Spectrum of solar radiation: description, features and interesting facts. Start in science

What is the Sun? On the scale of the visible universe, this is just a tiny star on the outskirts of the galaxy, which is called the Milky Way. But for the planet Earth, the Sun is not just a hot bunch of gas, but a source of heat and light necessary for the existence of all life.

Since prehistoric times, the daylight has been an object of worship, its movement across the firmament has been associated with the manifestation of divine powers. Studies of the Sun and its radiation began even before the adoption of the heliocentric model of Nicolaus Copernicus, they racked their brains over his riddles the greatest minds ancient civilizations.

Technological progress has given humanity the opportunity to study not only the processes inside and on the surface of the Sun, but also changes in the Earth's climate under its influence. Statistical data allow us to give a clear answer to the question of what is solar radiation in which it is measured and determine its impact on the living organisms that inhabit the planet.

What is called solar radiation

The nature of solar radiation remained unclear until, at the beginning of the twentieth century, the eminent astronomer Arthur Eddington suggested that the source of the colossal solar energy are the fusion reactions that occur in its depths. The temperature near its core (about 15 million degrees) is sufficient for the protons to overcome the force of mutual repulsion and, as a result of the collision, form Helium nuclei.

Subsequently, scientists (in particular, Albert Einstein) discovered that the mass of the Helium nucleus is somewhat less than the total mass of the four protons from which it is formed. This phenomenon is called the mass defect. After tracing the relationship between mass and energy, scientists found that this excess is released in the form of gamma quanta.

When passing the path from the core to the surface of the Sun through the layers of its constituent gases, gamma quanta are crushed and turn into electromagnetic waves, among which is the light visible to the human eye. This process takes about 10 million years. And it takes only 8 minutes to reach the solar radiation of the earth's surface.

Solar radiation includes electromagnetic waves with a wide range and the solar wind, which is a stream of light particles and electrons.

What are the types of solar radiation and its characteristics

At the boundary of the Earth's atmosphere, the intensity of solar radiation is a constant value. The energy of the Sun is discrete and is transferred in portions (quanta) of energy, but their corpuscular contribution is relatively small, so the sun's rays are considered as electromagnetic waves that propagate evenly and rectilinearly.

The main wave characteristic is the wavelength, with which the types of radiation are distinguished:

radio waves;
infrared (thermal);
visible (white) light;
ultraviolet;
gamma rays.

Solar radiation is represented by infrared (IR), visible (VS) and ultraviolet (UV) radiation in the ratio of 52%, 43% and 5%, respectively. The quantitative measure of solar radiation is considered to be energy illumination (energy flux density) - radiant energy arriving per unit of time per unit of surface.

Distribution of solar radiation over the earth's surface

Most of the radiation is absorbed by the earth's atmosphere and heats it up to the usual temperature for living organisms. The ozone layer passes only 1% ultraviolet rays and serves as a shield against more aggressive shortwave radiation.

The atmosphere absorbs about 20% of the sun's rays, scatters 30% in different directions. Thus, only half of the radiant energy, called direct solar radiation, reaches the earth's surface.

Several factors influence the intensity of direct solar radiation:

the angle of incidence of the sun's rays (geographical latitude);
distance from the point of impact to the Sun (season);
the nature of the reflective surface;
transparency of the atmosphere (cloudiness, pollution).

Scattered and direct radiation make up the total solar radiation, the intensity of which is measured in calories per unit surface. It is clear that solar radiation has an effect only in daytime days and is distributed unevenly over the earth's surface. Its intensity increases as it approaches the poles, but the snows reflect a large share radiant energy, as a result of which the air does not heat up. Therefore, the total indicator decreases as you move away from the equator.

Solar activity shapes the Earth's climate and affects the life processes of the organisms that inhabit it. On the territory of the CIS countries (in the northern hemisphere) in winter time during the year, diffuse radiation prevails, in summer - direct radiation.

Infrared radiation and its role in the life of mankind

Solar radiation is represented predominantly invisible to the human eye. It is it that heats the earth's soil, which subsequently gives off heat to the atmosphere. Thus, the temperature and habitual climatic conditions are optimal for life on Earth.

In addition to the Sun, all heated bodies are sources of infrared radiation. All heating devices and devices that allow you to see more or less heated objects in conditions of poor visibility work according to this principle.

The fact that a person is not able to perceive infrared light does not reduce its effect on the body. This type of radiation has found application in medicine due to the following properties:

expansion of blood vessels, normalization of blood flow;
an increase in the number of leukocytes;
treatment of chronic and acute inflammation of internal organs;
prevention of skin diseases;
removal of colloid scars, treatment of non-healing wounds.

Infrared thermographs allow timely detection of diseases that cannot be diagnosed using other methods (blood clots, cancerous tumors, etc.). Infrared radiation is a kind of "antidote" for negative ultraviolet radiation, so its healing properties are used to restore people's health, long time living in outer space.

The mechanism of action of infrared rays is not fully understood and, like any type of radiation, if used improperly, can be harmful to human health. Treatment with infrared rays is contraindicated in the presence of purulent inflammation, bleeding, malignant tumors, insufficiency of cerebral circulation and the cardiovascular system.

Spectral composition and properties of visible light

Light beams propagate in a straight line and do not overlap, which raises a fair question, why the world striking variety of different shades. The secret lies in the basic properties of light: reflection, refraction and absorption.

It is known for certain that objects do not emit light, it is partially absorbed by them and reflected at different angles depending on the frequency. Human vision has evolved over the centuries, but the retina of the eye can only perceive a limited range of reflected light in the narrow gap between infrared and ultraviolet radiation.

The study of the properties of light has given rise not only to a separate branch of physics, but also to a number of non-scientific theories and practices based on the effect of color on the mental and physical state of the individual. Using this knowledge, a person decorates the surrounding space in the most pleasing color for the eyes, which makes life as comfortable as possible.

Ultraviolet radiation and its effect on the human body

The ultraviolet spectrum of sunlight consists of long, medium and short waves, which differ physical properties and the nature of the impact on living organisms. Ultraviolet rays, which belong to the long-wave spectrum, are mainly scattered in the atmosphere and do not reach the earth's surface. The shorter the wavelength, the deeper the ultraviolet penetrates into the skin.

Ultraviolet radiation is essential for sustaining life on Earth. UV rays have the following effects on the human body:

saturation with vitamin D, necessary for the formation of bone tissue;
prevention of osteochondrosis and rickets in children;
normalization of metabolic processes and synthesis of beneficial enzymes;
activation of tissue regeneration;
improvement of blood circulation, expansion of blood vessels;
increased immunity;
removal of nervous excitement by stimulating the production of endorphins.

Despite the long list positive qualities, sunbathing not always effective. Prolonged exposure to the sun at unfavorable times or during periods of abnormally high solar activity nullifies beneficial features UV rays.

Ultraviolet irradiation in high doses has the opposite result as expected:

erythema (reddening of the skin) and sunburn;
hyperemia, puffiness;
increase in body temperature;
headache;
dysfunction of the immune and central nervous systems;
loss of appetite, nausea, vomiting.

These signs are symptoms of sunstroke, in which the deterioration of a person's condition can occur imperceptibly. Procedure for sunstroke:

move the person from the area exposed to direct sunlight to a cool place;
put on your back and raise your legs to an elevation to normalize blood circulation;
rinse your face and neck with cool water, preferably make a compress on your forehead;
provide the opportunity to breathe freely and get rid of tight clothing;
for half an hour, give a drink of a small amount of clean cold water.

In severe cases, with loss of consciousness, it is necessary to call an ambulance team and, if possible, bring the victim to his senses. Health care the patient consists in the emergency administration of glucose or ascorbic acid intravenously.

Safe tanning rules

UV rays stimulate the synthesis of a special hormone melanin, with the help of which human skin darkens and takes on a bronze hue. Disputes about the benefits and harms of tanning have been going on for decades.

It has been proven that sunburn is defensive reaction body to ultraviolet radiation, and excessive sunbathing increases the risk of malignant tumors.

If the desire to pay tribute to fashion prevails, you need to understand what solar radiation is, how to protect yourself from it and follow simple recommendations:

sunbathe gradually exclusively in the morning or evening;
do not stay in direct sunlight for more than an hour;
apply protective agents to the skin;
drink more clean water to avoid dehydration;
include in the diet foods that contain vitamin E, beta-carotene, tyrosine and selenium;
limit the consumption of alcoholic beverages.

The reaction of the body to ultraviolet irradiation is individual, so the time for sunbathing and their duration should be selected taking into account the type of skin and the state of human health.

Tanning is highly contraindicated for pregnant women, the elderly, people with skin diseases, heart failure, mental disorders and in the presence of malignant tumors.

This is harmful because:

1. The sun increases the risk of cancer. We are talking about skin cancer - melanoma. Ultraviolet is especially dangerous for those who have a lot of moles on their skin and there is a hereditary risk factor.

2. The sun weakens the immune system. With a lack of ultraviolet radiation, a decrease in immunity is noted. But even more dangerous is an excess of sunlight - it suppresses the reactions of the human immune system. That is why you can catch a cold even in sunny weather. Against the background of severe overheating and a decrease in the protective reaction of the body, the herpes virus can also wake up.

3. The sun ages the skin. Without damage to health, you can stay in the sun for no more than 15-20 minutes, and for people with very fair skin - no more than 7 minutes. Then the process of photoaging begins: under the influence of the sun, the skin loses moisture, becomes dry, wrinkles and age spots appear on it. In the US, scientists conducted a study on the example of twin sisters. One lived in the north of the country, the other in sunny California. The first looked much younger than the second.

4. The sun makes ladies courageous. Women struggling with excess facial and body hair need to sunbathe very carefully. Due to excess sunlight, the hairs become thicker and coarser. For those who have vascular networks and asterisks on their skin, an excess of sun is also harmful: under its action, the blood vessels become even more fragile.

It is strictly forbidden to sunbathe with the following diseases: various diseases heart, hypertension diabetes, thyroid disease, gynecological inflammatory diseases, epilepsy, acute kidney and liver diseases, oncological diseases, tuberculosis, you can not sunbathe during pregnancy.

This is useful because:

1. The sun protects against sclerosis. American scientists believe that people who were more exposed to ultraviolet radiation in childhood have a reduced risk of developing multiple sclerosis. Especially beneficial in this respect, the sun acts on the weaker sex.

2. The sun preserves men's health. Sun exposure cuts men's chances of developing prostate cancer in half, according to separate studies. Doctors explain this effect with vitamin D, which is synthesized in our body under the influence of ultraviolet rays. Scientists believe that this vitamin promotes the growth of normal cells in the prostate and blocks the activity and spread of malignant cells throughout the body. The researchers also found that men who get enough vitamin D are less likely to suffer heart attacks or strokes. To replenish vitamin D reserves, it is not necessary to actively sunbathe, it is enough just to be outside more often.

3. The sun fights fungus. It is useful to sunbathe with two very common lichen - pink and pityriasis. Despite the intimidating name, these fungal infections are not life-threatening and cause only superficial skin lesions. They are very common in adolescents who, due to age-related hormonal changes, are prone to excessive sweating. Under the influence of ultraviolet light, fungi die, and healthy skin forms at the sites of rashes. Moderate sunbathing is also useful for psoriasis.

4. The sun improves mood. It has been scientifically proven that sunbathing saves from depression: sunlight stimulates the production of the “happiness hormone” serotonin.

Safety regulations

Even those who are sure that sunbathing is only beneficial, you need to remember certain rules:

- do not sunbathe on an empty stomach or immediately after eating;

- it is even easier to burn in the water than on the shore, it performs the function of a lens: it enhances sunlight, and solar radiation passes to a depth of up to a meter. For the same reason, one should not stay in the sun without drying off immediately after bathing: water droplets form small lenses on the skin, which increase the possibility of sunburn;

- it is best to sunbathe in the shade - this reduces UV exposure by 50%, and the tan turns out no worse (although you will have to spend more time).

Menu for sunbathing

Some products help to get a tan while protecting the skin from UV damage.

This list includes cheese (20 g per day is enough), eggs (preferably soft-boiled), cottage cheese, liver, oily fish, brown rice, bananas, dates, beans, walnuts, almonds, peanuts, carrots, tomatoes, peaches, apricots, watermelon, melon.

Foods rich in vitamin C are necessary in summer, but you should not abuse them: an excess of this vitamin slows down the tanning process.

The tanning process is also slowed down by tea, coffee, chocolate.

By the way

According to a number of studies, sunscreens protect the skin only from burns, but not from the harmful effects of ultraviolet radiation on cell DNA. In other words, if you sunbathe, but do not burn out in the sun, the risk of melanoma still remains.

Comment

Alexander Syromyatnikov, oncologist:

- Melanoma (skin cancer) is the pathology that is directly related to increased insolation. Where there is a lot of sun, this disease is more common. And we, oncologists, constantly repeat: you need to be careful with the sun, you can’t sunbathe from 10 to 16 hours. And for those who have a lot of moles on their skin (it is moles that are the main risk areas), in general, it is worth visiting the sun as little as possible. And with any suspicious behavior of a mole: if it has changed color, increased or decreased in size, started to bleed - you need to see a doctor without delay!

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The article is interesting	August 24, 2014, 02:28:28
e-mail: [email protected], city: DELRAY BEACH Florida

At what time of the day is the sun beneficial?

Talking about the influence of the sun on human body, it is impossible to accurately determine the harm or benefit it brings. The sun's rays are like kilocalories from food.. Their deficiency leads to malnutrition, and in excess they cause obesity. So it is in this situation. In moderate amounts, solar radiation has a beneficial effect on the body, while an excess of ultraviolet radiation provokes burns and the development of numerous diseases. Let's take a closer look.

Solar radiation: general effect on the body

Solar radiation is a combination of ultraviolet and infrared waves.. Each of these constituent parts affects the body in its own way.

Influence of infrared radiation:

The main feature of infrared rays is the thermal effect they create. Warming up the body contributes to the expansion of blood vessels and the normalization of blood circulation.
Warming up has a relaxing effect on the muscles, providing a slight anti-inflammatory and analgesic effect.
Under the influence of heat, metabolism increases, the processes of assimilation of biologically active components are normalized.
Infrared radiation from the sun stimulates the brain and visual apparatus.
Synchronization occurs due to solar radiation biological rhythms organism, sleep and wakefulness modes are launched.
Treatment with solar heat improves the condition of the skin, relieving acne.
Warm light uplifts the mood and improves the emotional background of a person.
And according to recent studies, it also improves the quality of sperm in men.

Despite all the debate about the negative impact ultraviolet radiation on the body, its lack can lead to serious health problems. It is one of the vital factors of existence. And in conditions of ultraviolet deficiency in the body, the following changes begin to occur:

First of all, immunity weakens. This is caused by a violation of the absorption of vitamins and minerals, a malfunction in metabolism at the cellular level.
There is a tendency to develop new or exacerbate chronic diseases, most often occurring with complications.
Lethargy, chronic fatigue syndrome are noted, the level of working capacity decreases.
The lack of ultraviolet light for children interferes with the production of vitamin D and provokes a decrease in growth.

However, you need to understand that excessive solar activity will not benefit the body!

Sunbathing contraindications

Despite all the benefits of sunlight for the body, not everyone can afford to enjoy the warm rays. Contraindications include:

acute inflammatory processes;
tumors, regardless of their location;
progressive tuberculosis;
angina pectoris, ischemic disease;
endocrine pathologies;
damage to the nervous system;
dysfunction of the thyroid and adrenal glands;
diabetes;
mastopathy;
uterine fibroids;
pregnancy;
recovery period after surgery.

In all cases, active radiation will aggravate the course of the disease, provoking the development of new complications..

Do not get involved in the sun and the elderly, infants. For these categories of the population, treatment with sunlight in the shade is indicated. Required dose there will be enough safe heat.

Stories from our readers

Vladimir
61 years old

The negative influence of the sun

The time of exposure to infrared and ultraviolet waves must be strictly limited. In excess solar radiation:

may cause deterioration general condition the body (the so-called heat stroke due to overheating);
negatively affects the skin, causing permanent changes;
impairs vision;
provokes hormonal disruptions in the body;
can provoke the development of allergic reactions.

So that hours of lying on the beach during periods of maximum solar activity cause enormous damage to the body.

To get the necessary portion of light, a twenty-minute walk on a sunny day is enough.

The effect of the sun on the skin

Excessive solar radiation leads to serious skin problems. In the short term, you risk getting a burn or dermatitis. This is the smallest problem you can face when you get carried away with a tan on a hot day. If a similar situation repeated with enviable regularity, the radiation of the sun will be the impetus for the formation of malignant formations on the skin, melanoma.

In addition, UV exposure dries out the skin, making it thinner and more sensitive. And constant exposure to direct rays accelerates the aging process, provoking the appearance of early wrinkles.

In order to protect yourself from the negative effects of solar radiation, it is enough to follow simple safety measures:

Be sure to use sunscreen in the summer? Apply it to all exposed areas of the body, including the face, arms, legs and décolleté. The SPF badge on the packaging is the same UV protection. And its degree will depend on the number indicated near the abbreviation. For going to the store, cosmetics with an SPF 15 or SPF 20 level are suitable. If you plan to spend time on the beach, use special means with higher scores. For children's skin, a cream with a maximum protection of SPF 50 is suitable.
If you need to be outdoors for a long time at maximum intensity of sunlight, wear clothes made of light fabrics with long sleeves. Be sure to wear a wide-brimmed hat to hide the delicate skin of your face.
Control the duration of sunbathing. The recommended time is 15-20 minutes. If you are outside for a longer time, try to get some shade from the direct sunlight.

And remember that in the summer, solar radiation affects the skin at any time of the day, with the exception of night hours. You may not feel obvious heat from infrared waves, but ultraviolet does. high level activity, both in the morning and in the afternoon.

Negative effect on vision

The influence of sunlight on the visual apparatus is enormous. After all, thanks to light rays, we receive information about the world around us. artificial lighting to some extent it can become an alternative to natural light, but in the conditions of reading and writing with a lamp, the load on the eyes increases.

Speaking of negative impact on a person and the vision of sunlight, implies damage to the eyes during prolonged exposure to the sun without sunglasses.

Of the unpleasant sensations that you may encounter, one can single out cutting pains in the eyes, their redness, photophobia. The most serious lesion is a retinal burn.. It is also possible dry skin of the eyelids, the formation of small wrinkles.

Wear sunglasses. When buying, first of all, pay attention to the degree of protection. Image models often slightly obscure the light, but do not prevent the penetration of ultraviolet radiation. Therefore, it is recommended to put aside a bright frame and opt for quality lenses.
Make sure that direct rays do not fall on your face. Stay in the shade, wear a hat, cap or other headgear with a visor.
Don't look at the sun. If you do not experience discomfort, this does not indicate the safety of this undertaking. Even winter sun enough activity to provide vision problems.

Is there a safe time of year

The use of solar radiation as a health treatment is a common practice. That ultraviolet, that heat belongs to the category of strong irritants. And abuse of these benefits can earn serious problems.

Sunburn is the production of melanin. And to be more precise, the protective reaction of the skin to an irritant.

Is the radiation of the sun so dangerous at any time of the year? It is difficult to give a definite answer to this question. Everything will depend not so much on the season as on geographical location. So, in the middle latitudes, the activity of solar radiation increases by 25-35% in the summer. Therefore, the recommendations regarding staying outside on a clear day apply only to the hot season. In winter, residents of these regions are not threatened by ultraviolet radiation.

But the inhabitants of the equator face direct sunlight all year round. Therefore, the likelihood of a negative impact on the body is present both in summer and in winter. The inhabitants of the northern latitudes in this regard were more fortunate. After all, with distance from the equator, the angle of incidence of the sun's rays on the earth changes, and with it the radiation activity. The length of the thermal wave increases, and at the same time the amount of heat decreases (energy loss). Hence the winter all year round, as the surface of the earth does not have enough heat to warm up.

Solar radiation is a friend of our body. But do not abuse this friendship. Otherwise, the consequences can be the most serious. Just enjoy the warmth without forgetting the precautions.

The sun radiates 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 infrared rays of the near and far range. Gamma rays, X-rays, ultraviolet and radio radiation account for only about 8%.

The visible part of solar radiation, when studied with the help of spectrum-analyzing instruments, turns out to be inhomogeneous - absorption lines are observed in the spectrum, first described by J. Fraunhofer in 1814. 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 extremely accurately characterizes chemical element. So, for example, with the help of observations of the spectrum of the Sun, the discovery of helium was predicted, which was isolated on Earth later.

In the course of observations, scientists found that the Sun is a powerful source of radio emission. Radio waves penetrate into interplanetary space, which are emitted by the chromosphere (centimeter waves) and the corona (decimeter and meter waves). The radio emission of the Sun has two components - constant and variable (bursts, "noise storms"). During strong solar flares, the radio emission from the Sun increases thousands and even millions of times compared to the radio emission from the quiet Sun. This radio emission has a non-thermal nature.

X-rays come mainly from the upper layers of the chromosphere and the 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, and heavier 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 - coronary holes, and also, possibly, with long-lived active regions on the Sun. Finally, the most powerful short-term particle fluxes, mainly electrons and protons, are associated with solar flares. As a result of the most powerful flashes, particles can acquire velocities that make up a significant 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 above all on the upper layers of its atmosphere and magnetic field, causing many geophysical phenomena. From harmful influence The radiation of the Sun protects us from the magnetosphere and the atmosphere of the Earth.

Solar radiation - this is electromagnetic and corpuscular radiation, that is, the radiation of photons and elementary particles(mainly electrons and protons). In fact, despite the terrible name, solar radiation is not life-threatening. The thing is that radiation is not only ionizing radiation, which is usually called radiation in everyday life. Radiation is all types of radiation. The sun radiates energy, without which life on Earth would not be possible at all. Solar radiation reaches the Earth in the form of direct and scattered rays, and the intensity of the Sun's radiation depends on huge amount factors. The wavelength of sunlight includes γ rays, X-rays, ultraviolet, visible light, infrared radiation, microwave radiation and radio waves.

Let's say that you're not lying, and solar radiation is really not harmful, but why do we see only part of the solar radiation? This is because it is on waves of this length that the maximum intensity of the radiation of the sun falls. That is why, in the process of evolution, the organs of vision of living organisms have adapted to distinguish between waves of this length. And, by the way, it is because of the intensity of the “blue” waves that the sky appears blue. The fact is that light has the ability to scatter, which is what it does when it enters the atmosphere. Rays of any frequency are scattered, but the higher the frequency, the stronger the scattering. Waves have the highest frequency purple, then blue, then green, then yellow, and finally red. That's why the sky is blue!

Wait, why blue and not purple? Due to the intensity of the radiation of blue color! There are far fewer violet rays than blue rays, so the sky is blue, not purple. But during sunset, the Sun shines on the Earth at an angle, so the light has to pass through a much larger layer of the atmosphere, and therefore, the red waves have time to dissipate. And that is why the sky turns red during sunset. In other words, depending on the position of the Earth in relation to the Sun, solar radiation has varying degrees intensity. And it's not just useful to know. This is important to know! Why? Because this directly affects the influence of the sun on living organisms, to which we can temporarily reckon ourselves.

Solar radiation in human life

As we wrote above, life on Earth would be impossible without solar energy. That is why even the highest predators, which are people, need to periodically appear in the sun. What for? Then what the sun is the best sources vitamin D. Vitamin D is fat soluble and is available in two bioequivalent forms D 2 and D 3 . Both forms of the vitamin can be ingested with food, but D 3 can also be synthesized in the body under the influence of ultraviolet rays. The intensity of D 3 synthesis depends on the season, skin color and age. Accordingly, the lighter the skin and younger man, the more intense it produces vitamin D 3 under the influence of the sun. The intensity of the sun's influence is more powerful in the summer.

Reference values for vitamin D are in the range of 30–80 nmol/l, while optimal value is 50nmol / l, and intoxication of the body can be achieved at values of more than 150nmol / l. The latter unambiguously hints that being in the sun too much is not recommended. In this regard, it must be recalled that vitamin D is fat-soluble, that is, it has the ability to accumulate in the body. On average, people with fair skin are recommended to be under the influence of solar radiation for 15–30 minutes a day in the summer. In winter, if you are not a resident of Africa or Australia, it is likely that you will lack vitamin D, as well as sunlight in general.

Vitamin D deficiency is accompanied by muscle weakness, bone fragility, development cardiovascular diseases and other factors that increase the risk of mortality. Dietary sources of vitamin D are fish, eggs, baked goods, and milk. That is why residents of the northern regions are less likely to have lactose intolerance. Quite simply, the ability to digest dairy products was an important factor natural selection in these regions. But even if a person does not digest lactose, this is not a reason to take sunbaths. It is quite possible to get by with vitamin D supplements in dosages from 400 to 1000 IU per day. You should not be afraid of poisoning, since vitamin D supplements in both forms have been shown to be effective and safe.

But in the summer you want to be exposed to solar radiation, don't you? You need to do it right! Firstly, in the summer you should be in the sun before 10 am and after 3 pm. This is due to the intensity of solar radiation. Secondly, even if you are hiding from the sun during its peak hours, you still need to use sunscreen. Especially if you intentionally sunbathe while lying on the beach and drinking a cocktail. If this is not done, then the excessive intensity of the effect of solar radiation on the skin can lead to the destruction of collagen fibers, denaturation of vitamin A and the development oncological diseases. It is important to note that sun creams are different. They are characterized by different SPF (Sun Protection Factor) indicators.

SPF 50 is the ultimate in proven effectiveness. Using creams with SPF over 50 is pointless. The frequency of applying the cream should be indicated on the package. It must be applied exactly in this mode, as indicated by the manufacturer. It is recommended to use sunscreen not only while visiting the beach, but also if you are regularly in the sun. Sunscreen is the most important means protecting the skin from aging. That is why regularly sunbathing in natural conditions may not be best idea. From the point of view of skin health and beauty, it is much more reasonable to use artificial tanning products.

Conclusion

Solar radiation is not dangerous and does not cause mutations. Radiation is not only ionizing radiation, it is all types of radiation. That is why it is good to be in the sun, but you need to bathe in the sun in moderation.
In summer, it is recommended to appear in the sun for at least 15 minutes a day, while in the summer it is recommended to apply sunscreen on the skin. Sunscreen is especially needed when visiting the beach.
You can compensate for the lack of vitamin D with seafood, eggs, baked goods and milk. Vitamin D supplements at doses of 400 to 1000 IU per day are also safe and effective.

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