What is ultraviolet radiation - properties, application, ultraviolet protection. Ozone screen Which layer of the atmosphere blocks ultraviolet rays

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The significance of the ozone layer - ozonosphere. The impact of ultraviolet rays from the sun on humans and other living organisms.

The importance of the ozone layer for the biosphere - humans and other living organisms.

Despite the negligible amount of ozone in the atmosphere, its significance is truly enormous. Life on Earth, as we currently observe it, would be very different if it were not protected by a thin three-millimeter ozone layer. And if the ozone “screen” disappeared today, life would probably survive only deep underwater in the World Ocean or underground.

The fact is that the ozone layer (ozonosphere) absorbs especially destructive short-wave ultraviolet rays, thereby preventing damage to living systems.

A decrease in ozone concentration in the atmosphere as a whole by at least 10% already affects living organisms - plant yields decrease, various types of pathologies are observed in animals and humans, for example, impaired pulmonary function, an increase in chronic diseases of the lungs, nervous and immune systems, skin and retinal cancer eye. Noticeable changes under the influence of increased ultraviolet radiation can also be observed in the state of entire ecosystems, especially terrestrial vegetation and phytoplankton, as well as in the implementation of biogeochemical cycles.

Ozone is an active gas and can have adverse effects on humans. Usually its concentration in the lower atmosphere is insignificant and it does not have a harmful effect on humans. Large amounts of ozone are formed in major cities with heavy traffic as a result of photochemical transformations of vehicle exhaust gases.

The importance of the Earth's ozone layer. Absorption spectra of ozone and nucleic acids.

To visualize the importance of the ozone layer for all life on the planet, let us consider the absorption spectra of ozone and the most important components of living organisms - nucleic acids and proteins.

Any substance has its own absorption bands. Both ozone, nucleic acids (DNA, RNA), and proteins absorb most intensely in the spectral region with a wavelength of 200-300 nm. And UV rays, which are destructive to living organisms, occupy precisely this part of the solar radiation spectrum.

Fig. 1. Spectral curve of damage to the genetic apparatus of microorganisms by ultraviolet rays.

In order not to be unfounded and to convince the most incredulous of the enormous importance of the ozone layer, let’s delve a little into the theory and prove that the ozone layer absorbs ultraviolet rays that are fatal to all living things. To do this, consider the absorption spectra of ozone (ozone layer) and nucleic acids and proteins.

First, let's define the concepts.

LIGHT ABSORPTION - a decrease in the intensity of optical radiation when passing through any medium due to interaction with it, as a result of which light energy is converted into other types of energy or into optical radiation of a different spectral composition.

ABSORPTION SPECTRUM is a set of frequencies absorbed by a given substance.

Ozone absorption spectrum.

Ozone (O 3) has a very complex absorption spectrum, where the most intense absorption bands are highlighted. Like many other absorption bands in molecular spectroscopy, these bands are named after the researcher who discovered them.

Ozone absorption bands:

• Hartley band (200 - 300 nm; l max = 255 nm);
• Huggins band (320-340 nm);
• Chalon–Lefevre band (330-350 nm);
• Chappuis band (500 - 650 nm; l max = 600 nm).

Figure 2. Ozone absorption bands.

Main absorption band – Hartley strip. Its maximum absorption is achieved at a wavelength of 255 nm. Please note that in Figure 1, the maximum damage to the genetic apparatus in living organisms also occurs at this wavelength. Consequently, the maximum value of the Earth's ozone layer for living organisms appears precisely in this band.

At wavelengths greater than 300 nm, weaker Hartley bands are adjacent stripes Huggins and Chalon-Lefebvre(Fig. 2). The absorption coefficient in these bands is several orders of magnitude lower than that of the Hartley bands. Individual bands located closely in these systems have clearly visible sharp maxima and minima. Finally, in the visible part of the spectrum there is a wide band Chappuis strip, which is associated with the blue color of ozone.

Very strong absorption of ozone is also observed in the vacuum ultraviolet region (100 – 200 nm). Together with absorption in the Hartley bands, this absorption leads to a break in the solar spectrum on the Earth's surface at wavelengths less than 290 nm, which is very important for protecting life on our planet from short-wave radiation.

Absorption spectra of nucleic acids and proteins.

Nucleic acids absorb only in the UV region (180-220 and 240-280 nm). Their chromophores are mainly purine and pyrimidine bases.

Figure 3. Absorption spectrum of proteins and nucleic acids.

Chromophores - unsaturated groups of atoms that cause color chemical compound and absorbing electromagnetic radiation.

Proteins have three types of chromophoric groups: the peptide groups themselves, side groups of amino acid residues and prosthetic groups. The first two absorb in the UV region and do not absorb in the visible region. Peptide groups -CO-NH- absorb around 190 nm. The side groups of three aromatic acids—tryptophan, tyrosine, and phenylalanine—also absorb at these wavelengths, much more strongly than the peptide groups. In addition, they have an absorption band in the range of 260-280 nm.

Prosthetic groups (heme in hemoglobin and other chromophores) absorb in the UV and visible region. They are what gives protein its color (for example, red color to hemoglobin).

The importance of the ozone layer as a thermostat of the atmosphere.

The ozone layer is important not only as a shield of the biosphere from damage by hard ultraviolet radiation, but also determines the thermal regime of the Earth's atmosphere. In the infrared region of the spectrum, ozone also has an important absorption band with a maximum of 960 nm. Thanks to this, O 3 absorbs the infrared energy (thermal) released by the Earth, prevents it from dissipating in Space, and thereby retains heat in the atmosphere of our planet.

Ozone blocks about 20% of the Earth's radiation, increasing the warming effect of the atmosphere.

The impact of ultraviolet rays from the sun on humans and other living organisms.

Why are ultraviolet rays so dangerous? Why do we give this great importance the ozone layer, which absorbs them. Let's take a closer look at the ultraviolet part of the solar radiation spectrum.

How does the ultraviolet part of the solar spectrum affect plants? Let's return to theory again. The ultraviolet wavelength range is divided into “far”, at 100-200 nm (we don’t care about it, this “light” is absorbed by oxygen molecules in upper layers does not reach the atmosphere and surface of the Earth) and “near”, at 200-380 nm, which, in turn, is conventionally divided into 3 parts.

UFA– “useful”, with a wavelength from 320 nm to the usual “violet” (it starts at 380 nm). Ultraviolet radiation with this wavelength penetrates most deeply into the tissues of animals and plants. In humans, for example, it is involved in the production of vitamin D; some species of lizards even see it with their eyes, not to mention the fact that UVA stimulates some species of reptiles during the mating season.

UVB– 280-320 nm – mid-ultraviolet range. It causes not only premature aging of human skin and a slowdown in the vegetative growth of most plants, but also ongoing debate about its impact on the biosphere. Thanks to UVB, Europeans get golden brown skin color during summer holidays. The closer to the border with UVC (280 nm), the more deadly the rays.

And finally UFS– “hard” ultraviolet with a wavelength from 200 to 280 nm. It is believed that at some stages of the development of life on Earth, UVC was very actively involved in the creation of DNA, because the absorption spectrum of nucleic acids has a peak in the region of 254 nm. This is demonstrated in Fig. 1. As can be seen from the figure, not only the beginning of life on Earth is associated with UVC, but also, under certain conditions, its end. In the UVC range, at a wavelength of 254 nm, sterilizers emit - low-pressure mercury ultraviolet lamps, used only in medicine.

So, ultraviolet solar radiation, according to the degree of impact on living organisms, is divided into three types:

1. UVA (wavelength 0.4–0.315 microns) is the least dangerous type of ultraviolet radiation for living matter. The largest number of these rays reaches the surface of the earth.
2. UV-B (wavelength 0.315–0.280 microns) reaches the ground only in small doses.
3. UV-C (wavelength 0.28–0.01 microns) is the most dangerous type of ultraviolet rays for living matter: even in small doses it has a detrimental effect on living organisms. Fortunately, UV-C is almost completely absorbed by the ozone layer and practically does not reach the ground.

Water, sunlight and oxygen contained in the earth’s atmosphere are the main conditions for the emergence and factors that ensure the continuation of life on our planet. At the same time, it has long been proven that the spectrum and intensity of solar radiation in the vacuum of space are unchanged, and on Earth the impact of ultraviolet radiation depends on many reasons: time of year, geographic location, altitude above sea level, thickness of the ozone layer, cloudiness and the level of concentration of natural and industrial impurities in the air.

What are ultraviolet rays

The sun emits rays in ranges visible and invisible to the human eye. The invisible spectrum includes infrared and ultraviolet rays.

Infrared radiation is electromagnetic waves with a length of 7 to 14 nm, which carry a colossal flow of thermal energy to the Earth, and therefore they are often called thermal. The share of infrared rays in solar radiation is 40%.

Ultraviolet radiation is a spectrum of electromagnetic waves, the range of which is divided conventionally into near and far ultraviolet rays. Distant or vacuum rays are completely absorbed by the upper layers of the atmosphere. Under terrestrial conditions, they are artificially generated only in vacuum chambers.

Near ultraviolet rays are divided into three subgroups of ranges:

• long – A (UVA) from 400 to 315 nm;
• medium – B (UVB) from 315 to 280 nm;
• short – C (UVC) from 280 to 100 nm.

How is it measured? ultraviolet radiation? Today, there are many special devices, both for domestic and professional use, that allow you to measure the frequency, intensity and magnitude of the received dose of UV rays, and thereby assess their likely harmfulness to the body.

Despite the fact that ultraviolet radiation in the composition of sunlight occupies only about 10%, it is thanks to its influence that there has been a qualitative leap in evolutionary development life - the emergence of organisms from water to land.

Main sources of ultraviolet radiation

Chief and natural spring ultraviolet radiation is, of course, the Sun. But man has also learned to “produce ultraviolet light” using special lamp devices:

• high-pressure mercury-quartz lamps operating in the general range of UV radiation - 100-400 nm;
• vital fluorescent lamps generating wavelengths from 280 to 380 nm, with a maximum emission peak between 310 and 320 nm;
• ozone and non-ozone (with quartz glass) bactericidal lamps, 80% of ultraviolet rays of which are at a length of 185 nm.

Both ultraviolet radiation from the sun and artificial ultraviolet light have the ability to affect the chemical structure of cells of living organisms and plants, and at the moment, only some species of bacteria are known that can do without it. For everyone else, the lack of ultraviolet radiation will lead to inevitable death.

So what is real biological effect ultraviolet rays, what are the benefits and is there any harm from ultraviolet radiation for humans?

The effect of ultraviolet rays on the human body

The most insidious ultraviolet radiation is short-wave ultraviolet radiation, since it destroys all types of protein molecules.

So why is terrestrial life possible and continuing on our planet? What layer of the atmosphere blocks harmful ultraviolet rays?

Living organisms are protected from hard ultraviolet radiation by the ozone layers of the stratosphere, which completely absorb rays in this range, and they simply do not reach the surface of the Earth.

Therefore, 95% of the total mass of solar ultraviolet comes from long waves (A), and approximately 5% from medium waves (B). But it’s important to clarify here. Despite the fact that there are many more long UV waves and they have great penetrating power, affecting the reticular and papillary layers of the skin, it is the 5% of medium waves that cannot penetrate beyond the epidermis that have the greatest biological impact.

It is mid-range ultraviolet radiation that intensively affects the skin, eyes, and also actively affects the functioning of the endocrine, central nervous and immune systems.

On the one hand, ultraviolet irradiation can cause:

• strong sunburn skin – ultraviolet erythema;
• clouding of the lens leading to blindness - cataracts;
• skin cancer – melanoma.

In addition, ultraviolet rays have a mutagenic effect and cause disruptions in the functioning of the immune system, which cause the occurrence of other oncological pathologies.

On the other hand, it is the effect of ultraviolet radiation that has a significant impact on the metabolic processes occurring in human body generally. The synthesis of melatonin and serotonin increases, the level of which has a positive effect on the functioning of the endocrine and central nervous system. Ultraviolet light activates the production of vitamin D, which is the main component for the absorption of calcium, and also prevents the development of rickets and osteoporosis.

Ultraviolet irradiation of the skin

Skin lesions can be both structural and functional in nature, which, in turn, can be divided into:

1. Acute injuries– arise due to high doses of solar radiation from mid-range rays received in a short time. These include acute photodermatosis and erythema.
2. Delayed damage– occur against the background of prolonged irradiation with long-wave ultraviolet rays, the intensity of which, by the way, does not depend on the time of year or the time of daylight. These include chronic photodermatitis, photoaging of the skin or solar geroderma, ultraviolet mutagenesis and the occurrence of neoplasms: melanoma, squamous cell and basal cell skin cancer. Among the list of delayed injuries is herpes.

It is important to note that both acute and delayed damage can be caused by excessive exposure to artificial sunbathing, not wearing sunglasses, as well as by visiting solariums that use uncertified equipment and/or do not carry out special preventive calibration of ultraviolet lamps.

Skin protection from ultraviolet radiation

If you do not abuse any “sunbathing”, then human body will cope with radiation protection on its own, because more than 20% is retained by healthy epidermis. Today, protection from ultraviolet radiation of the skin comes down to the following techniques that minimize the risk of the formation of malignant neoplasms:

• limiting time spent in the sun, especially during midday summer hours;
• wearing light but closed clothing, because to receive the necessary dose that stimulates the production of vitamin D, it is not at all necessary to cover yourself with a tan;
• selection of sunscreens depending on the specific ultraviolet index characteristic of the area, time of year and day, as well as your own skin type.

Attention! For indigenous residents of central Russia, a UV index above 8 not only requires the use of active protection, but also represents real threat for good health. Radiation measurements and solar indices forecasts can be found on leading weather websites.

Exposure to ultraviolet radiation on the eyes

Damage to the structure of the eye cornea and lens (electro-ophthalmia) is possible with visual contact with any source of ultraviolet radiation. Despite the fact that a healthy cornea does not transmit and reflects 70% of hard ultraviolet radiation, there are many reasons that can become a source of serious diseases. Among them:

• unprotected observation of flares, solar eclipses;
• a casual glance at a star on the sea coast or in high mountains;
• photo injury from camera flash;
• observing the operation of a welding machine or neglecting safety precautions (lack of a protective helmet) when working with it;
• long-term operation of the strobe light in discos;
• violation of the rules for visiting a solarium;
• long-term stay in a room in which quartz bactericidal ozone lamps operate.

What are the first signs of electroophthalmia? Clinical symptoms, namely redness of the eye sclera and eyelids, pain when moving the eyeballs and the sensation of a foreign body in the eye, as a rule, occur 5-10 hours after the above circumstances. However, means of protection against ultraviolet radiation are available to everyone, because even ordinary glass lenses do not transmit most UV rays.

The use of safety glasses with a special photochromic coating on the lenses, the so-called “chameleon glasses,” will be the best “household” option for eye protection. You won't have to worry about wondering what color and shade level of UV filter actually provides effective protection in specific circumstances.

And of course, if you expect eye contact with ultraviolet flashes, it is necessary to wear protective glasses in advance or use other devices that block rays harmful to the cornea and lens.

Application of ultraviolet radiation in medicine

Ultraviolet light kills fungus and other microbes in the air and on the surface of walls, ceilings, floors and objects, and after exposure to special lamps, mold is removed. People use this bactericidal property of ultraviolet light to ensure the sterility of manipulation and surgical rooms. But ultraviolet radiation in medicine is used not only to combat hospital-acquired infections.

The properties of ultraviolet radiation have found their application in a wide variety of diseases. At the same time, new techniques are emerging and constantly being improved. For example, ultraviolet blood irradiation, invented about 50 years ago, was initially used to suppress the growth of bacteria in the blood during sepsis, severe pneumonia, extensive purulent wounds and other purulent-septic pathologies.

Today, ultraviolet irradiation of blood or blood purification helps fight acute poisoning, drug overdose, furunculosis, destructive pancreatitis, obliterating atherosclerosis, ischemia, cerebral atherosclerosis, alcoholism, drug addiction, acute mental disorders and many other diseases, the list of which is constantly expanding. .

Diseases for which the use of ultraviolet radiation is indicated, and when any procedure with UV rays is harmful:

INDICATIONS	CONTRAINDICATIONS
sun starvation, rickets	individual intolerance
wounds and ulcers	oncology
frostbite and burns	bleeding
neuralgia and myositis	hemophilia
psoriasis, eczema, vitiligo, erysipelas	ONMK
respiratory diseases	photodermatitis
diabetes	renal and liver failure
adnexitis	malaria
osteomyelitis, osteoporosis	hyperthyroidism
non-systemic rheumatic lesions	heart attacks, strokes

In order to live without pain, people with joint damage will benefit from an ultraviolet lamp as an invaluable aid in general complex therapy.

The influence of ultraviolet radiation in rheumatoid arthritis and arthrosis, the combination of ultraviolet therapy techniques with the correct selection of biodose and a competent antibiotic regimen is a 100% guarantee of achieving a systemic health effect with a minimal drug load.

In conclusion, we note that the positive effect of ultraviolet radiation on the body and just one single procedure of ultraviolet irradiation (purification) of the blood + 2 sessions in a solarium will help a healthy person look and feel 10 years younger.

The ozone screen is a layer of the atmosphere with the highest concentration of ozone molecules O3 at an altitude of about 20 - 25 km, absorbing hard ultraviolet radiation, which is fatal to organisms. Destruction o.e. As a result of anthropogenic pollution of the atmosphere, it poses a threat to all living things, and above all to humans.
The ozone screen (ozonosphere) is a layer of the atmosphere within the stratosphere, located at different heights from the Earth's surface and having the highest density (concentration of molecules) of ozone at an altitude of 22 - 26 km.
The ozone screen is a part of the atmosphere where ozone is found in low concentrations.
Nitrate content in crop products. The destruction of the ozone screen is associated with nitrogen oxide, which serves as a source of the formation of other oxides that catalyze the photochemical reaction of the decomposition of ozone molecules.
The emergence of the ozone screen, which fenced off the Earth's surface from the chemically active radiation permeating outer space, dramatically changed the course of the evolution of living matter. Under the conditions of the protobiosphere (primary biosphere), mutagenesis was very intense: new forms of living matter rapidly arose and changed in various ways, and a rapid accumulation of gene pools occurred.
The ozonosphere (ozone screen), lying above the biosphere, in a layer from 20 to 35 km, absorbs ultraviolet radiation, which is fatal to living beings of the biosphere, and is formed due to oxygen, biogenic in origin, i.e. also created by the living matter of the Earth. However, even if living matter penetrates into these layers in the form of spores or aeroplankton, it does not reproduce in them and its concentration is negligible. Let us note that, penetrating into this shell of the Earth and even higher, into space, a person takes with him spaceship like a piece of the biosphere, i.e. the entire life support system.
Explain how the ozone shield is formed and what leads to its destruction.
The biosphere occupies the space from the ozone screen, where bacterial and fungal spores are found at an altitude of 20 km, to a depth of more than 3 km below the earth's surface and about 2 km below the ocean floor. There, in the waters of oil fields, anaerobic bacteria are found. The highest concentration of biomass is concentrated at the interfaces between geospheres, i.e. in coastal and surface waters ocean and on the land surface. This is explained by the fact that the source of energy in the biosphere is sunlight, and autotrophic, and after them heterotrophic organisms, mainly inhabit places where solar radiation is most intense.
The most dangerous consequences of ozone depletion for humans and many animals is an increase in the incidence of skin cancer and eye cataracts. In turn, this, according to official UN data, leads to the appearance of 100 thousand new cases of cataracts and 10 thousand cases of skin cancer in the world, as well as a decrease in immunity in both humans and animals.
The wall of environmental prohibitions, which has reached a global level (destruction of the ozone shield, precipitation acidification, climate change, etc.), turned out to be not the only factor social development. Changed simultaneously and in parallel economic structure.
Dynamics of the ozone hole within Antarctica (according to N.F. Reimers, 1990 (space without shading. The consequences of depletion of the ozone screen are extremely dangerous for humans and many animals - an increase in the number of diseases of skin cancer and eye cataracts. In turn, this, according to official According to the UN, it leads to the appearance of 100 thousand new cases of cataracts and 10 thousand cases of skin cancer in the world, as well as a decrease in immunity in both humans and animals.
Approximately the same thing happened with the increase in the production of freons and their impact on the planet’s ozone screen.
We have already said that life is preserved because an ozone shield has formed around the planet, protecting the biosphere from deadly ultraviolet rays. But in recent decades, a decrease in the ozone content in the protective layer has been noted.

As a result of photosynthesis, more and more oxygen began to appear in the atmosphere and an ozone screen formed around the planet, which became a reliable protection of organisms from the destructive ultraviolet radiation of the sun and short-wave cosmic radiation. Under his protection, life began to flourish rapidly: plants suspended in water (phytoplankton), which released oxygen, began to develop in the surface layers of the ocean. From the ocean, organic life moved to land; The first living beings began to populate the earth approximately 400 million years ago. Organisms that develop on earth and are capable of photosynthesis (plants) further increased the flow of oxygen into the atmosphere. It is believed that it took at least half a billion years for the oxygen content in the atmosphere to reach its current level, which has not changed for about 50 million years.
But the high cost of such flights has slowed down the development of supersonic travel so much that it no longer poses a significant threat to the ozone shield.
Global monitoring is carried out to obtain information about the biosphere as a whole or about individual biosphere processes, in particular, climate change, the state of the ozone screen, etc. The specific goals of global monitoring, as well as its objects, are determined in the course of international cooperation within the framework of various international agreements and declarations.
Global monitoring - tracking general processes and phenomena, including anthropogenic impacts on the biosphere, and warning about emerging extreme situations, such as the weakening of the planet’s ozone screen, and other phenomena in the Earth’s ecosphere.
The shortest wavelength (200 - 280 nm) zone of this part of the spectrum (ultraviolet C) is actively absorbed by the skin; In terms of danger, UV-C is close to JT rays, but is almost completely absorbed by the ozone screen.
The emergence of plants onto land was apparently associated with the achievement of an oxygen content in the atmosphere of approximately 10% of the present level. Now the ozone screen was able to at least partially protect organisms from ultraviolet radiation.
The destruction of the Earth's ozone screen is accompanied by a number of dangerous obvious and hidden negative impacts per person and wildlife.
At the upper boundary of the troposphere, under the influence of cosmic radiation, ozone is formed from oxygen. Consequently, the ozone shield, which protects life from deadly radiation, is also the result of the activity of the living substance itself.
Natural conditions are not directly involved in material production and non-production. Earth, the ozone shield of the planet, protecting all living things from cosmic radiation. Many natural conditions with development it produces, forces become resources, so the boundary between these concepts is conditional.
The lower boundary of the biosphere lies at a depth of 3 km on land and 2 km below the ocean floor. The upper limit is the ozone screen, above which UV radiation from the sun excludes organic life. basis organic life is carbon.
Microorganisms have been found in oil-bearing waters at this depth. The upper limit is the protective ozone screen, which protects living organisms on Earth from the harmful effects of ultraviolet rays. Humans also belong to the biosphere.
What are the mechanisms for retaining the ozonosphere as a layer in the stratosphere with the highest ozone density at altitudes of 22 - 25 km above the Earth's surface is not yet entirely clear. If human impact on the ozone screen is limited to chemicals, then protecting the ozonosphere from destruction is quite possible by banning chlorofluorocarbons and other chemical agents dangerous to it. If the thinning of the ozonosphere is associated with a change in the Earth's magnetic field, as some researchers suggest, then the reasons for this change need to be established.
In fact, as we see, the geographic envelope includes the earth’s crust, atmosphere, hydrosphere and biosphere. Borders geographic envelope are determined from above by an ozone screen, and from below - earth's crust: under continents at a depth of 30 - 40 km (including under mountains - up to 70 - 80 km), and under oceans - 5 - 8 km.
In most cases, the ozone layer is indicated as the upper theoretical boundary of the biosphere without specifying its boundaries, which is quite acceptable if the difference between the neo- and paleobiosphere is not discussed. Otherwise, it should be taken into account that the ozone screen formed only about 600 million years ago, after which organisms were able to reach land.

Regulatory processes in the biosphere are also based on the high activity of living matter. Thus, the production of oxygen maintains the ozone screen and, as a consequence, the relative constancy of the flow of radiant energy reaching the surface of the planet. The constancy of the mineral composition of ocean waters is maintained by the activity of organisms that actively extract individual elements, which balances their influx with the river runoff entering the ocean. Similar regulation occurs in many other processes.
Nuclear explosions have a destructive effect on the stratospheric ozone screen, which is known to protect living organisms from the harmful effects of short-wave ultraviolet radiation.
To preserve the Earth's ozone layer, measures are being taken to reduce emissions of freons and replace them with environmentally friendly substances. Currently, solving the problem of preserving the ozone screen and destroying ozone holes is necessary to preserve earthly civilization. At the UN Conference on environment and the developments that took place in Rio de Janeiro, it was concluded that our atmosphere is increasingly affected by gases that cause Greenhouse effect and threatened by climate change, as well as chemical substances that reduce the ozone layer.
Ozone is found in low concentrations in the upper layers of the stratosphere. Therefore, this part of the atmosphere is often called the ozone shield. Ozone plays a large role in shaping the temperature regime of the underlying layers of the atmosphere and, consequently, air currents. Over various areas earth's surface and in different time The ozone content varies throughout the year.
The biosphere is the planetary shell of the Earth where life exists. In the atmosphere, the upper limits of life are determined by the ozone screen - a thin layer of ozone at an altitude of 16 - 20 km. The ocean is completely saturated with life. The biosphere is a global ecosystem supported by the biological cycle of matter and flows solar energy. All ecosystems of the Earth are all components.
Ozone O3 is a gas whose molecule consists of three oxygen atoms. Active oxidizing agent capable of destroying pathogens; The ozone shield in the upper atmosphere protects our planet from ultraviolet radiation from the Sun.
The gradual increase in CCL in the atmosphere occurring today, associated with industrial emissions, may be the cause of an increase in the greenhouse effect and climate warming. At the same time, the currently observed partial destruction of the ozone screen can to a certain extent compensate for this effect by increasing heat loss from the Earth's surface. At the same time, the flow of short-wave ultraviolet radiation will increase, which is dangerous for many living organisms. As we see, anthropogenic interference in the structure of the atmosphere is fraught with unpredictable and undesirable consequences.
Hydrocarbons in oil and gas are practically harmless, but when released when using fossil fuels, they accumulate in the atmosphere, water, soil and turn out to be pathogens. dangerous diseases. The production and massive release of freons into the atmosphere can destroy the protective ozone shield.
Let us consider the most typical consequences of human atmospheric pollution. Typical consequences are acid precipitation, the greenhouse effect, disruption of the ozone layer, dust and aerosol pollution from large industrial centers.
Ozone is constantly formed in the upper parts of the atmosphere. It is believed that at an altitude of about 25 - 30 km, ozone forms a powerful ozone screen, which blocks the bulk of ultraviolet rays, protecting organisms from their destructive effects. Together with carbon dioxide in the air and water vapor, it protects the Earth from hypothermia and delays long-wave infrared (thermal) radiation from our planet.
Suffice it to say that the oxygen in our atmosphere, without which life is impossible, the ozone shield, the absence of which would destroy earthly life, soil cover, on which all the vegetation of the planet develops, coal deposits and oil deposits - all this is the result of the long-term activity of living organisms.
In farming practice, up to 30 - 50% of all applied mineral fertilizers are uselessly lost. The release of nitrogen oxides into the atmosphere entails not only economic losses, but also threatens to violate the planet’s ozone shield.
Converted enterprises should be aimed at the design, production and implementation of ultra-modern technological systems for the production of civilian products at the level of world standards and mass demand. Only specialized scientific institutions and military-industrial complex plants are able to solve, for example, the most important task of replacing freons, which destroy the Earth’s ozone shield, with other environmentally safer refrigerants.
The upper limit of life in the atmosphere is determined by the level of UV radiation. At an altitude of 25 - 30 km, most of the ultraviolet radiation from the Sun is absorbed by the relatively thin layer of ozone located here - the ozone screen. If living organisms rise above the protective ozone layer, they die. The atmosphere above the Earth's surface is saturated with a variety of living organisms that move through the air either actively or passively. Spores of bacteria and fungi are found up to a height of 20 - 22 km, but the bulk of aeroplankton is concentrated in a layer up to 1 - 15 km.
It is assumed that global atmospheric pollution with certain substances (freons, nitrogen oxides, etc.) can disrupt the functioning of the ozone screen.

OZONOSPHERE OZONE SCREEN - a layer of the atmosphere that closely coincides with the stratosphere, lying between 7 - 8 (at the poles), 17 - 18 (at the equator) and 50 km (with the highest ozone density at altitudes of 20 - 22 km) above the surface of the planet and characterized by increased concentration of ozone molecules, reflecting hard cosmic radiation, fatal to living things. It is assumed that global atmospheric pollution with certain substances (freons, nitrogen oxides, etc.) can disrupt the functioning of the ozone screen.
The ozone layer effectively absorbs electromagnetic radiation with wavelengths in the region of 220 - 300 nm, performing the function of a screen. Thus, UV with a wavelength of up to 220 nm is completely absorbed by atmospheric oxygen molecules, and in the region of 220 - 300 nm is effectively blocked by the ozone screen. An important part of the solar spectrum is the region adjacent to 300 nm on both sides.
The process of photodissociation also underlies the formation of ozone from molecular oxygen. The ozone layer is located at an altitude of 10 - 100 km; The maximum ozone concentration is recorded at an altitude of about 20 km. The ozone screen is of great importance for the preservation of life on Earth: the ozone layer absorbs most of the ultraviolet radiation coming from the Sun, and in its short-wave part, which is the most destructive for living organisms. Only a soft part of the flow of ultraviolet rays with a wavelength of about 300 - 400 nm reaches the Earth's surface, relatively harmless, and according to a number of parameters necessary for the normal development and functioning of living organisms. On this basis, some scientists draw the boundary of the biosphere precisely at the height of the ozone layer.
The evolutionary factor is a modern environmental factor generated by the evolution of life. For example, the ozone screen is currently in operation environmental factor, affecting organisms, populations, biocenoses, ecological systems, including the biosphere, existed in past geological eras. The emergence of the ozone screen is associated with the emergence of photosynthesis and the accumulation of oxygen in the atmosphere.
Another limiting factor for the upward penetration of life is hard cosmic radiation. At an altitude of 22 - 24 km from the Earth's surface, the maximum concentration of ozone is observed - the ozone screen. The ozone screen reflects cosmic radiation (gamma and x-rays) and partially ultraviolet rays that are harmful to living organisms.
Biological effects caused by radiation of different wavelengths. The most important source of natural radiation is solar radiation. The bulk of solar energy incident on the Earth (approximately 75%) comes from visible rays, almost 20% from the IR region of the spectrum, and only approximately 5% from UV with a wavelength of 300 - 380 nm. The lower limit of the wavelengths of solar radiation incident on the earth's surface is determined by the density of the so-called ozone screen.

Atmosphere(from the Greek atmos - steam and spharia - ball) - air envelope The earth rotating with it. The development of the atmosphere was closely related to the geological and geochemical processes occurring on our planet, as well as to the activities of living organisms.

The lower boundary of the atmosphere coincides with the surface of the Earth, since air penetrates into the smallest pores in the soil and is dissolved even in water.

The upper boundary at an altitude of 2000-3000 km gradually passes into outer space.

Thanks to the atmosphere, which contains oxygen, life on Earth is possible. Atmospheric oxygen is used in the breathing process of humans, animals, and plants.

If there were no atmosphere, the Earth would be as quiet as the Moon. After all, sound is the vibration of air particles. The blue color of the sky is explained by the fact that the sun's rays, passing through the atmosphere, like through a lens, are decomposed into their component colors. In this case, the rays of blue and blue colors are scattered the most.

The atmosphere traps most of the sun's ultraviolet radiation, which has a detrimental effect on living organisms. It also retains heat near the Earth's surface, preventing our planet from cooling.

The structure of the atmosphere

In the atmosphere, several layers can be distinguished, differing in density (Fig. 1).

Troposphere

Troposphere- the lowest layer of the atmosphere, the thickness of which above the poles is 8-10 km, in temperate latitudes - 10-12 km, and above the equator - 16-18 km.

Rice. 1. The structure of the Earth's atmosphere

The air in the troposphere is heated by the earth's surface, that is, by land and water. Therefore, the air temperature in this layer decreases with height by an average of 0.6 °C for every 100 m. At the upper boundary of the troposphere it reaches -55 °C. At the same time, in the region of the equator on upper limit troposphere, the air temperature is -70 °C, and in the area North Pole-65 °C.

About 80% of the mass of the atmosphere is concentrated in the troposphere, almost all the water vapor is located, thunderstorms, storms, clouds and precipitation occur, and vertical (convection) and horizontal (wind) movement of air occurs.

We can say that weather is mainly formed in the troposphere.

Stratosphere

Stratosphere- a layer of the atmosphere located above the troposphere at an altitude of 8 to 50 km. The color of the sky in this layer appears purple, which is explained by the thinness of the air, due to which the sun's rays are almost not scattered.

The stratosphere contains 20% of the mass of the atmosphere. The air in this layer is rarefied, there is practically no water vapor, and therefore almost no clouds and precipitation form. However, stable air currents are observed in the stratosphere, the speed of which reaches 300 km/h.

This layer is concentrated ozone(ozone screen, ozonosphere), a layer that absorbs ultraviolet rays, preventing them from reaching the Earth and thereby protecting living organisms on our planet. Thanks to ozone, the air temperature at the upper boundary of the stratosphere ranges from -50 to 4-55 °C.

Between the mesosphere and stratosphere is located transition zone- stratopause.

Mesosphere

Mesosphere- a layer of the atmosphere located at an altitude of 50-80 km. The air density here is 200 times less than at the Earth's surface. The color of the sky in the mesosphere appears black, and stars are visible during the day. The air temperature drops to -75 (-90)°C.

At an altitude of 80 km begins thermosphere. The air temperature in this layer rises sharply to a height of 250 m, and then becomes constant: at an altitude of 150 km it reaches 220-240 ° C; at an altitude of 500-600 km exceeds 1500 °C.

In the mesosphere and thermosphere, under the influence of cosmic rays, gas molecules disintegrate into charged (ionized) particles of atoms, so this part of the atmosphere is called ionosphere- a layer of very rarefied air, located at an altitude of 50 to 1000 km, consisting mainly of ionized oxygen atoms, nitrogen oxide molecules and free electrons. This layer is characterized by high electrification, and long and medium radio waves are reflected from it, like from a mirror.

In the ionosphere there are auroras- glow of rarefied gases under the influence of electrically charged particles flying from the Sun - and sharp fluctuations in the magnetic field are observed.

Exosphere

Exosphere- the outer layer of the atmosphere located above 1000 km. This layer is also called the scattering sphere, since gas particles move here at high speed and can be scattered into outer space.

Atmospheric composition

The atmosphere is a mixture of gases consisting of nitrogen (78.08%), oxygen (20.95%), carbon dioxide(0.03%), argon (0.93%), a small amount of helium, neon, xenon, krypton (0.01%), ozone and other gases, but their content is negligible (Table 1). The modern composition of the Earth's air was established more than a hundred million years ago, but the sharply increased human production activity nevertheless led to its change. Currently, there is an increase in CO 2 content by approximately 10-12%.

The gases that make up the atmosphere perform various functional roles. However, the main significance of these gases is determined primarily by the fact that they very strongly absorb radiant energy and thereby have a significant impact on the temperature regime of the Earth's surface and atmosphere.

Table 1. Chemical composition dry atmospheric air near the earth's surface

	Volume concentration. %	Molecular weight, units
Oxygen
Carbon dioxide
Nitrous oxide
	from 0 to 0.00001
Sulfur dioxide	from 0 to 0.000007 in summer; from 0 to 0.000002 in winter
	From 0 to 0.000002	46,0055/17,03061
Azog dioxide
Carbon monoxide

Nitrogen, The most common gas in the atmosphere, it is chemically little active.

Oxygen, unlike nitrogen, is a chemically very active element. The specific function of oxygen is oxidation organic matter heterotrophic organisms, rocks and under-oxidized gases released into the atmosphere by volcanoes. Without oxygen, there would be no decomposition of dead organic matter.

The role of carbon dioxide in the atmosphere is extremely large. It enters the atmosphere as a result of combustion processes, respiration of living organisms, and decay and is, first of all, the main building material for the creation of organic matter during photosynthesis. In addition, the ability of carbon dioxide to transmit short-wave solar radiation and absorb part of the thermal long-wave radiation is of great importance, which will create the so-called greenhouse effect, which will be discussed below.

Atmospheric processes, especially the thermal regime of the stratosphere, are also influenced by ozone. This gas serves as a natural absorber of ultraviolet radiation from the sun, and the absorption of solar radiation leads to heating of the air. Average monthly values general content ozone in the atmosphere varies depending on the latitude and time of year within the range of 0.23-0.52 cm (this is the thickness of the ozone layer at ground pressure and temperature). There is an increase in ozone content from the equator to the poles and an annual cycle with a minimum in autumn and a maximum in spring.

A characteristic property of the atmosphere is that the content of the main gases (nitrogen, oxygen, argon) changes slightly with altitude: at an altitude of 65 km in the atmosphere the content of nitrogen is 86%, oxygen - 19, argon - 0.91, at an altitude of 95 km - nitrogen 77, oxygen - 21.3, argon - 0.82%. The constancy of the composition of atmospheric air vertically and horizontally is maintained by its mixing.

In addition to gases, the air contains water vapor And solid particles. The latter can have both natural and artificial (anthropogenic) origin. These are pollen, tiny salt crystals, road dust, and aerosol impurities. When the sun's rays penetrate the window, they can be seen with the naked eye.

There are especially many particulate particles in the air of cities and large industrial centers, where emissions of harmful gases and their impurities formed during fuel combustion are added to aerosols.

The concentration of aerosols in the atmosphere determines the transparency of the air, which affects solar radiation reaching the Earth's surface. The largest aerosols are condensation nuclei (from lat. condensatio- compaction, thickening) - contribute to the transformation of water vapor into water droplets.

The importance of water vapor is determined primarily by the fact that it delays long-wave thermal radiation from the earth's surface; represents the main link of large and small moisture cycles; increases the air temperature during condensation of water beds.

The amount of water vapor in the atmosphere varies in time and space. Thus, the concentration of water vapor at the earth's surface ranges from 3% in the tropics to 2-10 (15)% in Antarctica.

The average content of water vapor in the vertical column of the atmosphere in temperate latitudes is about 1.6-1.7 cm (this is the thickness of the layer of condensed water vapor). Information regarding water vapor in different layers of the atmosphere is contradictory. It was assumed, for example, that in the altitude range from 20 to 30 km, specific humidity increases strongly with altitude. However, subsequent measurements indicate greater dryness of the stratosphere. Apparently, the specific humidity in the stratosphere depends little on altitude and is 2-4 mg/kg.

The variability of water vapor content in the troposphere is determined by the interaction of the processes of evaporation, condensation and horizontal transport. As a result of condensation of water vapor, clouds form and precipitation falls in the form of rain, hail and snow.

The processes of phase transitions of water occur predominantly in the troposphere, which is why clouds in the stratosphere (at altitudes of 20-30 km) and mesosphere (near the mesopause), called pearlescent and silvery, are observed relatively rarely, while tropospheric clouds often cover about 50% of the entire earth's surface. surfaces.

The amount of water vapor that can be contained in the air depends on the air temperature.

1 m 3 of air at a temperature of -20 ° C can contain no more than 1 g of water; at 0 °C - no more than 5 g; at +10 °C - no more than 9 g; at +30 °C - no more than 30 g of water.

Conclusion: The higher the air temperature, the more water vapor it can contain.

The air may be rich And not saturated water vapor. So, if at a temperature of +30 °C 1 m 3 of air contains 15 g of water vapor, the air is not saturated with water vapor; if 30 g - saturated.

Absolute humidity is the amount of water vapor contained in 1 m3 of air. It is expressed in grams. For example, if they say “absolute humidity is 15,” this means that 1 m L contains 15 g of water vapor.

Relative humidity- this is the ratio (in percentage) of the actual content of water vapor in 1 m 3 of air to the amount of water vapor that can be contained in 1 m L at a given temperature. For example, if the radio broadcast a weather report that the relative humidity is 70%, this means that the air contains 70% of the water vapor it can hold at that temperature.

The higher the relative humidity, i.e. The closer the air is to a state of saturation, the more likely precipitation is.

Always high (up to 90%) relative air humidity is observed in equatorial zone, since the air temperature remains high there throughout the year and large evaporation occurs from the surface of the oceans. The relative humidity is also high in the polar regions, but because at low temperatures even a small amount of water vapor makes the air saturated or close to saturated. In temperate latitudes, relative humidity varies with the seasons - it is higher in winter, lower in summer.

The relative air humidity in deserts is especially low: 1 m 1 of air there contains two to three times less water vapor than is possible at a given temperature.

To measure relative humidity, a hygrometer is used (from the Greek hygros - wet and metreco - I measure).

When cooled, saturated air cannot retain the same amount of water vapor; it thickens (condenses), turning into droplets of fog. Fog can be observed in summer on a clear, cool night.

Clouds- this is the same fog, only it is formed not at the earth’s surface, but at a certain height. As the air rises, it cools and the water vapor in it condenses. The resulting tiny droplets of water make up clouds.

Cloud formation also involves particulate matter suspended in the troposphere.

Clouds can have different shapes, which depend on the conditions of their formation (Table 14).

The lowest and heaviest clouds are stratus. They are located at an altitude of 2 km from the earth's surface. At an altitude of 2 to 8 km, more picturesque cumulus clouds can be observed. The highest and lightest are cirrus clouds. They are located at an altitude of 8 to 18 km above the earth's surface.

Families	Kinds of clouds	Appearance
A. Upper clouds - above 6 km	I. Cirrus	Thread-like, fibrous, white
	II. Cirrocumulus	Layers and ridges of small flakes and curls, white
	III. Cirrostratus	Transparent whitish veil
B. Mid-level clouds - above 2 km	IV. Altocumulus	Layers and ridges of white and gray color
	V. Altostratified	Smooth veil of milky gray color
B. Low clouds - up to 2 km	VI. Nimbostratus	Solid shapeless gray layer
	VII. Stratocumulus	Non-transparent layers and ridges of gray color
	VIII. Layered	Non-transparent gray veil
D. Clouds of vertical development - from the lower to the upper tier	IX. Cumulus	Clubs and domes are bright white, with torn edges in the wind
	X. Cumulonimbus	Powerful cumulus-shaped masses of dark lead color

Atmospheric protection

The main source is industrial enterprises and cars. IN big cities The problem of gas pollution on main transport routes is very acute. That is why many large cities around the world, including our country, have introduced environmental control of the toxicity of vehicle exhaust gases. According to experts, smoke and dust in the air can reduce the supply of solar energy to the earth's surface by half, which will lead to a change in natural conditions.