Sun radiation. What is solar radiation? Types of radiation and its effect on the body

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

K = E:E n ⋅100%

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

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

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

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

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

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

Speaking about the influence of the sun on the human body, it is impossible to accurately determine the harm or benefit it brings. The sun's rays are like kilocalories from food.. Their deficiency leads to malnutrition, and in excess they cause obesity. So it is in this situation. In moderate amounts, solar radiation has a beneficial effect on the body, while an excess of ultraviolet radiation provokes burns and the development of numerous diseases. Let's take a closer look.

Solar radiation: general effect on the body

Solar radiation is a combination of ultraviolet and infrared waves.. Each of these components affects the body in its own way.

Influence of infrared radiation:

1. The main feature of infrared rays is the thermal effect they create. Warming up the body contributes to the expansion of blood vessels and the normalization of blood circulation.
2. Warming up has a relaxing effect on the muscles, providing a slight anti-inflammatory and analgesic effect.
3. Under the influence of heat, metabolism increases, the processes of assimilation of biologically active components are normalized.
4. Infrared radiation from the sun stimulates the brain and visual apparatus.
5. Thanks to solar radiation, the biological rhythms of the body are synchronized, sleep and wakefulness modes are launched.
6. Treatment with solar heat improves the condition of the skin, relieving acne.
7. Warm light uplifts the mood and improves the emotional background of a person.
8. And according to recent studies, it also improves the quality of sperm in men.

Despite all the debate about the negative effects of ultraviolet radiation on the body, its lack can lead to serious health problems. It is one of the vital factors of existence. And in conditions of ultraviolet deficiency in the body, the following changes begin to occur:

1. First of all, immunity weakens. This is caused by a violation of the absorption of vitamins and minerals, a malfunction in metabolism at the cellular level.
2. There is a tendency to develop new or exacerbate chronic diseases, most often occurring with complications.
3. Lethargy, chronic fatigue syndrome are noted, the level of working capacity decreases.
4. The lack of ultraviolet light for children interferes with the production of vitamin D and provokes a decrease in growth.

However, you need to understand that excessive solar activity will not benefit the body!

Sunbathing contraindications

Despite all the benefits of sunlight for the body, not everyone can afford to enjoy the warm rays. Contraindications include:

• acute inflammatory processes;
• tumors, regardless of their location;
• progressive tuberculosis;
• angina pectoris, ischemic disease;
• endocrine pathologies;
• damage to the nervous system;
• dysfunction of the thyroid and adrenal glands;
• diabetes;
• mastopathy;
• uterine fibroids;
• pregnancy;
• recovery period after surgery.

In all cases, active radiation will aggravate the course of the disease, provoking the development of new complications..

Do not get involved in the sun and the elderly, infants. For these populations, treatment is indicated sunlight in the shadow. The necessary dose of safe heat will be enough there.

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The negative influence of the sun

The time of exposure to infrared and ultraviolet waves must be strictly limited. In excess solar radiation:

• can provoke a deterioration in the general condition of the body (the so-called heat stroke due to overheating);
• negatively affects the skin, causing permanent changes;
• impairs vision;
• provokes hormonal disruptions in the body;
• can provoke the development of allergic reactions.

So that hours of lying on the beach during periods of maximum solar activity cause enormous damage to the body.

To get the necessary portion of light, a twenty-minute walk on a sunny day is enough.

The effect of the sun on the skin

Excessive solar radiation leads to serious skin problems. In the short term, you risk getting a burn or dermatitis. This is the smallest problem you can face when you get carried away with a tan on a hot day. If such a situation is repeated with enviable regularity, the radiation of the sun will be the impetus for the formation of malignant formations on the skin, melanoma.

In addition, UV exposure dries out the skin, making it thinner and more sensitive. And constant exposure to direct rays accelerates the aging process, provoking the appearance of early wrinkles.

In order to protect yourself from the negative effects of solar radiation, it is enough to follow simple safety measures:

1. Be sure to use sunscreen in the summer? Putting it on everything open areas body, including face, arms, legs and décolleté. The SPF badge on the packaging is the same UV protection. And its degree will depend on the number indicated near the abbreviation. For going to the store, cosmetics with an SPF 15 or SPF 20 level are suitable. If you plan to spend time on the beach, use special products with higher rates. For children's skin, a cream with a maximum protection of SPF 50 is suitable.
2. If you need to be outdoors for a long time at the maximum intensity of sunlight, wear clothes made of light fabrics with long sleeve. Be sure to wear a wide-brimmed hat to hide the delicate skin of your face.
3. Control the duration of sunbathing. The recommended time is 15-20 minutes. If you are outside for a longer time, try to get some shade from the direct sunlight.

And remember that in the summer, solar radiation affects the skin at any time of the day, with the exception of night hours. You may not feel obvious heat from infrared waves, but ultraviolet does. high level activity, both in the morning and in the afternoon.

Negative effect on vision

The influence of sunlight on the visual apparatus is enormous. After all, thanks to light rays, we receive information about the world around us. Artificial lighting to some extent can become an alternative to natural light, but in conditions of reading and writing with a lamp, eye strain increases.

Speaking about the negative impact on a person and vision of sunlight, it means damage to the eyes during prolonged exposure to the sun without sunglasses.

Of the unpleasant sensations that you may encounter, one can single out cutting pains in the eyes, their redness, photophobia. The most serious lesion is a retinal burn.. It is also possible dry skin of the eyelids, the formation of small wrinkles.

1. Wear sunglasses. When buying, first of all, pay attention to the degree of protection. Image models often slightly obscure the light, but do not prevent the penetration of ultraviolet radiation. Therefore, it is recommended to put aside a bright frame and opt for quality lenses.
2. Make sure that direct rays do not fall on your face. Stay in the shade, wear a hat, cap or other headgear with a visor.
3. Don't look at the sun. If you do not experience discomfort, this does not indicate the safety of this undertaking. Even the winter sun has enough activity to provide vision problems.

Is there a safe time of year

The use of solar radiation as a health treatment is a common practice. That ultraviolet, that heat belongs to the category of strong irritants. And abuse of these benefits can earn serious problems.

Sunburn is the production of melanin. And to be more precise, the protective reaction of the skin to an irritant.

Is the radiation of the sun so dangerous at any time of the year? It is difficult to give a definite answer to this question. Everything will depend not so much on the season as on the geographical location. So, in the middle latitudes, the activity of solar radiation increases by 25-35% in the summer. Therefore, the recommendations regarding staying outside on a clear day apply only to the hot season. In winter, residents of these regions are not threatened by ultraviolet radiation.

But the inhabitants of the equator face direct sunlight all year round. Therefore, the likelihood of a negative impact on the body is present both in summer and in winter. The inhabitants of the northern latitudes in this regard were more fortunate. After all, with distance from the equator, the angle of incidence of the sun's rays on the earth changes, and with it the radiation activity. The length of the thermal wave increases, and at the same time the amount of heat decreases (energy loss). Hence the winter all year round, as the surface of the earth does not have enough heat to warm up.

Solar radiation is a friend of our body. But do not abuse this friendship. Otherwise, the consequences can be the most serious. Just enjoy the warmth without forgetting the precautions.

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

Electromagnetic waves

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

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

Solar radiation: spectral composition

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

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

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

Our luminary

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

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

Solar radiation: definition

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

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

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

How is the distribution

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

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

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

Daylight

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

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

Total radiation

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

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

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

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

Effective Radiation

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

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

On the geographical distribution of radiation

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

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

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

Are we facing global warming?

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

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

Card balance distribution

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

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

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

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

How about us?

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

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

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

About solar insolation

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

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

Pudovkin O.L. Structure and electromagnetic radiation of the Sun 0 Moscow, 2014

Pudovkin O.L. Structure and electromagnetic radiation of the Sun Moscow, 2014 1

UDC 52 + 55 Pudovkin O.L. Structure and electromagnetic radiation of the Sun. – Open e-publishing platform SPUBLER. Publication date: 2014-08-17. - 22 s. Necessary for developers of space systems for remote sensing of the Earth and users of space information are presented. general information on the electromagnetic radiation of the sun. The structure of the Sun and the physical foundations of the processes occurring in it, the energy and spectral characteristics of radiation are considered in relation to the classification tables of frequency ranges adopted by the ITU, IEEE and GOST 24375-80. Pudovkin Oleg Leonidovich. Scientific interests in the areas of: systems analysis, systems and control theory, man-made and cosmogenic space debris, international space law, geophysics, global space communication and navigation systems, project management. More than 100 scientific publications and 8 monographs. Doctor technical sciences, Corresponding Member of the Academy of Cosmonautics and the Academy of Military Sciences. In the space industry since 1968: VIKA im. A.F. Mozhaisky, Command and Measurement Complex of the Ministry of Defense of the Russian Federation, Scientific and Technical Committee of the Strategic Missile Forces, Military Scientific Committee of the Space Forces; vice-president, chief designer, adviser in organizations of the space industry; expert of the space cluster of the Skolkovo Foundation. Doctor of Technical Sciences Pudovkin O.L. e-mail: [email protected] 2

1. Structure of the Sun The Sun is the closest star to the Earth, distant from us at a distance of 8.32 ± 0.16 light minutes. All other stars are much further away. Closest to us is the star Proxima Centauri [from. lat roxima - nearest] is a red dwarf belonging to the star system Alpha Centauri, located at a distance of 4.2421 ± 0.0016 light years, which is 270,000 times the distance from the Earth to the Sun. In terms of its size, the Sun belongs to typical stars - dwarfs of the spectral class G2 according to the Hertzsprung-Russell diagram. This means that sunlight, which we are accustomed to perceive as white, is actually slightly yellowish. The Sun is removed from the Earth at an average distance of 149,597,870 km. Since this distance is the most important scale in the solar system, it is accepted as one of the main units of measurement of distances in astronomy and is called the astronomical unit (au, au). In the SI system 1 au = 149 597 870 700 m. The Sun is the central body of the Solar System, more than 99.86% of its total mass is concentrated in it. It is believed that the planets and the Sun arose 4-5 billion years ago from a giant gas and dust nebula. At the same time, the Sun has absorbed the largest part of the mass, which at present is about 2 × 1027 tons, which is 333 thousand times the mass of the Earth and 743 times the mass of all the planets combined. The chemical composition of the solar matter is dominated by hydrogen - 72% and helium - 26% of the mass of the Sun. A little less than a percent is oxygen, 0.4% is carbon, about 0.1% is neon. If these ratios are expressed in terms of the number of atoms, it turns out that there are 98,000 helium atoms per million hydrogen atoms, 850 oxygen atoms, 360 carbon atoms, 120 neon atoms, 110 nitrogen atoms, and 40 iron and silicon atoms each. Knowing the distance to the Sun and its apparent angular radius, it is easy to determine that the Sun is 109 times more earth, and its radius reaches 696 thousand kilometers. Consequently, the volume of the Sun is more than 1,300,000 times the volume of the Earth, and therefore the average density turns out to be almost 4 times less than the earth's and is about 1.4 g/cm3. By earthly standards, the luminosity of the Sun is colossal and reaches 3.85 × 1023 kW. Even a tiny fraction of the solar energy that irradiates the globe (and this is approximately one ten-billionth) is tens of thousands of times more powerful than the total power of all power plants in the world. The energy of the sun's rays falling on a 1 m2 area perpendicular to them on Earth could make a 1.4 kW engine work, and 1 m2 of the Sun's atmosphere radiates energy with a power of 60 mW. Figure 1 - Structure of the Sun. The Sun consists of inner layers – the zone of nuclear reactions, the zone of radiant energy transfer and the convection zone, as well as the atmosphere, including the photosphere, chromosphere and corona, which turns into the solar wind. 3

1.1. Inner layers of the Sun Theoretical studies of the last century, confirmed by the experimental data of recent decades, showed that the inner (not directly observable) layers of the Sun consist of three main parts, approximately equal in depth: the zone of nuclear reactions; radiant energy transfer zone; convective zone. Nuclear reaction zone ( central part, core) is characterized by the maximum values ​​of temperature, pressure, and density of matter compressed by gravity and constantly heated by the energy of thermonuclear reactions. The solar core is believed to extend from the center of the Sun to a distance of about 175,000 km (approximately 0.2 solar radii) and is the hottest part of the Sun. The temperature in the solar core is about 15,000,000 K (for comparison: the temperature of the solar surface in the chromosphere is about 60,000 K). The density of the core is 150,000 kg/m³, which is 150 times higher than the density of water on Earth. An analysis of the data obtained by the SOHO spacecraft showed that in the core the speed of the Sun's rotation around its axis is much higher than on the surface. Figure 2 - SOHO [from English. Solar and Heliospheric Observatory, observatory code “249”] is a spacecraft for observing the Sun. Joint project between ESA and NASA. It was launched on December 2, 1995 at 08:08:00 UTC, international designation 1995-065A, launched to the Lagrange point L1 of the Earth-Sun system, started operation in May 1996. A proton-proton thermonuclear reaction takes place in the nucleus, as a result of which the most common of the two natural isotopes of helium, 4 He, is formed out of four protons, which is approximately 99.999863% of the volume of all helium on Earth. At the same time, 4.26 million tons of matter (3.6 1038 protons) are converted into energy every second, but this value is negligible compared to the mass of the Sun - 2 1027 tons. The time after which the Sun will use up its "fuel" and the thermonuclear reaction will stop is estimated at 6 billion years. The power of the Sun's core is 380 iottawatts (1 IW = 1024 W), which is equivalent to the detonation of 9.1 1010 megatons of TNT per second. It is known that the most powerful energy device ever put into action by people was the Soviet Tsar Bomba (the project code name is Ivan), exploded on October 30, 1961 on Novaya Zemlya. Its power was 50 megatons, which is equivalent to 5.3 IW or about one percent of the solar energy released in one second. The core is the only place on the Sun where energy and heat are obtained from a thermonuclear reaction, the rest of the star is heated by this energy. All core energy 4

sequentially passes through the layers, up to the photosphere, from which it is emitted in the form of sunlight and kinetic energy. During the movement of high-energy photons (gamma and X-rays) to the surface of the Sun, they scatter part of the energy in less energetic layers compared to the core. Estimates of the "photon transit time" range from 40,000 years to 50 million years. Each gamma-quantum from the core of the Sun is converted into several million visible photons, which are emitted from its surface. Radiant energy transfer zone (radiant zone, radiation zone) is the zone of nuclear energy transfer through the radiation of individual atoms, which constantly absorb it and re-emit it in all directions. The zone is located directly above the solar core, at distances approximately from 0.2-0.25 to 0.7 of the Sun's radius from its center. The lower boundary of the zone is considered to be the line below which nuclear reactions occur, and the upper boundary is the boundary above which active mixing of matter begins (convective zone). The temperature difference is from 7,000,000 K to 2,000,000 K. Hydrogen in the radiative transfer zone is compressed so tightly that neighboring protons cannot change places, which makes the transfer of energy by mixing the substance very difficult. Additional obstacles to the mixing of the substance are created by the low rate of temperature decrease as it moves from the lower layers to the upper layers, which is due to the high thermal conductivity of hydrogen. Direct emission to the outside is also impossible, since hydrogen is opaque to the radiation that occurs during the nuclear fusion reaction. Energy transfer, in addition to heat transfer, also occurs through successive absorption and emission of photons by individual layers of particles. Due to the fact that the energy of an emitted photon is always less than the energy of an absorbed one, the spectral composition of radiation changes as it passes through the radiative zone. If at the entrance to the zone all radiation is represented by extremely short-wavelength gamma radiation, then leaving the radiant zone, the luminous flux of radiation is a “mixture” covering almost all wavelengths, including the visible one. The convective zone begins at a depth of 0.3 radius and extends up to the surface of the Sun (or rather, its atmosphere). Its lower part is heated to 2,000,000 K, while the temperature of the outer boundary does not reach 60,000 K. The essence of convection on the Sun is that a denser gas is distributed over the surface, cools on it, then again rushes to the center. Thus, in the convective zone of the Sun, the process of mixing is constantly taking place. It is believed that plasma flows moving in it make the main contribution to the formation of the solar magnetic field. The mass of the convective zone is only two percent of the mass of the Sun. At the lower boundary, the plasma density is equal to 0.2 of the density of water, and when it enters the atmosphere of the Sun, it decreases to 0.0001 of the density of the earth's air above sea level. The substance of the convective zone moves in a very complex way. Powerful but slow streams of hot plasma with a diameter of a hundred thousand kilometers rise from the depths, the speed of which does not exceed a few centimeters per second. Not so powerful jets of less heated plasma descend towards them, the speed of which is already measured in meters per second. At a depth of several thousand kilometers, the ascending high-temperature plasma is divided into giant cells, the largest of which have linear dimensions of about 30-35 thousand kilometers and are called supergranules. Closer to the surface, mesogranules with a characteristic size of about 5000 km are formed, and even closer to the surface, 3–4 times smaller granules are formed. Depending on the size of the granules, they live from a day to fractions of an hour. When these products of the collective motion of the plasma reach the surface of the Sun, they can be easily observed with a telescope with a special filter. 5

1.2. Atmosphere of the Sun The atmosphere of the Sun is called its three outer layers - the photosphere, chromosphere and corona. The corona passes into the solar wind. The layers are located above the convective zone and consist mainly (according to the number of atoms) of hydrogen, helium - 10%, carbon, nitrogen and oxygen - 0.0001%, metals, together with all other chemical elements - 0.00001%. The deepest of the outer layers is the photosphere, which is often incorrectly called the "surface of the Sun", although a gaseous spherical body cannot have a surface. We agreed to understand the radius of the Sun as the distance from the center to the layer with the minimum temperature. Photosphere [translated from Greek - “sphere of light”] is a layer of the atmosphere of a star, the apparent surface of the Sun. A continuous spectrum of optical radiation that reaches us is formed in the photosphere. The thickness of the solar photosphere is about 500 km. For the Sun, the temperature in the photosphere decreases with altitude from 8,000 - 10,0000 K to the minimum temperature on the Sun of about 43,000 K. The density of the photosphere is from 10-8 to 10-9 g/cm3 (particle concentration from 1015 to 1016 cm-3), pressure is about 0.1 atmosphere. Under such conditions, all atoms with low ionization potentials (for example, Na, K, Ca) are ionized. The remaining elements, including hydrogen, whose ionization energy is about 13.6 eV (2.18 10−18 J), remain predominantly in the neutral state, so the photosphere is the only layer on the Sun where hydrogen is almost neutral. The surface of the solar photosphere is covered with granules, the size of which is from 200 to 2000 km, the duration of their existence is from 1 to 10 minutes. The granules are the tops of the convective cells formed in the convective zone. The main source of sunlight is the lower layer of the photosphere, 150 km away. Along the layer thickness, the plasma temperature decreases from 64,000 to 44,000 K, while regions of temperature decrease to 37,000 K constantly appear, which glow more weakly and are found in the form of dark spots. Their number varies with a period of 11 years, but they never cover more than 0.5% of the solar disk. Figure 3 - A group of sunspots photographed in visible light by the HINODE-3 spacecraft, December 2006. Chromosphere [from other Greek. χρομα - color, σφαίρα - ball, sphere) - the outer shell of the Sun with a thickness of about 2000 km, surrounding the photosphere. The origin of the name of this part of the solar atmosphere is associated with its reddish color, caused by the fact that the red H-alpha hydrogen emission line from the Balmer series dominates in the visible spectrum of the chromosphere. The upper boundary of the chromosphere does not have a pronounced smooth surface; hot ejecta, called spicules, constantly originate from it. 6

The spicule is the main element of the fine structure of the solar chromosphere. If the limb of the Sun is observed in the light of a certain and strictly constant frequency, then the spicules will be seen as columns of luminous gas, quite thin on solar scales with a diameter of about 1000 km. These columns first rise from the lower chromosphere by 5000-10000 km, and then fall back, where they fade. All this happens at a speed of about 20,000 m/s. Spicula lives 5-10 minutes. The number of spicules simultaneously existing on the Sun exceeds tens of thousands and can reach up to a million. The chromospheric network practically consists of them. The temperature of the chromosphere increases with altitude from 40,000 K to 20,000 K. The density of the chromosphere is low, so the brightness is insufficient for observation under normal conditions. But during a total solar eclipse, when the Moon covers the bright photosphere, the chromosphere located above it becomes visible and glows red. It can also be observed at any time using special narrow-band optical filters. In addition to the already mentioned H-alpha line with a wavelength of 656.3 nm, the filter can also be tuned to the Ca II K (393.4 nm) and Ca II H (396.8 nm) lines. The main chromospheric structures that are visible in these lines are: the chromospheric grid covering the entire surface of the Sun and consisting of lines surrounding cells of supergranules up to 30,000 km across; flocculi are light cloud-like formations, most often associated with areas with strong magnetic fields - active regions surrounding sunspots; fibers and filaments (fibrils) are dark lines of various widths and lengths, as are flocculi, which are often found in active areas. Figure 4 - Solar eclipse August 11, 1999. The chromosphere is visible as a thin red stripe around the disk, the corona as an area. The corona is the last outer shell of the sun. The corona mainly consists of prominences and energetic eruptions, erupting and erupting several hundred and even more than a million kilometers into space, forming the solar wind. The average temperature of the corona is from 1,000,0000 K to 2,000,0000 K, and the maximum, in some areas, is from 8,000,0000 K to 20,000,0000 K. Despite such a high temperature, it is visible to the naked eye only in the time of a total solar eclipse, since the density of matter in the corona is low, and therefore the brightness is also low. The shape of the corona changes depending on the phase of the solar activity cycle: during periods of maximum activity, it has a rounded shape, and at minimum, it is elongated along the solar equator. Since the temperature of the corona is very high, it radiates intensely in the ultraviolet and X-ray ranges. These radiations do not pass through the earth's atmosphere, but are studied using spacecraft. Radiation in different regions of the corona occurs unevenly. 7

There are hot active and quiet regions, as well as corona holes with a relatively low temperature of 600,000 K, from which magnetic field lines emerge into space. Such an “open” magnetic configuration allows particles to leave the Sun unhindered, so the solar wind is emitted mainly from coronal holes. The visible spectrum of the solar corona consists of three distinct components called the L, K, and F components (or, respectively, the L-corona, K-corona, and F-corona; another name for the L-component is the E-corona). The K-component is the continuous spectrum of the corona. Against its background, up to a height of 9-10' from the visible edge of the Sun, the emission L-component is visible. Starting from a height of about 3" (the angular diameter of the Sun is about 30") and higher, the Fraunhofer spectrum is visible, the same as the spectrum of the photosphere. It makes up the F component of the solar corona. At a height of 20" the F component dominates in the spectrum of the corona. A height of 9"-10" is taken as the boundary separating the inner corona from the outer corona. The solar wind flows out from the outer part of the solar corona and is a stream of ionized particles (mainly protons, electrons and α-particles), propagating with a gradual decrease in its density, to the boundaries of the heliosphere. The solar wind is divided into two components - the slow solar wind and the fast solar wind. The slow solar wind has a speed of about 400 km/s and a temperature of 1.4 10 6 - 1.6 106 0K and closely corresponds in composition to the corona Fast solar wind has a speed of about 750 km/s, temperature 8 105 0K, and is similar in composition to the matter of the photosphere Slow solar wind is twice as dense and less constant than the fast one.The slow solar wind has a more complex structure with regions of turbulence.On average, the Sun radiates about 1.3 1036 particles per second with the wind. The mass loss by the Sun for this type of radiation is 2-3·10−14 solar mass per year. This is equivalent to the loss of a mass equal to the Earth's in 150 million years. Many natural phenomena on Earth are associated with disturbances due to the solar wind, including geomagnetic storms and auroras. 2. Spectrum of electromagnetic radiation from the Sun The Sun generates and releases into outer space two main energy flows - electromagnetic radiation (solar radiation, radiant energy) and corpuscular radiation (solar wind). The radiation emanating from the central region of the Sun, as it moves to the outer spheres, is rebuilt from short-wave to long-wave. If gamma radiation and X-rays are present in the center, then ultraviolet rays predominate in the middle layers of the solar globe, and in the radiating surface of the Sun - the photosphere - they are already transformed into waves of the light range of radiation. The spectrum of the radiant energy of the Sun at the upper boundary of the Earth's atmosphere is a distribution with a single maximum, which is quite well described by the model of the radiation spectrum of a black body at a temperature of about 60,000 K. The distribution of energy over the spectrum is uneven. The entire short-wavelength part of the spectrum - gamma rays, x-rays and ultraviolet rays - accounts for only 7% of the energy of solar radiation, the optical range of the spectrum - 48% of the energy of solar radiation. It is precisely in the optical range that the emission maximum corresponds to the blue-green range of the light emission range. Remaining 45% energy 8

solar radiation is contained mainly in the infrared range, and only a small part is accounted for by radio emission. An absolutely black body is a body that absorbs 100% of any radiation that falls on it (the absorption coefficient is 1, the reflection coefficient is 0). This refers not only to visible light, but also to radio waves, ultraviolet, X-rays, and so on. If an absolutely black body is heated, then it will begin to radiate electromagnetic waves in the entire range from radio waves to gamma radiation. Moreover, it radiates in the entire spectrum of electromagnetic radiation, but not uniformly. The spectral density has a peak. The stronger the heating, the greater the shift towards high frequencies. Absolutely black bodies do not exist in nature - this is a mathematical model. The radiation spectrum of stars is closest to the radiation spectrum of an absolutely black body. Therefore, cold stars are red and hot stars are blue. The radiation from the sun comes from different layers. The temperature range is 5712–58120 K, for which the wavelength range is 0.499–0.5077 µm (border of blue and green). The average value is 57850 K, the wavelength is 0.5012 µm. The spectral distribution of blackbody radiation is described by Planck's law: . (1) This formula is usually written as: . (2) Here is the spectral density of radiation, W cm-2 μm-1; λ is the wavelength, µm; h is Planck's constant (6.6256±0.0005) 10-34 W s2; T is absolute temperature, 0K; s is the speed of light (2.997925 ± 0.000003) 1010 cm s-1; = (3.7415 ± 0.0003) 104 W cm-2 μm4; = (1.43879 ± 0.00019) 104 µm 0K; k is the Boltzmann constant (1.38054 ± 0.00018) 10-23 W s 0K-1. The total flow of energy radiated by a blackbody is determined by the Stefan-Boltzmann law (an integral of the Planck equation): ∫ (3) where σ = (5.6697 ± 0.0029) 10-12 W cm-2 0K-4. Thus, the total radiation of a blackbody increases in proportion to the fourth power of temperature. By differentiating the Planck equation, we obtain the Wien displacement law: (4) where λmax is the wavelength at which the maximum distribution of the spectral density of radiation over wavelengths is observed; a = 2897.8 ± 0.4 μm 0K. 9

The radiant energy of the Sun is the main source of energy for the Earth. The radiation from the stars and the Moon is negligible compared to the solar radiation and does not make a significant contribution to the processes on the Earth. Also negligibly small is the flow of energy, which is directed to the surface of the Earth from the depths of the planet. The amount of energy coming from the Sun to the Earth is determined by an integral parameter that depends very little on time and is called the solar constant. The solar constant S0 is the amount of solar energy coming per unit of time to a unit area perpendicular to the sun's rays at the average distance of the Earth from the Sun. According to the latest data, its value is 1366±1 W m-2. The distribution of electromagnetic radiation emitted by the Sun and arriving at the upper boundary of the Earth's atmosphere, depending on the wavelength λ, is called the spectrum of the Sun. It is convenient to add to the definition of the spectrum of the Sun the requirements from the definition of the solar constant as the incoming solar energy per unit time per unit area, at a certain frequency, perpendicular to the rays, at an average distance from the Earth to the Sun. This quantity is often called the spectral solar constant S0(λ). Then for the solar constant, introduced earlier, the definition is refined by the term – integral solar constant. The standard spectrum of the Sun with a "coarse spectral resolution" and the spectrum of a black body at T = 57850 K are shown in Figure 5. Figure 5 - The standard spectrum of the Sun with a coarse spectral resolution and the spectrum of a black body, T = 57850 K. UV, VD , IR, Microwaves - ultraviolet, visible, infrared and microwave radiation. If we consider the spectrum of the Sun at high spectral resolution, then the picture is not so smooth, but has many Fraunhofer lines due to the absorption of various elements in the photosphere and chromosphere. It can be seen from the figure that the Planck function at T = 57850 K approximates well the spectrum of the Sun in its middle part – the wavelength range from 0.2 μm to 1 cm. This is due to the fact that the formation of outgoing solar radiation in different spectral regions occurs at different altitudes at different temperatures. ten

The short-wave part of the spectrum is the most detrimental to life on Earth and includes: gamma radiation (gamma rays, γ-rays) - a type of electromagnetic radiation with an extremely short wavelength - less than 5 10 6 1019 Hz), pronounced corpuscular and weakly expressed wave properties. Source - nuclear and space processes, radioactive decay; x-ray radiation - electromagnetic waves, whose photon energy lies on the scale of electromagnetic waves between ultraviolet and gamma radiation, which corresponds to wavelengths from 5·10−3 nm to 10 nm and frequencies of 3·1016 - 6·1019 Hz. Source - atomic processes under the influence of accelerated charged particles; ultraviolet radiation - radiation of atoms under the influence of accelerated electrons. Of the 7% of short-wavelength solar radiation, the largest part is ultraviolet radiation, which is strongly absorbed by the Earth's atmosphere. The absorption spectrum of ozone has a peak approximately at a wavelength of 250 nm, oxygen has two peaks - 110 and 200 nm. The short-wave range of ultraviolet absorption is overlapped by oxygen, in the middle range - by ozone. At an electromagnetic wavelength of 250 nm, ozone absorbs almost all radiation, at 300 nm - 97%. The ultraviolet part of the spectrum occupies the range between the violet border of visible radiation and X-rays. In 1801, the German physicist Johann Wilhelm Ritter discovered that silver chloride, which decomposes under the action of light, decomposes most rapidly under the action of invisible radiation outside the violet region of the spectrum. Then many scientists, including Ritter, came to the agreement that light consists of three separate components: an oxidizing or thermal (infrared) component, an illuminating component (visible light), and a reducing (ultraviolet) component. At that time, ultraviolet radiation was also called actinic radiation, after the ability to act on specific light-sensitive materials in a prescribed manner. In accordance with the ISO-DIS-2134 standard, the characteristics of ultraviolet solar radiation are introduced, Table 1. The UV-A, UV-B, UV-C ranges presented in the table are introduced by biologists as the most important in their work. Table 1 - Characteristics of ultraviolet solar radiation Amount of energy Name Abbreviation Wavelength, nm per photon, eV Near NUV 400 nm - 300 nm 3.10 - 4.13 eV Medium MUV 300 nm - 200 nm 4.13 - 6.20 eV Far FUV 200 nm - 122 nm 6.20 - 10.2 eV Extreme EUV, XUV 121 nm - 10 nm 10.2 - 124 eV Ultraviolet A, long wavelength UVA, UVA 400 nm - 315 nm 3.10 - 3.94 eV range Ultraviolet B, mid wavelength UVB, UVB 315 nm - 280 nm 3.94 - 4.43 eV range Ultraviolet C, shortwave UV-C, UVC 280 nm - 100 nm 4.43 - 12.4 eV range 11

The near ultraviolet range is often referred to as "black light" because it is not recognizable by the human eye, but when reflected from some materials, the spectrum goes into the visible radiation region. The term "vacuum" (VUV) is often used for the far and extreme range, due to the fact that waves in this range are strongly absorbed by the Earth's atmosphere. Most of the UV-A radiation is not absorbed by atmospheric oxygen and ozone and reaches the Earth's surface. UV-B ultraviolet radiation is absorbed by ozone and how much of it reaches the surface depends on the amount of ozone in the Earth's atmosphere. Ultraviolet radiation UV-C is absorbed by ozone and atmospheric oxygen, and a very small part of this radiation reaches the Earth's surface. Ultraviolet can be very harmful to human health, so in 1994 the World Meteorological Organization, together with the World Health Organization, proposed the introduction of a solar ultraviolet index - UV index, W/m2. The visible part of the spectrum (visible light, or simply light) perceived by the human eye occupies the wavelength range from 380 nm (violet) to 780 nm (red), or the frequency range from 400 to 790 terahertz (1 THz = 1012 Hz). The human eye has the highest sensitivity to light in the region of 555 nm (540 THz) - the green part of the spectrum. Although the phenomenon of the rainbow was explained by the refraction of sunlight in raindrops back in 1267 by Roger Bacon, only Newton was able to analyze the light. Having refracted a beam of light through a prism, he first counted five colors: red, yellow, green, blue, violet. Then he added two more colors and became the father of the seven-color rainbow. It should be noted that the question of “colors of the rainbow” is not from the sphere of physics and biology. They should be dealt with by linguists and philologists. There are seven colors in the rainbow of the Slavic peoples only because there is a separate name for the color blue (compared to the British) and green (compared to the Japanese). From the point of view of modern biology, physiologically, a person sees three colors in a rainbow: red, green, blue. Therefore, the question practically does not make sense, and the ranges of visible color can be designated with whatever colors are convenient. The first explanations of the spectrum of visible radiation were given by Isaac Newton in Optics and by Johann Goethe in The Theory of Colors. Newton discovered the dispersion of light in prisms and was the first to use the word spectrum [from lat. spectrum - vision, appearance] in print in 1671. He made the observation that when a beam of light hits the surface of a glass prism at an angle to the surface, some of the light is reflected and some passes through the glass, forming bands of different colors. Figure 6 - Newton's circle of colors from Optics (1704), showing the relationship between colors and musical notes. The colors of the spectrum from "red" to "violet" are separated by notes, starting with the note "re" (D). The circle makes up a full octave. 12

When splitting the beam white color A spectrum is formed in a prism in which radiation of different wavelengths is refracted at different angles. The colors included in the spectrum, that is, those colors that can be obtained by light waves of one wavelength (or a very narrow range), are called spectral colors. The main spectral colors of visible light have their own names, and their characteristics are presented in the table. Table 2 - Characteristics of visible light Range Length range Range Color wave energy, nm frequencies, THz photons, eV Violet 380 - 440 790 - 680 2.82 - 3.26 Blue 440 - 485 680 - 620 2.56 - 2.82 Light blue 485 - 500 620 - 600 2.48 - 2.56 Green 500 - 565 600 - 530 2.19 - 2.48 Yellow 565 - 590 530 - 510 2.10 - 2.19 Orange 590 - 625 510 - 480 1, 98 - 2.10 Red 625 - 740 480 - 400 1.68 - 1.9 Visible radiation enters the "optical window" and is practically not absorbed by the earth's atmosphere. Clean air scatters blue light a little more than longer wavelengths (toward the red end of the spectrum), so the midday sky looks blue. The infrared part of the electromagnetic spectrum occupies the range between the red end of the visible spectrum with a wavelength of 0.74 µm and the beginning of the microwave radiation with a wavelength of 1 mm. Recently, the long-wave edge of this part of the spectrum has been isolated into a separate, independent range of electromagnetic waves - terahertz radiation with a wavelength of 3-0.03 mm (1011-1013 Hz), or submillimeter radiation with a wavelength of 1-0.1 mm. Infrared radiation is also called "thermal" radiation, since infrared radiation from heated objects is perceived by the human skin as a sensation of warmth. In this case, the wavelengths emitted by bodies depend on the heating temperature: the higher the temperature, the shorter the wavelength and the higher the radiation intensity. Infrared radiation was discovered in 1800 by the English astronomer William Herschel, who discovered that in the spectrum of the Sun obtained with a prism beyond the red color boundary (in the invisible part of the spectrum), the temperature of the thermometer rises. In the 19th century it was proved that infrared radiation obeys the laws of optics and is of the same nature as visible light. Now the entire range of infrared radiation is divided into three sub-ranges: short-wave 0.74 - 2.5 microns; medium wave 2.5 - 50 microns; longwave 50 - 2000 microns. In the short-wavelength subrange, infrared radiation is scattered almost in the same way as in the visible range, and the main source of this radiation is the Sun. In the middle subrange, most of the radiation is absorbed by the components of the atmosphere 13

(water vapor, carbon dioxide). In the far subrange, less energy is dissipated in the atmosphere, and the main source of radiation is the Earth's surface. Table 3 - Characteristics of infrared radiation Color Wavelength range Frequency range Short wave IR-A 740 nm - 2.5 µm 400 THz - 120 THz Medium wave IR-B 2.5 µm - 50 µm 120 THz - 6 THz Long wave IR-C 50 µm - 2 mm 6 THz - 150 GHz The considered ranges of electromagnetic radiation of the Sun are of decisive importance for life on earth. Ultraviolet radiation UV-C less than 280 nm is fatal to plants. When exposed to it, after 10-15 minutes, plant proteins lose their structure and stop the activity of the cell. Outwardly, this manifests itself in yellowing and browning of the leaves, twisting of the stems and the death of growth points. But the solar part of the hard ultraviolet does not reach the earth's surface, being delayed by the ozone layer. UV radiation of ZF-A above 315 nm is necessary for plant metabolism and growth. It delays the elongation of the stems, increases the content of vitamin C. ZF-B ultraviolet radiation (280 - 315 nm) acts like low temperatures, promotes the hardening process of plants and increases their cold resistance. Ultraviolet rays practically do not affect chlorophyll. Violet and blue rays inhibit the growth of stems, leaf petioles and blades, form compact plants and thicker leaves, allowing better absorption and use of light in general. These rays stimulate the formation of proteins, plant organosynthesis, the transition to flowering of short-day plants, and slow down the development of long-day plants. The blue and violet parts of the light spectrum are almost completely absorbed by chlorophyll, which creates conditions for the maximum intensity of photosynthesis. Green rays practically pass through the leaf blades without being absorbed by them. Under their action, the latter become very thin, and the axial organs of plants are elongated. The level of photosynthesis is the lowest. Red rays combined with orange represent the main form of energy for photosynthesis. The most important is the region of 625-680 nm, which promotes intensive growth of leaves and axial organs of plants. This light is very completely absorbed by chlorophyll and increases the formation of carbohydrates during photosynthesis. The red and orange light zones are of decisive importance for all physiological processes in plants. Scientists have established the ability of red rays (600-690 nm) of low intensity (not higher than 620 lux) to actively influence physiological processes in plants that are sensitive to light-to-darkness and vice versa (photoperiodic). Infrared rays affect plants in different ways. To infrared light up to 1100 nm weakly react, for example, tomatoes and rather strongly cucumbers. This range of light acts on the stretching of the hypocotyl genus, stems and shoots. Near radiation at low temperatures can be partially absorbed by chlorophyll and not overheat the leaf, which will be useful for photosynthesis. fourteen

Figure 7 - Influence of wavelength on the development of plants Radio waves (microwaves). The sun emits not only energy from gamma to infrared radiation, but also radio waves, which are transmitted by the Earth's atmosphere in the range of lengths from a few millimeters to tens of meters. Despite a number of early attempts to register radio waves from the Sun, they were discovered only in February 1942 as a source of interference on British radar screens during the Second World War. After its completion in 1945, the rapid development of radio astronomy, including solar astronomy, began. If the radio emission of the Sun in 1942 was associated with its activity and influence on radar, then in 1963 solar activity was already measured by the “Index F10.7” parameter, which is determined by the magnitude of the radio emission flux at a wave of 10.7 cm (frequency 2800 MHz). This index correlates well with the "Wolf Number" - named after the Swiss astronomer Rudolf Wolf, a numerical indicator of the number of spots on the Sun. It is one of the most common indicators of solar activity. Radio waves are emitted by hot, highly ionized gases in the Sun's outer atmosphere. These rarefied gases, which are practically transparent to visible light, turn out to be opaque to radio emission with certain wavelengths. The opacity increases with an increase in the concentration of free electrons and a decrease in temperature, as well as with an increase in the wavelength. The chromosphere, which has a fairly high concentration of electrons and a temperature of 5000-100000 K, is opaque for decimeter and meter waves, so only centimeter waves can leave it and reach the Earth. Meter waves can only come from the more rarefied and hot solar corona lying above with a temperature of about 1000 000 - 2000 0000 K. Since waves of different lengths come from different layers of the solar atmosphere, this makes it possible to study the properties of the chromosphere and corona by their radio emission . In the radio range, the size of the solar disk depends on the wavelength at which the observation is made. At meter wavelengths, the Sun's radius is greater than at centimeter wavelengths, and in both cases it is greater than the radius of the visible disk. Radio emission from the Sun includes thermal and non-thermal components. Thermal radio emission, caused by collisions of electrons and ions moving with thermal velocities, determines the lower limit of the radio emission intensity of the “calm” Sun. The intensity of radio emission is usually characterized by the value of the brightness temperature Tb. fifteen

Figure 8 - Dependence of the intensity of the main components of the solar radio emission (their brightness temperature) on the frequency (wavelength) Brightness temperature is a photometric value that characterizes the radiation intensity. Often used in radio astronomy. By definition, the brightness temperature is the temperature that a black body would have if it had the same intensity in a given frequency range. It should be noted that the brightness temperature is not temperature in the usual sense. It characterizes the radiation, and depending on the radiation mechanism, it can differ significantly from the physical temperature of the emitting body. For example, in pulsars it reaches 1026 0K. In the case of radiation from a “calm” Sun at centimeter waves, Tb ~ 104 0K, and at meter wavelengths Tb ~ 106 0K. Naturally, for thermal radiation, the value of Tb coincides with the kinetic temperature of the layer from which the radiation emerges, if this layer is opaque for this radiation. The concept of the level of radio emission from a “calm” Sun is an idealization, but in reality the Sun is never completely calm: turbulent processes in the solar atmosphere lead to the appearance of local regions, the radio emission of which greatly increases the observed intensity compared to the level “ calm" Sun. The formation of activity centers (flares and spots) on the surface of the Sun is accompanied by the appearance of coronal condensations above them, dense and hot, as if covering the active region. Directly above the spots, the hot corona descends, as it were, to altitudes of 2–3 thousand km, where the magnetic field strength is about 1000 Oe. radiation). Such radiation causes the appearance of bright radio spots above the active regions, which appear and disappear at about the same time as the visible spots. Since the spots change slowly (days and weeks), the radio emission from coronal condensations changes just as slowly. Therefore, it is called the slowly varying component. This component manifests itself mainly in the wavelength range from 2 to 50 cm. Basically, it is also thermal, since the radiating electrons have a thermal distribution of velocities. However, at a certain stage of development of active 16

The regions in the space between the sunspots contain sources that apparently have a nonthermal nature. Sometimes in the region of condensations, sudden amplifications of radio emission at the same wavelengths are observed - centimeter bursts. Their duration varies from several minutes to tens of minutes or even hours. Such radio bursts are associated with rapid plasma heating and particle acceleration in the solar flare region. An increase in the temperature and density of the gas in condensation can be the reason for the generation of centimeter bursts with Tb of 107–108 K. More intense bursts at centimeter wavelengths are apparently due to cyclotron or plasma radiation of subrelativistic electrons with energies from tens to hundreds of keV in flare magnetic loops . Even higher above the coronal condensations, enhanced radio emission is also observed, but already at meter wavelengths of about 1.5 meters - the so-called noise storms; they can be observed for hours and even days. There are many bursts with a duration of about 1 second (type I radio bursts) in narrow frequency intervals. This radio emission is associated with plasma turbulence, which is excited in the corona above developing active regions containing large spots. Ejections of fast electrons and other charged particles from the region of a chromospheric flare cause a number of effects in the radio emission of the active Sun. The most common of them are type III radio bursts. Their characteristic feature is that the frequency of radio emission changes with time, and at each moment of time it appears at once at two frequencies (harmonics), related as 2:1. The burst starts at a frequency of about 500 MHz (λ ~ 60 cm), and then the frequency of both its harmonics decreases rapidly, by about 20 MHz per second. The entire burst lasts about 10 seconds. Type III radio bursts are created by a stream of particles ejected by a flare and moving through the corona. The flow excites plasma oscillations (plasma waves) at a frequency that is determined by the electron density at the point in the corona where the flow is currently located. And since the electron density decreases with distance from the surface of the Sun, the motion of the flow is accompanied by a gradual decrease in the frequency of plasma waves. Part of the energy of these waves can be converted into electromagnetic waves with the same or twice the frequency, which are registered on Earth in the form of type III radio bursts with two harmonics. As spacecraft observations have shown, electron flows propagating in interplanetary space generate type III radio bursts up to frequencies of 30 kHz. Following type III radio bursts, radio emission is observed in 10% of cases in a wide frequency range with a maximum intensity at a frequency of ~ 100 MHz (λ ~ 3 m). This radiation is called type V radio bursts, bursts last about 1-3 minutes. Apparently, they are also due to the generation of plasma waves. During very strong flares on the Sun, type II radio bursts occur, also with a varying frequency. Their duration is approximately 5-30 minutes, and the frequency range is 200-30 MHz. The burst is generated by a shock wave moving at a speed v ~ 108 cm/s, which arises as a result of gas expansion during a strong flare. Plasma waves are formed at the front of this wave. Then they, just as in the case of type III radio bursts, partially transform into electromagnetic waves. The similarity of radio bursts of types II and III is also emphasized by the fact that bursts are characterized by emission at two harmonics. When propagating in interplanetary space, the flare shock wave continues to generate a type II radio burst at hectometric and kilometer wavelengths. When a strong shock wave reaches the upper part of the corona, a continuous radio emission appears in a wide frequency range - type IV radio emission. It is similar to type V radio bursts, but differs from the latter in a longer duration (sometimes up to several hours). Type IV radio emission is generated by subrelativistic electrons in dense plasma clouds with their own magnetic field, which are carried out 17

in the upper layers of the crown. Type IV radio emission sources usually rise in the corona at a speed of several hundred km/s and can be traced up to heights of 5 solar radii above the photosphere. Flares, which are associated with intense centimeter bursts and type II and IV radio emission at meter wavelengths, are often accompanied by geophysical effects: an increase in the intensity of proton fluxes in near-Earth outer space, the termination of short-wave radio communications through the polar regions, and geomagnetic storms, etc. Radio emission in a wide range of frequencies can be used for short-term prediction of these effects. Almost all of these types of bursts have various fine structures. The listed types of bursts do not limit the radio emission of the Sun, however, the components described above are the main ones. In accordance with the regulations of the International Telecommunication Union (ITU), radio waves are divided into ranges from 0.3·10N Hz to 3·10N Hz, where N is the range number. Russian GOST 24375-80 almost completely repeats this classification. It should be noted that this classification is not widely used. The radio emission of the Sun corresponds to bands 8-11, which are widely used in the practice of television and radio broadcasting, radio communications, navigation, personal communications, location, etc. It should be noted that this classification is not widely used. Table 4 - Classification of radio waves according to the ITU regulations and GOST 24375-80 Range N - Range Range Name Range Name designation of wavelengths of energy of frequencies of frequencies of ITU photon waves 1 - ELF 10 - 100 Mm Decamegameter 3 - 30 Hz Extremely low (ELF) 12.4 - 124 fev 2 - SLF 1 - 10 Mm Megameter 30 - 300 Hz Ultra low (ELF) 124 fev - 1.24 pV 3 - ULF 100 - 1000 km Hectokilometer 300 - 3000 Hz Intra low (INF) 1.24 - 12.4 peV 4 – VLF 10 - 100 km Myriameter 3 - 30 kHz Very low (VLF) 12.4 - 124 peF 5 - LF 1 - 10 km Kilometer 30 - 300 kHz Low (LF) 124 peF - 1.24 neF 6 - MF 100 - 1000 m Hectometer 300 - 3000 kHz Medium (MF) 1.24 - 12.4 neF 7 - HF 10 - 100 m Decameter 3 - 30 MHz High (HF) 12.4 - 124 neF Very high 8 - VHF 1 - 10 m Meter 30 - 300 MHz 124 neF - 1.24 µeF (VHF) 300 - 3000 Ultra High 9 - UHF 10 cm - 1 m UHF 1.24 - 12.4 µeF MHz (UHF) 10 - SHF 10 - 100 mm Centimeter 3 - 30 GHz Ultra High (UHF) 12.4 - 124 microns eF Extreme high 124 μeF - 11 - EHF 1 - 10 mm Millimeter 30 - 300 GHz (EHF) 1.24 meF 300 - 3000 12 - THF 0.1 - 1 mm Decimum Hyper-high 1.24 - 12.4 meF GHz Worldwide widely used classification, which was adopted by the IEEE. Institute of Electrical and Electronics Engineers - IEEE Institute of Electrical and Electronics Engineers] is an international non-profit association of engineering professionals. IEEE appeared in 1963 as a result of the merger of the Institute of Radio Engineering [from English. Institute of Radio Engineers, IRE], established in 1912 and the American Institute of Radio Engineering 18

electrical engineers [from English. American Institute of Electrical Engineers, AIEE], established in 1884. The main goal of the IEEE is information and material support for specialists for the organization and development scientific activity in electrical engineering, electronics, computer engineering and informatics, the application of their results for the benefit of society, as well as the professional growth of IEEE members, the dissemination of information about the latest research and developments in radio electronics and electrical engineering. Table 5 - Classification of radio waves according to IEEE Range Range Range Etymology of HF wavelength frequencies Eng. High freguency 3-30MHz 10-100M P English Previous Less than 300 MHz More than 1m VHF Eng. Very high freguency 50-330MHz 0.9-6m UHF Eng. Ultra high freguency 300-1000MHz 0.3-1m L English Long 1-2GHz 15-30cm S Eng. Short 2-4 GHz 7.5-15 cm C English Compromise 4-8GHz 3.75-7.5cm X 8-12GHz 2.5-3.75cm KU English Unter K 12-18 GHz 1.67-2.5 cm K German Kurz - short 18-27 GHz 1.11-1.67 cm KA Eng. Abode K 27-40 GHz 0.75-1.11 cm mm 40-300 GHz 0.1-7.5 cm V 40-75 GHz 0.4-7.5 mm W 75-110 GHz 0.27-0 .4 mm At first glance, the IEEE classification of radio waves is not as systematic as the ITU classification, but it is more convenient in the field of microwaves and came from practice. For example, X-band is the frequency range of centimeter wavelengths used for terrestrial and satellite radio communications. According to the IEEE definition, it extends from 8 to 12 GHz (from 3.75 to 2.5 cm), although in satellite communications it is "shifted" towards the C-band and lies approximately between 7 and 10.7 GHz. During the Second World War, the X-band was classified, and therefore received the name X-band. 19

3. Solar insolation at the upper boundary of the Earth's atmosphere The most important parameter that determines the physical conditions on the planets of the solar system is the amount of energy received from the Sun, which is characterized by the solar constant S0. For planet Earth, the change in the value of the solar constant over the past 35 years is shown in the figure. Figure 9 - Change in the value of the solar constant over the past 35 years. It follows from the figure that the value of the solar constant for the Earth is in the range of 1367±0.13 W/m² and has a change period of about 11 years. Monthly averaging is shown in red, yearly averaging is shown in black. The solar constant is determined for any planet of the solar system and is a characteristic of the amount of solar energy coming per unit of time to a unit area perpendicular to the sun's rays at the average distance of the planet from the Sun. Insolation is the flux of solar radiation incident on a single horizontal area during a given period of time (): ∫ () (4) Insolation at the upper boundary of the Earth's atmosphere determines the amount of energy coming from the Sun at different latitudes and at different times of the year . The solar energy flux at the upper boundary of the atmosphere is determined by the formula If we take into account that the distance between the Earth and the Sun changes when the Earth moves in orbit, then we can write (6) where r0 and r are the average and instantaneous distances of the Earth from the Sun. twenty

The relative change in the solar flux at the upper boundary of the Earth's atmosphere (()) for different months of the year is presented in the table. Table 6 - Relative changes in solar flux by months Month number 1 2 3 4 5 6 7 8 9 10 11 12 in year d, % 3.4 2.8 1.8 0.2 -1.5 -2.8 -3 .5 -3.1 -1.7 -0.3 1.6 1.8 It follows from the table that the Earth receives more energy from the Sun in winter than in summer. The Earth is closer to the Sun in winter than in summer and therefore receives almost 7% more energy. The total solar energy coming per day to a single site can be determined based on the expression [ ()], (7) where H is half the daylight hours, i.e. from sunrise and sunset to noon; ω - angular velocity the rotation of the earth; φ - geographical latitude; δ is the solar declination. The results of calculations of the total solar energy coming per day to a single area at the upper boundary of the atmosphere, depending on latitude and day of the year, are shown in the figure. Figure 10 - Daily sums of solar energy coming to a single site at the upper boundary of the atmosphere, depending on latitude and season (Ku-Nan Liou, Fundamentals of radiation processes in the atmosphere. L .: Gidrometeoizdat, 1984. - 376 p.) . 21

Since the Sun is closest to the Earth in January (winter in the northern hemisphere), the distribution of daily amounts of solar energy is not quite uniform. Maximum insolation takes place in the summer at the poles, which is associated with the duration of daylight hours (24 hours). The minimum number is zero at the poles during polar nights. ⃰ ⃰ ⃰ The Sun is the central body of the Solar System, it contains more than 99.86% of its entire mass and is removed from the Earth at an average distance of 149,597,870 km. By earthly standards, the luminosity of the Sun is colossal and reaches 3.85 1023 kW. Even a tiny fraction of the energy that irradiates the globe (and this is approximately one ten-billionth) is tens of thousands of times more powerful than all the power plants in the world can generate. The energy of solar rays falling on an area of ​​1 m2 perpendicular to them on Earth could make a 1.4 kW engine work, and 1 m 2 of the Sun's atmosphere radiates energy with a power of 60 mW. The spectrum of the electromagnetic radiation of the Sun is close to the spectrum of the radiation of an absolutely black body with a temperature of about 60,000 K. The daily amounts of solar energy arriving at a single area at the upper boundary of the atmosphere depend on latitude and season. The maximum insolation at the upper boundary of the atmosphere takes place in the summer at the poles, which is associated with the duration of daylight hours (24 hours), the minimum insolation occurs at both poles during the polar nights. To solve the problems of remote sensing of the Earth from space, the most important are solar electromagnetic radiation reflected from terrestrial objects in the ultraviolet, visible, and infrared parts of the spectrum. Most of the UV-A radiation is not absorbed by atmospheric oxygen and ozone and reaches the Earth's surface. UV-B ultraviolet radiation is absorbed by ozone and how much of it reaches the surface depends on the amount of ozone in the Earth's atmosphere. Ultraviolet radiation UV-C is absorbed by ozone and atmospheric oxygen, and a very small part of this radiation reaches the Earth's surface. Visible radiation enters the "optical windows" and is practically not absorbed by the earth's atmosphere. Clean air scatters blue light a little more than light with longer wavelengths, so the midday sky looks blue. Infrared radiation is also called "thermal" radiation, since infrared radiation from heated objects is perceived by the human skin as a sensation of warmth. In the short-wavelength subrange, infrared radiation is scattered almost in the same way as in the visible range, and the main source of this radiation is the Sun. In the middle subrange, most of the radiation is absorbed by the components of the atmosphere (water vapor, carbon dioxide). In the far subrange, less energy is dissipated in the atmosphere, and the main source of radiation is the Earth's surface. In addition to knowing the spectral characteristics of the solar electromagnetic radiation arriving at the upper boundary of the Earth’s atmosphere, developers of space remote sensing systems and users of space information need to know the dependence of the incoming energy of the solar electromagnetic radiation on time and the geographic latitude of the monitoring object. 22

The Earth receives from the Sun 1.36 * 10v24 cal of heat per year. Compared to this amount of energy, the remaining amount of radiant energy reaching the Earth's surface is negligible. Thus, the radiant energy of the stars is one hundred millionth of the solar energy, cosmic radiation is two billionths, the internal heat of the Earth at its surface is equal to one five thousandth of the solar heat.
Radiation of the Sun - solar radiation- is the main source of energy for almost all processes occurring in the atmosphere, hydrosphere and in the upper layers of the lithosphere.
The unit of measurement of the intensity of solar radiation is the number of calories of heat absorbed by 1 cm2 of an absolutely black surface perpendicular to the direction of the sun's rays in 1 minute (cal/cm2*min).

The flux of radiant energy from the Sun, reaching earth's atmosphere, is very stable. Its intensity is called the solar constant (Io) and is taken on average to be 1.88 kcal/cm2 min.
The value of the solar constant fluctuates depending on the distance of the Earth from the Sun and on solar activity. Its fluctuations during the year are 3.4-3.5%.
If the sun's rays everywhere fell vertically on the earth's surface, then in the absence of an atmosphere and with a solar constant of 1.88 cal / cm2 * min, each square centimeter of it would receive 1000 kcal per year. Due to the fact that the Earth is spherical, this amount is reduced by 4 times, and 1 sq. cm receives an average of 250 kcal per year.
The amount of solar radiation received by the surface depends on the angle of incidence of the rays.
The maximum amount of radiation is received by the surface perpendicular to the direction of the sun's rays, because in this case all the energy is distributed to the area with a cross section equal to the cross section of the beam of rays - a. With oblique incidence of the same beam of rays, the energy is distributed over large area(section c) and a unit of surface receives a smaller amount of it. The smaller the angle of incidence of the rays, the lower the intensity of solar radiation.
The dependence of the intensity of solar radiation on the angle of incidence of rays is expressed by the formula:

I1 = I0 * sinh,

R \u003d Q * (1-α) - I,