Radiation from the sun. Spectral composition of sunlight

>What is the Sun made of?

Find out what is the sun made of: description of the structure and composition of the star, listing of chemical elements, number and characteristics of layers with photos, diagram.

From Earth, the Sun looks smooth fireball, and before the Galileo spacecraft discovered sunspots, many astronomers believed that it perfect shape no defects. Now we know that The sun consists from several layers, like the Earth, each of which performs its own function. This massive furnace-like structure of the Sun is the supplier of all the energy on Earth needed for terrestrial life.

What elements does the Sun consist of?

If you could take the star apart and compare its constituent elements, you would realize that the composition is 74% hydrogen and 24% helium. Also, the Sun consists of 1% oxygen, and the remaining 1% is such chemical elements periodic tables, such as chromium, calcium, neon, carbon, magnesium, sulfur, silicon, nickel, iron. Astronomers believe that an element heavier than helium is a metal.

How did all these elements of the Sun come into being? As a result Big Bang hydrogen and helium appeared. At the beginning of the formation of the Universe, the first element, hydrogen, emerged from elementary particles. Because of high temperature and the pressure conditions in the Universe were like in the core of a star. Later, hydrogen was fused into helium while the universe had the high temperature required for the fusion reaction to occur. The existing proportions of hydrogen and helium that are in the Universe now developed after the Big Bang and have not changed.

The remaining elements of the Sun are created in other stars. In the cores of stars, the process of synthesis of hydrogen into helium constantly occurs. After producing all the oxygen in the core, they switch to nuclear fusion of heavier elements such as lithium, oxygen, helium. Many heavy metals, which are in the Sun, were also formed in other stars at the end of their lives.

The heaviest elements, gold and uranium, were formed when stars many times larger than our Sun detonated. In a split second of black hole formation, the elements collided high speed and the most heavy elements. The explosion scattered these elements throughout the Universe, where they helped form new stars.

Our Sun has collected elements created by the Big Bang, elements from dying stars, and particles created as a result of new star detonations.

What layers does the Sun consist of?

At first glance, the Sun is just a ball consisting of helium and hydrogen, but upon deeper study it is clear that it is composed of different layers. When moving towards the core, temperature and pressure increase, as a result of this layers were created, since when different conditions Hydrogen and helium have different characteristics.

solar core

Let's begin our movement through the layers from the core to the outer layer of the Sun's composition. In inner layer The sun is the core, the temperature and pressure are very high, conducive to the occurrence of nuclear fusion. The sun creates helium atoms from hydrogen, as a result of this reaction, light and heat are formed, which reach. It is generally accepted that the temperature on the Sun is about 13,600,000 degrees Kelvin, and the density of the core is 150 times higher than the density of water.

Scientists and astronomers believe that the Sun's core reaches about 20% of the length of the solar radius. And inside the core, high temperature and pressure cause hydrogen atoms to break apart into protons, neutrons and electrons. The sun converts them into helium atoms, despite their free-floating state.

This reaction is called exothermic. When this reaction occurs, it releases large number heat equal to 389 x 10 31 J. per second.

Radiation zone of the Sun

This zone originates at the core boundary (20% of the solar radius), and reaches a length of up to 70% of the solar radius. Inside this zone there is solar matter, which in its composition is quite dense and hot, so thermal radiation passes through it without losing heat.

Inside solar core A nuclear fusion reaction occurs - the creation of helium atoms as a result of the fusion of protons. This reaction produces a large amount of gamma radiation. IN this process Photons of energy are emitted, then absorbed in the radiation zone and emitted again by various particles.

The trajectory of a photon is usually called a “random walk.” Instead of moving in a straight path to the surface of the Sun, the photon moves in a zigzag pattern. As a result, each photon needs approximately 200,000 years to overcome the radiation zone of the Sun. When moving from one particle to another particle, the photon loses energy. This is good for the Earth, because we could only receive gamma radiation coming from the Sun. A photon entering space needs 8 minutes to travel to Earth.

A large number of stars have radiation zones, and their sizes directly depend on the scale of the star. How less star, the smaller the zones will be, most of which will be occupied by the convective zone. The smallest stars may lack radiation zones, and the convective zone will reach the distance to the core. At the most big stars the situation is the opposite, the radiation zone extends to the surface.

Convective zone

The convective zone is outside the radiative zone, where the sun's internal heat flows through columns of hot gas.

Almost all stars have such a zone. For our Sun, it extends from 70% of the Sun's radius to the surface (photosphere). The gas in the depths of the star, near the very core, heats up and rises to the surface, like bubbles of wax in a lamp. Upon reaching the surface of the star, heat loss occurs; as it cools, the gas sinks back toward the center, recovering thermal energy. As an example, you can bring a pan of boiling water on fire.

The surface of the Sun is like loose soil. These irregularities are columns of hot gas that carry heat to the surface of the Sun. Their width reaches 1000 km, and the dispersal time reaches 8-20 minutes.

Astronomers believe that low-mass stars such as red dwarfs, which have only convective zone, which extends to the core. They have no radiation zone, which cannot be said about the Sun.

Photosphere

The only layer of the Sun visible from Earth is . Below this layer, the Sun becomes opaque, and astronomers use other methods to study the interior of our star. Surface temperatures reach 6000 Kelvin and glow yellow-white, visible from Earth.

The atmosphere of the Sun is located behind the photosphere. That part of the Sun that is visible during solar eclipse, called .

Structure of the Sun in the diagram

NASA specially developed for educational needs schematic representation of the structure and composition of the Sun, indicating the temperature for each layer:

• (Visible, IR and UV radiation) - this is visible radiation, infrared radiation and ultraviolet radiation. Visible radiation is the light that we see coming from the Sun. Infrared radiation is the heat we feel. Ultraviolet radiation- This is the radiation that gives us a tan. The sun produces these radiations simultaneously.
• (Photosphere 6000 K) – The photosphere is top layer The sun, its surface. A temperature of 6000 Kelvin is equal to 5700 degrees Celsius.
• Radio emissions - In addition to visible radiation, infrared radiation and ultraviolet radiation, the Sun emits radio emissions, which astronomers have discovered using a radio telescope. Depending on the number of sunspots, this emission increases and decreases.
• Coronal Hole - These are places on the Sun where the corona has a low plasma density, as a result it is darker and colder.
• 2100000 K (2100000 Kelvin) – The radiation zone of the Sun has this temperature.
• Convective zone/Turbulent convection (lane Convective zone/Turbulent convection) – These are places on the Sun where thermal energy nuclei are transmitted by convection. Columns of plasma reach the surface, give up their heat, and again rush down to heat up again.
• Coronal loops (trans. Coronal loops) - loops consisting of plasma in the solar atmosphere, moving along magnetic lines. They look like huge arches extending from the surface for tens of thousands of kilometers.
• Core (trans. Core) is the solar heart in which nuclear fusion occurs, with the help high temperature and pressure. All solar energy comes from the core.
• 14,500,000 K (per. 14,500,000 Kelvin) – Temperature of the solar core.
• Radiative Zone (trans. Radiation zone) - A layer of the Sun where energy is transmitted using radiation. The photon overcomes the radiation zone beyond 200,000 and goes into outer space.
• Neutrinos (trans. Neutrino) are negligibly small particles emanating from the Sun as a result of a nuclear fusion reaction. Hundreds of thousands of neutrinos pass through the human body every second, but they do not cause us any harm, we do not feel them.
• Chromospheric Flare (translated as Chromospheric Flare) - The magnetic field of our star can twist, and then abruptly break into various forms. As a result of breaks in magnetic fields, powerful X-ray flares appear from the surface of the Sun.
• Magnetic Field Loop - The Sun's magnetic field is located above the photosphere, and is visible as hot plasma moves along magnetic lines in the Sun's atmosphere.
• Spot– A sunspot (trans. Sunspots) – These are places on the surface of the Sun where magnetic fields pass through the surface of the Sun, and their temperature is lower, often in the form of a loop.
• Energetic particles (trans. Energetic particles) - They come from the surface of the Sun, resulting in the creation solar wind. IN solar storms their speed reaches the speed of light.
• X-rays (trans. X-rays) - rays invisible to the human eye, produced during solar flares.
• Bright spots and short-lived magnetic regions (trans. Bright spots and short-lived magnetic regions) - Due to temperature differences, bright and dim spots appear on the surface of the Sun.

Spectral composition solar radiation varies depending on the height of the Sun above the horizon.

By international classification highlight:

1. Infrared radiation – 760-2600 (3000) nm

2. Visible radiation – 400-760 nm

3. Ultraviolet radiation - at the border with the atmosphere 400-100 nm, on the surface of the earth - 400-290 nm

All types of radiation differ from each other in wavelength (oscillation frequency) and quantum energy. The shorter the wavelength, the greater the energy of the quantum and the correspondingly more pronounced the biological effect of this radiation. Consequently, ultraviolet radiation is characterized by the greatest biological activity.

Infrared radiation makes up most of the solar spectrum (up to 50%). Ultraviolet rays occupy 5% of the spectrum at the boundary with the atmosphere and 1% of UV radiation reaches the earth's surface. Short-wavelength UV radiation (less than 300 nm) is delayed ozone layer Earth.

The body's reaction to action sunlight is the result of the action of all parts of the spectrum. Solar radiation is perceived by the skin and eyes. The physiological action of solar rays is based on various photochemical reactions, the occurrence of which depends on the wavelength and energy of the absorbed quanta of the active radiation.

Infrared radiation

Infrared radiation is produced by any body whose temperature is higher absolute zero. The more it is heated, that is, the higher its temperature, the higher the intensity of the radiation. Infrared radiation penetrates the atmosphere, water, soil, clothing, and window glass.

The absorption coefficient of infrared rays is related to the wavelength, which determines the depth of penetration.

Based on wavelength, infrared radiation is divided into :

1. long wave(over 1400 nm) - retained by the surface layers of the skin and penetrates to a depth of 3 mm, as a result, metabolism accelerates, blood flow, cell growth and tissue regeneration increase, but in large doses it can cause a burning sensation.

2. medium wave(wavelength 1000 – 1400 nm)

3. shortwave(wavelength from 760 to 1000 nm) has great penetrating power. Penetrates to a depth of 4-5 cm, 14% of rays within wavelengths of 1000-1400 nm - to a depth of 3-4 cm.

IR radiation has :

1. thermal effect- influencing molecules and atoms of substances, strengthening them oscillatory movements IR radiation leads to an increase in the temperature of the biosubstrate.

2. photochemical effect - associated with the absorption of energy by tissues and cells, which leads to the activation of enzymatic processes and, as a consequence, to the acceleration of metabolism, the formation of biologically active substances, and the strengthening of regeneration processes and immunogenesis. IR radiation has local and general effects.

When exposed locally to tissue, IF radiation somewhat accelerates biochemical reactions, enzymatic and immunobiological processes, cell growth and tissue regeneration, blood flow, and enhances the biological effect of UV rays.

The general effect is manifested by anti-inflammatory, analgesic, and general tonic effects. These effects are widely used in physiotherapy - through the use of artificial sources IR radiation for the treatment of inflammatory diseases in order to reduce pain in rheumatism, osteochondrosis, etc.

3. affects climate and microclimate. Due to uneven heating earth's surface and evaporation of water occurs air movement and water masses, formation of cyclones and anticyclones, warm and cold currents, diversity climatic zones, weather conditions that indirectly affect humans.

At optimal intensity, infrared radiation produces a pleasant thermal sensation.

The negative impact of infrared radiation is associated with a thermal effect, since the body may overheat with the development of heat or sunstroke.

Visible radiation

Visible radiation affects the skin (penetrates to a depth of 2.5 cm) and eyes. Skin absorbs visible rays differently. Red rays penetrate to a depth of 2.5 cm in an amount of 20%, violet rays up to 1%.

Biological action :

1. causes a sensation of light. Associated with a photochemical effect, which manifests itself in the excitation of molecules of visual pigments in the retina. As a result, electrical impulses are generated in the retina, causing the sensation of light. Thus, visible rays have informational value (information about volume, color, shape, etc.)

2. has a beneficial effect on the body, stimulates its vital functions, improves overall well-being, emotional mood, and increases performance. Poor lighting negatively affects function visual analyzer, as a result of which fatigue quickly develops.

3. enhances metabolism, immunological reactivity, improves the activity of other analyzers, activates excitation processes in the cerebral cortex.

4. thermal effect - about 50% of the total thermal energy of the solar spectrum comes from visible radiation.

5. improving the environment

6. psychogenic significance. Visible radiation can create a range of colors that have different effects on humans. The attitude towards colors is very individual and each color evokes certain sensations in a person (blue - a feeling of coolness, a calming effect, green - calmness, reliability, bright yellow - irritation, red - excitement, purple and blue - depress and promote sleep, blue can enhance state of depression).

7. The intensity and color of visible light changes throughout the day, which has a signaling character and determines the daily biological rhythm of human activity and serves as a source of reflex and conditioned reflex activity.

In the process of evolution, man began to lead an active lifestyle during the daylight hours. Visible light affects sleep and wakefulness, and, consequently, the physiological functions of the body (regulation of body temperature, hormone levels, etc.). Now there is a concept of “light starvation” syndrome, which is characterized by a decrease in performance, emotional instability, increased appetite and need for sleep. This syndrome occurs in people in the autumn-winter period, when living in the Arctic Circle, in people working on the night shift, etc.

In the 80s years XIX centuries in America and Europe, a tanned body was considered beautiful and desirable, which many people aspired to. This gave scientists a lot of reasons and materials for research. They found that skin changes, called age-related, for the most part depend not on the number of years a person has lived, but on harmful effects ultraviolet radiation, which is responsible for tanning.

This is how the theory of photoaging arose - premature aging of the skin under the influence of UV radiation. It is confirmed by data that the skin of residents southern countries ages faster than those who are not spoiled by the sun. Besides, open areas bodies that are not protected by clothing undergo various changes more quickly.

Mechanism of photoaging

Penetrating the skin, UV rays encounter a natural ultraviolet filter - melanin, which blocks more than 90% of ultraviolet radiation. Thus, tanning is nothing more than a reaction of the skin to a traumatic effect. solar radiation. Now many people know that prolonged exposure to ultraviolet radiation contributes to the development of melanoma, skin cancer, accelerates aging and the appearance of wrinkles.

Types of UV radiation

Types of Sun Rays
Ultraviolet radiation is divided into three components: rays A, B and C (UVA, UVB, UVC rays, respectively). When sunlight passes through earth's atmosphere The most dangerous UVC rays and about 90% of mid-range UVB rays are absorbed by ozone, oxygen and carbon dioxide. Therefore, radiation reaching a person is to a greater extent contains ultraviolet UVA and small quantity UVB.

Why are UVB rays dangerous?
UVB rays promote the formation of melanin, lead to photoaging of the skin, and also stimulate the development of most types of skin cancer, but they are blocked by protective substances contained in sunscreens.

Why are UVA rays dangerous?
UVA rays are less active in stimulating the development of many types of skin cancer than UVB, but they contribute to the formation of melanoma, the most dangerous type of skin cancer. In addition, this radiation is not blocked by many solar filters, so the main protection against it is clothing.

Why is ultraviolet radiation dangerous for humans?

• it reduces the production of collagen - a protein in the body's connective tissue, due to the lack of which the skin loses its elasticity and wrinkles appear on it;
• it provokes coarsening and thickening of the stratum corneum of the skin, as a result of which it becomes dry, dull and rough;
• it provokes vascular changes, impaired skin pigmentation, and the development of neoplasms.

About the benefits of the sun

A place in the sun
Despite the dangers of ultraviolet radiation for the body, it can be beneficial in small doses. To do this, it is enough just to expose your face or hands to sunlight a few times a week for 10-15 minutes.

Healing ultraviolet light:

• Under the influence of ultraviolet radiation, vitamin D is synthesized in the body, which regulates calcium metabolism and serves as a building material for bone tissue;
• sunlight activates immune system, increases the body's resistance to viruses and infections;
• the sun has a beneficial effect on nervous system a person, increasing the production of endorphins (the hormone of joy) and thereby improving mood;
• in small doses, ultraviolet radiation prevents the occurrence of diseases cardiovascular system, musculoskeletal system (osteochondrosis, arthritis) and respiratory system (bronchitis, rhinitis), dermatological diseases (psoriasis, neurodermatitis, eczema, etc.), cerebrovascular insufficiency.

How to tan properly

You need to start sunbathing little by little, in the morning and evening hours, spending 10 to 15 minutes in the sun intermittently. Both dark-skinned and pale-skinned people should be sure to use sunscreens that are appropriate for their skin type and have the appropriate SPF. They should be applied to the skin 20-30 minutes before going outside.
Those with particularly sun-sensitive skin should stay in the shade as often as possible and use products with the highest SPF factor (Sun Protection Factor). Your eyes and lips also need protection from the sun, so you should use sunscreen around your eyes, lip balm with SPF, and wear sunglasses when going outside.

Peels are considered effective means to eliminate
symptoms of skin photoaging. They have exfoliating
action, and also restore tone and beauty to the skin.

Elena Kobozeva, dermatovenerologist, cosmetologist:“Ultraviolet radiation is the main factor in skin aging. With excessive sun exposure, it provokes the so-called fine-wrinkle type of aging. The skin becomes like a wrinkled baked apple, covered with a network of fine wrinkles. In addition, ultraviolet radiation provokes the formation of age spots. This becomes especially noticeable over the age of 35. Therefore, in summer it is necessary to constantly protect the skin with sunscreens with high factor protection."

Expert: Elena Kobozeva, dermatovenerologist, cosmetologist
Katerina Kapustina

Life-giving rays.

The sun emits three types ultraviolet rays. Each of these types affects the skin differently.

Most of us feel healthier and healthier after spending time at the beach. full of life. Thanks to the life-giving rays, vitamin D is formed in the skin, which is necessary for the complete absorption of calcium. But they only have a beneficial effect on the body small doses solar radiation.

But heavily tanned skin is still damaged skin and, as a consequence, premature aging and high risk development of skin cancer.

Sunlight - electromagnetic radiation. In addition to the visible spectrum of radiation, it contains ultraviolet radiation, which is actually responsible for tanning. Ultraviolet light stimulates the ability of melanocyte pigment cells to produce more melanin, which performs a protective function.

Types of UV rays.

There are three types of ultraviolet rays, which differ in wavelength. Ultraviolet radiation is able to penetrate through the epidermis of the skin into deeper layers. This activates the production of new cells and keratin, resulting in tighter, rougher skin. Sun rays penetrating the dermis destroy collagen and lead to changes in the thickness and texture of the skin.

Ultraviolet rays A.

These rays have the most low level radiation. Previously, it was generally believed that they were harmless, however, it has now been proven that this is not the case. The level of these rays remains almost constant throughout the day and year. They even penetrate glass.

UV A rays penetrate through the layers of the skin, reaching the dermis, damaging the base and structure of the skin, destroying collagen and elastin fibers.

A-rays promote the appearance of wrinkles, reduce skin elasticity, accelerate the appearance of signs of premature aging, and weaken the skin's defense system, making it more susceptible to infections and possibly cancer.

Ultraviolet rays B.

This type of rays are emitted by the sun only at certain times of the year and hours of the day. Depending on the air temperature and geographical latitude they usually enter the atmosphere between 10 a.m. and 4 p.m.

UVB rays cause more serious damage to the skin because they interact with DNA molecules found in skin cells. B rays damage the epidermis, leading to sunburn. B rays damage the epidermis, leading to sunburn. This type of radiation enhances activity free radicals, which weaken the skin's natural defense system.

Ultraviolet B rays promote tanning and cause sunburn, lead to premature aging and the appearance of dark age spots, make the skin rough and rough, accelerate the appearance of wrinkles, and can provoke the development of precancerous diseases and skin cancer.

The peculiarities of the impact of direct sunlight on the body today are of interest to many, primarily those who want to spend the summer profitably and stock up on solar energy and get a beautiful healthy tan. What is solar radiation and what effect does it have on us?

Definition

Sun rays (photo below) are a stream of radiation, which is represented by electromagnetic oscillations of waves of different lengths. The spectrum of radiation emitted by the sun is diverse and wide, both in wavelength and frequency, and in its effect on the human body.

Types of sun rays

There are several regions of the spectrum:

1. Gamma radiation.
2. X-ray radiation (wavelength less than 170 nanometers).
3. Ultraviolet radiation (wavelength - 170-350 nm).
4. Sunlight (wavelength - 350-750 nm).
5. Infrared spectrum, which has a thermal effect (wavelengths greater than 750 nm).

In terms of biological influence The most active rays of the sun on a living organism are ultraviolet rays. They promote tanning, have a hormonal protective effect, stimulate the production of serotonin and other important components, increasing vitality and vitality.

Ultraviolet radiation

There are 3 classes of rays in the ultraviolet spectrum that affect the body differently:

1. A-rays (wavelength - 400-320 nanometers). They have the lowest level of radiation and remain constant in the solar spectrum throughout the day and year. There are almost no barriers for them. Harmful influence This class of sun rays on the body is the lowest, however, their constant presence accelerates the process of natural aging of the skin, because, penetrating to the germ layer, they damage the structure and base of the epidermis, destroying elastin and collagen fibers.
2. B-rays (wavelength - 320-280 nm). Only in certain times years and hours of the day reach the Earth. Depending on the geographic latitude and air temperature, they usually enter the atmosphere from 10 a.m. to 4 p.m. These sun rays take part in activating the synthesis of vitamin D3 in the body, which is their main positive property. However, with prolonged exposure to the skin, they can change the genome of cells in such a way that they begin to multiply uncontrollably and form cancer.
3. C-rays (wavelength - 280-170 nm). This is the most dangerous part of the UV radiation spectrum, which unconditionally provokes the development of cancer. But in nature everything is arranged very wisely, and the harmful rays of the sun, like most(90 percent) B-rays are absorbed by the ozone layer before reaching the Earth's surface. This is how nature protects all living things from extinction.

Positive and negative influence

Depending on the duration, intensity, frequency of exposure to UV radiation in human body positive and negative effects. The first include the formation of vitamin D, the production of melanin and the formation of a beautiful, even tan, the synthesis of mediators that regulate biorhythms, and the production of an important regulator endocrine system- serotonin. That’s why after summer we feel a surge of strength, an increase in vitality, and a good mood.

The negative effects of ultraviolet exposure include skin burns, damage to collagen fibers, the appearance of cosmetic defects in the form of hyperpigmentation, and the provocation of cancer.

Vitamin D synthesis

When exposed to the epidermis, the energy of solar radiation is converted into heat or spent on photochemical reactions, as a result of which various biochemical processes are carried out in the body.

Vitamin D is supplied in two ways:

• endogenous - due to formation in the skin under the influence of UV rays B;
• exogenous - due to intake from food.

The endogenous route is quite complex process reactions that occur without the participation of enzymes, but with the obligatory participation of UV irradiation with B-rays. With sufficient and regular insolation, the amount of vitamin D3 synthesized in the skin during photochemical reactions fully meets all the body's needs.

Tanning and vitamin D

Activity photochemical processes in the skin directly depends on the spectrum and intensity of exposure ultraviolet irradiation and is located in inverse relationship from tanning (degree of pigmentation). It has been proven that the more pronounced the tan, the longer it takes for provitamin D3 to accumulate in the skin (instead of fifteen minutes to three hours).

From a physiological point of view, this is understandable, since tanning is defense mechanism our skin, and the layer of melanin formed in it acts as a certain barrier to both UV B rays, which serve as a mediator of photochemical processes, and class A rays, which provide the thermal stage of the conversion of provitamin D3 into vitamin D3 in the skin.

But vitamin D supplied with food only compensates for the deficiency in case of insufficient production during the process of photochemical synthesis.

Vitamin D formation during sun exposure

Today it has already been established by science that to ensure daily requirement In endogenous vitamin D3, it is enough to stay in open sunlight class UV rays for ten to twenty minutes. Another thing is that such rays are not always present in the solar spectrum. Their presence depends both on the season of the year and on geographic latitude, since the Earth, when rotating, changes the thickness and angle of the atmospheric layer through which the sun's rays pass.

Therefore, solar radiation is not always able to form vitamin D3 in the skin, but only when UV B rays are present in the spectrum.

Solar radiation in Russia

In our country, taking into account geographical location rich in UV rays of the class During periods of solar radiation are distributed unevenly. For example, in Sochi, Makhachkala, Vladikavkaz they last about seven months (from March to October), and in Arkhangelsk, St. Petersburg, Syktyvkar they last about three (from May to July) or even less. Add to this the number cloudy days per year, atmospheric smoke in major cities, and it becomes clear that most of the Russian population lacks hormonotropic solar exposure.

This is probably why intuitively we strive for the sun and rush to the southern beaches, while forgetting that the sun's rays in the south are completely different, unusual for our body, and, in addition to burns, can provoke strong hormonal and immune surges that can increase the risk of cancer and other ailments .

At the same time, the southern sun can heal, you just have to follow a reasonable approach in everything.