun's rays as a percentage is as follows: infrared rays 43%, light 52 and ultraviolet 5%. At the earth's surface, at a sun height of 40 °, solar radiation has (according to N. P. Kalitin) the following composition: infrared rays 59%, light 40 and ultraviolet 1% of all energy. The intensity of solar radiation increases with height above sea level, and also when the sun's rays fall vertically, since the rays have to pass through a smaller thickness of the atmosphere. In other cases, the surface will receive less sunlight, the lower the sun, or depending on the angle of incidence of the rays. The voltage of solar radiation decreases due to cloudiness, air pollution with dust, smoke, etc.

And first of all, there is a loss (absorption) of short-wave rays, and then thermal and light. The radiant energy of the sun is the source of life on earth of plant and animal organisms and the most important environmental factor. air environment. It has a variety of effects on the body, which at optimal dosing can be very positive, and when excessive (overdose) can be negative. All rays have both thermal and chemical effects. Moreover, for rays with a large wavelength, the thermal effect comes to the fore, and with a shorter wavelength, the chemical effect.

The biological effect of rays on the animal organism depends on the wavelength and their amplitude: the shorter the waves, the more frequent their oscillations, the greater the energy of the quantum and the stronger the reaction of the organism to such radiation. Short-wave, ultraviolet rays, when exposed to tissues, cause phenomena of the photoelectric effect in them with the appearance of split off electrons and positive ions in atoms. The depth of penetration of different rays into the body is not the same: infrared and red rays penetrate a few centimeters, visible (light) - a few millimeters, and ultraviolet - only 0.7-0.9 mm; rays shorter than 300 millimicrons penetrate into animal tissues to a depth of 2 millimicrons. With such an insignificant depth of penetration of the rays, the latter have a diverse and significant effect on the entire organism.

Solar radiation- a very biologically active and constantly acting factor, which is of great importance in the formation of a number of body functions. Thus, for example, through the medium of the eye, visible light rays affect the entire organism of animals, causing unconditioned and conditioned reflex reactions. Infrared heat rays exert their influence on the body both directly and through objects surrounding animals. The body of animals continuously absorbs and itself emits infrared rays (radiation exchange), and this process can vary significantly depending on the temperature of the skin of animals and surrounding objects. Ultraviolet chemical rays, the quanta of which have a much higher energy than the quanta of visible and infrared rays, are distinguished by the greatest biological activity, act on the body of animals by humoral and neuroreflex pathways. UV rays primarily act on the exteroreceptors of the skin, and then reflexively affect the internal organs, in particular the endocrine glands.

Prolonged exposure to optimal doses of radiant energy leads to adaptation of the skin, to its lesser reactivity. Under the influence of sunlight, hair growth, the function of sweat and sebaceous glands increase, the stratum corneum thickens and the epidermis thickens, which leads to an increase in the body's skin resistance. In the skin, the formation of biologically active substances (histamine and histamine-like substances) occurs, which enter the bloodstream. The same rays accelerate cell regeneration during the healing of wounds and ulcers on the skin. Under the action of radiant energy, especially ultraviolet rays, the pigment melanin is formed in the basal layer of the skin, which reduces the sensitivity of the skin to ultraviolet rays. Pigment (tan) is like a biological screen that contributes to the reflection and scattering of rays.

The positive effect of the sun's rays affects the blood. Their systematic moderate impact significantly enhances hematopoiesis with a simultaneous increase in the number of erythrocytes and hemoglobin content in the peripheral blood. In animals after blood loss or recovering from serious illnesses, especially infectious ones, moderate exposure to sunlight stimulates blood regeneration and increases its coagulability. From moderate exposure to sunlight in animals, gas exchange increases. The depth increases and the frequency of respiration decreases, the amount of oxygen introduced increases, more carbon dioxide and water vapor are released, in connection with which oxygen supply to tissues improves and oxidative processes increase.

An increase in protein metabolism is expressed by an increased deposition of nitrogen in tissues, as a result of which growth in young animals is faster. Excessive solar exposure can cause a negative protein balance, especially in animals suffering from acute infectious diseases, as well as other diseases accompanied by elevated body temperature. Irradiation leads to increased deposition of sugar in the liver and muscles in the form of glycogen. In the blood, the amount of underoxidized products (acetone bodies, lactic acid, etc.) sharply decreases, the formation of acetylcholine increases and metabolism is normalized, which is of particular importance for highly productive animals.

In malnourished animals, the intensity of fat metabolism slows down and fat deposition increases. Intensive lighting in obese animals, on the contrary, increases fat metabolism and causes increased fat burning. Therefore, semi-greasy and greasy fattening of animals should be carried out under conditions of less solar radiation.

Under the influence of ultraviolet rays of solar radiation, located in fodder plants ergosterol and dehydrocholesterol in the skin of animals are converted into active vitamins D 2 and D 3, which enhance phosphorus-calcium metabolism; the negative balance of calcium and phosphorus turns into a positive one, which contributes to the deposition of these salts in the bones. Sunlight and artificial irradiation with ultraviolet rays is one of the effective modern methods for the prevention and treatment of rickets and other animal diseases associated with calcium and phosphorus metabolism disorders.

Solar radiation, especially light and ultraviolet rays, is the main factor causing seasonal sexual periodicity in animals, since light stimulates the gonadotropic function of the pituitary gland and other organs. In spring, during the period of increased intensity of solar radiation and light exposure, the secretion of the gonads, as a rule, increases in most animal species. An increase in sexual activity in camels, sheep and goats is observed with a shortening of daylight hours. If sheep are kept in darkened rooms in April-June, then their estrus will not come in the fall (as usual), but in May. The lack of light in growing animals (during growth and puberty), according to K.V. Svechin, leads to deep, often irreversible qualitative changes in the sex glands, and in adult animals it reduces sexual activity and fertility or causes temporary infertility.

Visible light, or degree of illumination, has a significant effect on egg development, estrus, breeding season, and pregnancy. In the northern hemisphere, the breeding season is usually short, and in the southern hemisphere the longest. Under influence artificial lighting animals, their duration of pregnancy is reduced from several days to two weeks. The effect of visible light rays on the gonads can be widely used in practice. Experiments conducted in the laboratory of zoohygiene VIEV proved that the illumination of the premises by a geometric coefficient of 1: 10 (according to KEO, 1.2-2%) compared with the illumination of 1: 15-1: 20 and lower (according to KEO, 0.2 -0.5%) positively affects the clinical and physiological state of pregnant sows and piglets up to 4 months of age, provides strong and viable offspring. The weight gain of piglets is increased by 6% and their safety by 10-23.9%.

The sun's rays, especially ultraviolet, violet and blue, kill or weaken the viability of many pathogenic microorganisms, delay their reproduction. Thus, solar radiation is a powerful natural disinfectant of the external environment. Under the influence of sunlight, the general tone of the body and its resistance to infectious diseases increase, as well as specific immune reactions increase (P. D. Komarov, A. P. Onegov, etc.). It has been proven that moderate irradiation of animals during vaccination contributes to an increase in the titer and other immune bodies, an increase in the phagocytic index, and, conversely, intense irradiation lowers the immune properties of the blood.

From all that has been said, it follows that the lack of solar radiation must be considered as a very unfavorable external condition for animals, in which they are deprived of the most important activator of physiological processes. With this in mind, animals should be placed in fairly bright rooms, regularly provided with exercise, and kept on pasture in summer.

Rationing of natural lighting in the premises is carried out according to geometric or lighting methods. In the practice of building livestock and poultry buildings, the geometric method is mainly used, according to which the norms of natural light are determined by the ratio of the area of ​​​​windows (glass without frames) to the floor area. However, despite the simplicity of the geometric method, the illumination norms are not set accurately with the help of it, since in this case they do not take into account the light and climatic features of different geographical areas. For more exact definition illumination in rooms use the lighting method, or the definition daylight factor(KEO). The coefficient of natural illumination is the ratio of the illumination of the room (measured point) to the outdoor illumination in horizontal plane. KEO is derived by the formula:

K = E:E n ⋅100%

Where K is the coefficient of natural light; E - illumination in the room (in lux); E n - outdoor illumination (in lux).

It must be borne in mind that the excessive use of solar radiation, especially on days with high insolation, can cause significant harm to animals, in particular, cause burns, eye disease, sunstroke, etc. Sensitivity to sunlight increases significantly from the introduction into the body of the so-called sensitizers (hematoporphyrin, bile pigments, chlorophyll, eosin, methylene blue, etc.). It is believed that these substances accumulate short-wave rays and turn them into long-wave rays with the absorption of part of the energy released by the tissues, as a result of which the tissue reactivity increases.

Sunburn in animals is more often observed on areas of the body with delicate, little hair, unpigmented skin as a result of exposure to heat (solar erythema) and ultraviolet rays (photochemical inflammation of the skin). Horses sunburn noted on non-pigmented areas of the scalp, lips, nostrils, neck, groin and limbs, and in cattle on the skin of the udder teats and perineum. In the southern regions, sunburn is possible in white-colored pigs.

Strong sunlight can cause irritation of the retina, cornea and vascular membranes of the eye and damage to the lens. With prolonged and intense radiation, keratitis, clouding of the lens and disturbance of accommodation of vision occur. Disturbance of accommodation is more often observed in horses if they are kept in stables with low windows facing south, against which horses are tied.

Sunstroke occurs as a result of strong and prolonged overheating of the brain, mainly by thermal infrared rays. The latter penetrate the scalp and cranium, reach the brain and cause hyperemia and an increase in its temperature. As a result, the animal first appears oppression, and then excitation, the respiratory and vasomotor centers are disturbed. Weakness, uncoordinated movements, shortness of breath, rapid pulse, hyperemia and cyanosis of the mucous membranes, trembling and convulsions are noted. The animal does not stay on its feet, falls to the ground; severe cases often end in the death of the animal with symptoms of paralysis of the heart or respiratory center. Sunstroke is especially severe if it is combined with heat stroke.

To protect animals from direct sunlight, it is necessary to keep them in the shade during the hottest hours of the day. To prevent sunstroke, particularly in working horses, white canvas browbands are worn.