Calculation formula direct and total solar radiation. What determines the amount of solar radiation

TASK-RES

How is the total amount of energy radiated by 1 m 2 of the surface in 1 sec determined. ANSWER How the total amount of energy emitted by 1 m 2 of the surface in 1 sec is determined E (T) \u003d aT 4

where a \u003d 5.67 10 -8 W / (m 2 K 4), T- the absolute temperature of a completely black body on the Kelvin scale. This pattern is called by the Stefan-Boltzmann radiation law. It was established in the last century on the basis of numerous experimental observations and Stefan, theoretically substantiated by L. Boltzmann, based on the classical laws of thermodynamics and electrodynamics of equilibrium radiation, and later, at the beginning of our century, it was found that this regularity follows from the quantum law of energy distribution in spectrum of equilibrium radiation, derived by M. Planck.

Calculation method for determining the wavelength λ m , which accounts for the maximum radiation energy of a blackbodyAccording to Wien's displacement law, the wavelength λm, which accounts for the maximum radiation energy of a blackbody, is inversely proportional to the absolute temperature T:

The law of distribution of the spectral power of the radiation of a completely black body was established by Planck, it is called therefore Planck's law of radiation. This law establishes that the radiation power in a unit wavelength interval is determined by the temperature T absolutely black body: Moreover, The derivation of this formula, in addition to the assumption of thermodynamic equilibrium of radiation, is based on its quantum nature, i.e., the radiation energy is summed from the energy of individual photons with the energy E h \u003d hv. Note that it represents the total energy radiated by a unit of the surface of a completely black body into a solid angle of 2π in 1 sec, over the entire frequency range, and it coincides with the Stefan-Boltzmann law

The calculation method for determining the optical mass of direct sunlight through the atmosphere The distance traveled by direct sunlight through the atmosphere depends on the angle of incidence (zenith angle) and the height of the observer above sea level. We assume the presence of a clear sky without clouds, dust or air pollution. Since the upper boundary of the atmosphere is not exactly defined, more important than the distance traveled is the interaction of radiation with atmospheric gases and vapors. A direct stream that normally passes through the atmosphere at normal pressure, interacts with a certain mass of air. Increasing the length of the path with an oblique incidence of the beam.

A direct stream, normally passing through the atmosphere at normal pressure, interacts with a certain mass of air. Increasing the length of the path with an oblique incidence of the beam.

optical mass m = secθz:1-length of run, increased by a factor t; 2-normal-incidence At an angle θ z , compared to the normal-incidence path, is called optical mass and is denoted by the symbol t. From the figure, without taking into account the curvature of the earth's surface, we obtain m=secθz .

Calculation technique for determining the intensity of space solar radiation(solar constant) S o received from the Sun Earth radius R, and the intensity of cosmic solar radiation (solar constant) S o, then the energy received from the Sun is π R2 (1 - ρ 0)So. This energy is equal to the energy emitted in space Earth with emissivity ε = 1 and average temperature T e, Hence .

The spectral distribution of long-wave radiation of the Earth's surface, observed from space, approximately corresponds to the spectral distribution of a blackbody at a temperature of 250 K. Atmospheric radiation propagates both towards the Earth's surface and in the opposite direction. The effective temperature of the Earth's black body as a radiator is equivalent to the temperature at which the outer layers of the atmosphere radiate, and not the Earth's surface.

Calculation method for determining the flux and density of the radiant energy of the sun In meteorology, radiant energy fluxes are subdivided into short-wave radiation with wavelengths from 0.2 to 5.0 µm and long-wave radiation with wavelengths from 5.0 to 100 µm. Streams of short-wave solar radiation are divided into:- straight;

- scattered (diffuse); - total. Solar energy W- called the energy carried by electromagnetic waves. The unit of radiation energy W in the international system of units SI is 1 joule. radiant streamФ e - which is determined by the formula: F e \u003d W / t,

where W- radiation energy over time t.

Assuming W=1 j, t=1 s, we get: 1 SI (F e) \u003d 1 J / 1 sec \u003d 1 W. Radiant flux density radiation ( radiation flux I) which is defined by the formula: where F e is the radiation flux uniformly incident on the surface S.

Assuming F e \u003d 1 W, S \u003d 1 m 2, we find: 1 SI (E e) \u003d 1 W / 1 m 2 \u003d 1 W / m 2.

Calculation formula direct and total solar radiation

Direct solar radiation-I p represents the flux of radiation coming from the solar disk and measured in a plane perpendicular to the sun's rays. Direct radiation coming to a horizontal surface (S ") is calculated by the formula:

S" \u003d I p sin h, where h is the height of the sun above the horizon. Savinov-Yanishevsky actinometer is used to measure direct solar radiation. Scattered solar radiation (D) - called radiation arriving on a horizontal surface from all points of the firmament, with the exception of the solar disk and the near-solar zone with a radius of 5 0, as a result of the scattering of solar radiation by atmospheric gas molecules, water drops or ice crystals of clouds and solid particles suspended in the atmosphere. Total solar radiation Q- includes radiation incident on a horizontal plane, of two types: direct and diffuse. Q=S"+D(4.7) The total radiation that has reached the earth's surface is mostly absorbed in the upper, thin layer of soil or water and passes into heat, and is partially reflected.

Determine the main points of the celestial sphere Celestial sphere is an imaginary sphere of arbitrary radius. Its center, depending on the problem being solved, is combined with one or another point in space. The plumb line intersects the surface of the celestial sphere at two points: at the top Z - zenith - and at the bottom Z "- nadir Basic points and circles on the celestial sphere

Determine the Celestial Coordinates of the SunBasic the circles relative to which the place of the Sun (luminaries) is determined are the true horizon and the celestial meridian; the coordinates are Sun height (h) and its azimuth (A) .The apparent position of the Sun at any point on the Earth is determined by these two angles Horizontal coordinate system Height h of the Sun above the horizon – the angle between the direction to the Sun from the point of observation and the horizontal plane passing through this point. Azimuth A of the Sun - the angle between the meridian plane and the vertical plane drawn through the observation point and the Sun. Zenith angleZ - the angle between the direction to the zenith (Z) and the direction to the Sun. This angle is complementary to the height of the solstice. h + z = 90. When the Earth is facing the Sun with its south side, the azimuth is zero, and the height is maximum. From this comes the concept noon, which is taken as the beginning of the countdown time of the day (or the second half of the day).

Calculation technique for determining angular solar time (hour angle of the Sun) Angular solar time (hour angle of the Sun) τ - represents the angular displacement of the Sun from noon (1 h corresponds to π/12 glad, or 15° angular displacement). The displacement to the East from the South (i.e., the morning value) is considered positive. The hourly angle of the Sun τ varies between the planes of the local meridian and the solar meridian. Once every 24 hours, the Sun enters the meridional plane. Due to the daily rotation of the Earth, the hour angle τ changes during the day from 0 to 360 o or 2π rad (radian), in 24 hours, thus, the Earth, moving along the Orbit, rotates around its axis with an angular velocity If we take solar time from true noon, corresponding to the moment the Sun passes through the planes of the local meridian, then we can write: hail or glad

Calculation Method for Determining the Declination of the Sun declination sun - the angle between the direction to the Sun and the equatorial plane is called declination δ and is a measure of seasonal variation. Declination is usually expressed in radians (or degrees) north or south of the equator. Measured from 0° to 90° ( positive value north of the equator, negative - south). The earth revolves around the sun in a year. The direction of the earth's axis remains fixed in space at an angle δ 0 \u003d 23.5 ° to the normal to the plane of rotation, In the northern hemisphere, δ changes smoothly from δ 0 \u003d + 23.5 ° during the summer solstice to δ 0 \u003d -23.5 ° during the winter solstice. Analytically obtained hail

where P- day of the year ( n= 1 corresponds to January 1). At the equinoxes δ = 0 , and the points of sunrise and sunset are located strictly on the line of the E-Z horizon. Thus, the trajectory of the Sun along the celestial sphere is not a closed curve, but is a kind of spherical spiral, stuffed onto the side surface of the sphere within the strip - .

During the summer half-year from March 21 to September 23, the Sun is above the equatorial plane in the northern celestial hemisphere. During the winter half-year from September 23 to March 21, the Sun is below the equatorial plane in the southern celestial hemisphere.

Solar radiation- radiation inherent in the luminary of our planetary system. The Sun is the main star around which the Earth revolves, as well as neighboring planets. In fact, this is a huge hot gas ball, constantly emitting energy flows into the space around it. This is what they call radiation. Deadly, at the same time it is this energy - one of the main factors that make life possible on our planet. Like everything in this world, the benefits and harms of solar radiation for organic life are closely interrelated.

General view

To understand what solar radiation is, you must first understand what the Sun is. The main source of heat, which provides the conditions for organic existence on our planet, in the universal spaces is only a small star on the galactic outskirts of the Milky Way. But for earthlings, the Sun is the center of a mini-universe. After all, it is around this gas clot that our planet revolves. The sun gives us heat 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 evidence God's will. Attempts to delve into the essence of the phenomenon, to explain what this luminary is, have been made for a long time, and Copernicus made a particularly significant contribution to them, having formed the idea of ​​heliocentrism, which was strikingly different from the geocentrism generally accepted in 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 life forms 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 take place 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 large knowledge base to say with confidence: it was possible to find out what the radiation emitted by the Sun is, 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 solar depths, which allows a huge amount of energy to be released into the space around the star. Trying to estimate the amount of solar radiation, efforts were made to determine the actual parameters of the environment on the star. Thus, the core temperature, 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 an attempt to estimate the amount of solar radiation, scientists found that helium nuclei are inferior in mass to the total value of 4 protons required to form a new structure. Thus, a feature of the reactions, called the "mass defect", was revealed. But in nature, nothing can disappear without a trace! In an attempt to find "escaped" quantities, scientists compared the energy recovery and the specifics of the change in mass. It was then that it was possible to reveal that the difference is emitted by gamma quanta.

The radiated 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 on their basis. Among other types of solar radiation is the light perceived by the human eye. Approximate estimates suggested that the process of passage of gamma rays takes about 10 million years. Another eight minutes - and the radiated energy reaches the surface of our planet.

How and what?

Solar radiation is called the total complex of electromagnetic radiation, which is characterized by a fairly wide range. This includes the so-called solar wind, that is, the energy flow formed by electrons, light particles. At the boundary layer of the atmosphere of our planet, the same intensity of solar radiation is constantly observed. The energy of a star is discrete, its transfer is carried out through quanta, while the corpuscular nuance is so insignificant that one can consider the rays as electromagnetic waves. And their distribution, as physicists have found out, 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:

• warmly;
• radio wave;
• White light;
• ultraviolet;
• gamma;
• x-ray.

The ratio of infrared, visible, ultraviolet best is 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.

Studies have shown that solar radiation is mainly absorbed by the planetary atmosphere. Due to this, heating occurs to a temperature comfortable for organic life, characteristic of the Earth. The existing ozone shell allows only one hundredth of the ultraviolet radiation to pass through. At the same time, short wavelengths that are dangerous to living beings are completely blocked. Atmospheric layers are able to scatter almost a third of the sun's rays, another 20% are absorbed. Consequently, no more than half of all energy reaches the surface of the planet. It is this "residue" in science that is called direct solar radiation.

How about in more detail?

Several aspects are known that determine how intense direct radiation will be. The most significant are considered to be the angle of incidence depending on latitude ( geographical feature terrain on the globe), a season that determines how far a particular point is from a radiation source. Much depends on the characteristics of the atmosphere - how polluted it is, how many clouds there are at a given moment. Finally, the nature of the surface on which the beam falls, namely, its ability to reflect the incoming waves, plays a role.

Total solar radiation is a value that combines scattered volumes and direct radiation. The parameter used to estimate the intensity is estimated in calories per unit area. At the same time, remember that in different time days, the values ​​inherent in 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 that the air does not get the opportunity to warm up. Therefore, the farther from the equator, the lower the total indicators of solar wave radiation will be.

As scientists managed to reveal, the energy of solar radiation has a serious impact on the planetary climate, subjugates the vital activity of various organisms that exist on Earth. In our country, as well as in the territory of its nearest neighbors, 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 is heated, gradually transferring thermal energy to air masses. This helps to maintain a comfortable climate, maintain conditions for the existence of organic life. If there are no serious failures, the climate remains conditionally unchanged, which means that all creatures can live in their usual conditions.

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

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

It's curious

Based on the study of solar radiation factors, it was possible to create truly unique devices called thermographs. They enable timely detection various diseases not available for detection by other means. This is how you can find cancer or a blood clot. IR to some extent protects against ultraviolet radiation, which is dangerous for organic life, which made it possible to use waves of this spectrum to restore the health of astronauts who were 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 is still not fully explored. 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 impaired functioning of the heart, blood vessels, including those located in the brain.

visible light

One of the elements of total solar radiation is the light visible to the human eye. Wave beams propagate in straight lines, so there is no superposition on each other. At one time, this became the topic of a considerable number scientific works: scientists set out to understand why there are so many shades around us. It turned out that the key parameters of light play a role:

• refraction;
• reflection;
• absorption.

As the scientists found out, objects are not capable of being visible light sources by themselves, but they can absorb radiation and reflect it. Reflection angles, wave frequency vary. Over the centuries, the ability of a person to see has been 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 light features not only became the subject of many works, but also were the basis for the birth of a new physical discipline. At the same time, non-scientific practices appeared, theories, the adherents of which believe that color can affect the physical state human, 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 the total solar radiation is the ultraviolet study, formed by waves of large, medium and small lengths. They differ from each other both in physical parameters and in the peculiarities of their influence on the forms of organic life. Long ultraviolet waves, for example, are mainly 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. Such 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, 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 endorphins, which means that nervous overexcitation decreases.

but on the other hand

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

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

Prolonged ultraviolet irradiation provokes a violation of appetite, the functioning of the central nervous system, and the immune system. Also, my head starts to hurt. The symptoms described 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 has become ill, first aid should be provided. The scheme is as follows:

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

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

How to sunbathe properly?

In order not to learn from experience how unpleasant the excessive amount of solar radiation received during tanning can be, it is important to follow the rules of safe spending time in the sun. Ultraviolet 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 into bronze. To this day, disputes about how useful and harmful it is for a person do not subside.

On the one hand, sunburn 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, tan is considered fashionable and beautiful. In order to minimize risks for yourself, it is reasonable to analyze before starting beach procedures how dangerous the amount of solar radiation received during sunbathing is, how to minimize risks for yourself. To make the experience as pleasant as possible, sunbathers should:

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

The value of solar radiation for the human body is exceptionally high, both positive and negative aspects should not be overlooked. It should be realized that different people biochemical reactions occur with individual characteristics, therefore, for someone, half an hour sunbathing may be dangerous. It is reasonable to consult a doctor before the beach season, assess the type and condition of the skin. This will help prevent harm to health.

If possible, sunburn should be avoided in old age, during the period of bearing a baby. Cancer diseases, mental disorders, skin pathologies and heart failure are not combined with sunbathing.

Total radiation: where is the shortage?

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

The ultraviolet is absorbed to some extent by the oxygen layer. This is characteristic of radiation with a wavelength of 0.13-0.24 microns. Carbon dioxide, water vapor can absorb a small percentage of the infrared spectrum. 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 here. Inhomogeneous elements, particles whose dimensions are inferior to the wavelength, provoke molecular scattering, and for larger ones, the phenomenon described by the indicatrix, that is, aerosol, is characteristic.

The rest of the solar radiation reaches the earth's surface. It combines direct radiation, diffused.

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 cloudiness in the total radiation, diffuse is one fourth.

Our country belongs to the northern ones, therefore most years in southern regions 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 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 daylight hours are longer than in other months of the year. At the same time, 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 wave radiation is observed at noon, and the annual maximum occurs in June, when the sun is highest in the sky.

The total solar radiation is the amount solar energy reaching our planet. At the same time, it must be remembered that various atmospheric factors lead to the fact that the annual arrival of total radiation is less than it could be. The biggest difference between the actually observed and the maximum possible is typical for the Far Eastern regions in the summer. Monsoons provoke exceptionally dense clouds, so the total radiation is reduced by about half.

curious to know

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

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

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

Based on 12 months, special attention should be paid to astronomical phenomena as determining the overall numerical indicators. At the same time, cloudiness leads to the fact that the real radiation maximum can 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 a mortal danger to humans. As early as 1964, an important popular science work on defense methods was published. Its authors were Soviet scientists Kamanin, 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 it should be 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 obliges to take additional measures to protect against waves of different lengths.

After the Apollo missions, during which methods of protection were tested, factors affecting human health were studied, more than one decade has passed, but to this day scientists cannot find effective, reliable methods for predicting geomagnetic storms. You can make a forecast for hours, sometimes for several days, but even for a weekly forecast, the chances of realization 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, can fall into powerful radiation fluxes. This makes even more important the issue of both research and prediction of radiation features, and the development of methods of protection against it.

Answer from Caucasian[newbie]
Total radiation - part of the reflected and part of the direct radiation. Depends on clouds and cloud cover.

Answer from Arman Shaysultanov[newbie]
solar radiation value in saryarka

Answer from Vova Vasiliev[newbie]
Solar radiation - electromagnetic and corpuscular radiation of the Sun

Answer from Nasopharynx[active]
Solar radiation - electromagnetic and corpuscular radiation of the Sun. Electromagnetic radiation propagates in the form of electromagnetic waves at the speed of light and penetrates into the earth's atmosphere. Solar radiation reaches the earth's surface in the form of direct and diffuse radiation.
Solar radiation is the main source of energy for all physical and geographical processes occurring on the earth's surface and in the atmosphere. Solar radiation is usually measured by its thermal effect and is expressed in calories per unit area per unit of time. In total, the Earth receives from the Sun less than one two-billionth of its radiation.
Total solar radiation is measured in kilocalories per square centimeter.
When moving from north to south, the amount of solar radiation received by the territory increases.
Solar radiation is the radiation of light and heat from the Sun.

Solar radiation- the energy of solar radiation arriving at the Earth in the form of a stream of electromagnetic waves.

The sun spreads powerful electromagnetic radiation around itself. Only one two-billionth of it enters the upper layers of the Earth's atmosphere, but it is huge number calories per minute.

Far from the entire energy flow reaches the Earth's surface - most of it is thrown by the planet into the world space. The earth reflects the attack of those rays that are detrimental to the living matter of the planet. On their way to 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 part of the rays, scatters them, 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 even from this part, much is reflected in accordance with the reflectivity of various surfaces.

A little more than 100,000 calories per 1 cm2 per minute enter the entire surface of the Earth. This radiation is absorbed by vegetation, soil, the surface of the seas and oceans. It turns into heat, which is spent on heating the layers of the atmosphere, the movement of air and water masses, and the creation of all the great variety of life forms on Earth.

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

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

Direct and diffuse radiation comes only during the day. Together they make up the total radiation. That solar radiation, which remains after the 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, therefore, in last years Increasing attention is paid to the problem of using solar energy in the economy. AT different countries solar desalination plants, water heaters, and dryers are already in operation. Artificial satellites, spacecraft, and laboratories launched from the Earth operate entirely on the energy of solar radiation.

Solar radiation wikipedia
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Changes in heat influx in short periods of time and its uneven distribution in the landscape envelope are 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, consequently, its distance from the Sun changes. At perihelion, i.e., at the point of the orbit closest to the Sun (the Earth is in it at the present epoch 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, in early January, the radiation increases by 3.4% compared to the average (i.e., calculated for the average distance from the Earth to the Sun), and in early July it decreases by 3.5%.

A very important factor determining the amount of radiation received by one or another part of the earth's surface is the angle of incidence of the sun's rays. If J is the radiation intensity during vertical incidence of rays, then when they meet the surface at an angle α, the radiation intensity will be J sin α: the sharper the angle, the large area the energy of the beam of rays should be distributed and, therefore, the less it will have per unit area.

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

On the uneven terrain(it doesn't matter if we are talking about mountains or small irregularities) various elements of the relief are illuminated by the Sun unequally. On the sunny slope of the hill, 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 slope of the hill, facing south and inclined at an angle of 10 °, is in the same thermal conditions as the horizontal platform near Kharkov.

In winter, south-facing steep slopes are warmed better than gently sloping ones (because the Sun is generally low on the horizon). In summer, the gentle slopes of the southern exposure receive more heat, and the steep ones less than the horizontal surface. The slopes of the northern exposure in our hemisphere in all seasons receive the least amount of radiation.

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

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

Consequently, the largest angle of incidence of sunlight 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 the Sun's immersion under the horizon).

Plays an important role in the conversion of solar radiation gas envelope Earth. Particles of air, water vapor and dust particles scatter sunlight; Thanks to this, it is bright during the day 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 partly reflected back into space. Clouds are especially strong reflectors.

As a result, not all of the radiation that has entered the boundary of the atmosphere reaches the Earth's surface, but only a part of it, and, moreover, qualitatively (in terms of spectral composition) changed, since waves shorter than 0.3 μ, vigorously absorbed by oxygen and ozone, do not reach the Earth's surface, and visible waves scatter unequally.

Obviously, in the absence of an atmosphere, the thermal regime of the Earth would differ from what is actually observed. For a whole series of calculations and comparisons, it is often convenient to eliminate the influence of the atmosphere on radiation, to have a concept of radiation in its purest form. For this purpose, the so-called solar constant is calculated, that is, the amount of heat per 1 minute. per 1 sq. cm of the black (absorbing all radiation) surface 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 an atmosphere, such a factor influencing radiation as the length of the path of a solar ray in the atmosphere acquires special significance. The greater the thickness of the air must penetrate the sun's beam, the more energy it will lose in the processes of scattering, reflection and absorption. The length of the path of the beam directly depends on the height of the Sun above the horizon and, consequently, on the time of day and season. If the length of the path of a solar ray through the atmosphere at a height of the Sun of 90 ° is taken as unity, then the length of the path at a height of the Sun of 40 ° will double, at a height of 10 ° it will become equal to 5.7, etc.

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

Finally, it must be remembered that although the intensity of radiation is measured in relation to a surface that absorbs all radiation, in fact, solar energy falling on bodies of different nature 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 space, the surface of a reservoir, etc., vary 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 soil: dry blue clay reflects 23% of radiation, the same wet clay 16%. Consequently, even with the same influx of radiation, in the same relief conditions, different points on the earth's surface will receive different amounts of heat.

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

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Solar radiation is understood as the radiation of 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 scattered radiation together make up total solar radiation.

The total solar radiation is determined by the thermal action per unit surface per unit of 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, 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. When moving towards the poles, the sun's rays fall already at an increasing inclination 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, the total solar radiation is affected not only by geographic latitude.

Solar radiation and its impact on the human body and climate

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

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

Causes of solar radiation

Solar radiation is generated in the daytime during chromospheric flares - giant explosions that occur in the Sun's atmosphere. Part 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 the primary cosmic radiation, giving rise to a cascade 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 that affects a person.

Spectrum of solar radiation

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 solar radiation falls on 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 it passes through the layers of the atmosphere, the action of the sun's rays weakens - all ionizing radiation, X-rays and almost 98% of ultraviolet are retained by the earth's atmosphere. Almost without loss, visible light and infrared radiation reach the earth, 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 the geographical location of the area.

Where is solar ionizing radiation stronger?

The greatest power of cosmic rays is fixed 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, the radiation increases with height - at an altitude of 10 kilometers above sea level, its figure increases by 20-25 times. Residents of high mountains are exposed to the active influence of higher doses of solar radiation, since the atmosphere in the mountains is thinner and easier to be shot through by gamma quanta and elementary particles coming from the sun.

Important. A radiation level of up to 0.3 mSv/h does 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 on its territory for no more than six months. If the readings are doubled, 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 height every hundred meters this figure increases by 0.03 mSv / year. After carrying out small calculations, we can conclude that a weekly vacation in the mountains at an altitude of 2000 meters will give an exposure of 1 mSv / year and provide almost half of the total annual norm (2.4 mSv / year).

It turns out that the inhabitants of the mountains receive an annual dose of radiation many times higher than the norm, and should suffer from leukemia and cancer more often than people living on the plains. Actually, it is not. On the contrary, lower mortality from these diseases is recorded in mountainous regions, and part of the population is long-livers. This confirms the fact that a long stay in places of high radiation activity does not adversely affect the human body.

Solar flares - high radiation hazard

Flares on the Sun are a great danger to humans and all life on Earth, since the density of the solar radiation flux can exceed the usual 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. On the basis of the charts 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 lot of data has been received that testifies to the connection of eleven-year cycles of solar activity with 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 have increased blood clotting, and since in patients with heart diseases the compensatory activity is depressed, there are malfunctions in its work, up to necrosis of the heart tissue and hemorrhages in the brain.

Large solar flares do not occur as often - once every 4 years. At this time, the number and size of spots increases, powerful coronal rays are formed in the solar corona, consisting of protons and a small amount of alpha particles. Astrologers registered their most powerful stream in 1956, when the density of cosmic radiation on the earth's surface increased by 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, the increased background radiation in the mountains is not a reason to refuse trips to the mountains. True, 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. In an area where the meter reading shows an ionizing radiation value of 7 μSv / h, you should not stay for more than one month.

Total solar radiation and radiation balance

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

Before sunrise, the total radiation consists entirely, and at low altitudes of the sun - mainly from scattered radiation. With an increase in the height of the sun, the fraction of scattered radiation in the composition of the total at 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 proportion of scattered radiation in the total.

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

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

Solar radiation or ionizing radiation from the sun

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

The total radiation also significantly depends on the latitude of the place. With a decrease in latitude, its daily totals increase, and the smaller 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 variation. For example, in Pavlovsk (φ \u003d 60 °) its monthly amounts range from 12 to 407 cal / cm 2, in Washington (φ \u003d 38.9 °) - from 142 to 486 cal / cm 2, and in Takubai (φ \u003d 19 °) - from 307 to 556 cal / cm 2. 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 total radiation in this area in the warmest month (December) is approximately 1.5 times greater than at the same latitudes in the Arctic, and is equal to the corresponding amounts in the Crimea and in Tashkent. Even the annual amount of total radiation in Antarctica is greater than, for example, in St. Petersburg. Such a significant arrival of solar radiation in Antarctica is explained by the dryness of the air, the high altitude of the Antarctic stations above sea level, and the high reflectivity of the snow surface (70-90%), which increases scattered radiation.

The difference between all the radiant energy flows coming to 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 input and output 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 counterradiation of the atmosphere. The radiation consumption is composed of the reflected short-wave, long-wave radiation of the active surface and the part of the counter-radiation of the atmosphere reflected from it.

The radiation balance is the actual income or consumption of radiant energy on the active surface, which determines whether it will be heated or cooled. If the income of radiant energy is greater than its consumption, then the radiation balance is positive and the surface heats up. If the input is less than the output, 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 affected by the height of the sun, the duration of sunshine, the nature and condition of the active surface, clouding of the atmosphere, the content of water vapor in it, cloudiness, etc.

The instantaneous (minute) balance during the day is usually positive, especially in 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. Approximately 1 hour after sunrise, it becomes positive again. The daily variation of the balance in the daytime with a clear sky is approximately parallel to the course of direct radiation. During the night, the radiation balance usually changes little, but under the influence of variable cloudiness, 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 of 40° north latitude and south of 40° south 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 sums 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 sums 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 the atmosphere, and the outgoing part consists of that part of the long-wave radiation of the earth's surface and atmosphere that goes into the world space. The radiation balance of the Earth-atmosphere system is positive in the belt from 30°S to 30°N, while 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 water body, but also the layers of the atmosphere adjacent to them depends on its value. Knowledge of the radiation balance is of great importance in calculating evaporation, in studying the question of the formation and transformation air masses, when considering the effect of radiation on humans and the plant world.

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DISTRIBUTION OF HEAT AND LIGHT ON THE EARTH

The Sun is the star of the solar system, which is the source of a huge amount of heat and blinding light for the planet Earth. Despite the fact that the Sun is 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 the Earth is observed from a spacecraft during the year, then one can notice that the Sun always illuminates only one half of the Earth, therefore, there will be day there, and at that time there will be night on the opposite half. 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 strongly heat the Earth. The farther from the equator, the angle of incidence of the beam becomes smaller, and consequently, these territories receive less heat. The same power beam of solar radiation heats a much smaller area near the equator, since it falls vertically. In addition, rays falling at a smaller angle than at the equator - penetrating the atmosphere, pass through it bigger way, as a result of which part of the sun's rays are scattered in the troposphere and do not reach the earth's surface. All this indicates that as you move away from the equator to the north or south, the air temperature decreases, as the angle of incidence of the sun's beam decreases.

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

Electromagnetic waves

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

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

Solar radiation: spectral composition

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

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

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

Our luminary

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

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

Solar radiation: definition

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

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

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

How is the distribution

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

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

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

Daylight

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

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

Total radiation

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

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

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

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

Effective Radiation

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

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

On the geographical distribution of radiation

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

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

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

Are we facing global warming?

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

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

Card balance distribution

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

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

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

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

How about us?

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

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

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

About solar insolation

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

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