Properties ultraviolet radiation determined by many parameters. Ultraviolet radiation is called invisible electromagnetic radiation, which occupies a certain spectral region between X-ray and visible radiation within the respective wavelengths. The wavelength of ultraviolet radiation is 400 - 100 nm and has weak biological effects.
The higher the biological activity of the waves of this radiation, the weaker the effect, respectively, the lower the wavelength, the stronger the biological activity. Waves with a length of 280 - 200 nm have the strongest activity, which have bactericidal effects and actively affect body tissues.
The frequency of ultraviolet radiation is closely related to wavelengths, so the higher the wavelength, the lower the frequency of the radiation. The range of ultraviolet radiation reaching the Earth's surface is 400 - 280 nm, and shorter waves emanating from the Sun are absorbed even in the stratosphere with the help of ozone layer.
The area of UV radiation is conditionally divided into:
- Near - from 400 to 200 nm
- Far - from 380 to 200 nm
- Vacuum - from 200 to 10 nm
The spectrum of ultraviolet radiation depends on the nature of the origin of this radiation and can be:
- Linear (radiation of atoms, light molecules and ions)
- Continuous (deceleration and recombination of electrons)
- Consisting of bands (radiation of heavy molecules)
Properties of UV radiation
The properties of ultraviolet radiation are chemical activity, penetrating power, invisibility, destruction of microorganisms, beneficial effects on the human body (in small doses) and negative effects on humans (in large doses). Properties of ultraviolet radiation in optical area have significant differences from the optical properties of the ultraviolet of the visible region. Most feature is an increase in a special absorption coefficient, which leads to a decrease in the transparency of many bodies that have transparency in visible area.
The reflection coefficient of various bodies and materials decreases taking into account the decrease in the wavelength of the radiation itself. The physics of ultraviolet radiation corresponds to modern ideas and ceases to be an independent dynamics at high energies, and is also combined into one theory with all gauge fields.
Do you know what is different for different intensities of such radiation? Read detailed information about beneficial and harmful doses of UV radiation in one of our articles.
We also have usage information available at personal plot. Many gardeners are already using solar panels in their homes. Try it by reading our material.
History of the discovery of ultraviolet radiation
Ultraviolet radiation, whose discovery history dates back to 1801, was announced only in 1842. This phenomenon was discovered by the German physicist Johann Wilhelm Ritter and was called " actinic radiation". This radiation was part of the individual components of light, and played the role of a reducing element.
The very concept of ultraviolet rays was first encountered in history in the 13th century, in the work of the scientist Sri Madhacharaya, who described the atmosphere of the Bhutakashi area containing violet rays invisible to human eyes.
In the course of experiments in 1801, a group of scientists found that light has several separate components: oxidative, thermal (infrared), illuminating (visible light) and reducing (ultraviolet).
UV radiation is a continuously acting environmental factor external environment and has a strong impact on various physiological processes that occur in organisms.
According to scientists, it was it that played the main role in the course of evolutionary processes on Earth. Thanks to this factor an abiogenic synthesis of organic terrestrial compounds took place, which influenced the increase in the diversity of species of life forms.
It turned out that all living beings, in the course of evolution, have adapted to use the energy of all parts of the spectrum solar energy. The visible part of the solar range is for photosynthesis, the infrared for heat. UV components are used as photochemical synthesis vitamin D, which plays an important role in the exchange of phosphorus and calcium in the body of living beings and humans.
The ultraviolet range is located from visible light from the short-wave side, and the rays of the near region are perceived by a person as the appearance of a tan on the skin. Short waves cause destructive impact to biological molecules.
The ultraviolet radiation of the sun has the biological effectiveness of three spectral regions, which differ significantly from each other and have corresponding ranges that affect living organisms in different ways.
This radiation is taken for therapeutic and prophylactic purposes in certain dosages. For such medical procedures special artificial radiation sources are used, the radiation spectrum of which consists of shorter rays, which has a more intense effect on biological tissues.
Harm from ultraviolet radiation brings a strong impact given source radiation to the body and can cause injury mucous membranes and various skin dermatitis. Most of the damage from ultraviolet radiation is observed in workers various areas activities that come into contact with artificial sources of these waves.
Measurement of ultraviolet radiation is carried out by multichannel radiometers and continuous wave spectroradiometers, which are based on the use of vacuum photodiodes and photoids with a limited wavelength range.
Properties of ultraviolet radiation photo
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The sun is a powerful source of heat and light. Without it, there can be no life on the planet. The sun emits rays that are not visible to the naked eye. We will find out what properties ultraviolet radiation has, its effect on the body and possible harm.
The solar spectrum has infrared, visible and ultraviolet parts. UV has both positive and negative effects on humans. It is used in different areas vital activity. Widespread use is noted in medicine, ultraviolet radiation tends to change the biological structure of cells, affecting the body.
Sources of exposure
The main source of ultraviolet rays is the sun. They are also obtained using special light bulbs:
- Mercury-quartz high pressure.
- Vital luminescent.
- Ozone and quartz bactericidal.
Currently, only a few types of bacteria are known to mankind that can exist without ultraviolet radiation. For other living cells, its absence will lead to death.
What is the effect of ultraviolet radiation on the human body?
positive action
Today, UV is widely used in medicine. It has a calming, analgesic, anti-rachitic and anti-spastic effect. Positive influence ultraviolet rays on the human body:
- the intake of vitamin D, it is needed for the absorption of calcium;
- improved metabolism, as enzymes are activated;
- reduction of nervous tension;
- increased production of endorphins;
- vasodilatation and normalization of blood circulation;
- acceleration of regeneration.
Ultraviolet for humans is also useful in that it affects the immunobiological activity, helps to activate the protective functions of the body against various infections. At a certain concentration, radiation causes the production of antibodies that affect pathogens.
Negative influence
The harm of an ultraviolet lamp on the human body often exceeds it. beneficial features. If its use in medicinal purposes performed incorrectly, safety measures were not observed, an overdose is possible, characterized by the following symptoms:
- Weakness.
- Apathy.
- Decreased appetite.
- Memory problems.
- Heart palpitations.
Prolonged exposure to the sun is harmful to the skin, eyes and immunity. The consequences of excessive sunburn, such as burns, dermatological and allergic rashes, disappear after a few days. Ultraviolet radiation slowly accumulates in the body and causes dangerous diseases.
Skin exposure to UV can cause erythema. The vessels dilate, which is characterized by hyperemia and edema. The histamine and vitamin D that accumulate in the body enter the bloodstream, which contributes to changes in the body.
The stage of development of erythema depends on:
- range of UV rays;
- radiation doses;
- individual sensitivity.
Excessive irradiation causes a burn on the skin with the formation of a bubble and subsequent convergence of the epithelium.
But the harm of ultraviolet radiation is not limited to burns, its irrational use can provoke pathological changes in the body.
The effect of UV on the skin
Most girls strive for a beautiful tanned body. However, the skin becomes dark color under the action of melanin, so the body is protected from further radiation. But it will not protect against the more serious effects of radiation:
- Photosensitivity - high sensitivity to ultraviolet light. Its minimal action can provoke burning, itching or burning. This is mainly due to the use medicines, cosmetics or certain foods.
- Aging - UV rays penetrate into the deeper layers of the skin, destroy collagen fibers, elasticity is lost and wrinkles appear.
- Melanoma is a skin cancer that develops as a result of frequent and prolonged exposure to the sun. An excessive dose of ultraviolet radiation causes the development of malignant neoplasms on the body.
- Basal cell and squamous cell carcinoma is a cancerous growth on the body that requires surgical removal of the affected areas. Often this disease occurs in people whose work involves a long stay in the sun.
Any skin dermatitis caused by UV rays can cause skin cancer.
The effect of UV on the eyes
Ultraviolet light can also adversely affect the eyes. As a result of its influence, the following diseases may develop:
- Photophthalmia and electrophthalmia. It is characterized by redness and swelling of the eyes, lacrimation, photophobia. Appears in those who are often in the bright sun in snowy weather without sunglasses or in welders who do not follow safety rules.
- Cataract is clouding of the lens. This disease mainly appears in old age. It develops as a result of the action of sunlight on the eyes, which accumulates throughout life.
- Pterygium is an overgrowth of the conjunctiva of the eye.
Some types of cancers on the eyes and eyelids are also possible.
How does UV affect the immune system?
How does radiation affect the immune system? In a certain dose, UV rays increase the protective functions of the body, but their excessive action weakens the immune system.
Radiation radiation changes protective cells, and they lose their ability to fight various viruses, cancer cells.
Skin protection
To protect yourself from the sun's rays, you must follow certain rules:
- You need to be in the open sun moderately, a small tan has a photoprotective effect.
- It is necessary to enrich the diet with antioxidants and vitamins C and E.
- You should always use sunscreen. In this case, you need to choose a tool with high level protection.
- The use of ultraviolet for medicinal purposes is allowed only under the supervision of a specialist.
- Those who work with UV sources are advised to protect themselves with a mask. This is required when applying germicidal lamp which is dangerous to the eyes.
- Fans of an even tan should not visit the solarium too often.
To protect yourself from radiation, you can also use special clothing.
Contraindications
UV exposure is contraindicated for the following people:
- those who have too light and sensitive skin;
- with an active form of tuberculosis;
- children;
- in acute inflammatory or oncological diseases;
- albinos;
- during II and III stages of hypertension;
- at in large numbers moles;
- those who suffer from systemic or gynecological ailments;
- long-term use of certain drugs;
- with hereditary predisposition to skin cancer.
Infrared radiation
Another part of the solar spectrum is infrared radiation, which has thermal effect. It is used in the modern sauna.
is a small wooden room with built-in infrared emitters. Under the influence of their waves, the human body warms up.
The air in the infrared sauna does not rise above 60 degrees. However, the rays warm the body up to 4 cm, when in traditional bath heat penetrates only 5 mm.
This is because infrared waves are the same length as heat waves coming from a person. The body accepts them as its own and does not resist penetration. The temperature of the human body rises to 38.5 degrees. This kills viruses and dangerous microorganisms. Infrared sauna has a healing, rejuvenating, and preventive effect. It is indicated for all ages.
Before visiting such a sauna, you should consult with a specialist, as well as follow the safety precautions for being in a room with infrared emitters.
Video: ultraviolet.
UV in medicine
In medicine, there is a term "ultraviolet starvation". This happens when the body does not get enough sunlight. To avoid any pathologies from this, artificial sources of ultraviolet radiation are used. They help fight winter vitamin D deficiency and boost immunity.
Also, such radiation is used in the treatment of joints, allergic and dermatological diseases.
In addition, UV has the following medicinal properties:
- Normalizes the work of the thyroid gland.
- Improves respiratory function and endocrine systems.
- Increases hemoglobin.
- Disinfects the room and medical instruments.
- Reduces sugar levels.
- Helps in the treatment of purulent wounds.
It must be borne in mind that an ultraviolet lamp is not always a benefit, and great harm is possible.
In order for UV radiation to have a beneficial effect on the body, you should use it correctly, follow safety precautions and do not exceed the time spent in the sun. An excessive excess of the radiation dose is dangerous for human health and life.
The sun, like other stars, emits not only visible light - it produces a whole spectrum of electromagnetic waves that differ in frequency, length and amount of energy transferred. This spectrum is divided into ranges from radiation to radio waves, and the most important among them is ultraviolet, without which life is impossible. Depending on various factors, UV radiation can be both beneficial and harmful.
Ultraviolet is the portion of the electromagnetic spectrum that lies between visible and X-ray radiation and has a wavelength of 10 to 400 nm. It got this name just because of its location - just beyond the range that is perceived by the human eye as a purple color.
The ultraviolet range is measured in nanometers and is divided into subgroups according to international standard ISO:
- short-range (long-wavelength) - 300-400 nm;
- medium (medium wave) - 200−300 nm;
- far (shortwave) - 122−200 nm;
- extreme - the wavelength is 10−121 nm.
Depending on which group ultraviolet radiation belongs to, its properties may change. So, the vast majority of the range is invisible to humans, but the near ultraviolet can be seen if it has a wavelength of 400 nm. Such violet light is emitted, for example, by diodes.
Since different ranges of light differ in the amount of energy transferred and frequency, the subgroups differ significantly in penetrating power. For example, when exposed to humans, near-UV rays are blocked by the skin, while medium-wavelength radiation can penetrate cells and cause DNA mutations. This property is used in biotechnology to obtain genetically modified organisms.
As a rule, on Earth you can meet only near and middle ultraviolet: such radiation comes from the Sun without being blocked by the atmosphere, and is also generated artificially. It is the rays of 200–400 nm that play an important role in the development of life, because with their help plants produce oxygen from carbon dioxide. The hard short-wave radiation dangerous for living organisms does not reach the surface of the planet due to the ozone layer, which partially reflects and absorbs photons.
UV Sources
Stars are natural generators of electromagnetic radiation: in the process of thermonuclear fusion, which takes place in the center of a star, a full spectrum of rays is created. Accordingly, most of the ultraviolet radiation on Earth comes from the Sun. The intensity of radiation reaching the surface of the planet depends on many factors:
- thickness of the ozone layer;
- the height of the Sun above the horizon;
- height above sea level;
- the composition of the atmosphere;
- weather;
- coefficient of reflection of radiation from the Earth's surface.
There are many myths associated with solar ultraviolet radiation. So, it is believed that in cloudy weather it is impossible to tan, however, although cloudiness affects the intensity of UV radiation, most of it is able to penetrate clouds. In the mountains and in winter at sea level, it may seem that the risk of damage from ultraviolet radiation is minimal, but in fact it even increases: at high altitude, the radiation intensity increases due to rarefied air, and snow cover becomes an indirect source of ultraviolet radiation, since up to 80% rays are reflected from it.
You need to be especially careful on a sunny but cold day: even if you don’t feel heat from the Sun, there is always ultraviolet. Heat and UV rays are at opposite ends of the visible spectrum and have different wavelengths. When infrared radiation passes tangentially to the Earth in winter and is reflected, ultraviolet always reaches the surface.
Natural UV radiation has a significant drawback - it cannot be controlled. Therefore, artificial sources of ultraviolet radiation are being developed for use in medicine, sanitation, chemistry, cosmetology and other areas. The required range of the electromagnetic spectrum is generated in them by heating gases with an electric discharge. As a rule, the rays are emitted by mercury vapor. This operating principle is characterized different types lamps:
- luminescent - additionally produce visible light due to the effect of photoluminescence;
- mercury-quartz - emit waves with a wavelength of 185 nm (hard ultraviolet) to 578 nm (orange);
- bactericidal - have a flask made of special glass that blocks rays shorter than 200 nm, which prevents the formation of toxic ozone;
- excilamps - do not have mercury, ultraviolet is emitted in the general range;
- - due to the effect of electroluminescence, they can work in any narrow range from to ultraviolet.
AT scientific research, experiments, biotechnology uses special ultraviolet . The source of radiation in them can be inert gases, crystals or free electrons.
Thus, different artificial sources of ultraviolet generate radiation of different subtypes, which determines their scope. Lamps operating in the >300 nm range are used in medicine,<200 - для обеззараживания и т. д.
Applications
Ultraviolet light is able to accelerate some chemical processes, for example, the synthesis of vitamin D in human skin, the degradation of DNA molecules and polymer compounds. In addition, it causes the effect of photoluminescence in some substances. Due to these properties, artificial sources of this radiation are widely used in various fields.
The medicine
First of all, the bactericidal property of ultraviolet radiation has found application in medicine. With the help of UV rays, the growth of pathogenic microorganisms in wounds, frostbite, and burns is suppressed. Blood irradiation is used for poisoning with alcohol, narcotic substances and medicines, inflammation of the pancreas, sepsis, and severe infectious diseases.
Irradiation with a UV lamp improves the patient's condition in diseases of various body systems:
- endocrine - vitamin D deficiency, or rickets, diabetes mellitus;
- nervous - neuralgia of various etiologies;
- musculoskeletal - myositis, osteomyelitis, osteoporosis, arthritis and other joint diseases;
- genitourinary - adnexitis;
- respiratory;
- skin diseases - psoriasis, vitiligo, eczema.
It should be borne in mind that ultraviolet is not the main means of treating these diseases: irradiation is used as a physiotherapeutic procedure that has a positive effect on the patient's well-being. It has a number of contraindications, so it is impossible to use an ultraviolet lamp without consulting a doctor.
UV radiation is also used in psychiatry to treat "winter depression", in which, due to a decrease in the level of natural sunlight, the synthesis of melatonin and serotonin in the body decreases, which affects the work of the central nervous system. For this, special fluorescent lamps are used that emit a full spectrum of light from ultraviolet to infrared.
Sanitation
The most useful is the use of ultraviolet radiation for the purpose of disinfection. For the disinfection of water, air and hard surfaces, low-pressure mercury-quartz lamps are used that generate beams with a wavelength of 205–315 nm. Such radiation is best absorbed by DNA molecules, which leads to a disruption in the structure of the genes of microorganisms, due to which they stop multiplying and quickly die out.
Ultraviolet disinfection is characterized by the absence of a long-term effect: immediately after the completion of the treatment, the effect subsides, and microorganisms begin to multiply again. On the one hand, this makes disinfection less effective, on the other hand, it deprives it of its ability to negatively affect a person. UV irradiation cannot be used to fully treat drinking water or household fluids, but can be used as a supplement to chlorination.
Irradiation with medium wave ultraviolet is often combined with hard radiation treatment at a wavelength of 185 nm. In this case, oxygen turns into poisonous for pathogenic organisms. This disinfection method is called ozonation, and it is several times more effective than conventional UV lamp illumination.
Chemical analysis
Due to the fact that light with different wavelengths is absorbed by matter to different degrees, UV rays can be used for spectrometry - a method for determining the composition of a substance. The sample is irradiated with an ultraviolet generator with a variable wavelength, absorbs and reflects part of the rays, on the basis of which a graph-spectrum is built, unique for each substance.
The effect of photoluminescence is used in the analysis of minerals, which include substances that can glow when irradiated with ultraviolet light. The same effect is used to protect documents: they are marked with a special ink that emits visible light under a black light lamp. Also, with the help of luminescent paint, you can determine the presence of UV radiation.
Among other things, UV emitters are used in cosmetology, for example, for creating a tan, drying and other procedures, in printing and restoration, entomology, genetic engineering, etc.
The negative effects of UV rays on humans
Although UV rays are widely used for the treatment of diseases and have a healing effect, the harmful effects of ultraviolet radiation on the human body are also possible. It all depends on how much energy will be transferred to living cells by solar radiation.
Short-wave rays (UVC type) have the highest energy; in addition, they have the greatest penetrating power and can destroy DNA even in the deep tissues of the body. However, such radiation is completely absorbed by the atmosphere. Among the rays reaching the surface, 90% are long-wave (UVA) and 10% - medium-wave (UVB) radiation.
Long-term exposure to UVA rays or short-term exposure to ultraviolet UVB leads to a sufficiently large dose of radiation, which entails sad consequences:
- skin burns of varying severity;
- skin cell mutations leading to accelerated aging and melanoma;
- cataract;
- burn of the cornea of the eye.
Delayed lesions - skin cancer and cataracts - may develop over time; At the same time, UVA radiation can operate at any time of the year and in any weather. Therefore, you should always protect yourself from the sun, especially for people with increased photosensitivity.
UV Protection
A person has natural protection against ultraviolet radiation - melanin contained in skin cells, hair, and the iris of the eye. This protein absorbs most of the ultraviolet radiation, preventing it from affecting other body structures. The effectiveness of protection depends on skin color, which is why UVA rays contribute to sunburn.
However, with excessive exposure, melanin can no longer cope with UV rays. To prevent sunlight from harming, you should:
- try to stay in the shadows;
- wear closed clothes;
- protect your eyes with special glasses or contact lenses that block UV radiation but are transparent to visible light;
- use protective creams, which include mineral or organic substances that reflect UV rays.
Of course, it is not necessary to always use the full range of protective equipment. You should focus on the ultraviolet index, which describes the presence of excess UV radiation near the surface of the earth. It can take values from 1 to 11, and active protection is required at 8 points or more. Information about this index can be found in the weather forecast.
Thus, ultraviolet is a type of electromagnetic radiation that can be both beneficial and harmful. It is important to remember that sunbathing heals and rejuvenates the body only with moderate use; Excessive exposure to light can lead to serious health problems.
We most often observe the use of ultraviolet radiation for cosmetic and medical purposes. Also, ultraviolet radiation is used in printing, in the disinfection and disinfection of water and air, if necessary, polymerization and changes in the physical state of materials.
Ultraviolet radiation is a type of radiation that has a certain wavelength and occupies an intermediate position between the X-ray and the violet zone of visible radiation. This radiation is invisible to the human eye. However, due to its properties, such radiation has become very widespread and is used in many areas.
Currently, many scientists are purposefully studying the effect of ultraviolet radiation on many life processes, including metabolic, regulatory, and trophic ones. It is known that ultraviolet radiation has a beneficial effect on the body in certain diseases and disorders, contributing to the treatment. That is why it has been widely used in the field of medicine.
Thanks to the work of many scientists, the effect of ultraviolet radiation on biological processes in the human body has been studied so that these processes can be controlled.
UV protection is essential when the skin is exposed to the sun for a long time.
It is believed that it is ultraviolet rays that are responsible for photoaging of the skin, as well as for the development of carcinogenesis, since when exposed to them, a lot of free radicals that adversely affect all processes in the body.
In addition, when using ultraviolet radiation, the risk of damaging DNA chains is very high, and this can already lead to very tragic consequences and the emergence of such terrible diseases as cancer and others.
Do you know what can be useful for a person? About such properties, as well as about the properties of ultraviolet radiation, which allow it to be used in various production processes, you can learn everything from our article.
We also have an overview available. Read our material and you will understand all the main differences between natural and artificial light sources.
The main natural source of this type of radiation is the sun. And among the artificial ones, there are several types:
- Erythema lamps (invented in the 60s, used mainly to compensate for the insufficiency of natural ultraviolet radiation. For example, to prevent rickets in children, to irradiate the young generation of farm animals, in fotaries)
- Mercury-quartz lamps
- Excilamps
- germicidal lamps
- Fluorescent lamps
- LEDs
Many lamps emitting in the ultraviolet range are designed to illuminate rooms and other objects, and the principle of their operation is associated with ultraviolet radiation, which is converted in various ways into visible light.
Ways to generate ultraviolet radiation:
- Temperature radiation (used in incandescent lamps)
- Radiation created due to gases and metal vapors moving in an electric field (used in mercury and gas discharge lamps)
- Luminescence (used in erythema, bactericidal lamps)
The use of ultraviolet radiation due to its properties
The industry produces many types of lamps for various applications of ultraviolet radiation:
- Mercury
- Hydrogen
- Xenon
The main properties of UV - radiation, which determine its use:
- High chemical activity (contributes to the acceleration of many chemical reactions, as well as the acceleration of biological processes in the body):
Under the influence of ultraviolet radiation, vitamin D and serotonin are formed in the skin, the tone and vital activity of the body improves. - Ability to kill various microorganisms (bactericidal property):
The use of ultraviolet germicidal radiation contributes to air disinfection, especially in places where many people gather (hospitals, schools, universities, railway stations, subways, large stores).
Disinfection of water with ultraviolet radiation is also in great demand, as it gives good results. With this method of purification, water does not acquire an unpleasant odor and taste. It is great for water purification in fish farms, swimming pools.
The ultraviolet disinfection method is often used during processing surgical instruments. - The ability to cause luminescence of certain substances:
Thanks to this property, forensic experts detect traces of blood on various objects. And also thanks to special paint you can detect marked banknotes that are used in anti-corruption operations.
Application of ultraviolet radiation photo
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The ultraviolet range of electromagnetic radiation lies beyond the violet (shortwave) edge of the visible spectrum.
The near ultraviolet from the Sun passes through the atmosphere. It causes sunburn on the skin and is necessary for the production of vitamin D. But excessive exposure is fraught with the development of skin cancer. UV radiation is harmful to the eyes. Therefore, on the water and especially on the snow in the mountains, it is imperative to wear goggles.
Harder UV radiation is absorbed in the atmosphere by molecules of ozone and other gases. It can only be observed from space, which is why it is called vacuum ultraviolet.
The energy of ultraviolet quanta is sufficient to destroy biological molecules, in particular DNA and proteins. This is one of the methods for the destruction of microbes. It is believed that as long as there was no ozone in the Earth's atmosphere, which absorbs a significant part of ultraviolet radiation, life could not leave the water on land.
Ultraviolet is emitted by objects with temperatures ranging from thousands to hundreds of thousands of degrees, such as young, hot, massive stars. However, UV radiation is absorbed by interstellar gas and dust, so we often see not the sources themselves, but the cosmic clouds illuminated by them.
To collect UV radiation, mirror telescopes are used, and photomultipliers are used for registration, and in the near UV, as in visible light, CCD matrices are used.
Sources
The glow is produced when charged particles in the solar wind collide with molecules in Jupiter's atmosphere. Most of the particles under the influence of the planet's magnetic field enter the atmosphere near its magnetic poles. Therefore, radiance occurs in a relatively small area. Similar processes are taking place on Earth and on other planets with an atmosphere and a magnetic field. The image was taken by the Hubble Space Telescope.
Receivers
Hubble Space Telescope
sky surveys
The survey was built by the Extreme Ultraviolet Explorer (EUVE, 1992–2001) orbital ultraviolet observatory. The line structure of the image corresponds to the orbital motion of the satellite, and the inhomogeneity of the brightness of individual bands is associated with changes in the calibration of the equipment. Black stripes are areas of the sky that could not be observed. The small number of details in this review is due to the fact that there are relatively few sources of hard ultraviolet and, in addition, ultraviolet radiation is scattered by cosmic dust.
Earth application
Installation for dosed irradiation of the body with near ultraviolet for tanning. Ultraviolet radiation leads to the release of the pigment melanin in the cells, which changes the color of the skin.
Doctors divide the near ultraviolet into three sections: UV-A (400–315 nm), UV-B (315–280 nm) and UV-C (280–200 nm). The mildest UV-A light stimulates the release of melanin stored in melanocytes, the cellular organelles where it is produced. The harsher UV-B triggers the production of new melanin and also stimulates the production of vitamin D in the skin. Tanning bed models differ in their output power in these two areas of the UV range.
In the composition of sunlight near the Earth's surface, up to 99% of ultraviolet is in the UV-A region, and the rest is in UV-B. Radiation in the UV-C range has a bactericidal effect; in the solar spectrum it is much less than UV-A and UV-B, in addition, most of it is absorbed in the atmosphere. Ultraviolet radiation causes drying and aging of the skin and promotes the development of cancer. Moreover, radiation in the UV-A range increases the likelihood of the most dangerous type of skin cancer - melanoma.
UV-B radiation is almost completely blocked by protective creams, in contrast to UV-A, which penetrates through such protection and even partially through clothing. In general, it is believed that very small doses of UV-B are good for health, and the rest of the UV is harmful.
Ultraviolet radiation is used to determine the authenticity of banknotes. Polymer fibers with a special dye are pressed into banknotes, which absorbs ultraviolet quanta, and then emits less energetic visible radiation. Under the influence of ultraviolet light, the fibers begin to glow, which is one of the signs of authenticity.
The ultraviolet radiation of the detector is invisible to the eye, the blue glow that is noticeable during the operation of most detectors is due to the fact that the ultraviolet sources used also emit in the visible range.