Life-giving rays.
The sun emits three types of 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 only small doses of solar radiation have a beneficial effect on the body.
But heavily tanned skin is still damaged skin and, as a result, premature aging and a high risk of developing skin cancer.
Sunlight is 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, weaken protective system skin, making it more susceptible to infections and possibly cancer.
Ultraviolet rays B.
Rays of this type 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 increases the activity of free radicals, which weaken the skin's natural defense system.
Ultraviolet B rays promote tanning and cause sunburn, leading to premature aging and the appearance of dark pigment spots, make the skin rough and rough, accelerate the appearance of wrinkles, and can provoke the development of precancerous diseases and skin cancer.
The sun emits its energy in all wavelengths, but in different ways. Approximately 44% of the radiation energy is in the visible part of the spectrum, and the maximum corresponds to the yellow-green color. About 48% of the energy lost by the Sun is carried away by near and far infrared rays. Gamma rays, X-rays, ultraviolet and radio radiation account for only about 8%.
The visible part of solar radiation, when studied using spectrum-analyzing instruments, turns out to be inhomogeneous - absorption lines first described by J. Fraunhofer in 1814 are observed in the spectrum. These lines arise when photons of certain wavelengths are absorbed by atoms of various chemical elements in the upper, relatively cold, layers of the Sun's atmosphere. Spectral analysis makes it possible to obtain information about the composition of the Sun, since a certain set of spectral lines exclusively accurately characterizes chemical element. For example, using observations of the spectrum of the Sun, the discovery of helium was predicted, which was isolated later on Earth.
During observations, scientists found that the Sun is a powerful source of radio emission. Radio waves penetrate into interplanetary space and are emitted by the chromosphere (centimeter waves) and the corona (decimeter and meter waves). Radio emission from the Sun has two components – constant and variable (bursts, “noise storms”). During strong solar flares, radio emission from the Sun increases thousands and even millions of times compared to radio emission from the quiet Sun. This radio emission is non-thermal in nature.
X-rays come mainly from upper layers chromosphere and corona. The radiation is especially strong during the years of maximum solar activity.
The sun emits not only light, heat and all other types of electromagnetic radiation. It is also a source of a constant flow of particles - corpuscles. Neutrinos, electrons, protons, alpha particles, as well as heavier ones atomic nuclei all together constitute the corpuscular radiation of the Sun. A significant part of this radiation is a more or less continuous outflow of plasma - the solar wind, which is a continuation of the outer layers of the solar atmosphere - the solar corona. Against the background of this constantly blowing plasma wind, individual regions on the Sun are sources of more directed, enhanced, so-called corpuscular flows. Most likely, they are associated with special regions of the solar corona - coronal holes, and also, possibly, with long-lived active regions on the Sun. Finally, the most powerful short-term fluxes of particles, mainly electrons and protons, are associated with solar flares. As a result of the most powerful flares, particles can acquire speeds that are a noticeable fraction of the speed of light. Particles with such high energies are called solar cosmic rays.
Solar corpuscular radiation has a strong influence on the Earth, and primarily on the upper layers of its atmosphere and magnetic field, causing many geophysical phenomena. The Earth's magnetosphere and atmosphere protect us from the harmful effects of solar radiation.
The spectral composition of solar radiation changes 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 response to sunlight is the result 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 above 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 action - 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 of infrared 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, the movement of air and water masses occurs, the formation of cyclones and anticyclones, warm and cold currents, a variety of 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 differently visible rays. 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 the function of the 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 action per person. 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 decreased performance, emotional instability, increased appetite and the 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.
Main part solar energy reaches the earth in the form of three components: visible light (40%) and infrared radiation (50%), ultraviolet (10%). The most significant and well-studied part of solar radiation is ultra-violet rays. They are represented by three types of different wavelengths and are designated by letters of the Latin alphabet: UVC rays are the shortest (190-280 nm). UVB rays are mid-wave (280-320 nm) and UVA rays are long-wave (320-400 nm). When talking about the effects of ultraviolet radiation on humans, we mean exposure to UVB and UVA rays. Short UVC rays are almost completely absorbed by the ozone layer of the atmosphere, as are short and very active cosmic γ rays. These rays are destructive to all life on the surface of the earth, so the problem of the integrity of the ozone layer is of concern to scientists around the world. Artificial UVC rays are used to disinfect rooms.
UVB rays are more scattered when passing through atmospheric layers than UVA, and the level of UVB radiation decreases with increasing latitude. In addition, its intensity depends on the time of year and varies significantly throughout the day.
Most UVB is absorbed by the ozone layer, unlike UVA, and its share of all ultraviolet radiation energy on a summer afternoon is about 3%.
The penetration ability through the barrier is also different. skin. Thus, UVB rays are reflected by 70% by the stratum corneum, attenuated by 20% when passing through the epidermis, and reach only 10% by the dermis. Due to absorption, reflection and scattering, UVA rays penetrate into the dermis with less loss - 20-30% and about 1% of the total energy reaches the subcutaneous tissue.
For a long time it was believed that the share of UVB rays in the damaging effects of ultraviolet radiation is 80%, since it is this spectrum that is responsible for the occurrence of sunburn erythema. Today, a number of biological effects of solar radiation are known, with a predominance of different ultraviolet ranges. Darkening of melanin (light and quickly passing tan) occurs under the influence of UVA within a few hours and is associated with photooxidation of existing melanin and its rapid redistribution along the processes of melanocytes into epidermal cells. Delayed tanning develops after 3 days and is caused by exposure to UVB rays. It is caused by the active synthesis of melanin in melanosomes, an increase in the number of melanocytes and the activation of synthetic processes in previously inactive melanocytes. Delayed tanning is more permanent.
Vitamin D3 synthesis occurs under the influence of UVB rays. Daily exposure of the face and hands for approximately 15 minutes is considered sufficient, according to WHO. It is also necessary to take into account the geographical factor, since at some latitudes high level UVA irradiation and low UVB rays, which may be insufficient for the synthesis of vitamin D 3 .
Strong exposure to ultraviolet radiation manifests itself in the form of solar erythema and/or burn. UVB rays are erythematogenous. The term “minimum erythemal dose” (MED) is often used to assess the effect of UV irradiation - the energetic exposure to UV radiation that causes barely noticeable erythema in previously unirradiated skin. For light skin, 1 MED is 200-300 J/m2. However, the amount of radiation required for the development of erythema is purely individual and depends on the type of skin and its physiological sensitivity to sunlight.
The effect of UVB on normal skin not accustomed to the sun causes a photoprotective reaction - the synthesis of melanin by melanocytes, an increase in the number of melanosomes. This limits the entry of ultraviolet radiation to the basal layer and to the melanocytes. Along with this, hyperplasia of the epidermis is observed due to the proliferation of keratinocytes, which also leads to the scattering and weakening of UV radiation. These changes are adaptive in nature and allow the skin to withstand subsequent irradiation.
UVA irradiation does not cause sunburn. However, with long-term exposure (months, years), it is these rays that cause the appearance of signs of photoaging, as well as UV-induced carcinogenesis. UVA is a major factor in the cytotoxic effects of sunlight in the basal layer of the epidermis, through the formation of free radicals and damage to DNA strands. Since UVA radiation does not thicken the epidermis, the tan it produces is ineffective as protection against subsequent radiation.
The effect of ultraviolet radiation on the immune system is known. A number of researchers suggest that UV irradiation suppresses the reactions of the human immune system. UVA and UVB radiation can activate the herpes virus. Experimental data on the possible activation of HIV, according to WHO, have not been confirmed. However, with a lack of ultraviolet radiation, a decrease in immunity is also observed (complement titer, lysozyme activity, etc. decreases). The use of preventive courses of UV radiation in conditions of its deficiency (in northern latitudes) has a pronounced adaptive effect.
Langerhans cells (migrating dendritic cells) play a role in immunological recognition and are extremely sensitive to ultraviolet light. Their function is disrupted when suberythemal radiation doses are reached (1/2 MED). Attracts attention and more long term restoration of the population of these cells after UVA irradiation (2-3 weeks) rather than after UVB (48 hours).
It is believed that the influence of UV radiation on the incidence of skin cancer has been reliably established. Experts have different opinions regarding the influence of UV on the occurrence of melanoma. Often there is a predominant development of melanomas in open areas of the body exposed to excessive sunlight. The incidence of melanoma continues to rise, with lower rates of incidence among black people in the same geographic areas. In Europe, morbidity and mortality are much higher than in northern countries.
Paradoxically, melanoma mortality decreases with increasing UVB dose. This positive influence may be associated both with the stimulation of the photoprotective effect and with the synthesis of vitamin D. Oncologists consider the hormonal form vit D 3 -calcitriol, synthesized in the kidneys, as a factor regulating the differentiation and proliferation of tumor cells. The required dose for the synthesis of vitD3 is small and amounts to about 55 MED per year.
Among the natural photoprotection factors of humans, melanin holds a special place. The quantity and quality of melanin determines resistance to ultraviolet exposure and is associated with the color of the skin, hair, and eyes. The activity of melanogenesis and the ability of the skin to tan formed the basis for dividing people into phototypes.
Type 1 - always burns, never tans (redheads, albinos);
Type 2 - sometimes get sunburned, have difficulty achieving a tan (blonds);
Type 3 - sometimes burn, may tan (Caucasians);
Type 4 - only small areas burn, always tan (Asians, Indians);
Type 5 - rarely burn, acquire an intense tan (Dravidians, Australian aborigines);
Type 6 - never burns, tans heavily (Negroids).
Significant differences were noted in the number and distribution of melanosomes in white and black people: the latter have a larger number of melanosomes, and with a more even distribution in the skin. As a result, even a tanned, white-skinned person is less protected from exposure to ultraviolet radiation.
Among the factors of natural photoprotection, the DNA repair system is especially important. Cells have a number of defense mechanisms by which they can repair damage to DNA strands. In particular, the repair mechanism is used by excision, during which small area The damaged DNA strand is removed and replaced by a newly synthesized undamaged section. Many cells use the photoreactivation mechanism for DNA repair, with the help of which damage can be corrected without splitting the DNA molecule. In this case, an enzyme binds to a DNA molecule containing a pyrimidine dimer. As a result of the absorption of light (300-500 nm) by the DNA enzyme complex, the enzyme is activated and restores the damaged part of the molecule, cleaving dimers to form normal pyrimidine bases.
Today, there are many requirements for newly created drugs, taking into account their effectiveness and safety for the consumer. The most familiar and understandable sun protection factor is SPF. This is a coefficient expressing the ratio of the DER of skin protected by a UV filter to the DER of unprotected skin. SPF targets the erythema effect caused by UVB radiation. Because UVA damage is not associated with erythema, SPF does not provide any information about UVA protection. Currently, several indicators are used, which are based on the severity of immediate and delayed skin pigmentation that occurs in response to the action of UVA rays, protected and unprotected by a photoprotector (IPD-immediate pigment darkening, PPD-persistent pigment darkening). A factor based on the degree of phototoxicity is also used.
For European manufacturers photoprotective agents today there is a unified Colipa classification that evaluates valid values SPF: low photoprotection - 2-4-6; average photoprotection - 8-10-12; high photoprotection - 15-20-25; very high photoprotection - 30-40-50; maximum photoprotection - 50+.
Sunscreens use two groups of compounds that differ in their mechanism of protective action. The first is screens, which are mineral compounds by chemical nature. They reflect and refract the sun's rays and, as a rule, “work” on the surface of the skin. These include zinc dioxide (ZnO), titanium dioxide (TiO 2), iron oxide (FeO Fe 3 O 4).
Another group is chemical filters, which are organic compounds. They absorb ultraviolet radiation and are converted into photoisomers. Absorbed energy at reverse process is released in safe long-wave radiation.
UVB filters include: cinnamates, benzophenone, para-aminobezoic acid, salicylates, camphor derivatives; UVA filters are dibenzoylmethane, benzophenone, camphor derivatives, compounds that can penetrate deep into the epidermis.
The most widely used drugs (until the end of the 1980s) were those containing para-aminobenzoic acid esters (PABA). Now they have been replaced by oxybenzone, octocrylene, anthranilates and cinnamates.
In addition to the absorption spectrum, the extinction coefficient is also important, i.e. how actively the drug absorbs energy (how effective it is). Values of at least 20,000 are considered effective (butyimethoxydibenzoyl methane - 31,000, octyldemethil PABA - 28,400, ethylhexyl p-methoxycinnamate - 24,200).
Next important feature sunscreens is photostability - the ability to maintain its structure and properties under the influence of radiation. Some chemical filters are subject to significant photolysis. For example, 15 minutes after exposure to sunlight, a decrease in activity is observed: octyldimetyl PABA - by 15%, avobenzone - up to 36%, octyl-p-methoxycinnamate - by 4.5%.
The stability of a drug reflects its ability to remain on the skin and maintain its absorption capacity. This is extremely important because the sunscreen is used outside comfortable conditions: in the heat (sweating), when swimming, physical activity.
If a sunscreen product (SFP) only absorbs UVB rays and is ineffective against UVA rays, it can create a false sense of safety for prolonged sun exposure.
The most high demands The sun protection line “Photoderm” corresponds to the requirements for SZP. The introduction of innovative molecules makes it possible to combine the advantages of both filters and screens, avoiding the disadvantages of both groups. Today, Photoderm has the widest possible spectrum of photoprotection, including UVB and UVA rays, and protects epidermal cells, including Langerhans cells, from the mutational effects of ultraviolet radiation.
The effect is created thanks to special microparticles: Tinosorb M - an organic screen, Tinosorb S - a new chemical filter. New generation compounds that can effectively absorb UVB and UVA rays, including short UVA (320-340 nm) and long UVA (340-400 nm). The “Cellular Bioprotection” filter developed by the Bioderma laboratory, consisting of two natural molecules (ectoine and mannitol), allows you to protect Langerhans cells, protect DNA structures, stimulate protein synthesis to prevent thermal shock, and preserve the immune system.
"Photoderm max" is a representative of an extreme degree of protection against the entire spectrum of ultraviolet exposure, endowed with oncoprotective activity.
The staff of the Bioderma laboratory have developed specific photoprotective products, taking into account the characteristics of photodependent conditions: for patients with vitiligo - “Photoderm max tonal”, for patients suffering from rosacea - “Photoderm AR”, for adolescents with acne - “Photoderm AKN”, for local hyperpigmentation - "Photoderm SPOT".
Until now, the subject of debate among supporters and opponents of tanning remains main question: is ultraviolet light useful or harmful for humans? The undoubted benefit is evidenced by the fact that sun rays have been used since the beginning of the century to treat a variety of diseases (so-called “heliotherapy”). Sun rays have a pronounced antidepressant effect. Full-spectrum lighting with low ultraviolet emission is used in the treatment of seasonal affective disorders. Dermatological diseases (psoriasis, atopic dermatitis, scleroderma, ichthyosis) can be treated with ultraviolet light.
The sun is a difficult friend and ally. Even a healthy person planning a vacation in an unfamiliar region needs to consult with a specialist so that the vacation will improve his health.
For questions regarding literature, please contact the editor.
L. O. Mechikova, V. V. Savenkov
KVD No. 3, Moscow
The sun plays an important role for us on Earth. It provides for the planet and everything on it important factors such as light and heat. But what is solar radiation, the spectrum of sunlight, how does all this affect us and the global climate as a whole?
What is solar radiation?
Bad thoughts usually come to mind when you think of the word radiation. But solar radiation is actually very a good thing- this is sunlight! Every living creature on Earth depends on it. It is essential for survival, warms the planet, and provides nutrition for plants.
Solar radiation is all the light and energy that comes from the sun, and there are many different forms of it. In the electromagnetic spectrum there are Various types light waves emitted by the sun. They are like the waves you see in the ocean: they move up and down and from one place to another. The solar study spectrum can have different intensities. There are ultraviolet, visible and infrared radiation.
Light is moving energy
The spectrum of solar radiation figuratively resembles a piano keyboard. One end has low notes, while the other has high notes. The same applies to the electromagnetic spectrum. One end has low frequencies and the other has high frequencies. Low frequency waves are long for a given period of time. These are things like radar, television and radio waves. High-frequency radiation is high-energy waves with a short wavelength. This means that the wavelength itself is very short for a given period of time. These are, for example, gamma rays, x-rays and ultraviolet rays.
You can think of it this way: low-frequency waves are like climbing a hill with a gradual rise, while high-frequency waves are like quickly climbing a steep, almost vertical hill. In this case, the height of each hill is the same. The frequency of an electromagnetic wave determines how much energy it carries. Electromagnetic waves, which have longer wavelengths and therefore lower frequencies, carry much less energy than those with shorter lengths and higher frequencies.
This is why X-rays can be dangerous. They carry so much energy that if they enter your body, they can damage cells and cause problems such as cancer and changes in DNA. Things like radio and infrared waves, which carry much less energy, don't really have any effect on us. This is good because you certainly don't want to put yourself at risk by simply turning on the stereo.
Visible light, which we and other animals can see with our eyes, is located almost in the middle of the spectrum. We don't see any other waves, but that doesn't mean they aren't there. In fact, insects see ultraviolet light, but not our visible light. Flowers look very different to them than they do to us, and this helps them know which plants to visit and which ones to stay away from.
Source of all energy
We take sunlight for granted, but it doesn't have to be that way because essentially all the energy on Earth depends on that big, bright star at the center of our planet. solar system. And while we're at it, we should also say thank you to our atmosphere, because it absorbs some of the radiation before it reaches us. It's an important balance: too much sunlight and the Earth gets hot, too little and it starts to freeze.
Passing through the atmosphere, the spectrum of solar radiation at the Earth's surface provides energy in different forms. First, let's look at various ways her transmissions:
- Conduction is when energy is transferred from direct contact. When you burn your hand on a hot frying pan because you forgot to put on an oven mitt, that's conduction. The cookware transfers heat to your hand through direct contact. Additionally, when your feet touch cold bathroom tiles in the morning, they transfer heat to the floor through direct contact - conduction in action.
- Dissipation is when energy is transferred through currents in a fluid. It can also be gas, but the process will be the same in any case. When a liquid is heated, the molecules are excited, loose and less dense, so they tend to move upward. When they cool, they fall back down, creating a cellular flow path.
- - this is when energy is transferred in the form electromagnetic waves. Think about how good it is to sit next to a fire and feel the welcoming warmth radiating from it to you - that's radiation. Radio waves and light can travel by moving from one place to another without the help of any materials.
Basic spectra of solar radiation
The sun has different radiations: from X-rays to radio waves. Solar energy is light and heat. Its composition:
- 6-7% ultraviolet light,
- about 42% visible light,
- 51% near infrared.
We receive solar energy at an intensity of 1 kilowatt per square meter at sea level for many hours a day. About half of the radiation is in the visible short-wavelength part of the electromagnetic spectrum. The other half is in the near-infrared, and a little in the ultraviolet part of the spectrum.
Ultraviolet radiation
It is ultraviolet radiation in the solar spectrum that has an intensity greater than others: up to 300-400 nm. The portion of this radiation that is not absorbed by the atmosphere produces tanning or sunburn for people who have been in sunlight for a while long periods time. Ultraviolet radiation in sunlight has both positive and negative consequences for good health. It is the main source of vitamin D.
Visible radiation
Visible radiation in the solar spectrum has an average intensity. Quantitative estimates of the flux and variations in its spectral distribution in the visible and near-infrared regions of the electromagnetic spectrum are of great interest in the study of solar-terrestrial forcing. The range from 380 to 780 nm is visible to the naked eye.
The reason is that the bulk of solar radiation energy is concentrated in this range and it determines the thermal equilibrium of the Earth's atmosphere. Sunlight is a key factor in the process of photosynthesis, which is used by plants and other autotrophic organisms to convert light energy into chemical energy that can be used as fuel for the body.
Infrared radiation
The infrared spectrum, which spans from 700 nm to 1,000,000 nm (1mm), contains an important part of the electromagnetic radiation that reaches the Earth. Infrared radiation in the solar spectrum has three types of intensities. Scientists divide this range into 3 types based on wavelength:
- A: 700-1400 nm.
- B: 1400-3000 nm.
- C: 3000-1 mm.
Conclusion
Many animals (including humans) have sensitivity ranging from about 400-700 nm, and the useful spectrum of color vision in humans, for example, is about 450-650 nm. In addition to the effects that occur at sunset and sunrise, the spectral composition changes primarily in relation to how directly sunlight hits the ground.
Every two weeks the Sun supplies our planet with so much energy that it is enough for all inhabitants to live. whole year. In this regard, solar radiation is increasingly being considered as an alternative source of energy.