Solar radiation or ionizing radiation from the sun. Solar radiation: geographical dictionary

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 earth's surface radiant energy turns back into thermal energy. Solar radiation thus carries light and heat.

Intensity solar radiation. 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.

Because 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.

Quantity solar heat and the light arriving 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 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 it receives more heat Southern Hemisphere, in July - northern. This is exactly what it is main reason seasonal rhythms 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 is at high transparency of the atmosphere on a surface perpendicular to the rays in tropical zone is equal to 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. From her to sunny days It is also light 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. Specific gravity 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. The same areas at the equator, in the middle and high latitudes account for different quantity radiation.

Solar insolation (lighting) is greatly reduced cloudiness. Large clouds equatorial and temperate latitudes and low cloudiness in 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, greatest number solar heat - from 7,530 to 9,200 MJ/m2 (180-220 kcal/cm2) is received by tropical latitudes. 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 the sun's rays vary slightly between months. The total radiation in all months is characterized by large values, the seasonal change in thermal conditions is either absent or very insignificant. IN equatorial belt Two maxima are faintly visible, corresponding to the zenithal position of the Sun.

IN temperate zone In the annual course of radiation, the summer maximum is clearly pronounced, in which the monthly value of total radiation is not less than the tropical value. Number 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).

I was among those who liked to lie on the beach under the scorching sun. Everything was like this until I received a very severe burn. The effects of the sun on humans are not so harmless. I'll tell you more about solar radiation and what to expect from it.

What is solar radiation and what types does it exist?

We all know how important the Sun is for our planet. All the energy it emits is called solar radiation. Its path from the star itself to the Earth is very long, and therefore part of the solar energy is absorbed, and part is scattered. Solar radiation is divided into several types:

• straight;
• absent-minded;
• total;
• absorbed;
• reflected.

Direct solar radiation is that which reaches the Earth's surface in full, while scattered radiation does not penetrate the atmosphere. Together these two radiations are called total. A certain portion of the sun's heat escapes into the earth's surface. Such radiation is usually called absorbed. Some areas of the ground may reflect the sun's rays. This is where the name comes from - reflected solar radiation. Before sunrise, the total energy of the Sun. When the Sun is not very high, most of the radiation is scattered.

Impact of solar radiation on humans

The sun can both improve your health and have a detrimental effect on it. If you are exposed to sunlight too often, your risk of developing skin diseases, including oncological ones. In addition, vision problems may appear.

Although being in the sun a lot is harmful, I would never want to live in the northern regions, where people are constantly waiting for sunny weather. Lack of sun exposure can disrupt the body's metabolism and cause excess weight. For children, lack of sunshine is also extremely undesirable.

At normal conditions life, solar radiation maintains human health at the desired level. All organs and systems function without failures. In general, solar radiation is good in moderation, and this should always be remembered.

Solar radiation— solar radiation energy arriving on Earth in the form of a stream of electromagnetic waves.

The sun radiates powerful electromagnetic radiation around itself. Only one two-billionth part of it enters the upper layers of the Earth's atmosphere, but it also amounts to a huge number of calories per minute.

Not all of the energy flow reaches the surface of the Earth - most of it is thrown out by the planet into outer space. The Earth reflects the attack of those rays that are destructive to the living matter of the planet. On the further path to the Earth, the sun's rays encounter obstacles in the form of water vapor filling the atmosphere, carbon dioxide molecules and dust particles suspended in the air. The atmospheric “filter” absorbs a significant portion of the rays, scatters them, and reflects them. The reflectivity of clouds is especially high. As a result, the earth's surface directly receives only 2/3 of the radiation that is transmitted by the ozone screen. But also from this part much is reflected in accordance with the reflectivity of various surfaces.

The entire surface of the Earth receives just over 100,000 calories per 1 cm2 per minute. This radiation is absorbed by vegetation, soil, and the surface of seas and oceans. It turns into heat, which is spent on warming up the layers of the atmosphere, moving air and water masses, to create all the great diversity of life forms on Earth.

Solar radiation reaches the earth's surface in various ways:

1. direct radiation: radiation coming directly from the Sun, if it is not covered by clouds;
2. diffuse radiation: radiation received from the sky or clouds scattering the sun's rays;
3. thermal: the entry of radiation comes from the atmosphere heated as a result of exposure to radiation.

Direct and diffuse radiation arrives only during the day. Together they make up the total radiation. The solar radiation that remains after loss by reflection from the surface is called absorbed.

Solar radiation is measured using an instrument called an actinometer.

The sun floods the Earth with a whole ocean of energy, which is practically inexhaustible, so in recent years more and more attention has been paid to the problem of using solar energy in the economy. IN different countries Solar desalinators, water heaters, and dryers are already operating. Launched from the Earth, they operate entirely on the energy of solar radiation. artificial satellites, spaceships, laboratories.

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To changes in heat flow into short periods time and its uneven distribution in the landscape envelope is influenced by a number of circumstances, of which we will consider the most important.

Small periodic changes in radiation depend primarily on the fact that the Earth revolves around the Sun in an elliptical orbit and, therefore, its distance from the Sun changes. At perihelion, that is, at the point of the orbit closest to the Sun (the Earth is there in the present era on January 1), the distance is 147 million km; at aphelion, i.e., the most distant point of the orbit from the Sun (July 3), this distance is already 152 million km; the difference is 5 million km. In accordance with this, at the beginning of January, radiation increases by 3.4% compared to the average (i.e., calculated for the average distance from the Earth to the Sun), and at the beginning of July it decreases by 3.5%.

A very important factor that determines the amount of radiation received by a particular area of ​​the earth’s surface is the angle of incidence of the sun’s rays. If J is the intensity of radiation when the rays are vertically incident, then when they meet the surface at an angle α, the radiation intensity will be J sin α: the sharper the angle, the larger the area the energy of the beam of rays should be distributed and, therefore, the less it will be per unit area.

The angle formed by the sun's rays with the earth's surface depends on the terrain, geographical latitude and the height of the Sun above the horizon, changing both during the day and throughout the year.

On uneven terrain (no matter whether we are talking about mountains or small uneven surfaces), different elements of the relief are illuminated differently by the Sun. On a sunny hillside the angle of incidence of the rays is greater than on the plain at the foot of the hill, but on the opposite slope this angle is very small. Near Leningrad, the hillside, facing south and inclined at an angle of 10°, is in the same thermal conditions as the horizontal platform near Kharkov.

In winter, steep slopes facing south are heated better than gentle ones (since the Sun is generally low above the horizon). In summer, gentle slopes with southern exposure receive more heat, while steep slopes receive less heat than a horizontal surface. Northern-facing slopes in our hemisphere receive the least amount of radiation in all seasons.

The dependence of the angle of incidence of the sun's rays on geographic latitude is quite complex, since with the existing angle of inclination of the ecliptic, the height of the Sun in a given place (which means the angle of incidence of the sun's rays on the horizon plane) changes not only per day, but also throughout the year.

The highest midday altitude at latitude φ. The sun reaches on the days of the equinoxes, is 90° - φ, per day summer solstice 90° - φ + 23°.5 and on the day of the winter solstice 90° - φ - 23°.5.

Consequently, the greatest angle of incidence of solar rays at noon at the equator in a year varies from 90° to 66°.5, and at the pole from -23°.5 to + 23°.5, i.e. practically from 0° to + 23 °.5 (since the negative angle characterizes the amount of immersion of the Sun below the horizon).

The gaseous shell of the Earth plays a major role in the transformation of solar radiation. Air particles, water vapor and dust particles disperse sunlight; Thanks to this, the day is light and in the absence of direct sunlight. The atmosphere, in addition, absorbs a certain amount of radiant energy, i.e., converts it into heat. Finally, solar radiation entering the atmosphere is partially reflected back into space. Clouds are particularly strong reflectors.

As a result, not all of the radiation received at the boundary of the atmosphere reaches the Earth’s surface, but only part of it, and, moreover, qualitatively (in spectral composition) changed, since waves shorter than 0.3 μ, energetically absorbed by oxygen and ozone, do not reach the Earth’s surface, and visible waves are scattered differently.

Obviously, in the absence of an atmosphere, the thermal regime of the Earth would be different from what is actually observed. For a number of calculations and comparisons, it is often convenient to eliminate the influence of the atmosphere on radiation and to have the concept of radiation in its pure form. For this purpose, the so-called solar constant is calculated, i.e. the amount of heat per minute. per 1 sq. cm of a black surface (absorbing all radiation) perpendicular to the sun's rays, which the Earth would receive at its average distance from the Sun and in the absence of an atmosphere. The solar constant is 1.9 cal.

In the presence of atmosphere special meaning acquires a factor that influences radiation, such as the path length of a solar ray in the atmosphere. The greater the thickness of air a solar ray must penetrate, the more energy it will lose in the processes of scattering, reflection and absorption. The length of the beam path directly depends on the height of the Sun above the horizon and, therefore, on the time of day and season. If the path length of a solar ray through the atmosphere at a solar altitude of 90° is taken as unity, then the path length at a solar altitude of 40° will double, at an altitude of 10° it will become equal to 5.7, etc.

For the thermal regime of the earth's surface, the duration of its illumination by the Sun is also very important. Since the Sun shines only during the day, the determining factor here will be the length of the day, which changes with the seasons.

Finally, it must be remembered that although the intensity of radiation is measured in relation to the surface that absorbs all the radiation, in fact, solar energy falling on bodies of different natures is not absorbed equally. The ratio of reflected radiation to incident radiation is called albedo. It has long been known that the albedo of black soil, light rocks, grassy areas, the surface of a reservoir, etc. varies greatly. Light sands reflect 30-35%, black soil (humus) 26%, green grass 26% radiation. For freshly fallen clean and dry snow, the albedo can reach 97%. Wet soil absorbs radiation differently than dry clay: blue dry clay reflects 23% of radiation, the same wet clay reflects 16%. Consequently, even with the same influx of radiation, under the same relief conditions, different points on the earth's surface will receive different amounts of heat.

Of the periodic factors that determine the known rhythm in radiation fluctuations, the change of seasons is of particular importance.

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Solar radiation refers to the radiation from the Sun, which is measured by its thermal effect and intensity.

The solar radiation that directly reaches the Earth's surface is called direct solar radiation. Part of the solar radiation is scattered in the atmosphere, after which it reaches the surface of the planet, such radiation is called scattered solar radiation. Direct and diffuse radiation together constitute total solar radiation.

Total solar radiation is determined by the thermal effect per unit surface per unit time. Expressed in calories or joules.

The amount of total solar radiation falling on the surface depends on the height of the Sun, the length of the day, and the properties of the atmosphere (its transparency, cloudiness).

Since the Earth is spherical, the Sun rises highest above the horizon at the equator. Here the sun's rays fall perpendicular to the surface. As they move toward the poles, the sun's rays fall at an ever greater angle and therefore bring less and less heat. In addition, the closer to the equator, the longer the day, and therefore the surface receives more heat.

However, it is not only geographic latitude that influences total solar radiation.

Solar radiation and its effect on the human body and climate

At the equator there is high cloudiness and humidity, which prevents the passage of sunlight. Therefore, the total solar radiation here is less than in the continental tropical climate(for example, the territory of the Sahara).

The sun is a source of light and heat that all living things on Earth need. But in addition to photons of light, it emits hard ionizing radiation, consisting of helium nuclei and protons. Why is this happening?

Causes of solar radiation

Solar radiation is produced in the daytime during chromospheric flares - giant explosions that occur in the solar atmosphere. Some of the solar matter is ejected into outer space, forming cosmic rays, mainly consisting of protons and a small amount of helium nuclei. These charged particles reach the earth's surface 15-20 minutes after the solar flare becomes visible.

The air cuts off primary cosmic radiation, generating a cascading nuclear shower, which fades with decreasing altitude. In this case, new particles are born - pions, which decay and turn into muons. They penetrate into the lower layers of the atmosphere and fall to the ground, burrowing up to 1500 meters deep. It is muons that are responsible for the formation of secondary cosmic radiation and natural radiation affecting humans.

Solar radiation spectrum

The spectrum of solar radiation includes both short-wave and long-wave regions:

• gamma rays;
• x-ray radiation;
• UV radiation;
• visible light;
• infrared radiation.

Over 95% of the sun's radiation falls in the region of the “optical window” - the visible part of the spectrum with adjacent regions of ultraviolet and infrared waves.

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

As they pass through the layers of the atmosphere, the effect of the sun's rays is weakened - all ionizing radiation, X-rays and almost 98% of ultraviolet radiation are blocked by the earth's atmosphere. Visible light reaches the ground virtually without loss and infrared radiation, although they are also partially absorbed by gas molecules and dust particles in the air.

In this regard, solar radiation does not lead to a noticeable increase in radioactive radiation on the Earth's surface. The contribution of the Sun, together with cosmic rays, to the formation of the total annual radiation dose is only 0.3 mSv/year. But this is an average value; in fact, the level of radiation incident on the ground is different and depends on geographical location terrain.

Where is solar ionizing radiation greatest?

The greatest power of cosmic rays is recorded at the poles, and the least at the equator. This is due to the fact that the Earth's magnetic field deflects charged particles falling from space towards the poles. In addition, radiation increases with altitude - at an altitude of 10 kilometers above sea level, its indicator increases by 20-25 times. Residents of high mountains are exposed to higher doses of solar radiation, since the atmosphere in the mountains is thinner and more easily penetrated by streams of gamma quanta and elementary particles coming from the sun.

Important. Radiation levels up to 0.3 mSv/h do not have a serious impact, but at a dose of 1.2 μSv/h it is recommended to leave the area, and in case of emergency, stay in its territory for no more than six months. If the readings exceed twice that, you should limit your stay in this area to three months.

If above sea level the annual dose of cosmic radiation is 0.3 mSv/year, then with an increase in altitude every hundred meters this figure increases by 0.03 mSv/year. After some small calculations, we can conclude that a week-long vacation in the mountains at an altitude of 2000 meters will give an exposure of 1 mSv/year and will provide almost half of the total annual norm (2.4 mSv/year).

It turns out that mountain residents receive an annual dose of radiation that is several times higher than normal, and should suffer from leukemia and cancer more often than people living on the plains. In fact, this is not true. On the contrary, in mountainous areas there is a lower mortality rate from these diseases, and part of the population is long-lived. This confirms the fact that long-term stay in places of high radiation activity does not affect negative influence on the human body.

Solar flares - high radiation hazard

Solar flares are a great danger to humans and all life on Earth, since the flux density of solar radiation can exceed the normal level of cosmic radiation by a thousand times. Thus, the outstanding Soviet scientist A.L. Chizhevsky connected the periods of sunspot formation with epidemics of typhus (1883-1917) and cholera (1823-1923) in Russia. Based on the graphs he made, back in 1930 he predicted the emergence of an extensive cholera pandemic in 1960-1962, which began in Indonesia in 1961, then quickly spread to other countries in Asia, Africa and Europe.

Today, a wealth of data has been obtained indicating the connection between eleven-year cycles of solar activity and outbreaks of diseases, as well as with mass migrations and seasons of rapid reproduction of insects, mammals and viruses. Hematologists have found an increase in the number of heart attacks and strokes during periods of maximum solar activity. Such statistics are due to the fact that at this time people’s blood clotting increases, and since in patients with heart disease compensatory activity is suppressed, malfunctions occur in its work, including necrosis of cardiac tissue and hemorrhages in the brain.

Large solar flares do not occur so often - once every 4 years. At this time, the number and size of sunspots increases, and powerful coronal rays are formed in the solar corona, consisting of protons and a small amount of alpha particles. Astrologers registered their most powerful flow in 1956, when the density of cosmic radiation on the surface of the earth increased 4 times. Another consequence of such solar activity was the aurora, recorded in Moscow and the Moscow region in 2000.

How to protect yourself?

Of course, increased background radiation in the mountains is not a reason to refuse trips to the mountains. However, it is worth thinking about safety measures and going on a trip with a portable radiometer, which will help control the level of radiation and, if necessary, limit the time spent in dangerous areas. You should not stay in an area where meter readings show ionizing radiation of 7 µSv/h for more than one month.

Total solar radiation and radiation balance

Total radiation is the sum of direct (on a horizontal surface) and diffuse radiation. The composition of total radiation, i.e. the ratio between direct and diffuse radiation, varies depending on the height of the sun, transparency, atmosphere and cloud cover.

Before sunrise, the total radiation consists entirely, and at low solar altitudes it consists mainly of scattered radiation. With increasing solar altitude, the share of scattered radiation in the total radiation in a cloudless sky decreases: at h = 8° it is 50%, and at h = 50° it is only 10-20%.

The more transparent the atmosphere, the smaller the share of scattered radiation in the total radiation.

3. Depending on the shape, height and number of clouds, the proportion of scattered radiation increases to varying degrees. When the sun is covered by dense clouds, the total radiation consists only of scattered radiation. With such clouds, scattered radiation only partially compensates for the decrease in direct radiation, and therefore an increase in the number and density of clouds is, on average, accompanied by a decrease in total radiation. But with small or thin clouds, when the sun is completely open or not completely covered by clouds, the total radiation due to an increase in scattered radiation may be greater than with clear sky.

The daily and annual variation of total radiation is determined mainly by changes in the altitude of the sun: the total radiation changes almost in direct proportion to the change in the altitude of the sun.

Solar radiation or ionizing radiation from the sun

But the influence of cloudiness and air transparency greatly complicates this simple relationship and disrupts the smooth course of total radiation.

The total radiation also depends significantly on the latitude of the place. With decreasing latitude, its daily amounts increase, and the lower the latitude of the place, the more evenly the total radiation is distributed over the months, i.e., the smaller the amplitude of its annual cycle. For example, in Pavlovsk (φ = 60°) its monthly amounts range from 12 to 407 cal/cm2, in Washington (φ = 38.9°) - from 142 to 486 cal/cm2, and in Takubay (φ = 19 °) – from 307 to 556 cal/cm2. The annual amounts of total radiation also increase with decreasing latitude. However, in some months the total radiation in the polar regions may be greater than in lower latitudes. For example, in Tikhaya Bay in June the total radiation is 37% more than in Pavlovsk, and 5% more than in Feodosia.

Continuous observations in Antarctica over the past 7-8 years show that the monthly amounts of total radiation in this area in the warmest month (December) are approximately 1.5 times greater than at the same latitudes in the Arctic, and are equal to the corresponding amounts in Crimea and in Tashkent. Even the annual amounts of total radiation in Antarctica are greater than, for example, in St. Petersburg. Such a significant influx of solar radiation in Antarctica is explained by dry air, the high altitude of Antarctic stations above sea level and the high reflectivity of the snow surface (70-90%), increasing scattered radiation

The difference between all fluxes of radiant energy arriving at the active surface and leaving it is called the radiation balance of the active surface. In other words, the radiation balance of an active surface is the difference between the inflow and outflow of radiation on this surface. If the surface is horizontal, then the incoming part of the balance includes direct radiation arriving at the horizontal surface, scattered radiation and counter radiation from the atmosphere. The radiation consumption is composed of the reflected short-wave and long-wave radiation of the active surface and the part of the oncoming atmospheric radiation reflected from it.

The radiation balance represents the actual arrival or expenditure of radiant energy on the active surface, which determines whether it will be heated or cooled. If the arrival of radiant energy is greater than its consumption, then the radiation balance is positive and the surface heats up. If the inflow is less than the outflow, then the radiation balance is negative and the surface cools. The radiation balance as a whole, as well as its individual elements, depends on many factors. It is especially strongly influenced by the altitude of the sun, the duration of sunshine, the nature and condition of the active surface, turbidity of the atmosphere, the content of water vapor in it, cloudiness, etc.

The instantaneous (minute) balance during the day is usually positive, especially in the summer. Approximately 1 hour before sunset (excluding winter time) the consumption of radiant energy begins to exceed its income, and the radiation balance becomes negative. About 1 hour after sunrise it becomes positive again. Daily cycle the balance during the day under clear skies is approximately parallel to the course of direct radiation. During the night, the radiation balance usually changes little, but under the influence of variable clouds it can change significantly

The annual sums of the radiation balance are positive over the entire surface of the land and oceans, except for areas with permanent snow or ice cover, such as Central Greenland and Antarctica. North 40° northern latitude and south of 40°S latitude, the winter monthly sums of the radiation balance are negative, and the period with a negative balance increases towards the poles. Thus, in the Arctic these amounts are positive only in the summer months, at a latitude of 60° for seven months, and at a latitude of 50° for nine months. The annual amounts of the radiation balance change when moving from land to sea.

The radiation balance of the Earth-atmosphere system is the balance of radiant energy in a vertical column of the atmosphere with a cross section of 1 cm 2, extending from the active surface to the upper boundary of the atmosphere. Its incoming part consists of solar radiation absorbed by the active surface and atmosphere, and its outgoing part consists of that part of the long-wave radiation of the earth's surface and atmosphere that goes into outer space. The radiation balance of the Earth-atmosphere system is positive in the zone from 30° south latitude to 30° north latitude, and at higher latitudes it is negative

The study of the radiation balance is of great practical interest, since this balance is one of the main climate-forming factors. The thermal regime of not only the soil or reservoir, but also the layers of the atmosphere adjacent to them depends on its value. Knowledge of the radiation balance has great importance when calculating evaporation, when studying the issue of formation and transformation air masses, when considering the effect of radiation on humans and flora.

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DISTRIBUTION OF HEAT AND LIGHT ON EARTH

The sun is a star solar system, which is a source of enormous amounts of heat and dazzling light for planet Earth. Despite the fact that the Sun is located at a considerable distance from us and only a small part of its radiation reaches us, this is quite enough for the development of life on Earth. Our planet revolves around the Sun in an orbit.

Solar radiation

If you observe the Earth from a spaceship throughout the year, you will notice that the Sun always illuminates only one half of the Earth, therefore, there will be day there, and on the opposite half at this time there will be night. The earth's surface receives heat only during the day.

Our Earth is heating unevenly.

The uneven heating of the Earth is explained by its spherical shape, so the angle of incidence of the sun's ray in different areas is different, which means that different parts of the Earth receive different amounts of heat. At the equator, the sun's rays fall vertically, and they greatly heat the Earth. The further from the equator, the smaller the angle of incidence of the beam becomes, and therefore the less heat these areas receive. A beam of solar radiation of the same power heats a much smaller area at the equator, since it falls vertically. In addition, rays falling at a smaller angle than at the equator, penetrating the atmosphere, pass through it longer way, as a result of which some of the sun's rays are scattered in the troposphere and do not reach the earth's surface. All this indicates that with distance from the equator to the north or south, the air temperature decreases, as the angle of incidence of the sun's ray decreases.

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

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

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

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

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

Radiation reaching the earth's surface consists of direct and diffuse.

Radiation that comes to Earth directly from the Sun in the form of direct sunlight under a cloudless sky is called straight. It carries the greatest amount of heat and light. If our planet had no atmosphere, the earth's surface would receive only direct radiation.

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

Total solar radiation

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

Rice. 1. Total solar radiation for the year

Distribution of solar radiation over the earth's surface

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

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

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

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

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

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

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

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

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

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

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

Solar radiation

Solar radiation

electromagnetic radiation emanating from the Sun and entering the earth's atmosphere. Solar radiation wavelengths are concentrated in the range from 0.17 to 4 µm with a max. at a wavelength of 0.475 µm. OK. 48% of the energy of solar radiation falls on the visible part of the spectrum (wavelength from 0.4 to 0.76 microns), 45% on the infrared (more than 0.76 microns), and 7% on the ultraviolet (less than 0.4 µm). Solar radiation is the main source of energy for processes in the atmosphere, ocean, biosphere, etc. It is measured in units of energy per unit area per unit time, for example. W/m². Solar radiation at the upper boundary of the atmosphere on Wednesday. the distance of the Earth from the Sun is called solar constant and amounts to approx. 1382 W/m². Passing through the earth's atmosphere, solar radiation changes in intensity and spectral composition due to absorption and scattering on air particles, gaseous impurities and aerosol. At the Earth's surface, the spectrum of solar radiation is limited to 0.29–2.0 μm, and the intensity is significantly reduced depending on the content of impurities, altitude and cloud cover. Direct radiation, weakened when passing through the atmosphere, as well as scattered radiation, formed when the direct line is scattered in the atmosphere, reaches the earth's surface. Part of the direct solar radiation is reflected from the earth's surface and clouds and goes into space; scattered radiation also partially escapes into space. The rest of the solar radiation is mainly turns into heat, heating the earth's surface and partly the air. Solar radiation, i.e., is one of the main. components of the radiation balance.

Geography. Modern illustrated encyclopedia. - M.: Rosman. Edited by prof. A. P. Gorkina. 2006 .

See what “solar radiation” is in other dictionaries:

Electromagnetic and corpuscular radiation of the Sun. Electromagnetic radiation covers the wavelength range from gamma radiation to radio waves, its energy maximum falls in the visible part of the spectrum. Corpuscular component of the solar... ... Big encyclopedic Dictionary

solar radiation- The total flow of electromagnetic radiation emitted by the Sun and falling on the Earth... Dictionary of Geography

This term has other meanings, see Radiation (meanings). This article lacks links to sources of information. Information must be verifiable, otherwise it may be called into question... Wikipedia

All processes on the surface of the globe, whatever they may be, have their source solar energy. Are purely mechanical processes being studied, chemical processes in air, water, soil, physiological processes or whatever... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Electromagnetic and corpuscular radiation of the Sun. Electromagnetic radiation covers the wavelength range from gamma radiation to radio waves, its energy maximum falls in the visible part of the spectrum. Corpuscular component of the solar... ... encyclopedic Dictionary

solar radiation- Saulės spinduliuotė statusas T sritis fizika atitikmenys: engl. solar radiation vok. Sonnenstrahlung, f rus. solar radiation, n; solar radiation, f; solar radiation, n pranc. rayonnement solaire, m … Fizikos terminų žodynas

solar radiation- Saulės spinduliuotė statusas T sritis ekologija ir aplinkotyra apibrėžtis Saulės atmosferos elektromagnetinė (infraraudonoji 0.76 nm sudaro 45%, matomoji 0.38–0.76 nm – 48%, ultravioletinė 0.38 nm – 7%) šviesos, radijo bangų, gama kvantų ir… … Ekologijos terminų aiškinamasis žodynas

Radiation from the Sun of electromagnetic and corpuscular nature. S. r. the main source of energy for most processes occurring on Earth. Corpuscular S. r. consists mainly of protons, which have velocities of 300–1500 near the Earth… … Great Soviet Encyclopedia

Email mag. and corpuscular radiation from the Sun. Email mag. radiation covers a range of wavelengths from gamma radiation to radio waves, its energy. the maximum falls on the visible part of the spectrum. Corpuscular component of S. r. consists of ch. arr. from… … Natural science. encyclopedic Dictionary

direct solar radiation- Solar radiation coming directly from the solar disk... Dictionary of Geography

Books

• Solar radiation and climate of the Earth, Fedorov Valery Mikhailovich. The book presents the results of studies of variations in Earth's insolation associated with celestial-mechanical processes. Low-frequency and high-frequency changes in solar climate are analyzed...