Solar radiation direct scattered total. Solar radiation

Necessary equipment and accessories: thermoelectric actinometer M-3, universal pyranometer M-80M, traveling albedometer, thermoelectric balance meter M-10M, universal heliograph model GU-1, lux meter Yu-16.

The main source of energy coming to the Earth is radiant energy coming from the Sun. The flow of electromagnetic waves emitted by the Sun is commonly called solar radiation. This radiation is practically the only source of energy for all processes occurring in the atmosphere and on the earth's surface, including all processes occurring in living organisms.

Solar radiation provides plants with energy, which they use in the process of photosynthesis to create organic matter, affects the processes of growth and development, the location and structure of leaves, the duration of the growing season, etc. Quantitatively, solar radiation can be characterized by radiation flux .

Radiation flux – this quantity radiant energy, which arrives per unit time per unit surface.

In the SI system of units, radiation flux is measured in watts per 1m2 (W/m2) or kilowatts per 1m2 (kW/m2). Previously, it was measured in calories per 1 cm 2 per minute (cal/(cm 2 min)).

1 cal/(cm 2 min) = 698 W/m 2 or 0.698 kW/m 2

The flux density of solar radiation at the upper boundary of the atmosphere at the average distance from the Earth to the Sun is called solar constant S 0. By international agreement 1981 S 0 = 1.37 kW/m 2 (1.96 1 cal/(cm 2 min)).

If the Sun is not at its zenith, then the amount of solar energy falling on a horizontal surface will be less than on a surface located perpendicular to the rays of the Sun. This amount depends on the angle of incidence of the rays on a horizontal surface. To determine the amount of heat received by a horizontal surface per minute, use the formula:

S′ = S sin h ©

where S′ is the amount of heat received per minute by a horizontal surface; S is the amount of heat received by the surface perpendicular to the beam; h© is the angle formed by a sun ray with a horizontal surface (angle h is called the height of the sun).

As solar radiation passes through the earth's atmosphere, it is attenuated due to absorption and scattering by atmospheric gases and aerosols. The attenuation of the solar radiation flux depends on the length of the path traversed by the beam in the atmosphere and on the transparency of the atmosphere along this path. The length of the beam's path in the atmosphere depends on the altitude of the sun. When the sun is at its zenith, the sun's rays travel the shortest path. In this case, the mass of the atmosphere traversed by the sun's rays, i.e. the mass of a vertical column of air with a base of 1 cm 2 is taken as one conventional unit (m = 1). As the sun descends to the horizon, the path of rays in the atmosphere increases, and therefore the number of passable masses(m>1). When the sun is near the horizon, the rays travel the longest distance through the atmosphere. As calculations show, m is 34.4 times greater than when the Sun is at its zenith. The weakening of the flux of direct solar radiation in the atmosphere is described by the Bouguer formula. Transparency factor p shows what fraction of solar radiation arriving at the upper boundary of the atmosphere reaches the earth's surface at m = 1.

S m = S 0 p m ,

where S m is the flux of direct solar radiation reaching the Earth; S 0 – solar constant; p – transparency coefficient; m– mass of the atmosphere.

The transparency coefficient depends on the content of water vapor and aerosols in the atmosphere: the more of them, the lower the transparency coefficient for the same number of passing masses. The transparency coefficient ranges from 0.60 up to 0.85.

Types of solar radiation

Direct solar radiation(S′) – radiation reaching the earth’s surface directly from the Sun in the form of a beam of parallel rays.

Direct solar radiation depends on the height of the sun above the horizon, air transparency, cloud cover, altitude above sea level and the distance between the Earth and the Sun.

Scattered solar radiation(D) – part of the radiation scattered earth's atmosphere and clouds and arriving on the earth's surface from the vault of heaven. Intensity scattered radiation depends on the height of the sun above the horizon, cloudiness, air transparency, altitude above sea level, snow cover. Cloudiness and snow cover have a very large influence on scattered radiation, which, due to the dispersion and reflection of direct and scattered radiation falling on them and their re-scattering in the atmosphere, can increase the flux of scattered radiation several times.

Scattered radiation significantly complements direct solar radiation and significantly increases the supply of solar energy to the earth's surface.

Total radiation(Q) – the sum of direct and diffuse radiation fluxes arriving on a horizontal surface:

Before sunrise, during the day and after sunset, when the sun is overcast, the total radiation reaches the earth in its entirety, and at low solar altitudes it mainly consists of scattered radiation. Under cloudless or partly cloudy skies, with increasing solar altitude, the proportion of direct radiation in the total radiation rapidly increases and in the daytime the flux is many times greater than the flux of scattered radiation.

Most of the flow total radiation, arriving at the earth's surface, is absorbed by the top layer of soil, water and vegetation. In this case, radiant energy is converted into heat, heating the absorbing layers. The rest of the total radiation flux is reflected by the earth's surface, forming reflected radiation(R). Almost the entire flux of reflected radiation passes through the atmosphere and goes into outer space, but some of it is scattered in the atmosphere and partially returns to the earth's surface, enhancing the scattered radiation, and, consequently, the total radiation.

The reflectivity of various surfaces is called albedo. It represents the ratio of the flux of reflected radiation to the entire flux of total radiation incident on a given surface:

Albedo is expressed in fractions of unity or as a percentage. Thus, a part of the total radiation flux equal to QA is reflected by the earth's surface, and is absorbed and converted into heat - Q(1-A). The last quantity is called absorbed radiation.

The albedo of different land surfaces depends mainly on the color and roughness of these surfaces. Dark and rough surfaces have lower albedo than light and smooth ones. Soil albedo decreases with increasing humidity, as their color becomes darker. Albedo values ​​for some natural surfaces are given in Table 1.

Table 1 - Albedo of various natural surfaces

The reflectivity of the upper surface of clouds is very high, especially when their thickness is high. On average, cloud albedo is about 50-60%, in in some cases– more than 80-85%.

Photosynthetically active radiation(PAR) – part of the total radiation flux that can be used green plants during photosynthesis. PAR flux can be calculated using the formula:

PAR = 0.43S′ + 0.57D,

where S′ is direct solar radiation arriving at the horizontal surface; D – scattered solar radiation.

PAR flow falling on a sheet for the most part absorbed by it, much smaller shares of this flow are reflected by the surface and passed through the sheet. The leaves of most tree species absorb approximately 80%, reflect and transmit up to 10-12% of the total PAR flux. Of the part of the PAR flux absorbed by the leaves, only a few percent of the radiant energy is used by plants directly for photosynthesis and is converted into chemical energy organic matter, synthesized by leaves. The rest, more than 95% of radiant energy, is converted into heat and is spent mainly on transpiration, heating the leaves themselves and their heat exchange with the surrounding air.

Long-wave radiation from the Earth and atmosphere.

Radiation balance of the earth's surface

Most of the solar energy entering the Earth is absorbed by its surface and atmosphere, some of it is emitted. Radiation from the earth's surface occurs around the clock.

Some of the rays emitted by the earth's surface are absorbed by the atmosphere and thus contribute to the heating of the atmosphere. The atmosphere, in turn, sends rays back to the surface of the earth, as well as into outer space. This property of the atmosphere to retain heat emitted by the earth's surface is called greenhouse effect. The difference between the arrival of heat in the form of counter radiation from the atmosphere and its consumption in the form of radiation from the active layer is called effective radiation active layer. Effective radiation is especially large at night, when the loss of heat from the earth's surface significantly exceeds the influx of heat emitted by the atmosphere. During the day, when the total solar radiation is added to the radiation of the atmosphere, an excess of heat is obtained, which is used to heat the soil and air, evaporate water, etc.

The difference between the absorbed total radiation and the effective radiation of the active layer is called radiation balance active layer.

The incoming part of the radiation balance consists of direct and diffuse solar radiation, as well as counter radiation from the atmosphere. The expenditure part consists of reflected solar radiation and long-wave radiation from the earth's surface.

The radiation balance represents the actual arrival of radiant energy on the Earth's surface, which determines whether it will warm or cool.

If the arrival of radiant energy is greater than its consumption, then the radiation balance is positive and the surface heats up. If the inflow is less than the outflow, then the balance is negative and the surface cools. The radiation balance of the earth's surface is one of the main climate-forming factors. It depends on the height of the Sun, the duration of sunshine, the nature and condition of the earth’s surface, the turbidity of the atmosphere, the content of water vapor in it, the presence of clouds, etc.

Instruments for measuring solar radiation

Thermoelectric actinometer M-3(Fig.3) is designed to measure the intensity of direct solar radiation on a surface perpendicular to the sun's rays.

The actinometer receiver is a thermopile made of alternating plates of manganin and constantan, made in the form of an asterisk. The internal junctions of the thermopile are glued through an insulating gasket to a disk made of silver foil; the side of the disk facing the sun is blackened. The external junctions are glued to a massive copper ring through an insulating gasket. It is protected from radiation heating by a chrome cap. The thermopile is located at the bottom of a metal tube, which is directed towards the sun during measurements. Inner surface The tube is blackened, and 7 diaphragms (ring-shaped constrictions) are arranged in the tube to prevent scattered radiation from reaching the actinometer receiver.

For observations, an arrow on the base of the device 11 (Fig. 2) are oriented to the north and to facilitate tracking the sun, an actinometer is installed according to the latitude of the observation site (by sector 9 and the risk in the upper part of the device stand 10 ). Aiming at the sun is done using a screw 3 and handles 6 located at the top of the device. The screw allows you to rotate the tube in a vertical plane; when rotating the handle, the tube is guided behind the sun. For precise aiming at the Sun, a small hole is made in the outer diaphragm. There is a white screen opposite this hole at the bottom of the device 5 . At correct installation device, the sunlight penetrating through this hole should give a light spot (bunny) in the center of the screen.

Rice. 3 Thermoelectric actinometer M-3: 1 – cover; 2, 3 – screws; 4 – axis; 5 – screen; 6 – handle; 7 – tube; 8 – axis; 9 – sector of latitudes; 10 – stand; 11 – base.

Universal pyranometer M-80M(Fig. 4) is designed to measure total (Q) and diffuse (D) radiation. Knowing them, we can calculate the intensity of direct solar radiation on the horizontal surface S′. The M-80M pyranometer has a device for tilting the instrument stand with the receiver down, which makes it possible to measure the intensity of reflected radiation and determine the albedo of the underlying surface.

Pyranometer receiver 1 is a thermoelectric battery arranged in the shape of a square. Its receiving surface is painted black and white in the form of a chessboard. Half of the thermopile junctions are under the white cells, the other half are under the black cells. The top of the receiver is covered with hemispherical glass to protect it from wind and precipitation. To measure the intensity of scattered radiation, the receiver is shaded by a special screen 3 . During measurements, the receiver of the device is installed strictly horizontally; for this purpose, the pyranometer is equipped with a round level 7 and set screws 4. At the bottom of the receiver there is a glass dryer filled with a water-absorbing substance, which prevents moisture from condensing on the receiver and glass. When not in use, the pyranometer receiver is covered with a metal cap.

Rice. 4 Universal pyranometer M–80M: 1 – pyranometer head; 2 – locking spring; 3 – shade hinge; 4 – setscrew; 5 – base; 6 – hinge of the folding tripod; 7 – level; 8 – screw; 9 – rack with desiccant inside; 10 – receiving surface of the thermopile.

Travel albedometer(Fig. 5) is designed to measure the intensities of total, scattered and reflective radiation in field conditions. The receiver is the pyranometer head 1 , mounted on a self-balancing gimbal 3 . This suspension allows you to install the device in two positions - with the receiver up and down, and the horizontality of the receivers is ensured automatically. When the receiving surface of the device is positioned upward, the total radiation Q is determined. Then, to measure the reflected radiation R, the albedometer handle is turned 180 0 . Knowing these values, you can determine the albedo.

Thermoelectric balance meter M-10M(Fig. 6) is designed to measure the total radiation balance of the underlying surface. The receiver of the balance meter is a square-shaped thermopile consisting of many copper bars 5 , wrapped with constantan tape 10 . Half of each screw of the tape is electroplated with silver, the beginning and end of the silver layer 9 are thermoseals. Half of the junctions are glued to the top, the other half to the bottom receiving surfaces, which are used as copper plates 2 , painted black. The balance meter receiver is placed in a round metal frame 1 . When measuring, it is positioned strictly horizontally using a special overhead level. To do this, the balance meter receiver is mounted on a ball joint 15 . To improve measurement accuracy, the balance meter receiver can be protected from direct solar radiation by a round screen 12 . The intensity of direct solar radiation is measured in this case with an actinometer or pyranometer.

Rice. 5 Travel albedometer: 1 – pyranometer head; 2 – tube; 3 – gimbal; 4 – handle

Rice. 6 Thermoelectric balance meter M-10M: a) – schematic cross-section: b) – separate thermopile; V) - appearance; 1 – receiver frame; 2 – receiving plate; 3, 4 – junctions; 5 – copper bar; 6, 7 – insulation; 8 – thermopile; 9 – silver layer; 10 – constantan tape; 11 – handle; 12 – shadow screen; 13, 15 – hinges; 14 – bar; 16 – screw; 17 - cover

Instruments for measuring solar duration

radiance and illumination

Sunshine duration is the time during which direct solar radiation is equal to or greater than 0.1 kW/m2. Expressed in hours per day.

The method for determining the duration of sunshine is based on recording the time during which the intensity of direct solar radiation is sufficient to produce a burn on a special tape mounted in the optical focus of a spherical glass lens, and is at least 0.1 kW/m 2.

The duration of sunshine is measured by a heliograph device (Fig. 7).

Universal heliograph model GU-1(Fig. 7). The base of the device is a flat metal plate with two stands 1 . Between racks on a horizontal axis 2 the moving part of the device, consisting of a column, is reinforced 3 with dial 4 and bottom stop 7 , staples 6 with a cup 5 and top stop 15 and glass ball 8 , which is a spherical lens. A sector is fixed at one end of the horizontal axis 9 with latitude scale. When moving the horizontal axis 2 device from west to east and turning the upper part of the device around it, the column axis 3 is installed parallel to the Earth's rotation axis (mundane axis). A screw is used to secure the set angle of inclination of the column axis. 11 .

Top part the device can be rotated around the column axis 3 and be fixed in four specific positions. A special pin is used for this 12 , which is inserted through the hole in the dial 4 into one of the four holes of the disk 13 , fixed on an axis 2 . Matching of the dial holes 4 and disk 13 determined by the coincidence of marks A, B, C and D on the dial 4 with index 14 on disk.

Rice. 7 Universal heliograph model GU-1.

1 – stand; 2 – horizontal axis; 3 – column; 4 – limb; 5 – cup; 6 – bracket; 7 – emphasis; 8 – glass ball; 9 – sector; 10 – latitude indicator; 11 – screw for fixing the angle of inclination of the axis; 12 – pin; 13 – disk; 14 – index on the disk; 15 – upper stop.

At a meteorological site, the heliograph is installed on a concrete or wooden pole 2 m high, on the top of which there is a platform made of boards at least 50 mm thick, so that at any position of the Sun relative to the sides of the horizon, individual buildings, trees and random objects do not obscure it. It is installed strictly horizontally and oriented along the geographic meridian and latitude of the meteorological station; The heliograph axis must be strictly parallel to the axis of the world.

The heliograph ball must be kept clean, since the presence of dust, traces of precipitation, deposition of dew, frost, frost and ice on the ball weakens and distorts the burn on the heliograph tape.

Depending on the possible duration of sunshine, recording for one day should be made on one, two or three tapes. Depending on the season, straight or curved strips should be used, which should be placed in the upper, middle or lower grooves of the cup. Ribbons for bookmarking throughout the month should be of the same color.

For the convenience of working with the heliograph, a ladder with a platform is installed to the south of the stand (pillar) with the device. The ladder should not touch the pole and should be quite comfortable.

Luxmeter Yu-16(Fig. 8) is used to measure the illumination created by light or artificial sources Sveta.

Rice. 8 Luxmeter Yu-16. 1 – photocell; 2 – wire; 3 – meter; 4 – absorber; 5 – terminals; 6 – switch of measurement limits; 7 – corrector.

The device consists of a selenium photocell 1 connected by wire 2 with meter 3 , and absorber 4 . The photocell is enclosed in a plastic case with a metal frame; to increase the measurement limits by 100 times, a milk glass absorber is placed on the case. The luxmeter meter is a magnetoelectric pointer device mounted in a plastic case with a window for a scale. There is a corrector at the bottom of the case 7 to set the arrow to zero, in the upper part there are terminals 5 for connecting wires from a photocell and a knob for switching measurement limits 6 .

The meter scale is divided into 50 divisions and has 3 rows of numbers corresponding to three measurement limits - up to 25, 100 and 500 lux (lx). When using an absorber, the limits increase to 2500, 10000 and 50000 lux.

When working with a lux meter, you must carefully monitor the cleanliness of the photocell and absorber; if they become dirty, wipe them with a cotton swab soaked in alcohol.

During measurements, the photocell is positioned horizontally. Using a corrector, set the meter needle to the zero division. Attach a photocell to the meter and take measurements after 4-5 s. To reduce overloads, start with a larger measurement range, then move to smaller limits until the arrow is in the working part of the scale. The count is taken in scale divisions. For small deviations of the needle, to increase the accuracy of measurements, it is recommended to switch the meter to a lower limit. To prevent fatigue of the selenium photocell, every 5-10 minutes of operation of the device it is necessary to shade the photocell for 3-5 minutes.

Illumination is determined by multiplying the reading by the value of the scale division and by the correction factor (for natural light it is equal to 0.8, for incandescent lamps -1). The scale division value is equal to the measurement limit divided by 50. When using one or two absorbers, the resulting value is multiplied by 100 or 10,000, respectively.

1 Familiarize yourself with the design of thermoelectric devices (actinometer, pyranometer, albedometer, balance meter).

2 Familiarize yourself with the design of a universal heliograph and how to install it at different times of the year.

3 Familiarize yourself with the device of a lux meter, measure natural and artificial illumination in the classroom.

Make notes in a notebook.

The amount of direct solar radiation (S) reaching the earth's surface under cloudless sky conditions depends on the height of the sun and transparency. Table for three latitudinal zones The distribution of monthly amounts of direct radiation under cloudless skies (possible amounts) is given in the form of averaged values ​​for the central months of the seasons and year.

The increased arrival of direct radiation in the Asian part is due to the higher transparency of the atmosphere in this region. High values ​​of direct radiation in summer in the northern regions of Russia are explained by a combination of high atmospheric transparency and long duration day

Reduces the arrival of direct radiation and can significantly change its daily and annual cycle. However, under average cloudy conditions, the astronomical factor is predominant and, therefore, the maximum direct radiation is observed at highest altitude sun.

In most of the continental regions of Russia in the spring and summer months, direct radiation in the afternoon hours is greater than in the afternoon. This is due to the development of convective clouds in the afternoon and a decrease in atmospheric transparency at this time of day compared to the morning hours. In winter, the ratio of pre- and afternoon radiation values ​​is the opposite - the pre-noon values ​​of direct radiation are lower due to the morning maximum of cloudiness and its decrease in the second half of the day. The difference between the before and afternoon direct radiation values ​​can reach 25–35%.

In the annual course, the maximum direct radiation occurs in June-July, with the exception of areas Far East, where it shifts to May, and in the south of Primorye a secondary maximum is noted in September.
The maximum monthly amount of direct radiation on the territory of Russia is 45–65% of what is possible under cloudless skies, and even in the south of the European part it reaches only 70%. Minimum values ​​are observed in December and January.

The contribution of direct radiation to the total arrival under actual cloudy conditions reaches its maximum in the summer months and averages 50–60%. The exception is Primorsky Krai, where the largest contribution of direct radiation occurs in the autumn and winter months.

The distribution of direct radiation under average (actual) cloud conditions over the territory of Russia largely depends on. This leads to a noticeable disruption of the zonal distribution of radiation in individual months. This is especially evident in the spring. Thus, in April there are two maximums - one in the southern regions

Solar radiation is radiation characteristic of the star of our planetary system. The Sun is the main star around which the Earth and its neighboring planets revolve. In fact, it is a huge hot ball of gas, constantly emitting streams of energy into the space around it. This is what is called radiation. Deadly, at the same time, this energy is one of the main factors that makes life possible on our planet. Like everything in this world, the benefits and harms of solar radiation for organic life are closely interrelated.

General overview

To understand what solar radiation is, you must first understand what the Sun is. The main source of heat that provides the conditions for organic existence on our planet in the universal expanses is only a small star on the galactic outskirts of the Milky Way. But for earthlings, the Sun is the center of the mini-universe. After all, it is around this gas clump that our planet revolves. The sun gives us warmth and light, that is, it supplies forms of energy without which our existence would be impossible.

In ancient times, the source of solar radiation - the Sun - was a deity, an object worthy of worship. The solar trajectory across the sky seemed to people obvious proof of God's will. Attempts to understand the essence of the phenomenon, to explain what this star is, have been made for a long time, and Copernicus made a particularly significant contribution to them, forming the idea of ​​heliocentrism, which was strikingly different from the generally accepted geocentrism of that era. However, it is known for certain that even in ancient times, scientists more than once thought about what the Sun is, why it is so important for any forms of life on our planet, why the movement of this luminary is exactly the way we see it.

The progress of technology has made it possible to better understand what the Sun is, what processes occur inside the star, on its surface. Scientists have learned what solar radiation is, how a gas object affects the planets in its zone of influence, in particular, the earth’s climate. Now humanity has a sufficiently voluminous knowledge base to say with confidence: it was possible to find out what the radiation emitted by the Sun is in its essence, how to measure this energy flow and how to formulate the features of its impact on different shapes organic life on Earth.

About terms

Most important step in mastering the essence of the concept was done in the last century. It was then that the eminent astronomer A. Eddington formulated an assumption: thermonuclear fusion occurs in the depths of the sun, which allows the release of a huge amount of energy emitted into the space around the star. Trying to estimate the magnitude of solar radiation, efforts were made to determine the actual parameters of the environment on the luminary. Thus, the temperature of the core, according to scientists, reaches 15 million degrees. This is sufficient to cope with the mutual repulsive influence of protons. The collision of units leads to the formation of helium nuclei.

New information attracted the attention of many prominent scientists, including A. Einstein. In attempts to estimate the amount of solar radiation, scientists found that helium nuclei in their mass are inferior to the total value of 4 protons necessary for the formation new structure. This is how a feature of the reactions was identified, called the “mass defect”. But in nature nothing can disappear without a trace! In an attempt to find the “escaped” values, scientists compared energy healing and the specificity of mass changes. It was then that it was possible to reveal that the difference was emitted by gamma rays.

Emitted objects make their way from the core of our star to its surface through numerous gaseous atmospheric layers, which leads to the fragmentation of elements and the formation of electromagnetic radiation. Among other types of solar radiation is light perceived by the human eye. Rough estimates suggest that the process of passing gamma rays takes about 10 million years. Another eight minutes - and the emitted energy reaches the surface of our planet.

How and what?

Solar radiation is the total complex of electromagnetic radiation, which has a fairly wide range. This includes the so-called solar wind, that is, an energy flow formed by electrons and light particles. At the boundary layer of our planet's atmosphere, the same intensity of solar radiation is constantly observed. The energy of a star is discrete, its transfer is carried out through quanta, and the corpuscular nuance is so insignificant that the rays can be considered as electromagnetic waves. And their distribution, as physicists have found, occurs evenly and in a straight line. Thus, in order to describe solar radiation, it is necessary to determine its characteristic wavelength. Based on this parameter, it is customary to distinguish several types of radiation:

• warm;
• radio wave;
• White light;
• ultraviolet;
• gamma;
• X-ray.

The ratio of infrared, visible, ultraviolet is best estimated as follows: 52%, 43%, 5%.

For a quantitative radiation assessment, it is necessary to calculate the energy flux density, that is, the amount of energy that reaches a limited area of ​​the surface in a given time period.

Research has shown that solar radiation is predominantly absorbed by the planetary atmosphere. Thanks to this, heating occurs to a temperature comfortable for organic life characteristic of the Earth. The existing ozone shell allows only one hundredth to pass through ultraviolet radiation. In this case, short-length waves that are dangerous to living beings are completely blocked. Atmospheric layers are capable of scattering almost a third of the Sun's rays, and another 20% are absorbed. Consequently, no more than half of the total energy reaches the planet's surface. It is this “residue” that science calls direct solar radiation.

How about more details?

There are several aspects that determine how intense the direct radiation will be. The most significant are the angle of incidence, which depends on latitude (geographical characteristics of the area in globe), the time of year that determines how great the distance is to a specific point from the radiation source. Much depends on the characteristics of the atmosphere - how polluted it is, how many clouds there are at a given moment. Finally, the nature of the surface on which the beam falls plays a role, namely, its ability to reflect incoming waves.

Total solar radiation is a quantity that combines scattered volumes and direct radiation. The parameter used to assess intensity is estimated in calories per unit area. At the same time, remember that at different times of the day the values ​​characteristic of radiation differ. In addition, energy cannot be distributed evenly over the surface of the planet. The closer to the pole, the higher the intensity, while the snow covers are highly reflective, which means the air does not get the opportunity to warm up. Consequently, the further from the equator, the lower the total solar wave radiation will be.

As scientists have discovered, the energy of solar radiation has a serious impact on the planetary climate and subjugates the life activity of various organisms existing on Earth. In our country, as well as in the territory of our closest neighbors, as well as in other countries located in the northern hemisphere, in winter the predominant share belongs to scattered radiation, but in summer direct radiation dominates.

Infrared waves

Of the total amount of total solar radiation, an impressive percentage belongs to the infrared spectrum, which is not perceived by the human eye. Due to such waves, the surface of the planet heats up, gradually transferring thermal energy air masses. This helps maintain a comfortable climate and maintain conditions for the existence of organic life. If no serious disruptions occur, the climate remains relatively unchanged, which means that all creatures can live in their usual conditions.

Our star is not the only source of waves infrared spectrum. Similar radiation is characteristic of any heated object, including an ordinary battery in a human home. It is on the principle of perception infrared radiation Numerous devices operate that make it possible to see heated bodies in the dark or in other conditions that are uncomfortable for the eyes. By the way, the ones that have become so popular in Lately compact devices for assessing through which areas of the building the greatest heat loss occurs. These mechanisms are especially widespread among builders, as well as owners of private houses, since they help to identify through which areas heat is lost, organize their protection and prevent unnecessary energy consumption.

Do not underestimate the influence of solar radiation in the infrared spectrum on the human body simply because our eyes cannot perceive such waves. In particular, radiation is actively used in medicine, since it allows increasing the concentration of leukocytes in circulatory system, and also normalize blood flow by increasing the lumens of blood vessels. Devices based on the IR spectrum are used as prophylactics against skin pathologies, therapeutic for inflammatory processes in acute and chronic forms. Most modern drugs help cope with colloid scars and trophic wounds.

This is interesting

Based on the study of solar radiation factors, it was possible to create truly unique devices called thermographs. They make it possible to timely detect various diseases that cannot be detected by other means. This is how you can find cancer or a blood clot. IR protects to some extent from ultraviolet radiation, which is dangerous to organic life, which has made it possible to use waves of this spectrum to restore the health of astronauts who have been in space for a long time.

The nature around us is still mysterious to this day, this also applies to radiation of various wavelengths. In particular, infrared light has not yet been thoroughly studied. Scientists know that it misuse may cause harm to health. Thus, it is unacceptable to use equipment that generates such light for the treatment of purulent inflamed areas, bleeding and malignant neoplasms. The infrared spectrum is contraindicated for people suffering from dysfunction of the heart and blood vessels, including those located in the brain.

Visible light

One of the elements of total solar radiation is light visible to the human eye. The wave beams travel in straight lines, so they do not overlap each other. At one time, this became the topic of a considerable number of scientific works: scientists set out to understand why there are so many shades around us. It turned out that key light parameters play a role:

• refraction;
• reflection;
• absorption.

As scientists have found, objects are not capable of being sources of visible light themselves, but can absorb radiation and reflect it. Reflection angles and wave frequencies vary. Over the course of many centuries, a person's ability to see has gradually improved, but certain limitations are due to the biological structure of the eye: the retina is such that it can perceive only certain rays of reflected light waves. This radiation is a small gap between ultraviolet and infrared waves.

Numerous curious and mysterious features of light not only became the topic of many works, but also were the basis for the emergence of a new physical discipline. At the same time, non-scientific practices and theories appeared, the adherents of which believe that color can affect a person’s physical condition and psyche. Based on such assumptions, people surround themselves with objects that are most pleasing to their eyes, making everyday life more comfortable.

Ultraviolet

An equally important aspect of total solar radiation is ultraviolet radiation, formed by waves of large, medium and short lengths. They differ from each other both in physical parameters and in the characteristics of their influence on forms of organic life. Long ultraviolet waves, for example, in atmospheric layers mostly dissipate, and only a small percentage reaches the earth's surface. The shorter the wavelength, the deeper such radiation can penetrate human (and not only) skin.

On the one hand, ultraviolet radiation is dangerous, but without it the existence of diverse organic life is impossible. This radiation is responsible for the formation of calciferol in the body, and this element is necessary for the construction of bone tissue. The UV spectrum is a powerful prevention of rickets and osteochondrosis, which is especially important in childhood. In addition, such radiation:

• normalizes metabolism;
• activates the production of essential enzymes;
• enhances regenerative processes;
• stimulates blood flow;
• expands blood vessels;
• stimulates the immune system;
• leads to the formation of endorphin, which means nervous overexcitation decreases.

but on the other hand

It was stated above that total solar radiation is the amount of radiation that reaches the surface of the planet and is scattered in the atmosphere. Accordingly, the element of this volume is ultraviolet of all lengths. It must be remembered that this factor has both positive and negative sides influence on organic life. Sunbathing, although often beneficial, can be a source of health hazards. Excessive exposure to direct sunlight, especially in conditions of increased solar activity, is harmful and dangerous. Long-term effects on the body, as well as too high radiation activity, cause:

• burns, redness;
• swelling;
• hyperemia;
• heat;
• nausea;
• vomiting.

Prolonged ultraviolet irradiation provokes disturbances in appetite, the functioning of the central nervous system, and the immune system. In addition, my head starts to hurt. Described signs - classic manifestations sunstroke. The person himself cannot always realize what is happening - the condition worsens gradually. If it is noticeable that someone nearby is feeling ill, first aid should be provided. The scheme is as follows:

• help move from direct light to a cool, shaded place;
• put the patient on his back so that his legs are higher than his head (this will help normalize blood flow);
• cool your neck and face with water, and put a cold compress on your forehead;
• unfasten your tie, belt, take off tight clothes;
• half an hour after the attack, give cool water (a small amount) to drink.

If the victim loses consciousness, it is important to immediately seek help from a doctor. The ambulance team will move the person to safety and give an injection of glucose or vitamin C. The medicine is given into a vein.

How to tan correctly?

In order not to learn from your own experience how unpleasant the excessive amount of solar radiation received from tanning can be, it is important to follow the rules of safe spending time in the sun. Ultraviolet light initiates the production of melanin, a hormone that helps the skin protect itself from the negative effects of waves. Under the influence of this substance, the skin becomes darker and the shade turns bronze. To this day, debate continues about how beneficial and harmful it is for humans.

On the one hand, tanning is an attempt by the body to protect itself from excessive exposure to radiation. This increases the likelihood of the formation of malignant neoplasms. On the other hand, tanning is considered fashionable and beautiful. To minimize the risks for yourself, it is wise, before starting beach procedures, to understand why the amount of solar radiation received during sunbathing is dangerous, and how to minimize the risks for yourself. To make the experience as pleasant as possible, sunbathers should:

• to drink a lot of water;
• use skin protecting products;
• sunbathe in the evening or in the morning;
• spend no more than an hour in direct sunlight;
• do not drink alcohol;
• include foods rich in selenium, tocopherol, and tyrosine in the menu. Don't forget about beta-carotene.

Solar radiation value for human body is exceptionally large, both positive and negative aspects should not be overlooked. It should be realized that different people biochemical reactions occur with individual characteristics, so for some, half an hour of sunbathing can be dangerous. It is wise to consult a doctor before the beach season to assess the type and condition of your skin. This will help prevent harm to health.

If possible, you should avoid tanning in old age, during the period of bearing a baby. Not compatible with sunbathing cancer, mental disorders, skin pathologies and heart failure.

Total radiation: where is the shortage?

The process of distribution of solar radiation is quite interesting to consider. As mentioned above, only about half of all waves can reach the surface of the planet. Where do the rest go? The different layers of the atmosphere and the microscopic particles from which they are formed play a role. An impressive part, as stated, is absorbed by the ozone layer - these are all waves whose length is less than 0.36 microns. Additionally, ozone is capable of absorbing some types of waves from the spectrum visible to the human eye, that is, the range of 0.44-1.18 microns.

Ultraviolet light is absorbed to some extent by the oxygen layer. This is typical for radiation with a wavelength of 0.13-0.24 microns. Carbon dioxide and water vapor can absorb a small percentage of the infrared spectrum. The atmospheric aerosol absorbs some part (IR spectrum) of the total amount of solar radiation.

Waves from the short category are scattered in the atmosphere due to the presence of microscopic inhomogeneous particles, aerosol, and clouds. Inhomogeneous elements, particles whose dimensions are smaller than the wavelength, provoke molecular scattering, and larger ones are characterized by the phenomenon described by the indicatrix, that is, aerosol.

The remaining amount of solar radiation reaches the earth's surface. It combines direct radiation and scattered radiation.

Total radiation: important aspects

The total value is the amount of solar radiation received by the territory, as well as absorbed in the atmosphere. If there are no clouds in the sky, the total amount of radiation depends on the latitude of the area, the altitude of the celestial body, the type of earth's surface in this area, and the level of air transparency. The more aerosol particles scattered in the atmosphere, the lower the direct radiation, but the proportion of scattered radiation increases. Normally, in the absence of clouds, scattered radiation is one fourth of the total radiation.

Our country is one of the northern ones, so most of the year in the southern regions the radiation is significantly greater than in the northern ones. This is due to the position of the star in the sky. But the short time period of May-July is a unique period when, even in the north, the total radiation is quite impressive, since the sun is high in the sky, and the duration daylight hours more than in other months of the year. Moreover, on average, in the Asian half of the country, in the absence of clouds, the total radiation is more significant than in the west. Maximum strength wave radiation occurs at midday, and the annual maximum occurs in June, when the sun is highest in the sky.

Total solar radiation is the amount of solar energy reaching our planet. It must be remembered that various atmospheric factors lead to the fact that the annual amount of total radiation is less than it could be. The most a big difference between the actually observed and the maximum possible is typical for the Far Eastern regions in the summer. Monsoons provoke extremely dense clouds, so the total radiation is reduced by approximately half.

Curious to know

The largest percentage of the maximum possible exposure to solar energy is actually observed (per 12 months) in the south of the country. The figure reaches 80%.

Cloud cover does not always result in the same dispersion rate solar radiation. The shape of the clouds and the features of the solar disk at a particular moment in time play a role. If it is open, then cloudiness causes a decrease in direct radiation, while scattered radiation increases sharply.

There may also be days when direct radiation is approximately the same in strength as scattered radiation. The daily total value may be even greater than the radiation characteristic of a completely cloudless day.

When calculating for 12 months, special attention must be paid to astronomical phenomena as they determine general numerical indicators. At the same time, cloudiness leads to the fact that the radiation maximum may actually be observed not in June, but a month earlier or later.

Radiation in space

From the boundary of the magnetosphere of our planet and further into outer space, solar radiation becomes a factor associated with mortal danger for humans. Back in 1964, an important popular science work was published on protection methods. Its authors were Soviet scientists Kamanin and Bubnov. It is known that for a person, the radiation dose per week should be no more than 0.3 roentgens, while for a year - within 15 R. For short-term exposure, the limit for a person is 600 R. Flights into space, especially in conditions of unpredictable solar activity , may be accompanied by significant exposure of astronauts, which requires additional protective measures to be taken against waves of different lengths.

After the Apollo missions, during which defense methods were tested, factors influencing human health, more than a decade has passed, but to this day scientists cannot find effective, reliable methods for predicting geomagnetic storms. You can make a forecast based on hours, sometimes for several days, but even for a weekly assumption, the chances of implementation are no more than 5%. The solar wind is an even more unpredictable phenomenon. With a probability of one in three, astronauts setting off on a new mission may find themselves in powerful streams of radiation. This makes it even more important question both research and prediction of radiation characteristics, and the development of methods of protection against it.

Direct solar radiation, which is often called simply solar radiation, is understood as radiation reaching the observation site in the form of a beam of parallel rays directly from the Sun.

Fluxes of solar radiation perpendicular to the rays ( I) and horizontal ( I΄ = I sin h) surfaces depend on the following factors: a) solar constant; b) the distance between the Earth and the Sun (flux I 0 ) at the upper boundary of the atmosphere in January is approximately 3.5% more, and in July 3.5% less than I* 0 ); V) physical condition atmosphere above the observation point (content of absorbing gases and solid atmospheric impurities, presence of clouds and fogs); d) the height of the Sun.

Depending on the specified factors, flows I To I΄ vary widely. At each point they have a clearly defined daily and annual cycle (maxima I And I΄ the course of the day is observed at local noon). Although the height of the Sun (on which it depends T.) and has a great influence on the fluxes of solar radiation, but the turbidity of the atmosphere has no less influence. This is confirmed by the maximum (midday) flux values I, which have ever been observed at various points (Tables 6.3 and 6.4). From those given in table. 6.3 of the data it follows that despite the large difference in the latitude of the stations and, therefore, in maximum height Suns, difference I Max there is little on them. Moreover, on about. Dixon meaning I max is greater than in points located further south. This is explained by the fact that the atmosphere at low latitudes contains more water vapor and impurities than at high latitudes.

6.5. Scattered radiation

Scattered radiation is solar radiation that has undergone dispersion in the atmosphere. The amount of scattered radiation arriving on a single horizontal surface per unit time is called the scattered radiation flux; the flux of scattered radiation will be denoted by i. Since the primary source of scattered radiation is direct solar radiation, the flux i should depend on the factors that determine I, namely: a) the height of the Sun h(the more h, the more i); b) transparency of the atmosphere (the more R, the less i; c) cloudiness.

6.6. Total radiation

The total radiation flux Q is the sum of direct (I΄) and scattered ( i) solar radiation arriving on a horizontal surface. By solving approximate radiation transfer equations, K. Ya. Kondratiev et al. obtained the following formula for the total radiation flux under cloudless conditions:

Here τ is the optical thickness for the integral flow, which, as shown by O. A. Avaste, can be assumed to be equal to τ 0.55 - the optical thickness for the monochromatic flow with λ = 0.55 μm; ε is a multiplier that takes the following values ​​at different heights of the Sun:

6.7. Albedo

Albedo, or the reflectivity of a surface, as already indicated, is the ratio of the flux of radiation reflected by a given surface to the flux of incident radiation, expressed in fractions of a unit or as a percentage.

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

The most important source from which the Earth's surface and atmosphere receive thermal energy is the Sun. It sends a colossal amount of radiant energy into cosmic space: thermal, light, ultraviolet. Emitted by the Sun electromagnetic waves propagate at a speed of 300,000 km/s.

The heating of the earth's surface depends on the angle of incidence of the sun's rays. All the sun's rays arrive at the surface of the Earth parallel to each other, but since the Earth has spherical shape, the sun's rays fall on different parts of its surface at different angles. When the Sun is at its zenith, its rays fall vertically and the Earth heats up more.

The entire set of radiant energy sent by the Sun is called solar radiation, it is usually expressed in calories per unit surface area per year.

Solar radiation determines the temperature regime of the Earth's air troposphere.

It should be noted that total solar radiation is more than two billion times the amount of energy received by the Earth.

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 under a cloudless sky is called straight. She carries greatest number warmth and light. If our planet had no atmosphere, earth's surface received only direct radiation.

However, passing through the atmosphere, approximately a quarter of solar radiation is scattered by gas molecules and impurities, deviating from straight path. Some of them reach the surface of the Earth, forming scattered solar radiation. Thanks to scattered radiation, light penetrates into places where direct sunlight (direct radiation) does not penetrate. This radiation creates daylight and gives color to the sky.

Total solar radiation

All the sun's rays reaching the Earth are total solar radiation, i.e., the totality of direct and diffuse radiation (Fig. 1).

Rice. 1. Total solar radiation for the year

Distribution of solar radiation over the earth's surface

Solar radiation is distributed unevenly across the earth. It depends:

1. on air density and humidity - the higher they are, the less radiation the earth’s surface receives;

2. depending on the geographic 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 through the shortest path and intensively give off their energy small area. On Earth, this occurs in the band between 23° N. w. and 23° S. sh., i.e. between the tropics. As you move away from this zone to the south or north, the path length of the sun's rays increases, that is, the angle of their incidence on the earth's surface decreases. The rays begin to fall on the Earth at a smaller angle, as if sliding, approaching the tangent line in the area of ​​the poles. As a result, the same energy flow is distributed across large area, therefore the amount of reflected energy increases. Thus, in the region of the equator, where the sun's rays fall on the earth's surface at an angle of 90°, the amount of direct solar radiation received by the earth's surface is higher, and as we move towards the poles, this amount sharply decreases. In addition, the length of the day at different times of the year depends on the latitude of the area, which also determines the amount of solar radiation reaching the earth's surface;

3. from annual and diurnal movement Earth - in the middle and high latitudes, the influx of solar radiation varies greatly with the seasons, which is associated with changes in the midday altitude of the Sun and the length of the day;

4. on the nature of the earth's surface - the lighter the surface, the more sunlight it reflects. The ability of a surface to reflect radiation is called albedo(from Latin whiteness). Snow reflects radiation especially strongly (90%), sand weaker (35%), and black soil even weaker (4%).

Earth's surface absorbing solar radiation (absorbed radiation), heats up and radiates heat into the atmosphere (reflected radiation). The lower layers of the atmosphere largely block terrestrial radiation. The radiation absorbed by the earth's surface is spent on heating the soil, air, and water.

That part of the total radiation that remains after reflection and thermal radiation earth's surface is called radiation balance. The radiation balance of the earth's surface varies during the day and according to the seasons of the year, but on average per year it is positive value everywhere except the ice deserts of Greenland and Antarctica. The radiation balance reaches its maximum values ​​at low latitudes (between 20° N and 20° S) - over 42*10 2 J/m 2 , at a latitude of about 60° in both hemispheres it decreases to 8*10 2 - 13*10 2 J/m 2.

Sun rays give up to 20% of their energy to the atmosphere, which is distributed throughout the entire thickness of the air, and therefore the heating of the air they cause is relatively small. The sun heats the Earth's surface, which transfers heat atmospheric air due to convection(from lat. convection- delivery), i.e. the vertical movement of air heated at the earth's surface, in place of which colder air descends. This is how the atmosphere receives most of its heat—on average, three times more than directly from the Sun.

The presence of carbon dioxide and water vapor does not allow heat reflected from the earth's surface to freely escape into outer space. They create Greenhouse effect, thanks to which the temperature difference on Earth during the day does not exceed 15 °C. In the absence of carbon dioxide in the atmosphere, the earth's surface would cool by 40-50 °C overnight.

As a result of the growing scale economic activity people - combustion of coal and oil at thermal power plants, emissions industrial enterprises, increasing automobile emissions - the content of carbon dioxide in the atmosphere increases, which leads to increased greenhouse effect and threatens global climate change.

The sun's rays, having passed through the atmosphere, hit the surface of the Earth and heat it, which, in turn, gives off heat to the atmosphere. This explains characteristic feature troposphere: decrease in air temperature with height. But there are cases when the higher layers of the atmosphere turn out to be warmer than the lower ones. This phenomenon is called temperature inversion(from Latin inversio - turning over).