Home fertilizers The distribution of solar radiation depends on. The value of solar radiation for climate. On the geographical distribution of radiation

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The distribution of solar radiation depends on. The value of solar radiation for climate. On the geographical distribution of radiation

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 fall on the Earth the shortest way and intensively give 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 the direct path. 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; in) 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 of the year differ in your area (natural conditions, people's lives, their activities). In which season of the year is life most active?

Difficult relief, large extent from north to south make it possible 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. The temperature regime varies depending on the relief. 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. Winter is cold here severe frosts, blizzards that 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.

Solar radiation is the leading climate-forming factor and practically the only source of energy for all physical processes occurring on the earth's surface and in its atmosphere. It determines the vital activity of organisms, creating one or another temperature regime; leads to the formation of clouds and precipitation; is the fundamental cause of the general circulation of the atmosphere, thereby exerting a huge impact on human life in all its manifestations. In construction and architecture, solar radiation is the most important environmental factor - the orientation of buildings, their constructive, space-planning, coloristic, plastic solutions and many other features depend on it.

According to GOST R 55912-2013 "Construction Climatology", the following definitions and concepts related to solar radiation are adopted:

direct radiation - part of the total solar radiation entering the surface in the form of a beam of parallel rays coming directly from the visible disk of the sun;
scattered solar radiation- part of the total solar radiation coming to the surface from the entire sky after scattering in the atmosphere;
reflected radiation- part of the total solar radiation reflected from the underlying surface (including from the facades, roofs of buildings);
solar radiation intensity- the amount of solar radiation passing per unit of time through a single area located perpendicular to the rays.

All values of solar radiation in modern domestic GOSTs, SP (SNiPs) and other regulatory documents related to construction and architecture are measured in kilowatts per hour per 1 m 2 (kW h / m 2). As a rule, a month is taken as a unit of time. To get the instantaneous (second) value of the power of the solar radiation flux (kW / m 2), the value given for the month should be divided by the number of days in a month, the number of hours in a day and seconds in hours.

In many early editions of building regulations and in many modern reference books on climatology, solar radiation values are given in megajoules or kilocalories per m 2 (MJ / m 2, Kcal / m 2). The coefficients for the conversion of these quantities from one to another are given in Appendix 1.

physical entity. Solar radiation comes to Earth from the Sun. The Sun is the closest star to us, which is on average 149,450,000 km away from the Earth. In early July, when the Earth is at its furthest from the Sun (“aphelion”), this distance increases to 152 million km, and in early January it decreases to 147 million km (“perihelion”).

Inside the solar core, the temperature exceeds 5 million K, and the pressure is several billion times greater than that of the earth, as a result of which hydrogen turns into helium. In the course of this thermonuclear reaction, radiant energy is born, which propagates from the Sun in all directions in the form of electromagnetic waves. At the same time, a whole spectrum of wavelengths comes to the Earth, which in meteorology is usually divided into short-wave and long-wave sections. shortwave call radiation in the wavelength range from 0.1 to 4 microns (1 micron \u003d 10 ~ 6 m). Radiation with long lengths (from 4 to 120 microns) is referred to as longwave. Solar radiation is predominantly short-wave - the indicated wavelength range accounts for 99% of all energy solar radiation, while the earth's surface and atmosphere emit long-wave radiation, and can only reflect short-wave radiation.

The sun is a source of not only energy, but also light. Visible light occupies a narrow range of wavelengths, only from 0.40 to 0.76 microns, but 47% of all solar radiant energy is contained in this interval. Light with a wavelength of about 0.40 microns is perceived as violet, with a wavelength of about 0.76 microns - as red. All other wavelengths are not perceived by the human eye; they are invisible to us 1 . Infrared radiation (from 0.76 to 4 microns) accounts for 44%, and ultraviolet (from 0.01 to 0.39 microns) - 9% of all energy. The maximum energy in the spectrum of solar radiation at the upper boundary of the atmosphere lies in the blue-blue region of the spectrum, and near the earth's surface - in the yellow-green.

A quantitative measure of solar radiation entering a certain surface is energy illumination, or flux of solar radiation, - the amount of radiant energy incident on a unit area per unit time. The maximum amount of solar radiation enters the upper boundary of the atmosphere and is characterized by the value of the solar constant. Solar constant - is the flux of solar radiation at the upper boundary of the earth's atmosphere through an area perpendicular to the sun's rays, at an average distance of the Earth from the Sun. According to the latest data approved by the World Meteorological Organization (WMO) in 2007, this value is 1.366 kW / m 2 (1366 W / m 2).

Much less solar radiation reaches the earth's surface, since as the sun's rays move through the atmosphere, radiation undergoes a number of significant changes. Part of it is absorbed by atmospheric gases and aerosols and passes into heat, i.e. goes to warm the atmosphere, and part is scattered and goes into a special form of diffuse radiation.

Process takeovers radiation in the atmosphere is selective - different gases absorb it in different areas spectrum and to varying degrees. The main gases that absorb solar radiation are water vapor (H 2 0), ozone (0 3) and carbon dioxide (CO 2). For example, as mentioned above, stratospheric ozone completely absorbs radiation harmful to living organisms with wavelengths shorter than 0.29 microns, which is why the ozone layer is a natural shield for the existence of life on Earth. On average, ozone absorbs about 3% of solar radiation. In the red and infrared regions of the spectrum, water vapor absorbs solar radiation most significantly. In the same region of the spectrum are the absorption bands of carbon dioxide, however

More details about light and color are discussed in other sections of the discipline "Architectural Physics".

in general, its absorption of direct radiation is small. Absorption of solar radiation occurs both by aerosols of natural and anthropogenic origin, especially strongly by soot particles. In total, about 15% of solar radiation is absorbed by water vapor and aerosols, and about 5% by clouds.

Scattering radiation is a physical process of interaction electromagnetic radiation and substances, during which molecules and atoms absorb part of the radiation, and then re-emit it in all directions. This is very important process, which depends on the ratio of the size of the scattering particles and the wavelength of the incident radiation. In absolutely pure air, where scattering is produced only by gas molecules, it obeys Rayleigh law, i.e. inversely proportional to the fourth power of the wavelength of the scattered rays. Thus, the blue color of the sky is the color of the air itself, due to the scattering of sunlight in it, since violet and blue rays are scattered by air much better than orange and red ones.

If there are particles in the air whose dimensions are comparable to the wavelength of radiation - aerosols, water droplets, ice crystals - then the scattering will not obey Rayleigh's law, and the scattered radiation will not be so rich in short-wavelength rays. On particles with a diameter greater than 1-2 microns, there will be no scattering, but diffuse reflection, which determines the whitish color of the sky.

Scattering plays a huge role in the formation of natural light: in the absence of the Sun in daytime it creates scattered (diffuse) light. If there were no scattering, it would be light only where direct sunlight would fall. Dusk and dawn, the color of the clouds at sunrise and sunset are also associated with this phenomenon.

So, solar radiation reaches the earth's surface in the form of two streams: direct and diffuse radiation.

direct radiation(5) comes to the earth's surface directly from the solar disk. In this case, the maximum possible amount of radiation will be received by a single site located perpendicular to the sun's rays (5). per unit horizontal surface will have a smaller amount of radiant energy Y, also called insolation:

Y \u003d? -8shA 0, (1.1)

where And 0- The height of the sun above the horizon, which determines the angle of incidence of the sun's rays on a horizontal surface.

scattered radiation(/)) comes to the earth's surface from all points of the firmament, with the exception of the solar disk.

All solar radiation reaching the earth's surface is called total solar radiation (0:

(1.2)
0 = + /) = And 0+ /).

The arrival of these types of radiation significantly depends not only on astronomical causes, but also on cloudiness. Therefore, in meteorology it is customary to distinguish possible amounts of radiation observed under cloudless conditions, and actual amounts of radiation taking place under real cloudiness conditions.

Not all solar radiation falling on the earth's surface is absorbed by it and converted into heat. Part of it is reflected and therefore lost by the underlying surface. This part is called reflected radiation(/? k), and its value depends on albedo ground surface (L to):

A k = - 100%.

The albedo value is measured in fractions of a unit or as a percentage. In construction and architecture, fractions of a unit are more often used. They also measure the reflectivity of building and finishing materials, the lightness of facades, etc. In climatology, albedo is measured as a percentage.

Albedo has a significant impact on the formation of the Earth's climate, as it is an integral indicator of the reflectivity of the underlying surface. It depends on the state of this surface (roughness, color, moisture) and varies over a very wide range. The highest albedo values (up to 75%) are characteristic of freshly fallen snow, while the lowest values are characteristic of the water surface during sheer sunlight (“3%). The albedo of the soil and vegetation surface varies on average from 10 to 30%.

If we consider the entire Earth as a whole, then its albedo is 30%. This value is called Earth's planetary albedo and represents the ratio of the reflected and scattered solar radiation leaving into space to the total amount of radiation entering the atmosphere.

On the territory of cities, the albedo is, as a rule, lower than in natural, undisturbed landscapes. Characteristic value of albedo for the territory major cities temperate climate is 15-18%. In southern cities, the albedo is, as a rule, higher due to the use of lighter tones in the color of facades and roofs; in northern cities with dense buildings and dark color schemes of buildings, the albedo is lower. This makes it possible to reduce the amount of absorbed solar radiation in southern hot countries, thereby reducing the thermal background of buildings, and in the northern cold regions, on the contrary, to increase the share of absorbed solar radiation, increasing the overall thermal background.

Absorbed radiation(* U P0GL) is also called balance of shortwave radiation (VC) and is the difference between the total and reflected radiation (two short-wave fluxes):

^abs \u003d 5 k = 0~ I K- (1.4)

It heats the upper layers of the earth's surface and everything that is located on it (vegetation cover, roads, buildings, structures, etc.), as a result of which they emit long-wave radiation invisible to the human eye. This radiation is often called own radiation of the earth's surface(? 3). Its value, according to the Stefan-Boltzmann law, is proportional to the fourth power of absolute temperature.

The atmosphere also emits long wavelength radiation, most of which comes to the earth's surface and is almost completely absorbed by it. This radiation is called counter radiation of the atmosphere (E a). The counter radiation of the atmosphere increases with an increase in cloudiness and air humidity and is very important source heat for the earth's surface. However, the long-wave radiation of the atmosphere is always slightly less than the earth's, due to which the earth's surface loses heat, and the difference between these values is called effective radiation of the Earth (E ef).

On average, in temperate latitudes, the earth's surface through effective radiation loses about half of the amount of heat that it receives from absorbed solar radiation. By absorbing terrestrial radiation and sending counter radiation to the earth's surface, the atmosphere reduces the cooling of this surface at night. During the day, it does little to prevent the heating of the Earth's surface. This influence of the earth's atmosphere on the thermal regime of the earth's surface is called greenhouse effect. Thus, the phenomenon of the greenhouse effect consists in the retention of heat near the surface of the Earth. Gases play an important role in this process. technogenic origin, first of all - carbon dioxide, the concentration of which in urban areas is especially high. But the main role still belongs to the gases of natural origin.

The main substance in the atmosphere that absorbs long-wave radiation from the Earth and sends back radiation is water vapor. It absorbs almost all long-wave radiation except for the wavelength range from 8.5 to 12 microns, which is called "transparency window" water vapor. Only in this interval does the terrestrial radiation pass into the world space through the atmosphere. In addition to water vapor, carbon dioxide strongly absorbs long-wave radiation, and it is in the transparency window of water vapor that ozone is much weaker, as well as methane, nitrogen oxide, chlorofluorocarbons (freons) and some other gas impurities.

Keeping heat close to the earth's surface is a very important process for sustaining life. Without it, the average temperature of the Earth would be 33 ° C lower than the current one, and living organisms could hardly live on the Earth. Therefore, the point is not in the greenhouse effect as such (after all, it arose from the moment the atmosphere was formed), but in the fact that under the influence of anthropogenic activity, gain this effect. The reason is the rapid growth in the concentration of greenhouse gases of technogenic origin, mainly CO 2 emitted during the combustion of fossil fuels. This can lead to the fact that with the same incoming radiation, the proportion of heat remaining on the planet will increase, and, consequently, the temperature of the earth's surface and atmosphere will also increase. Over the past 100 years, the air temperature of our planet has increased by an average of 0.6 ° C.

It is believed that when the concentration of CO 2 doubles relative to its pre-industrial value global warming will be about 3°C (according to various estimates - from 1.5 to 5.5°C). At the same time, the greatest changes should occur in the troposphere of high latitudes in the autumn winter period. As a result, the ice in the Arctic and Antarctica will begin to melt and the level of the World Ocean will begin to rise. This increase can range from 25 to 165 cm, which means that many cities located in coastal zones seas and oceans will be flooded.

Thus, this is a very important issue affecting the lives of millions of people. With this in mind, in 1988 the first International Conference on the problem of anthropogenic climate change was held in Toronto. Scientists have come to the conclusion that the consequences of an increase in the greenhouse effect due to an increase in the content of carbon dioxide in the atmosphere are second only to the consequences of the global nuclear war. At the same time, the Intergovernmental Panel on Climate Change (IPCC) was formed at the United Nations (UN). IPCC - Intergovernmental Panel on Climate Change), which studies the impact of an increase in surface temperature on the climate, the ecosystem of the World Ocean, the biosphere as a whole, including the life and health of the planet's population.

In 1992, the Framework Convention on Climate Change (FCCC) was adopted in New York, main goal which proclaimed the stabilization of greenhouse gas concentrations in the atmosphere at levels that prevent the dangerous consequences of human intervention in the climate system. For practical implementation convention in December 1997 in Kyoto (Japan) for international conference the Kyoto Protocol was adopted. It defines specific quotas for greenhouse gas emissions by member countries, including Russia, which ratified this Protocol in 2005.

At the time of writing this book, one of the latest conferences on climate change is the Climate Conference in Paris, which took place from November 30 to December 12, 2015. The purpose of this conference is to sign an international agreement to curb the increase in the average temperature of the planet by 2100 no higher 2°C.

So, as a result of the interaction of various flows of short-wave and long-wave radiation, the earth's surface continuously receives and loses heat. The resulting value of the incoming and outgoing radiation is radiation balance (AT), which determines the thermal state of the earth's surface and the surface layer of air, namely their heating or cooling:

AT = Q- «k - ?ef \u003d 60 - BUT)-? ef =

= (5 "sin / ^ > + D) (l-A) -E ^ f \u003d B to + B a. (

Radiation balance data are needed to estimate the degree of heating and cooling various surfaces both in natural conditions and in the architectural environment, calculation thermal regime buildings and structures, determination of evaporation, heat reserves in the soil, regulation of irrigation of agricultural fields and other national economic purposes.

Measurement methods. key value research radiation balance Earth for understanding the patterns of climate and the formation of microclimatic conditions determines the fundamental role of observational data on its components - actinometric observations.

At meteorological stations in Russia, thermoelectric method measurements of radiation fluxes. The measured radiation is absorbed by the black receiving surface of the devices, turns into heat and heats the active junctions of the thermopile, while the passive junctions are not heated by radiation and have a lower temperature. Due to the difference in temperatures of active and passive junctions, a thermoelectromotive force arises at the output of the thermopile, which is proportional to the intensity of the measured radiation. Thus, most actinometric instruments are relative- they do not measure the radiation fluxes themselves, but quantities proportional to them - current strength or voltage. To do this, devices are connected, for example, to digital multimeters, and earlier to pointer galvanometers. At the same time, in the passport of each device, the so-called "conversion factor" - division price of an electrical measuring instrument (W / m 2). This multiplier is calculated by comparing the readings of one or another relative instrument with the readings absolute appliances - pyrheliometers.

The principle of operation of absolute devices is different. So, in the Angstrom compensatory pyrheliometer, a blackened metal plate is exposed to the sun, while another similar plate remains in the shade. A temperature difference arises between them, which is transferred to the junctions of the thermoelement attached to the plates, and thus a thermoelectric current is excited. In this case, current from the battery is passed through the shaded plate until it heats up to the same temperature as the plate in the sun, after which the thermoelectric current disappears. By the strength of the passed "compensating" current, you can determine the amount of heat received by the blackened plate, which, in turn, will be equal to the amount of heat received from the Sun by the first plate. Thus, it is possible to determine the amount of solar radiation.

At the meteorological stations of Russia (and earlier - the USSR), conducting observations of the components of the radiation balance, the homogeneity of the series of actinometric data is ensured by the use of the same type of instruments and their careful calibration, as well as the same measurement and data processing methods. As receivers of integral solar radiation (

In the Savinov-Yanishevsky thermoelectric actinometer, the appearance of which is shown in Fig. 1.6, the receiving part is a thin metal blackened disk of silver foil, to which the odd (active) junctions of the thermopile are glued through the insulation. During measurements, this disk absorbs solar radiation, as a result of which the temperature of the disk and active junctions rises. The even (passive) junctions are glued through the insulation to the copper ring in the device case and have a temperature close to the outside temperature. This temperature difference, when the external circuit of the thermopile is closed, creates a thermoelectric current, the strength of which is proportional to the intensity of solar radiation.

Rice. 1.6.

In a pyranometer (Fig. 1.7), the receiving part is most often a battery of thermoelements, for example, from manganin and constantan, with blackened and white junctions, which are heated differently under the action of incoming radiation. The receiving part of the device must have a horizontal position in order to perceive scattered radiation from the entire firmament. From direct radiation, the pyranometer is shaded by a screen, and from the oncoming radiation of the atmosphere it is protected by a glass cap. When measuring total radiation, the pyranometer is not shaded from direct rays.

Rice. 1.7.

A special device (folding plate) allows you to give the head of the pyranometer two positions: receiver up and receiver down. In the latter case, the pyranometer measures short-wave radiation reflected from the earth's surface. In route observations, the so-called camping albe-meter, which is a pyranometer head connected to a tilting gimbal suspension with a handle.

The thermoelectric balance meter consists of a body with a thermopile, two receiving plates and a handle (Fig. 1.8). The disc-shaped body (/) has a square cutout where the thermopile is fixed (2). Handle ( 3 ), soldered to the body, serves to install the balance meter on the rack.

Rice. 1.8.

One blackened receiving plate of the balance meter is directed upwards, the other downwards, towards the earth's surface. The principle of operation of an unshaded balance meter is based on the fact that all types of radiation coming to the active surface (Y, /) and E a), are absorbed by the blackened receiving surface of the device, facing upwards, and all types of radiation leaving the active surface (/? k, /? l and E 3), absorbed by the downward facing plate. Each receiving plate itself also emits long-wave radiation, in addition, there is heat exchange with the surrounding air and the body of the device. However, due to the high thermal conductivity of the body, a large heat transfer occurs, which does not allow the formation of a significant temperature difference between the receiving plates. For this reason, the self-radiation of both plates can be neglected, and the difference in their heating can be used to determine the value of the radiation balance of any surface in the plane of which the balance meter is located.

Since the receiving surfaces of the balance meter are not covered with a glass dome (otherwise it would be impossible to measure long-wave radiation), the readings of this device depend on the wind speed, which reduces the temperature difference between the receiving surfaces. For this reason, the readings of the balance meter lead to calm conditions, having previously measured the wind speed at the level of the device.

For automatic registration measurements, the thermoelectric current arising in the devices described above is fed to a self-recording electronic potentiometer. Changes in current strength are recorded on a moving paper tape, while the actinometer must automatically rotate so that its receiving part follows the Sun, and the pyranometer must always be shaded from direct radiation by a special ring protection.

Actinometric observations, in contrast to the main meteorological observations, are carried out six times a day at the following times: 00:30, 06:30, 09:30, 12:30, 15:30 and 18:30. Since the intensity of all types of short-wave radiation depends on the height of the Sun above the horizon, the timing of observations is set according to mean solar time stations.

characteristic values. The values of direct and total radiation fluxes play one of the most important roles in architectural and climatic analysis. It is with their consideration that the orientation of buildings on the sides of the horizon, their space-planning and coloristic solution, internal layout, dimensions of light openings and a number of other architectural features are connected. Therefore, the daily and annual variation of characteristic values will be considered for these solar radiation values.

Energy illumination direct solar radiation in a cloudless sky depends on the height of the sun, the properties of the atmosphere in the path of the sun's ray, characterized by transparency factor(a value showing what fraction of solar radiation reaches the earth's surface during a sheer incidence of sunlight) and the length of this path.

Direct solar radiation with a cloudless sky has a fairly simple daily variation with a maximum around noon (Fig. 1.9). As follows from the figure, during the day, the solar radiation flux first rapidly, then more slowly increases from sunrise to noon and slowly at first, then rapidly decreases from noon to sunset. Differences in clear-sky noon irradiance in January and July are primarily due to differences in the Sun's noon height, which is lower in winter than in summer. At the same time, in continental regions, an asymmetry of the diurnal variation is often observed, due to the difference in the transparency of the atmosphere in the morning and afternoon hours. The transparency of the atmosphere also affects the annual course of average monthly values of direct solar radiation. The maximum radiation with a cloudless sky can shift to the spring months, since in spring the dust content and moisture content of the atmosphere are lower than in autumn.

5 1 , kW/m 2

b", kW / m 2

Rice. 1.9.

and under average cloudiness conditions (b):

7 - on the surface perpendicular to the rays in July; 2 - on a horizontal surface in July; 3 - on a perpendicular surface in January; 4 - on a horizontal surface in January

Cloudiness reduces the arrival of solar radiation and can significantly change its daily course, which is manifested in the ratio of pre- and post-noon hourly sums. Thus, in most of the continental regions of Russia in the spring-summer months, the hourly amounts of direct radiation in the pre-noon hours are greater than in the afternoon (Fig. 1.9, b). This is mainly determined by the daily course of cloudiness, which begins to develop at 9-10 am and reaches a maximum in the afternoon, thus reducing radiation. The general decrease in the influx of direct solar radiation under actual cloudy conditions can be very significant. For example, in Vladivostok, with its monsoon climate, these losses in summer amount to 75%, and in St. Petersburg, even on average per year, clouds do not transmit 65% of direct radiation to the earth's surface, in Moscow - about half.

Distribution annual amounts direct solar radiation under average cloudiness over the territory of Russia is shown in fig. 1.10. To a large extent, this factor, which reduces the amount of solar radiation, depends on the circulation of the atmosphere, which leads to a violation of the latitudinal distribution of radiation.

As can be seen from the figure, on the whole, the annual amounts of direct radiation arriving on a horizontal surface increase from high to lower latitudes from 800 to almost 3000 MJ/m 2 . A large number of clouds in the European part of Russia leads to a decrease in the annual totals compared to the regions of Eastern Siberia, where, mainly due to the influence of the Asian anticyclone, the annual totals increase in winter. At the same time, the summer monsoon leads to a decrease in the annual radiation inflow in coastal areas by Far East. The range of changes in the midday intensity of direct solar radiation on the territory of Russia varies from 0.54-0.91 kW / m 2 in summer to 0.02-0.43 kW / m 2 in winter.

scattered radiation, arriving at a horizontal surface also changes during the day, increasing before noon and decreasing after it (Fig. 1.11).

As in the case of direct solar radiation, the arrival of scattered radiation is affected not only by the height of the sun and the length of the day, but also by the transparency of the atmosphere. However, a decrease in the latter leads to an increase in scattered radiation (in contrast to direct radiation). In addition, scattered radiation depends on cloudiness to a very wide extent: under average cloudiness, its arrival is more than twice the values observed in clear skies. On some days, cloudiness increases this figure by 3-4 times. Thus, scattered radiation can significantly supplement the direct line, especially at a low position of the Sun.

Rice. 1.10. Direct solar radiation arriving on a horizontal surface under average cloudiness, MJ / m 2 per year (1 MJ / m 2 \u003d 0.278 kW h / m 2)

/), kW / m 2 0.3 g

0,2 -
0,1 -

4 6 8 10 12 14 16 18 20 22 hours

Rice. 1.11.

and under average cloudy conditions (b)

The value of scattered solar radiation in the tropics is from 50 to 75% of the direct; at 50-60° latitude it is close to a straight line, and at high latitudes it exceeds direct solar radiation for almost the entire year.

Highly an important factor, affecting the scattered radiation flux, is albedo underlying surface. If the albedo is large enough, then the radiation reflected from the underlying surface, scattered by the atmosphere in the opposite direction, can cause a significant increase in the arrival of scattered radiation. The effect is most pronounced in the presence of snow cover, which has the highest reflectivity.

Total radiation in a cloudless sky (possible radiation) depends on the latitude of the place, the height of the sun, the optical properties of the atmosphere and the nature of the underlying surface. Under clear sky conditions, it has a simple diurnal variation with a maximum at noon. The asymmetry of the diurnal variation, characteristic of direct radiation, is little manifested in the total radiation, since the decrease in direct radiation due to an increase in atmospheric turbidity in the second half of the day is compensated by an increase in scattered radiation due to the same factor. In the annual course, the maximum intensity of total radiation with a cloudless sky over most of the territory

The territory of Russia is observed in June due to the maximum midday height of the sun. However, in some regions this influence is overlapped by the influence of atmospheric transparency, and the maximum is shifted to May (for example, in Transbaikalia, Primorye, Sakhalin, and in a number of regions of Eastern Siberia). The distribution of monthly and annual total solar radiation in a cloudless sky is given in Table. 1.9 and in fig. 1.12 as latitude-averaged values.

From the above table and figure, it can be seen that in all seasons of the year, both the intensity and the amount of radiation increase from north to south in accordance with the change in the height of the sun. The exception is the period from May to July, when the combination of a long day and the height of the sun provides rather high values of total radiation in the north and, in general, on the territory of Russia, the radiation field is blurred, i.e. has no pronounced gradients.

Table 1.9

Total solar radiation on a horizontal surface

with a cloudless sky (kW h / m 2)

	Geographic latitude, ° N









September

Rice. 1.12. Total solar radiation to a horizontal surface with a cloudless sky at different latitudes (1 MJ / m 2 \u003d 0.278 kWh / m 2)

In the presence of clouds total solar radiation is determined not only by the number and shape of clouds, but also by the state of the solar disk. With the solar disk translucent through the clouds, the total radiation, compared with cloudless conditions, can even increase due to the growth of scattered radiation.

For medium cloudy conditions, a completely regular daily course of total radiation is observed: a gradual increase from sunrise to noon and a decrease from noon to sunset. At the same time, the daily course of cloudiness violates the symmetry of the course relative to noon, which is characteristic of a cloudless sky. Thus, in most regions of Russia, during the warm period, the pre-noon values of the total radiation are 3-8% higher than the afternoon values, with the exception of the monsoon regions of the Far East, where the ratio is reversed. In the annual course of the average long-term monthly sums of total radiation, along with the determining astronomical factor, a circulation factor is manifested (through the influence of cloudiness), so the maximum can shift from June to July and even to May (Fig. 1.13).

600 -
500 -
400 -
300 -
200 -

m. Chelyuskin

Salekhard

Arkhangelsk

St. Petersburg

Petropavlovsk

Kamchatsky

Khabarovsk

Astrakhan

Rice. 1.13. Total solar radiation on a horizontal surface in individual cities of Russia under real cloudiness conditions (1 MJ / m 2 \u003d 0.278 kWh / m 2)

5", MJ/m 2 700

So, the real monthly and annual arrival of the total radiation is only a part of the possible. The largest deviations of real amounts from those possible in summer are noted in the Far East, where cloudiness reduces the total radiation by 40-60%. In general, the total annual income of total radiation varies across the territory of Russia in the latitudinal direction, increasing from 2800 MJ / m 2 on the coasts of the northern seas to 4800-5000 MJ / m 2 in the southern regions of Russia - the North Caucasus, the Lower Volga region, Transbaikalia and Primorsky Krai (Fig. 1.14).

Rice. 1.14. Total radiation entering a horizontal surface, MJ / m 2 per year

In summer, differences in total solar radiation under real cloudiness conditions between cities located on different latitudes, not as "dramatic" as it might seem at first glance. For the European part of Russia from Astrakhan to Cape Chelyuskin, these values lie in the range of 550-650 MJ/m 2 . In winter, in most cities, with the exception of the Arctic, where the polar night sets in, the total radiation is 50-150 MJ / m 2 per month.

For comparison: the average heat values for January for 1 urban area (calculated according to actual data for Moscow) range from 220 MJ/m2 per month in urban urban development hubs to 120-150 MJ/m2 in inter-main areas with low-density residential development. On the territories of industrial and communal storage zones, the heat index in January is 140 MJ/m 2 . The total solar radiation in Moscow in January is 62 MJ/m 2 . Thus, in winter time due to the use of solar radiation, it is possible to cover no more than 10-15% (taking into account the efficiency of solar panels 40%) of the calculated calorific value of medium-density buildings even in Irkutsk and Yakutsk, known for their sunny winter weather, even if their territory is completely covered with photovoltaic panels.

In summer, total solar radiation increases by 6-9 times, and heat consumption is reduced by 5-7 times compared to winter. Heat values in July decrease to 35 MJ/m 2 or less in residential areas and 15 MJ/m 2 or less in industrial areas, i.e. up to values constituting no more than 3-5% of the total solar radiation. Therefore, in the summer, when the need for heating and lighting is minimal, there is an excess of this renewable natural resource throughout Russia that cannot be utilized, which once again casts doubt on the feasibility of using photovoltaic panels, according to at least, in cities and apartment buildings.

Electricity consumption (without heating and hot water supply), also associated with the uneven distribution of the total building area, population density and the functional purpose of various territories, is in the

Warmth - an average indicator of the consumption of all types of energy (electricity, heating, hot water supply) per 1 m 2 of the building area.

cases from 37 MJ / m 2 per month (calculated as 1/12 annual amount) in densely built-up areas and up to 10-15 MJ/m 2 per month in areas with low building density. During the daytime and in summer, electricity consumption naturally falls. Electricity consumption density in July in most areas of residential and mixed development is 8-12 MJ/m 2 with total solar radiation under real cloudy conditions in Moscow about 600 MJ/m 2 . Thus, to cover the needs in the power supply of urban areas (for example, Moscow), it is required to utilize only about 1.5-2% of solar radiation. The rest of the radiation, if disposed of, will be redundant. At the same time, the issue of accumulation and preservation of daytime solar radiation for lighting in the evening and at night, when the loads on the power supply systems are maximum, and the sun almost or does not shine, remains to be resolved. This will require the transmission of electricity over long distances between areas where the Sun is still high enough, and those where the Sun has already set below the horizon. At the same time, electricity losses in the networks will be comparable to its savings through the use of photovoltaic panels. Or you need to use batteries large capacity, the production, installation and subsequent disposal of which will require energy costs, which are unlikely to be covered by the energy savings accumulated over the entire period of their operation.

Another, no less important factor that makes doubtful the feasibility of switching to solar panels how alternative source power supply on a city scale is that, ultimately, the operation of photovoltaic cells will lead to a significant increase in solar radiation absorbed in the city, and, consequently, to an increase in air temperature in the city in summer time. Thus, simultaneously with cooling due to photopanels and air conditioners powered by them internal environment there will be a general increase in air temperature in the city, which will eventually negate all the economic and environmental benefits from saving electricity through the use of still very expensive photovoltaic panels.

It follows that the installation of equipment for converting solar radiation into electricity justifies itself in a very limited list of cases: only in summer, only in climatic regions with dry, hot, cloudy weather, only in small towns or individual cottage villages, and only if this electricity is used to operate installations for air conditioning and ventilation of the internal environment of buildings. In other cases - other areas, other urban conditions and at other times of the year - the use of photovoltaic panels and solar collectors for the needs of electricity and heat supply of ordinary buildings in medium and major cities located in temperate climates is inefficient.

Bioclimatic significance of solar radiation. The decisive role of the impact of solar radiation on living organisms is reduced to participation in the formation of their radiation and heat balances due to thermal energy in the visible and infrared parts of the solar spectrum.

Visible rays are of particular importance to organisms. Most animals, like humans, are good at distinguishing the spectral composition of light, and some insects can even see in the ultraviolet range. The presence of light vision and light orientation is an important survival factor. For example, in humans, the presence of color vision is one of the most psycho-emotional and optimizing factors of life. Staying in the dark has the opposite effect.

As you know, green plants synthesize organic matter and, consequently, produce food for all other organisms, including humans. This most important process for life occurs during the assimilation of solar radiation, and plants use specific range spectrum in the wavelength range of 0.38-0.71 μm. This radiation is called photosynthetically active radiation(PAR) and is very important for plant productivity.

The visible part of the light creates natural light. In relation to it, all plants are divided into light-loving and shade-tolerant. Insufficient illumination causes weakness of the stem, weakens the formation of ears and cobs on plants, reduces the sugar content and the amount of oils in cultivated plants, makes it difficult for them to use mineral nutrition and fertilizers.

Biological action infrared rays consists of thermal effect when they are absorbed by the tissues of plants and animals. In this case, the kinetic energy of molecules changes, and electrical and chemical processes are accelerated. Due to infrared radiation, the lack of heat (especially in high-mountainous regions and at high latitudes) received by plants and animals from the surrounding space is compensated.

Ultraviolet radiation according to biological properties and effects on humans, it is customary to divide into three areas: area A - with wavelengths from 0.32 to 0.39 microns; region B, from 0.28 to 0.32 μm; and region C, from 0.01 to 0.28 μm. Area A is characterized by a relatively weakly expressed biological effect. It causes only the fluorescence of a series organic matter, in humans, contributes to the formation of pigment in the skin and mild erythema (reddening of the skin).

The rays of area B are much more active. Diverse reactions of organisms to ultraviolet radiation, changes in the skin, blood, etc. mostly due to them. The well-known vitamin-forming effect of ultraviolet radiation is that ergosterone nutrients goes into vitamin O, which has a strong stimulating effect on growth and metabolism.

Rays of region C have the most powerful biological effect on living cells. The bactericidal effect of sunlight is mainly due to them. In small doses, ultraviolet rays are necessary for plants, animals and humans, especially children. However, in large quantities, the rays of region C are detrimental to all living things, and life on Earth is possible only because this short-wave radiation is almost completely blocked by the ozone layer of the atmosphere. The solution of the issue of the impact of excess doses of ultraviolet radiation on the biosphere and humans has become especially relevant in recent decades due to the depletion of the ozone layer of the Earth's atmosphere.

The effect of ultraviolet radiation (UVR), which reaches the earth's surface, on a living organism is very diverse. As mentioned above, in moderate doses, it has beneficial effect: increases vitality, enhances the body's resistance to infectious diseases. The lack of UVR leads to pathological phenomena, which are called UV deficiency or UV starvation and manifest themselves in a lack of vitamin E, which leads to a violation of phosphorus-calcium metabolism in the body.

Excess UVR can lead to very serious consequences: the formation of skin cancer, the development of other oncological formations, the appearance of photokeratitis (“snow blindness”), photoconjunctivitis and even cataracts; violation of the immune system of living organisms, as well as mutagenic processes in plants; change in the properties and destruction of polymeric materials widely used in construction and architecture. For example, UVR can discolor facade paints or lead to mechanical destruction of polymeric finishing and structural building products.

Architectural and construction significance of solar radiation. Solar energy data is used in the calculation of the heat balance of buildings and heating and air conditioning systems, in the analysis of aging processes various materials, taking into account the effect of radiation on the thermal state of a person, choosing the optimal species composition of green spaces for planting greenery in a particular area, and many other purposes. Solar radiation determines the mode of natural illumination of the earth's surface, the knowledge of which is necessary when planning the consumption of electricity, designing various structures and organizing the operation of transport. Thus, the radiation regime is one of the leading urban planning and architectural and construction factors.

Insolation of buildings is one of the most important conditions for the hygiene of buildings, therefore, irradiation of surfaces with direct sunlight is given special attention as an important environmental factor. At the same time, the Sun not only has a hygienic effect on the internal environment, killing pathogens, but also psychologically affects a person. The effect of such irradiation depends on the duration of the process of exposure to sunlight, so insolation is measured in hours, and its duration is normalized by the relevant documents of the Ministry of Health of Russia.

Required minimum solar radiation, providing comfortable conditions the internal environment of buildings, the conditions for work and rest of a person, consists of the required illumination of living and working premises, the amount of ultraviolet radiation required for the human body, the amount of heat absorbed by external fences and transferred into buildings, providing thermal comfort of the internal environment. Based on these requirements, architectural and planning decisions are made, the orientation of living rooms, kitchens, utility and work rooms is determined. With an excess of solar radiation, the installation of loggias, blinds, shutters and other sun protection devices is provided.

It is recommended to analyze the sums of solar radiation (direct and diffuse) arriving at variously oriented surfaces (vertical and horizontal) according to the following scale:

less than 50 kW h / m 2 per month - insignificant radiation;
50-100 kW h / m 2 per month - average radiation;
100-200 kW h / m 2 per month - high radiation;
more than 200 kW h / m 2 per month - excess radiation.

With insignificant radiation, which is observed in temperate latitudes mainly in the winter months, its contribution to the heat balance of buildings is so small that it can be neglected. With average radiation in temperate latitudes, there is a transition to the region negative values radiation balance of the earth's surface and buildings, structures, artificial pavements, etc. located on it. In this regard, they begin to lose more thermal energy in the daily course than they receive heat from the sun during the day. These losses in the thermal balance of buildings are not covered by internal heat sources (electrical appliances, hot water pipes, metabolic heat release of people, etc.), and they must be compensated for by the operation of heating systems - the heating season begins.

At high radiation and under real cloudy conditions, the thermal background of the urban area and the internal environment of buildings is in the comfort zone without the use of artificial heating and cooling systems.

With excess radiation in cities of temperate latitudes, especially those located in a temperate continental and sharply continental climate, overheating of buildings, their internal and external environments can be observed in summer. In this regard, architects are faced with the task of protecting the architectural environment from excessive insolation. They apply appropriate space-planning solutions, choose the optimal orientation of buildings on the sides of the horizon, architectural sun-protection elements of facades and light openings. If architectural means to protect against overheating are not enough, then there is a need for artificial conditioning of the internal environment of buildings.

The radiation regime also affects the choice of orientation and dimensions of light apertures. At low radiation, the size of the light openings can be increased to any size, provided that heat losses through external fences are maintained at a level not exceeding the standard. In case of excessive radiation, light openings are made minimal in size, meeting the requirements for insolation and natural illumination of the premises.

The lightness of the facades, which determines their reflectivity (albedo), is also selected based on the requirements of sun protection or, conversely, taking into account the possibility of maximum absorption of solar radiation in areas with a cool and cold humid climate and with an average or low level of solar radiation in the summer months. To select facing materials based on their reflectivity, it is necessary to know how much solar radiation enters the walls of buildings of various orientations and what is the ability of various materials to absorb this radiation. Since the arrival of radiation to the wall depends on the latitude of the place and how the wall is oriented in relation to the sides of the horizon, the heating of the wall and the temperature inside the premises adjacent to it will depend on this.

The absorbing capacity of various facade finishing materials depends on their color and condition (Table 1.10). If the monthly sums of solar radiation entering the walls of various orientations 1 and the albedo of these walls are known, then the amount of heat absorbed by them can be determined.

Table 1.10

Absorption capacity of building materials

Data on the amount of incoming solar radiation (direct and diffuse) with a cloudless sky on vertical surfaces of various orientations are given in the Joint Venture "Construction Climatology".

Material name and processing	Characteristic surfaces	surfaces	Absorbed radiation,%
Concrete	Rough
		light blue
		Dark grey
		Bluish
	Hewn
		Yellowish brown


	polished
	Clean hewn	light gray
	Hewn
Roof
Ruberoid		brown
Cink Steel		light gray
Roof tiles

Choosing the appropriate materials and colors for building envelopes, i.e. by changing the albedo of the walls, it is possible to change the amount of radiation absorbed by the wall and, thus, to reduce or increase the heating of the walls by solar heat. This technique is actively used in the traditional architecture of various countries. Everyone knows that southern cities are distinguished by a general light (white with colored decor) color of most residential buildings, while, for example, Scandinavian cities are mainly cities built of dark brick or using dark-colored tesa for cladding buildings.

It is calculated that 100 kWh/m 2 of absorbed radiation raises the temperature of the outer surface by about 4°C. This amount of radiation, on average, per hour is received by the walls of buildings in most regions of Russia if they are oriented to the south and east, as well as western, southwestern and southeastern ones, if they are made of dark brick and not plastered or have dark-colored plaster.

To move from the monthly average wall temperature without taking into account radiation to the most commonly used characteristic in thermal engineering calculations - the outside air temperature, an additional temperature additive is introduced At, depending on the monthly amount of solar radiation absorbed by the wall VC(Fig. 1.15). Thus, knowing the intensity of the total solar radiation coming to the wall and the albedo of the surface of this wall, it is possible to calculate its temperature by introducing an appropriate correction to the air temperature.

VC, kWh/m2

Rice. 1.15. Increase in the temperature of the outer surface of the wall due to the absorption of solar radiation

AT general case the temperature addition due to absorbed radiation is determined under otherwise equal conditions, i.e. at the same air temperature, humidity and thermal resistance of the building envelope, regardless of wind speed.

In clear weather at noon, the southern, before noon - southeastern and in the afternoon - southwestern walls can absorb up to 350-400 kWh / m 2 of solar heat and heat up so that their temperature can exceed 15-20 ° C outside air temperature. This creates large temperature con-

trusts between the walls of the same building. These contrasts in some areas turn out to be significant not only in summer, but also in the cold season with sunny low-wind weather, even at very low air temperatures. Especially severe overheating exposed metal structures. Thus, according to available observations, in Yakutia, located in a temperate sharply continental climate, characterized by cloudy weather in winter and summer, at midday hours with a clear sky, the aluminum parts of the enclosing structures and the roof of the Yakutskaya HPP heat up by 40-50 ° C above the air temperature, even at low values of the latter.

Overheating of insolated walls due to the absorption of solar radiation must be provided for already at the stage of architectural design. This effect requires not only the protection of walls from excessive insolation by architectural methods, but also the appropriate planning solutions for buildings, the use of heating systems of various capacities for differently oriented facades, laying in the project of seams to relieve stress in structures and violation of the tightness of joints due to their temperature deformations. etc.

In table. 1.11 as an example, the monthly sums of absorbed solar radiation in June for several geographical objects of the former USSR are given for given albedo values. This table shows that if the albedo of the northern wall of the building is 30%, and the southern one is 50%, then in Odessa, Tbilisi and Tashkent they will heat up to the same extent. If in the northern regions the albedo of the northern wall is reduced to 10%, then it will receive almost 1.5 times more heat than a wall with an albedo of 30%.

Table 1.11

Monthly sums of solar radiation absorbed by building walls in June at various albedo values (kWh/m2)

The above examples, based on data on total (direct and diffuse) solar radiation contained in the Joint Venture "Construction Climatology" and climate reference books, do not take into account the solar radiation reflected from the earth's surface and surrounding objects (for example, existing buildings) arriving at various building walls. It depends less on their orientation, therefore, it is not given in the regulatory documents for construction. However, this reflected radiation can be quite intense and comparable in power to direct or diffuse radiation. Therefore, when architectural design it must be taken into account when calculating for each specific case.

The blinding solar disk at all times excited the minds of people, served as a fertile topic for legends and myths. Since ancient times, people have guessed about its impact on the Earth. How close were our distant ancestors to the truth. It is the radiant energy of the Sun that we owe the existence of life on Earth.

What is the radioactive radiation of our luminary and how does it affect earthly processes?

What is solar radiation

Solar radiation is a combination of solar matter and energy entering the Earth. The energy propagates in the form of electromagnetic waves at a speed of 300 thousand kilometers per second, passes through the atmosphere and reaches the Earth in 8 minutes. The range of waves participating in this "marathon" is very wide - from radio waves to X-rays, including the visible part of the spectrum. The earth's surface is under the influence of both direct and scattered by the earth's atmosphere, the sun's rays. It is the scattering of blue-blue rays in the atmosphere that explains the blueness of the sky on a clear day. The yellow-orange color of the solar disk is due to the fact that the waves corresponding to it pass almost without scattering.

With a delay of 2–3 days, the “solar wind” reaches the earth, which is a continuation of solar corona and consisting of the nuclei of atoms of light elements (hydrogen and helium), as well as electrons. It is quite natural that solar radiation has a strong influence on the human body.

The effect of solar radiation on the human body

The electromagnetic spectrum of solar radiation consists of infrared, visible and ultraviolet parts. Since their quanta have different energies, they have a variety of effects on humans.

indoor lighting

The hygienic significance of solar radiation is also extremely high. Since visible light is a decisive factor in obtaining information about the outside world, it is necessary to provide indoor enough level illumination. Its regulation is carried out in accordance with SNiP, which for solar radiation are compiled taking into account the light and climatic features of various geographical areas and are taken into account in the design and construction of various facilities.

Even a superficial analysis of the electromagnetic spectrum of solar radiation proves how great the influence of this type of radiation on the human body.

Distribution of solar radiation over the territory of the Earth

Not all radiation coming from the Sun reaches the earth's surface. And there are many reasons for this. The earth steadfastly repels the attack of those rays that are detrimental to its biosphere. This function is performed by the ozone shield of our planet, preventing the most aggressive part of ultraviolet radiation from passing through. Atmospheric filter in the form of water vapor, carbon dioxide, dust particles suspended in the air - largely reflects, scatters and absorbs solar radiation.

That part of it that has overcome all these obstacles falls to the surface of the earth at different angles, depending on the latitude of the area. The life-giving solar heat is distributed unevenly over the territory of our planet. As the height of the sun changes during the year, the mass of air above the horizon changes, through which the path of the sun's rays lies. All this affects the distribution of the intensity of solar radiation over the planet. The general trend this is - this parameter increases from the pole to the equator, since the greater the angle of incidence of the rays, the more heat enters per unit area.

Solar radiation maps allow you to have a picture of the distribution of solar radiation intensity over the territory of the Earth.

The influence of solar radiation on the Earth's climate

The infrared component of solar radiation has a decisive influence on the Earth's climate.

It is clear that this occurs only at a time when the Sun is above the horizon. This influence depends on the distance of our planet from the Sun, which changes during the year. The Earth's orbit is an ellipse, inside which is the Sun. Making its annual journey around the Sun, the Earth moves away from its luminary, then approaches it.

In addition to changing the distance, the amount of radiation entering the earth is determined by the inclination of the earth's axis to the plane of the orbit (66.5 °) and the change of seasons caused by it. It is more in summer than in winter. At the equator, this factor is absent, but as the latitude of the observation site increases, the gap between summer and winter becomes significant.

All sorts of cataclysms take place in the processes taking place on the Sun. Their impact is partly offset by vast distances, the protective properties of the earth's atmosphere and the earth's magnetic field.

How to protect yourself from solar radiation

The infrared component of solar radiation is the coveted warmth that the inhabitants of the middle and northern latitudes look forward to all other seasons of the year. Solar radiation as a healing factor is used by both healthy and sick people.

However, we must not forget that heat, like ultraviolet, is a very strong irritant. Abuse of their action can lead to burns, general overheating of the body, and even exacerbation of chronic diseases. When sunbathing, you should follow the rules tested by life. You should be especially careful when sunbathing on clear sunny days. Infants and the elderly, patients with chronic tuberculosis and problems with the cardiovascular system, should be content with diffused solar radiation in the shade. This ultraviolet is quite enough to meet the needs of the body.

Even young people who do not have special health problems should be protected from solar radiation.

Now there is a movement whose activists oppose tanning. And not in vain. Tanned skin is undeniably beautiful. But the melanin produced by the body (what we call sunburn) is its protective reaction to the effects of solar radiation. No sunburn benefits! There is even evidence that sunburn shortens life, since radiation has a cumulative property - it accumulates throughout life.

If the situation is so serious, you should scrupulously follow the rules prescribing how to protect yourself from solar radiation:

strictly limit the time for sunbathing and do it only during safe hours;
being in the active sun, you should wear a wide-brimmed hat, closed clothes, Sunglasses and umbrella;
Use only high quality sunscreen.

Is solar radiation dangerous to humans at all times of the year? The amount of solar radiation reaching the earth is associated with the change of seasons. At mid-latitudes in summer it is 25% more than in winter. At the equator, this difference does not exist, but as the latitude of the place of observation increases, this difference increases. This is due to the fact that our planet is tilted at an angle of 23.3 degrees with respect to the sun. In winter, it is low above the horizon and illuminates the earth only with gliding rays, which warm the illuminated surface less. This position of the rays causes their distribution over a larger surface, which reduces their intensity compared to the summer sheer fall. In addition, the presence of an acute angle during the passage of rays through the atmosphere, "lengthens" their path, forcing them to lose more heat. This circumstance reduces the impact of solar radiation in winter.

The sun is a star that is a source of heat and light for our planet. It "governs" the climate, the change of seasons and the state of the entire biosphere of the Earth. And only knowledge of the laws of this powerful influence will allow using this life-giving gift for the benefit of people's health.

Dazhbog among the Slavs, Apollo among the ancient Greeks, Mithra among the Indo-Iranians, Amon Ra among the ancient Egyptians, Tonatiu among the Aztecs - in ancient pantheism, people called God the Sun with these names.

Since ancient times, people have understood how important the Sun is for life on Earth, and deified it.

The luminosity of the Sun is huge and amounts to 3.85x10 23 kW. Solar energy acting on an area of only 1 m 2 is capable of charging an engine of 1.4 kW.

The energy source is thermonuclear reaction passing through the core of the star.

The resulting 4 He is almost (0.01%) the entire helium of the earth.

The star of our system emits electromagnetic and corpuscular radiation. From the outer side of the Sun's corona, the solar wind, consisting of protons, electrons and α-particles, “blows” into outer space. With the solar wind, 2-3x10 -14 masses of the luminary are lost annually. Magnetic storms and polar lights are associated with corpuscular radiation.

Electromagnetic radiation (solar radiation) reaches the surface of our planet in the form of direct and scattered rays. Its spectral range is:

ultraviolet radiation;
X-rays;
γ-rays.

The shortwave part accounts for only 7% of the energy. Visible light makes up 48% of the solar radiation energy. It is mainly composed of a blue-green emission spectrum, 45% is infrared radiation, and only a small part is represented by radio emission.

Ultraviolet radiation, depending on the wavelength, is divided into:

Most long wavelength ultraviolet radiation reaches the earth's surface. The amount of UV-B energy reaching the planet's surface depends on the state of the ozone layer. UV-C is almost completely absorbed by the ozone layer and atmospheric gases. Back in 1994, WHO and WMO proposed to introduce an ultraviolet index (UV, W / m 2).

The visible part of the light is not absorbed by the atmosphere, but waves of a certain spectrum are scattered. Infrared color or thermal energy in the medium wave range is mainly absorbed by water vapor and carbon dioxide. The source of the long-wavelength spectrum is the earth's surface.

All of the above ranges are of great importance for life on Earth. A significant part of solar radiation does not reach the Earth's surface. The following types of radiation are recorded near the surface of the planet:

1% ultraviolet;
40% optical;
59% infrared.

Types of radiation

The intensity of solar radiation depends on:

latitude;
season;
time of day;
the state of the atmosphere;
features and topography of the earth's surface.

In different parts of the Earth, solar radiation affects living organisms in different ways.

Photobiological processes occurring under the action of light energy, depending on their role, can be divided into the following groups:

synthesis of biologically active substances (photosynthesis);
photobiological processes that help to navigate in space and help to obtain information (phototaxis, vision, photoperiodism);
damaging effects (mutations, carcinogenic processes, destructive effects on bioactive substances).

Insolation calculation

Light radiation has a stimulating effect on photobiological processes in the body - the synthesis of vitamins, pigments, cell photostimulation. The sensitizing effect of sunlight is currently being studied.

Ultraviolet radiation, affecting skin human body, stimulates the synthesis of vitamins D, B4 and proteins, which are regulators of many physiological processes. Ultraviolet radiation affects:

metabolic processes;
immune system;
nervous system;
endocrine system.

The sensitizing effect of ultraviolet depends on the wavelength:

The stimulating effect of sunlight is expressed in an increase in specific and nonspecific immunity. So, for example, in children who are exposed to moderate natural UV radiation, the number colds reduced by 1/3. At the same time, the effectiveness of treatment increases, there are no complications, and the period of the disease is reduced.

The bactericidal properties of the short-wave spectrum of UV radiation are used in medicine, Food Industry, pharmaceutical production for disinfection of media, air and products. Ultraviolet radiation destroys tubercle bacillus within a few minutes, staphylococcus - in 25 minutes, and the causative agent of typhoid fever - in 60 minutes.

Nonspecific immunity, in response to ultraviolet irradiation, responds with an increase in compliment and agglutination titers, an increase in the activity of phagocytes. But increased UV radiation causes pathological changes in the body:

skin cancer;
solar erythema;
damage to the immune system, which is expressed in the appearance of freckles, nevi, solar lentigo.

Visible part of sunlight:

makes it possible to obtain 80% of information using a visual analyzer;
accelerates metabolic processes;
improves mood and general well-being;
warms;
affects the state of the central nervous system;
determines daily rhythms.

The degree of exposure to infrared radiation depends on the wavelength:

long-wave - has a weak penetrating ability and is largely absorbed by the surface of the skin, causing erythema;
shortwave - penetrates deep into the body, providing vasodilating action, analgesic, anti-inflammatory.

In addition to the impact on living organisms, solar radiation is of great importance in shaping the Earth's climate.

Importance of solar radiation for climate

The sun is the main source of heat that determines the earth's climate. In the early stages of the Earth's development, the Sun radiated 30% less heat than it does now. But due to the saturation of the atmosphere with gases and volcanic dust, the climate on Earth was humid and warm.

In the intensity of insolation, a cyclicity is noted, which causes warming and cooling of the climate. Cyclicity explains the small ice Age, which came in the XIV-XIX centuries. and climate warming observed in the period 1900-1950.

In the history of the planet, the periodicity of the change in the axial tilt and the extremeness of the orbit are noted, which changes the redistribution of solar radiation on the surface and affects the climate. For example, these changes are reflected in the increase and decrease in the area of the Sahara desert.

Interglacial periods last about 10,000 years. The Earth is currently in an interglacial period called the Heliocene. Due to early human agricultural activity, this period lasts longer than calculated.

Scientists have described 35-45 year cycles of climate change, during which the dry and warm climate changes to cool and humid. They affect the filling of inland waters, the level of the World Ocean, changes in glaciation in the Arctic.

Solar radiation is distributed differently. For example, in the middle latitudes in the period from 1984 to 2008, there was an increase in total and direct solar radiation and a decrease in scattered radiation. Changes in intensity are also noted throughout the year. So, the peak falls on May-August, and the minimum - in the winter.

Since the height of the Sun and the duration of daylight hours in summer are longer, this period accounts for up to 50% of the total annual radiation. And in the period from November to February - only 5%.

The amount of solar radiation falling on a certain surface of the Earth affects important climatic indicators:

temperature;
humidity;
Atmosphere pressure;
cloudiness;
precipitation;
wind speed.

An increase in solar radiation increases temperature and atmospheric pressure, the rest of the characteristics are inversely related. Scientists have found that the levels of total and direct solar radiation have the greatest impact on climate.

Sun Protection Measures

Solar radiation has a sensitizing and damaging effect on a person in the form of heat and sunstroke, negative impact radiation to the skin. Now a large number of celebrities have joined the anti-tanning movement.

Angelina Jolie, for example, says that for the sake of two weeks of sunburn she does not want to sacrifice several years of her life.

To protect yourself from solar radiation, you must: