Total direct scattered absorbed solar radiation. See what “solar radiation” is in other dictionaries

Solar radiation (solar radiation) is the totality of solar matter and energy entering the Earth. Solar radiation consists of the following two main parts: first, thermal and light radiation, which is a combination of electromagnetic waves; secondly, corpuscular radiation.

On the Sun, the thermal energy of nuclear reactions turns into radiant energy. When the sun's rays fall on the earth's surface, radiant energy is again converted into thermal energy. Solar radiation thus carries light and heat.

Solar radiation intensity. Solar constant. Solar radiation is the most important source of heat for the geographic envelope. The second source of heat for the geographic shell is the heat coming from the inner spheres and layers of our planet.

Due to the fact that in the geographical shell there is one type of energy ( radiant energy ) equivalently goes into another form ( thermal energy ), then the radiant energy of solar radiation can be expressed in units of thermal energy - joules (J).

The intensity of solar radiation must be measured primarily outside the atmosphere, since when passing through the air sphere it is transformed and weakened. The intensity of solar radiation is expressed by the solar constant.

Solar constant - this is the flow of solar energy in 1 minute onto an area with a cross-section of 1 cm 2, perpendicular to the sun’s rays and located outside the atmosphere. The solar constant can also be defined as the amount of heat that is received in 1 minute at the upper boundary of the atmosphere by 1 cm 2 of a black surface perpendicular to the sun's rays.

The solar constant is 1.98 cal/(cm 2 x min), or 1,352 kW/m 2 x min.

Since the upper atmosphere absorbs a significant portion of radiation, it is important to know its magnitude at the upper boundary of the geographic envelope, i.e., in the lower stratosphere. Solar radiation at the upper boundary of the geographic envelope is expressed conventional solar constant . The value of the conventional solar constant is 1.90 - 1.92 cal / (cm 2 x min), or 1.32 - 1.34 kW / (m 2 x min).

The solar constant, contrary to its name, does not remain constant. It changes due to changes in the distance from the Sun to the Earth as the Earth moves along its orbit. No matter how small these fluctuations are, they always affect the weather and climate.

On average, each square kilometer of the troposphere receives 10.8 x 10 15 J (2.6 x 10 15 cal) per year. This amount of heat can be obtained by burning 400,000 tons of coal. The entire Earth receives an amount of heat per year that is determined by the value 5.74 x 10 24 J. (1.37 x 10 24 cal).

Distribution of solar radiation “at the upper boundary of the atmosphere” or with an absolutely transparent atmosphere. Knowledge of the distribution of solar radiation before it enters the atmosphere, or the so-called solar (sunny) climate , is important for determining the role and share of participation of the Earth’s air shell itself (atmosphere) in the distribution of heat over the earth’s surface and in the formation of its thermal regime.

The amount of solar heat and light received per unit area is determined, firstly, by the angle of incidence of the rays, depending on the height of the Sun above the horizon, and secondly, by the length of the day.

The distribution of radiation at the upper boundary of the geographic envelope, determined only by astronomical factors, is more uniform than its actual distribution at the earth's surface.

In the absence of an atmosphere, the annual amount of radiation at equatorial latitudes would be 13,480 MJ/cm2 (322 kcal/cm2), and at the poles 5,560 MJ/m2 (133 kcal/cm2). To the polar latitudes, the Sun sends heat slightly less than half (about 42%) of the amount that arrives at the equator.

It would seem that the solar irradiation of the Earth is symmetrical relative to the equatorial plane. But this happens only twice a year, on the days of the spring and autumn equinox. The tilt of the rotation axis and the annual motion of the Earth determine its asymmetric irradiation by the Sun. In the January part of the year, the southern hemisphere receives more heat, and in the July part, the northern hemisphere receives more heat. This is precisely the main reason for the seasonal rhythm in the geographical envelope.

The difference between the equator and the pole of the summer hemisphere is small: the equator receives 6,740 MJ/m2 (161 kcal/cm2), and the pole receives about 5,560 MJ/m2 (133 kcal/cm2 per half-year). But the polar countries of the winter hemisphere at the same time are completely deprived of solar heat and light.

On the day of the solstice, the pole receives even more heat than the equator - 46.0 MJ/m2 (1.1 kcal/cm2) and 33.9 MJ/m2 (0.81 kcal/cm2).

In general, the annual solar climate at the poles is 2.4 times colder than at the equator. However, we must keep in mind that in winter the poles are not heated by the Sun at all.

The actual climate of all latitudes is largely due to terrestrial factors. The most important of these factors are: firstly, the weakening of radiation in the atmosphere, and secondly, the different intensity of absorption of solar radiation by the earth’s surface in different geographical conditions.

Changes in solar radiation as it passes through the atmosphere. Direct sunlight penetrating the atmosphere under a cloudless sky is called direct solar radiation . Its maximum value with high transparency of the atmosphere on a surface perpendicular to the rays in the tropical zone is about 1.05 - 1.19 kW/m 2 (1.5 - 1.7 cal/cm 2 x min. In mid-latitudes, the voltage of midday radiation is usually about 0.70 - 0.98 kW / m 2 x min (1.0 - 1.4 cal/cm 2 x min).In the mountains, this value increases significantly.

Some of the sun's rays from contact with gas molecules and aerosols are scattered and become scattered radiation . Scattered radiation no longer comes to the earth's surface from the solar disk, but from the entire sky and creates widespread daylight. It makes it light on sunny days and where direct rays do not penetrate, for example under the forest canopy. Along with direct radiation, diffuse radiation also serves as a source of heat and light.

The more intense the direct line, the greater the absolute value of scattered radiation. The relative importance of scattered radiation increases with the decreasing role of direct radiation: in mid-latitudes in summer it makes up 41%, and in winter 73% of the total radiation arrival. The share of scattered radiation in the total amount of total radiation also depends on the height of the Sun. At high latitudes, scattered radiation accounts for about 30%, and at polar latitudes it accounts for approximately 70% of all radiation.

In general, scattered radiation accounts for about 25% of the total flux of solar rays arriving on our planet.

Thus, direct and diffuse radiation reaches the earth's surface. Together, direct and scattered radiation form total radiation , which determines thermal regime of the troposphere .

By absorbing and scattering radiation, the atmosphere significantly weakens it. Attenuation amount depends on transparency coefficient, showing what proportion of radiation reaches the earth's surface. If the troposphere consisted only of gases, then the transparency coefficient would be equal to 0.9, i.e., it would transmit about 90% of the radiation reaching the Earth. However, aerosols are always present in the air, reducing the transparency coefficient to 0.7 - 0.8. The transparency of the atmosphere changes with the weather.

Since the density of air decreases with height, the layer of gas penetrated by the rays should not be expressed in km of atmospheric thickness. The unit of measurement adopted is optical mass, equal to the thickness of the air layer with vertical incidence of rays.

The weakening of radiation in the troposphere is easy to observe during the day. When the Sun is near the horizon, its rays penetrate several optical masses. At the same time, their intensity weakens so much that one can look at the Sun with an unprotected eye. As the Sun rises, the number of optical masses that its rays pass through decreases, which leads to an increase in radiation.

The degree of attenuation of solar radiation in the atmosphere is expressed Lambert's formula :

I i = I 0 p m , where

I i – radiation reaching the earth’s surface,

I 0 – solar constant,

p – transparency coefficient,

m is the number of optical masses.

Solar radiation at the earth's surface. The amount of radiant energy per unit of the earth's surface depends, first of all, on the angle of incidence of the sun's rays. Equal areas at the equator and in the middle and high latitudes receive different amounts of radiation.

Solar insolation (lighting) is greatly reduced cloudiness. Large clouds at equatorial and temperate latitudes and low clouds at tropical latitudes make significant adjustments to the zonal distribution of solar radiant energy.

The distribution of solar heat over the earth's surface is depicted on maps of total solar radiation. As these maps show, tropical latitudes receive the greatest amount of solar heat - from 7,530 to 9,200 MJ/m2 (180-220 kcal/cm2). Equatorial latitudes, due to heavy cloudiness, receive slightly less heat: 4,185 – 5,860 MJ/m2 (100-140 kcal/cm2).

From tropical to temperate latitudes, radiation decreases. On the Arctic islands it is no more than 2,510 MJ/m2 (60 kcal/cm2) per year. The distribution of radiation over the earth's surface has a zonal-regional character. Each zone is divided into separate areas (regions), slightly different from each other.

Seasonal fluctuations in total radiation.

In equatorial and tropical latitudes, the height of the Sun and the angle of incidence of solar rays vary slightly from month to month. The total radiation in all months is characterized by large values, the seasonal change in thermal conditions is either absent or very insignificant. In the equatorial belt, two maxima are faintly visible, corresponding to the zenithal position of the Sun.

In the temperate zone In the annual course of radiation, the summer maximum is clearly pronounced, in which the monthly value of the total radiation is not less than the tropical one. The number of warm months decreases with latitude.

In the polar zones the radiation regime changes dramatically. Here, depending on the latitude, from several days to several months, not only heating, but also lighting stops. In summer, the lighting here is continuous, which significantly increases the amount of monthly radiation.

Assimilation of radiation by the earth's surface. Albedo. The total radiation that reaches the earth's surface is partially absorbed by soil and water bodies and turns into heat. On the oceans and seas, the total radiation is spent on evaporation. Part of the total radiation is reflected into the atmosphere ( reflected radiation).

If the atmosphere transmitted all the sun's rays to the surface of the earth, then the climate of any point on Earth would depend only on geographic latitude. This is what they believed in ancient times. However, when the sun's rays pass through the earth's atmosphere, as we have already seen, they are weakened due to the simultaneous processes of absorption and scattering. Water droplets and ice crystals that make up clouds absorb and scatter especially a lot.

That part of solar radiation that reaches the surface of the earth after being scattered by the atmosphere and clouds is called scattered radiation. That portion of solar radiation that passes through the atmosphere without being dissipated is calleddirect radiation.

Radiation is scattered not only by clouds, but also in clear skies by molecules, gases and dust particles. The ratio between direct and scattered radiation varies widely. If, with a clear sky and vertical incidence of sunlight, the proportion of scattered radiation is 0.1% of direct radiation, then

Under cloudy skies, scattered radiation may be greater than direct radiation.

In parts of the earth where clear weather prevails, such as Central Asia, the main source of heating of the earth's surface is direct solar radiation. Where cloudy weather predominates, as, for example, in the north and north-west of the European territory of the USSR, diffuse solar radiation becomes significant. Tikhaya Bay, located in the north, receives scattered radiation almost one and a half times more than direct radiation (Table 5). In Tashkent, on the contrary, diffuse radiation is less than 1/3 of direct radiation. Direct solar radiation in Yakutsk is greater than in Leningrad. This is explained by the fact that in Leningrad there are more cloudy days and less air transparency.

Albedo of the earth's surface. The earth's surface has the ability to reflect rays falling on it. The amount of absorbed and reflected radiation depends on the properties of the earth's surface. The ratio of the amount of radiant energy reflected from the surface of a body to the amount of incident radiant energy is called albedo. Albedo characterizes the reflectivity of the surface of a body. When, for example, they say that the albedo of freshly fallen snow is 80-85%, this means that 80-85% of all radiation falling on the snow surface is reflected from it.

The albedo of snow and ice depends on their purity. In industrial cities, due to the deposition of various impurities, mainly soot, on the snow, the albedo is less. On the contrary, in the Arctic regions the snow albedo sometimes reaches 94%. Since the albedo of snow is the highest compared to the albedo of other types of earth's surface, the warming of the earth's surface occurs weakly when there is snow cover. The albedo of grass vegetation and sand is much lower. The albedo of grass vegetation is 26%, and that of sand is 30%. This means that grass absorbs 74% of solar energy, and sand - 70%. The absorbed radiation is used for evaporation, plant growth and heating.

Water has the greatest absorption capacity. Seas and oceans absorb about 95% of the solar energy arriving at their surface, i.e., the albedo of water is 5% (Fig. 9). True, the albedo of water depends on the angle of incidence of sunlight (V.V. Shuleikin). When the rays fall vertically, only 2% of the radiation is reflected from the surface of clear water, and when the sun is low, almost all of it is reflected.

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

General overview

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

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

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

About terms

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

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

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

How and what?

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

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

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

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

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

How about more details?

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

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

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

Infrared waves

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

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

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

This is interesting

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

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

Visible light

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

refraction;
reflection;
absorption.

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

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

Ultraviolet

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

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

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

but on the other hand

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

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

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

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

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

How to tan correctly?

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

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

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

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

If possible, you should avoid tanning in old age, during the period of bearing a baby. Cancer diseases, mental disorders, skin pathologies and insufficient functioning of the heart are not combined with sunbathing.

Total radiation: where is the shortage?

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

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

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

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

Total radiation: important aspects

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

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

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

Curious to know

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

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

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

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

Radiation in space

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

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

Radiation arriving at the upper boundary of the atmosphere and then to the earth's surface directly from the Sun (from the solar disk) in the form of a beam of parallel rays is called direct solar radiation. Direct solar radiation arriving at the upper boundary of the atmosphere varies over time within small limits, therefore it is called the solar constant (Sq). With an average distance from the Earth to the Sun of 149.5 * 106 km, Sq is about 1400 W/m2.

When the flow of direct solar radiation passes through the atmosphere, it weakens due to the absorption (about 15%) and dissipation (about 25%) of energy by gases, aerosols, and clouds.

According to Bouguer's law of attenuation, direct solar radiation arriving at the Earth's surface with a vertical (perpendicular) incidence of rays,

where p is the atmospheric transparency coefficient; t is the number of optical masses of the atmosphere.

The weakening of the solar flux in the atmosphere depends on the height of the Sun above the Earth's horizon and the transparency of the atmosphere. The lower its height above the horizon, the greater the number of optical masses of the atmosphere that the sun's ray passes through. One optical mass of the atmosphere is taken to be the mass that the rays pass when the Sun is at its zenith (Fig. 2.1). When the Sun is at the horizon, the beam travels a path through the atmosphere that is almost 35 times greater than when the rays fall at an angle of 90° to the Earth's surface. The number of optical masses of the atmosphere (m) at various solar altitudes (Af) is given below.

t 1.0 1.0 1.1 1.2 1.3 1.6 2.0 2.9 5.6 10.4 26.0 34.4 L0 90 80 70 60 50 40 30 20 10 5 1 0

The further the sun's rays travel through the atmosphere, the stronger their absorption and scattering and the more their intensity changes.

The transparency coefficient depends on the content of water vapor and aerosols in the atmosphere: the more of them, the lower the transparency coefficient with the same number of optical masses passed through. On average, for the entire radiation flux in an ideally clean atmosphere, p at sea level is about 0.9, in actual atmospheric conditions - 0.70...0.85, in winter it is slightly higher than in summer. The arrival of direct radiation on the earth's surface depends on the angle of incidence of the sun's rays. The flow of direct solar radiation incident on a horizontal surface is called insolation."

S" = Ssin A. If the earth's surface is not horizontal, as is mostly the case in nature, then the arrival of radiation on it depends not only on the height of the Sun, but also on the inclination of the surface, and on its orientation in relation to the cardinal points ( from exposure).

At meteorological stations, thermometers are installed in a special booth, called a psychrometric booth, the walls of which are louvered. The rays of the Sun do not penetrate into such a booth, but at the same time air has free access to it.

Thermometers are installed on a tripod so that the reservoirs are located at a height of 2 m from the active surface.

Urgent air temperature is measured with a mercury psychrometric thermometer TM-4, which is installed vertically. At temperatures below -35 °C, use a low-degree alcohol thermometer TM-9.

Extreme temperatures are measured using maximum TM-1 and minimum TM-2 thermometers, which are laid horizontally.

For continuous recording of air temperature, an M-16A thermograph is used, which is placed in a louvered booth for recorders. Temperature fluctuations are perceived by a curved bimetallic strip. Depending on the rotation speed of the drum, thermographs are available for daily or weekly use.

In crops and plantings, the air temperature is measured without disturbing the vegetation cover. For this purpose, remote electric resistance thermometers with a small-sized receiving part are used.

Internal view of the psychrometric booth:

1 - hygrometer; 2 - dry and wet thermometers; 3 - maximum and minimum thermometers

Thermograph M-16A:

1 - drum with tape; 2- arrow with feather; 3 - bimetallic strip

The energy illumination created by radiation arriving on the Earth directly from the solar disk in the form of a beam of parallel solar rays is called direct solar radiation.
Direct solar radiation arriving at the upper boundary of the atmosphere varies over time within small limits, which is why it is called the solar constant (S0). With an average distance from the Earth to the Sun of 149.5·106 km, it is about 1400 W/m2.
When the flow of direct solar radiation passes through the atmosphere, it weakens due to the absorption (about 15%) and dissipation (about 25%) of energy by gases, aerosols, and clouds.

According to Bouguer's law of attenuation direct solar radiation arriving at the surface of the Earth with a vertical (perpendicular) incidence of rays,

Formula

Where? – atmospheric transparency coefficient; m is the number of optical masses of the atmosphere.

Figure 3.1. Diagram of the path of a solar ray in the atmosphere at different heights of the Sun(available when downloading the full version of the textbook)

Table(available when downloading the full version of the textbook)

The further the sun's rays travel through the atmosphere, the stronger their absorption and scattering and the more their intensity changes.
Transparency factor depends on the content of water vapor and aerosols in the atmosphere: the more of them, the lower the transparency coefficient with the same number of optical masses passed through. On average for the entire radiation flux in an ideally clean atmosphere? at sea level is about 0.9, in actual atmospheric conditions - 0.70-0.85, in winter it is slightly higher than in summer.

The arrival of direct radiation on the earth's surface depends on angle of incidence of sunlight. The flux of direct solar radiation falling on a horizontal surface is called insolation:

Formula(available when downloading the full version of the textbook)

where h0 is the height of the sun

The energy irradiance of direct radiation depends on the height of the Sun and the transparency of the atmosphere and increases with increasing altitude above sea level. In the main agricultural regions of Russia in summer, midday values of direct radiation energy are in the range of 700-900 W/m2. At an altitude of 1 km, the increase is 70-140 W/m2. At an altitude of 4-5 km, the illumination of direct radiation exceeds 1180 W/m2. Low-level clouds usually block direct radiation almost completely.
The arrival of direct solar radiation depends on the height of the sun above the horizon, which varies both during the day and throughout the year. This determines the daily and annual cycle of direct radiation.
The change in direct radiation during a cloudless day (diurnal cycle) is expressed by a single-peak curve with a maximum at true solar noon. In summer, over land, the maximum may occur before noon, as the dustiness of the atmosphere increases towards noon.
Annual course of direct radiation It is most pronounced at the poles, since in winter there is no solar radiation here at all, and in summer its arrival reaches 900 W/m2. In mid-latitudes, the maximum of direct radiation is sometimes observed not in summer, but in spring, since in the summer months, due to an increase in the content of water vapor and dust, the transparency of the atmosphere decreases. The minimum occurs in the period close to the winter solstice (December). At the equator there are two maxima equal to approximately 920 W/m2. on the days of the spring and autumn equinox, and two minimums (about 55 W/m2) on the days of the summer and winter solstices.

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