Changed the earth's surface. No less important was the activity of the wind, which carried small fractions of rocks over long distances. Temperature fluctuations and other atmospheric factors significantly influenced the destruction of rocks. Along with this, A. protects the Earth's surface from the destructive action of falling meteorites, most of which burn up when they enter the dense layers of the atmosphere.

The activity of living organisms, which has had a strong influence on the development of A. itself, to a very large extent, depends on atmospheric conditions. A. delays most of the ultraviolet radiation of the sun, which has a detrimental effect on many organisms. Atmospheric oxygen is used in the process of respiration by animals and plants, atmospheric carbon dioxide - in the process of plant nutrition. Climatic factors, in particular the thermal regime and the regime of moisture, affect the state of health and human activity. Agriculture is especially strongly dependent on climatic conditions. In turn, human activity exerts an ever-increasing influence on the composition of the atmosphere and on the climatic regime.

The structure of the atmosphere

Vertical temperature distribution in the atmosphere and related terminology.

Numerous supervision show that And. has accurately expressed layered structure (see fig.). The main features of the layered structure of an atmosphere are determined primarily by the features of the vertical temperature distribution. In the lowest part of A. - the troposphere, where intense turbulent mixing is observed (see Turbulence in the atmosphere and hydrosphere), the temperature decreases with increasing altitude, and the decrease in temperature along the vertical averages 6 ° per 1 km. The height of the troposphere varies from 8-10 km in polar latitudes to 16-18 km near the equator. Due to the fact that the air density decreases rapidly with height, about 80% of the total mass A is concentrated in the troposphere. Above the troposphere there is a transition layer - the tropopause with a temperature of 190-220, above which the stratosphere begins. In the lower part of the stratosphere, the decrease in temperature with height stops, and the temperature remains approximately constant up to an altitude of 25 km - the so-called. isothermal area(lower stratosphere); higher temperature begins to increase - inversion region (upper stratosphere). The temperature peaks at ~270 K at the level of the stratopause, located at an altitude of about 55 km. Layer A., ​​located at altitudes from 55 to 80 km, where the temperature again decreases with height, was called the mesosphere. Above it is a transition layer - mesopause, above which is the thermosphere, where the temperature, increasing with height, reaches very high values ​​(over 1000 K). Even higher (at altitudes ~ 1,000 km or more) is the exosphere, from where atmospheric gases are dissipated into world space due to dissipation and where a gradual transition from atmospheric air to interplanetary space takes place. Usually, all layers of the atmosphere above the troposphere are called the upper layers, although sometimes the stratosphere or its lower part is also referred to as the lower layers of the atmosphere.

All the structural parameters of an atmosphere (temperature, pressure, density) exhibit significant spatial and temporal variability (latitudinal, annual, seasonal, daily, etc.). Therefore, the data in Fig. reflect only the average state of the atmosphere.

Scheme of the structure of the atmosphere:
1 - sea level; 2 - the highest point of the Earth - Mount Chomolungma (Everest), 8848 m; 3 - cumulus clouds of good weather; 4 - powerful cumulus clouds; 5 - shower (thunderstorm) clouds; 6 - nimbostratus clouds; 7 - cirrus clouds; 8 - aircraft; 9 - layer of maximum ozone concentration; 10 - mother-of-pearl clouds; 11 - stratospheric balloon; 12 - radiosonde; 1З - meteors; 14 - noctilucent clouds; 15 - auroras; 16 - American X-15 rocket aircraft; 17, 18, 19 - radio waves reflected from ionized layers and returning to the Earth; 20 - sound wave reflected from the warm layer and returning to the Earth; 21 - the first Soviet artificial Earth satellite; 22 - intercontinental ballistic missile; 23 - geophysical research rockets; 24 - meteorological satellites; 25 - spacecraft "Soyuz-4" and "Soyuz-5"; 26 - space rockets leaving the atmosphere, as well as a radio wave penetrating the ionized layers and leaving the atmosphere; 27, 28 - dissipation (slipping) of H and He atoms; 29 - trajectory of solar protons P; 30 - penetration of ultraviolet rays (wavelength l> 2000 and l< 900).

The layered structure of the atmosphere has many other diverse manifestations. The chemical composition of the atmosphere is heterogeneous in height. If at heights up to 90 km, where there is intense mixing of the atmosphere, the relative composition of the constant components of the atmosphere remains practically unchanged (this entire thickness of the atmosphere is called the homosphere), then above 90 km - in heterosphere- under the influence of the dissociation of molecules of atmospheric gases by the ultraviolet radiation of the sun, a strong change in the chemical composition of atmospheric agents occurs with height. Typical features of this part of A. are layers of ozone and the own glow of the atmosphere. A complex layered structure is characteristic of atmospheric aerosol—solid particles of terrestrial and cosmic origin suspended in air. The most common aerosol layers are below the tropopause and at an altitude of about 20 km. Layered is the vertical distribution of electrons and ions in the atmosphere, which is expressed in the existence of D, E, and F layers of the ionosphere.

Composition of the atmosphere

One of the most optically active components is atmospheric aerosol - particles suspended in the air ranging in size from several nm to several tens of microns, formed during the condensation of water vapor and entering the atmosphere from the earth's surface as a result of industrial pollution, volcanic eruptions, and also from space. The aerosol is observed both in the troposphere and in the upper layers of A. The aerosol concentration decreases rapidly with altitude, but numerous secondary maxima associated with the existence of aerosol layers are superimposed on this trend.

upper atmosphere

Above 20–30 km, the molecules of an atom, as a result of dissociation, break down to one degree or another into atoms, and free atoms and new, more complex molecules appear in an atom. Somewhat higher, ionization processes become significant.

The most unstable region is the heterosphere, where the processes of ionization and dissociation give rise to numerous photochemical reactions that determine the change in air composition with height. The gravitational separation of gases also takes place here, which is expressed in the gradual enrichment of the atmosphere with lighter gases as the altitude increases. According to rocket measurements, the gravitational separation of neutral gases - argon and nitrogen - is observed above 105-110 km. The main components of A. in a layer of 100–210 km are molecular nitrogen, molecular oxygen, and atomic oxygen (the concentration of the latter at a level of 210 km reaches 77 ± 20% of the concentration of molecular nitrogen).

The upper part of the thermosphere consists mainly of atomic oxygen and nitrogen. At an altitude of 500 km, molecular oxygen is practically absent, but molecular nitrogen, whose relative concentration greatly decreases, still dominates atomic nitrogen.

In the thermosphere, an important role is played by tidal motions (see Ebb and flow), gravitational waves, photochemical processes, an increase in the mean free path of particles, and other factors. The results of observations of satellite deceleration at altitudes of 200-700 km led to the conclusion that there is a relationship between density, temperature and solar activity, which is associated with the existence of a daily, semi-annual and annual variation of structural parameters. It is possible that diurnal variations are largely due to atmospheric tides. During periods of solar flares, the temperature at an altitude of 200 km in low latitudes can reach 1700-1900°C.

Above 600 km, helium becomes the predominant component, and even higher, at altitudes of 2-20 thousand km, the Earth's hydrogen corona extends. At these altitudes, the Earth is surrounded by a shell of charged particles, the temperature of which reaches several tens of thousands of degrees. Here are the inner and outer radiation belts of the Earth. The inner belt, filled mainly with hundreds of MeV protons, is limited by altitudes of 500-1600 km at latitudes from the equator to 35-40°. The outer belt consists of electrons with energies on the order of hundreds of keV. Behind the outer belt, there is an "outermost belt", in which the concentration and fluxes of electrons are much higher. The intrusion of solar corpuscular radiation (solar wind) into the upper layers of an aurora gives rise to auroras. Under the influence of this bombardment of the upper atmosphere by the electrons and protons of the solar corona, the natural glow of the atmosphere is also excited, which was formerly called the glow of the night sky. When the solar wind interacts with the Earth's magnetic field, a zone is created, which received the name. the Earth 's magnetosphere , where solar plasma flows do not penetrate .

The upper layers of A. are characterized by the existence of strong winds, the speed of which reaches 100-200 m/sec. Wind speed and direction within the troposphere, mesosphere and lower thermosphere have a large space-time variability. Although the mass of the upper layers of the atmosphere is insignificant compared to the mass of the lower layers, and the energy of atmospheric processes in the high layers is relatively small, apparently, there is some influence of the high layers of the atmosphere on the weather and climate in the troposphere.

Radiation, heat and water balances of the atmosphere

Practically the only source of energy for all physical processes developing in Armenia is solar radiation. The main feature of the radiation regime of A. - so-called. greenhouse effect: A. weakly absorbs short-wave solar radiation (most of it reaches the earth's surface), but delays long-wave (entirely infrared) thermal radiation of the earth's surface, which significantly reduces the heat transfer of the earth into outer space and increases its temperature.

The solar radiation that enters A. is partially absorbed in A., mainly by water vapor, carbon dioxide, ozone, and aerosols, and is scattered by aerosol particles and fluctuations in the density of A. As a result of the scattering of the radiant energy of the Sun, not only direct solar energy is observed in A., but also scattered radiation, together they make up the total radiation. Reaching the earth's surface, the total radiation is partially reflected from it. The amount of reflected radiation is determined by the reflectivity of the underlying surface, the so-called. albedo. Due to the absorbed radiation, the earth's surface heats up and becomes a source of its own long-wave radiation directed towards the Earth. In turn, the Earth also emits long-wave radiation directed towards the earth's surface (the so-called anti-radiation of the earth) and into world space (the so-called space). outgoing radiation). Rational heat exchange between the earth's surface and A. is determined by effective radiation - the difference between the Earth's own surface radiation and the anti-radiation A absorbed by it. The difference between short-wave radiation absorbed by the earth's surface and effective radiation is called the radiation balance.

The conversion of the energy of solar radiation after it has been absorbed on the earth's surface and into atmospheric energy constitutes the heat balance of the earth. The main source of heat for the atmosphere is the earth's surface, which absorbs the bulk of solar radiation. Since the absorption of solar radiation in A. is less than the loss of heat from A. to the world space by long-wave radiation, the radiative heat consumption is replenished by the influx of heat to A. from the earth's surface in the form of turbulent heat transfer and the arrival of heat as a result of condensation of water vapor in A. Since the final the amount of condensation in all of Africa is equal to the amount of precipitation and also to the amount of evaporation from the earth's surface; the influx of condensation heat into Azerbaijan is numerically equal to the heat spent on evaporation on the Earth's surface (see also Water balance).

Some of the energy of solar radiation is spent on maintaining the general circulation of the atmosphere and on other atmospheric processes, but this part is insignificant compared with the main components of the heat balance.

air movement

Due to the high mobility of atmospheric air, winds are observed at all altitudes of the sky. Air movements depend on many factors, the main of which is the uneven heating of air in different regions of the globe.

Particularly large temperature contrasts near the Earth's surface exist between the equator and the poles due to the difference in the arrival of solar energy at different latitudes. Along with this, the distribution of temperature is influenced by the location of continents and oceans. Due to the high heat capacity and thermal conductivity of ocean waters, the oceans significantly attenuate temperature fluctuations that occur as a result of changes in the arrival of solar radiation during the year. In this regard, in temperate and high latitudes, the air temperature over the oceans in summer is noticeably lower than over the continents, and in winter it is higher.

The uneven heating of the atmosphere contributes to the development of a system of large-scale air currents - the so-called. general circulation of the atmosphere, which creates a horizontal transfer of heat in air, as a result of which differences in the heating of atmospheric air in individual regions are noticeably smoothed out. Along with this, the general circulation carries out a moisture cycle in Africa, in the course of which water vapor is transferred from the oceans to land and the continents are moistened. The movement of air in a general circulation system is closely related to the distribution of atmospheric pressure and also depends on the rotation of the Earth (see Coriolis force). At sea level, the distribution of pressure is characterized by a decrease near the equator, an increase in the subtropics (high-pressure zones), and a decrease in temperate and high latitudes. At the same time, over the continents of extratropical latitudes, the pressure is usually increased in winter, and lowered in summer.

A complex system of air currents is associated with the planetary distribution of pressure, some of them are relatively stable, while others are constantly changing in space and time. The stable air currents include the trade winds, which are directed from the subtropical latitudes of both hemispheres to the equator. Monsoons are also relatively stable - air currents that arise between the ocean and the mainland and have a seasonal character. In temperate latitudes, westerly air currents (from west to east) predominate. These currents include large eddies - cyclones and anticyclones, usually extending for hundreds and thousands of kilometers. Cyclones are also observed in tropical latitudes, where they are distinguished by their smaller size, but particularly high wind speeds, often reaching the strength of a hurricane (the so-called tropical cyclones). In the upper troposphere and lower stratosphere, there are relatively narrow (hundreds of kilometers wide) jet streams with sharply defined boundaries, within which the wind reaches enormous speeds - up to 100-150 m / s. Observations show that the features of atmospheric circulation in the lower part of the stratosphere are determined by processes in the troposphere.

In the upper half of the stratosphere, where there is an increase in temperature with height, the wind speed increases with height, with easterly winds dominating in summer and western winds in winter. The circulation here is determined by the stratospheric heat source, the existence of which is associated with the intensive absorption of ultraviolet solar radiation by ozone.

In the lower part of the mesosphere in temperate latitudes, the speed of winter western transport increases to maximum values ​​- about 80 m/sec, and summer eastern transport - up to 60 m/sec at a level of about 70 km. Recent studies have clearly shown that the features of the temperature field in the mesosphere cannot be explained solely by the influence of radiation factors. Dynamic factors are of primary importance (in particular, heating or cooling when air is lowered or raised), and heat sources resulting from photochemical reactions (for example, recombination of atomic oxygen) are also possible.

Above the cold layer of the mesopause (in the thermosphere), the air temperature begins to increase rapidly with height. In many respects, this region of Africa is similar to the lower half of the stratosphere. Probably, the circulation in the lower part of the thermosphere is determined by the processes in the mesosphere, while the dynamics of the upper layers of the thermosphere is due to the absorption of solar radiation here. However, it is difficult to study atmospheric motion at these heights due to their considerable complexity. Of great importance in the thermosphere are tidal movements (mainly solar semidiurnal and diurnal tides), under the influence of which the wind speed at heights of more than 80 km can reach 100-120 m/sec. A characteristic feature of atmospheric tides is their strong variability depending on latitude, season, height above sea level and time of day. In the thermosphere, there are also significant changes in wind speed with height (mainly near the level of 100 km), attributed to the influence of gravitational waves. Located in the altitude range of 100-110 km t. the turbopause sharply separates the region located above from the zone of intense turbulent mixing.

Along with large-scale air currents, numerous local air circulations are observed in the lower layers of the atmosphere (breeze, bora, mountain-valley winds, etc.; see Local winds). In all air currents, wind pulsations are usually noted, corresponding to the movement of air vortices of medium and small sizes. Such pulsations are associated with atmospheric turbulence, which significantly affects many atmospheric processes.

Climate and weather

Differences in the amount of solar radiation reaching different latitudes of the earth's surface, and the complexity of its structure, including the distribution of oceans, continents, and major mountain systems, determine the variety of Earth's climates (see Climate).

Literature

• Meteorology and hydrology for 50 years of Soviet power, ed. Edited by E. K. Fedorova. Leningrad, 1967.
• Khrgian A. Kh., Atmospheric Physics, 2nd ed., M., 1958;
• Zverev A. S., Synoptic meteorology and the basics of weather forecasting, L., 1968;
• Khromov S.P., Meteorology and climatology for geographical faculties, L., 1964;
• Tverskoy P. N., Course of meteorology, L., 1962;
• Matveev LT, Fundamentals of general meteorology. Physics of the atmosphere, L., 1965;
• Budyko M. I., Thermal balance of the earth's surface, L., 1956;
• Kondratiev K. Ya., Actinometry, L., 1965;
• Tails I. A., High layers of the atmosphere, L., 1964;
• Moroz V.I., Physics of planets, M., 1967;
• Tverskoy P. N., Atmospheric electricity, L., 1949;
• Shishkin N. S., Clouds, precipitation and lightning electricity, M., 1964;
• Ozone in the Earth's Atmosphere, ed. G. P. Gushchina, L., 1966;
• Imyanitov I. M., Chubarina E. V., Electricity of the free atmosphere, L., 1965.

M. I. Budyko, K. Ya. Kondratiev.

This article or section uses text

The Earth's atmosphere is the gaseous envelope of the planet. The lower boundary of the atmosphere passes near the earth's surface (the hydrosphere and the earth's crust), and the upper boundary is the area of ​​contact outer space (122 km). The atmosphere contains many different elements. The main ones are: 78% nitrogen, 20% oxygen, 1% argon, carbon dioxide, neon gallium, hydrogen, etc. Interesting facts can be viewed at the end of the article or by clicking on.

The atmosphere has distinct layers of air. Air layers differ in temperature, gas difference and their density and. It should be noted that the layers of the stratosphere and troposphere protect the Earth from solar radiation. In the higher layers, a living organism can receive a lethal dose of the ultraviolet solar spectrum. To quickly jump to the desired layer of the atmosphere, click on the corresponding layer:

Troposphere and tropopause

Troposphere - temperature, pressure, altitude

The upper limit is kept at around 8 - 10 km approximately. In temperate latitudes 16 - 18 km, and in polar 10 - 12 km. Troposphere It is the lower main layer of the atmosphere. This layer contains more than 80% of the total mass of atmospheric air and close to 90% of the total water vapor. It is in the troposphere that convection and turbulence arise, cyclones form, and occur. Temperature decreases with height. Gradient: 0.65°/100 m. The heated earth and water heat up the enclosing air. The heated air rises, cools and forms clouds. The temperature in the upper boundaries of the layer can reach -50/70 °C.

It is in this layer that changes in climatic weather conditions occur. The lower limit of the troposphere is called surface since it has a lot of volatile microorganisms and dust. Wind speed increases with height in this layer.

tropopause

This is the transitional layer of the troposphere to the stratosphere. Here, the dependence of the decrease in temperature with an increase in altitude ceases. The tropopause is the minimum height where the vertical temperature gradient drops to 0.2°C/100 m. The height of the tropopause depends on strong climatic events such as cyclones. The height of the tropopause decreases above cyclones and increases above anticyclones.

Stratosphere and Stratopause

The height of the stratosphere layer is approximately from 11 to 50 km. There is a slight change in temperature at an altitude of 11-25 km. At an altitude of 25–40 km, inversion temperature, from 56.5 rises to 0.8°C. From 40 km to 55 km the temperature stays at around 0°C. This area is called - stratopause.

In the Stratosphere, the effect of solar radiation on gas molecules is observed, they dissociate into atoms. There is almost no water vapor in this layer. Modern supersonic commercial aircraft fly at altitudes up to 20 km due to stable flight conditions. High-altitude weather balloons rise to a height of 40 km. There are steady air currents here, their speed reaches 300 km/h. Also in this layer is concentrated ozone, a layer that absorbs ultraviolet rays.

Mesosphere and Mesopause - composition, reactions, temperature

The mesosphere layer begins at about 50 km and ends at around 80-90 km. Temperatures decrease with elevation by about 0.25-0.3°C/100 m. Radiant heat exchange is the main energy effect here. Complex photochemical processes involving free radicals (has 1 or 2 unpaired electrons) since they implement glow atmosphere.

Almost all meteors burn up in the mesosphere. Scientists have named this area Ignorosphere. This zone is difficult to explore, as aerodynamic aviation here is very poor due to the air density, which is 1000 times less than on Earth. And for launching artificial satellites, the density is still very high. Research is carried out with the help of meteorological rockets, but this is a perversion. mesopause transitional layer between mesosphere and thermosphere. Has a minimum temperature of -90°C.

Karman Line

Pocket line called the boundary between the Earth's atmosphere and outer space. According to the International Aviation Federation (FAI), the height of this border is 100 km. This definition was given in honor of the American scientist Theodor von Karman. He determined that at about this height the density of the atmosphere is so low that aerodynamic aviation becomes impossible here, since the speed of the aircraft must be greater first space velocity. At such a height, the concept of a sound barrier loses its meaning. Here you can control the aircraft only due to reactive forces.

Thermosphere and Thermopause

The upper boundary of this layer is about 800 km. The temperature rises up to about 300 km, where it reaches about 1500 K. Above, the temperature remains unchanged. In this layer there is Polar Lights- occurs as a result of the effect of solar radiation on the air. This process is also called the ionization of atmospheric oxygen.

Due to the low rarefaction of the air, flights above the Karman line are possible only along ballistic trajectories. All manned orbital flights (except flights to the Moon) take place in this layer of the atmosphere.

Exosphere - Density, Temperature, Height

The height of the exosphere is above 700 km. Here the gas is very rarefied, and the process takes place dissipation— leakage of particles into interplanetary space. The speed of such particles can reach 11.2 km/sec. The growth of solar activity leads to the expansion of the thickness of this layer.

• The gas shell does not fly away into space due to gravity. Air is made up of particles that have their own mass. From the law of gravitation, it can be concluded that every object with mass is attracted to the Earth.
• Buys-Ballot's law states that if you are in the Northern Hemisphere and stand with your back to the wind, then there will be a high pressure zone on the right, and low pressure on the left. In the Southern Hemisphere, it will be the other way around.

The atmosphere is a mixture of various gases. It extends from the surface of the Earth to a height of up to 900 km, protecting the planet from the harmful spectrum of solar radiation, and contains gases necessary for all life on the planet. The atmosphere traps the heat of the sun, warming near the earth's surface and creating a favorable climate.

Composition of the atmosphere

The Earth's atmosphere consists mainly of two gases - nitrogen (78%) and oxygen (21%). In addition, it contains impurities of carbon dioxide and other gases. in the atmosphere exists in the form of vapor, drops of moisture in clouds and ice crystals.

Layers of the atmosphere

The atmosphere consists of many layers, between which there are no clear boundaries. The temperatures of different layers differ markedly from each other.

airless magnetosphere. Most of the Earth's satellites fly here outside the Earth's atmosphere. Exosphere (450-500 km from the surface). Almost does not contain gases. Some weather satellites fly in the exosphere. The thermosphere (80-450 km) is characterized by high temperatures reaching 1700°C in the upper layer. Mesosphere (50-80 km). In this sphere, the temperature drops as the altitude increases. It is here that most of the meteorites (fragments of space rocks) that enter the atmosphere burn down. Stratosphere (15-50 km). Contains an ozone layer, i.e. a layer of ozone that absorbs ultraviolet radiation from the sun. This leads to an increase in temperature near the Earth's surface. Jet planes usually fly here, as visibility in this layer is very good and there is almost no interference caused by weather conditions. Troposphere. The height varies from 8 to 15 km from the earth's surface. It is here that the weather of the planet is formed, since in this layer contains the most water vapor, dust and winds. The temperature decreases with distance from the earth's surface.

Atmosphere pressure

Although we do not feel it, the layers of the atmosphere exert pressure on the surface of the Earth. The highest is near the surface, and as you move away from it, it gradually decreases. It depends on the temperature difference between land and ocean, and therefore in areas located at the same height above sea level, there is often a different pressure. Low pressure brings wet weather, while high pressure usually sets clear weather.

The movement of air masses in the atmosphere

And the pressures cause the lower atmosphere to mix. This creates winds that blow from areas of high pressure to areas of low pressure. In many regions, local winds also occur, caused by differences in land and sea temperatures. Mountains also have a significant influence on the direction of the winds.

the greenhouse effect

Carbon dioxide and other gases in the earth's atmosphere trap the sun's heat. This process is commonly called the greenhouse effect, as it is in many ways similar to the circulation of heat in greenhouses. The greenhouse effect causes global warming on the planet. In areas of high pressure - anticyclones - a clear solar one is established. In areas of low pressure - cyclones - the weather is usually unstable. Heat and light entering the atmosphere. The gases trap the heat reflected from the earth's surface, thereby causing the temperature on the earth to rise.

There is a special ozone layer in the stratosphere. Ozone blocks most of the ultraviolet radiation from the Sun, protecting the Earth and all life on it from it. Scientists have found that the cause of the destruction of the ozone layer are special chlorofluorocarbon dioxide gases contained in some aerosols and refrigeration equipment. Over the Arctic and Antarctica, huge holes have been found in the ozone layer, contributing to an increase in the amount of ultraviolet radiation affecting the Earth's surface.

Ozone is formed in the lower atmosphere as a result between solar radiation and various exhaust fumes and gases. Usually it disperses through the atmosphere, but if a closed layer of cold air forms under a layer of warm air, ozone concentrates and smog occurs. Unfortunately, this cannot make up for the loss of ozone in the ozone holes.

The satellite image clearly shows a hole in the ozone layer over Antarctica. The size of the hole varies, but scientists believe that it is constantly increasing. Attempts are being made to reduce the level of exhaust gases in the atmosphere. Reduce air pollution and use smokeless fuels in cities. Smog causes eye irritation and choking in many people.

The emergence and evolution of the Earth's atmosphere

The modern atmosphere of the Earth is the result of a long evolutionary development. It arose as a result of the joint action of geological factors and the vital activity of organisms. Throughout geological history, the earth's atmosphere has gone through several profound rearrangements. On the basis of geological data and theoretical (prerequisites), the primordial atmosphere of the young Earth, which existed about 4 billion years ago, could consist of a mixture of inert and noble gases with a small addition of passive nitrogen (N. A. Yasamanov, 1985; A. S. Monin, 1987; O. G. Sorokhtin, S. A. Ushakov, 1991, 1993. At present, the view on the composition and structure of the early atmosphere has somewhat changed. The primary atmosphere (protoatmosphere) is at the earliest protoplanetary stage. 4.2 billion years, could consist of a mixture of methane, ammonia and carbon dioxide.As a result of the degassing of the mantle and active weathering processes occurring on the earth's surface, water vapor, carbon compounds in the form of CO 2 and CO, sulfur and its compounds began to enter the atmosphere , as well as strong halogen acids - HCI, HF, HI and boric acid, which were supplemented by methane, ammonia, hydrogen, argon and some other noble gases in the atmosphere.This primary atmosphere was through extremely thin. Therefore, the temperature near the earth's surface was close to the temperature of radiative equilibrium (AS Monin, 1977).

Over time, the gas composition of the primary atmosphere began to transform under the influence of the weathering of rocks that protruded on the earth's surface, the vital activity of cyanobacteria and blue-green algae, volcanic processes and the action of sunlight. This led to the decomposition of methane into and carbon dioxide, ammonia - into nitrogen and hydrogen; carbon dioxide began to accumulate in the secondary atmosphere, which slowly descended to the earth's surface, and nitrogen. Thanks to the vital activity of blue-green algae, oxygen began to be produced in the process of photosynthesis, which, however, at the beginning was mainly spent on “oxidizing atmospheric gases, and then rocks. At the same time, ammonia, oxidized to molecular nitrogen, began to intensively accumulate in the atmosphere. It is assumed that a significant part of the nitrogen in the modern atmosphere is relict. Methane and carbon monoxide were oxidized to carbon dioxide. Sulfur and hydrogen sulfide were oxidized to SO 2 and SO 3, which, due to their high mobility and lightness, were quickly removed from the atmosphere. Thus, the atmosphere from a reducing one, as it was in the Archean and early Proterozoic, gradually turned into an oxidizing one.

Carbon dioxide entered the atmosphere both as a result of methane oxidation and as a result of degassing of the mantle and weathering of rocks. In the event that all the carbon dioxide released over the entire history of the Earth remained in the atmosphere, its partial pressure could now become the same as on Venus (O. Sorokhtin, S. A. Ushakov, 1991). But on Earth, the process was reversed. A significant part of carbon dioxide from the atmosphere was dissolved in the hydrosphere, in which it was used by aquatic organisms to build their shells and biogenically converted into carbonates. Subsequently, the most powerful strata of chemogenic and organogenic carbonates were formed from them.

Oxygen was supplied to the atmosphere from three sources. For a long time, starting from the moment of the formation of the Earth, it was released during the degassing of the mantle and was mainly spent on oxidative processes. Another source of oxygen was the photodissociation of water vapor by hard ultraviolet solar radiation. appearances; free oxygen in the atmosphere led to the death of most of the prokaryotes that lived in reducing conditions. Prokaryotic organisms have changed their habitats. They left the surface of the Earth to its depths and regions where reducing conditions were still preserved. They were replaced by eukaryotes, which began to vigorously process carbon dioxide into oxygen.

During the Archean and a significant part of the Proterozoic, almost all oxygen, arising both abiogenically and biogenically, was mainly spent on the oxidation of iron and sulfur. By the end of the Proterozoic, all the metallic divalent iron that was on the earth's surface either oxidized or moved into the earth's core. This led to the fact that the partial pressure of oxygen in the early Proterozoic atmosphere changed.

In the middle of the Proterozoic, the concentration of oxygen in the atmosphere reached the Urey point and amounted to 0.01% of the current level. Starting from that time, oxygen began to accumulate in the atmosphere and, probably, already at the end of the Riphean, its content reached the Pasteur point (0.1% of the current level). It is possible that the ozone layer arose in the Vendian period and that time it never disappeared.

The appearance of free oxygen in the earth's atmosphere stimulated the evolution of life and led to the emergence of new forms with a more perfect metabolism. If earlier eukaryotic unicellular algae and cyanides, which appeared at the beginning of the Proterozoic, required an oxygen content in water of only 10 -3 of its modern concentration, then with the emergence of non-skeletal Metazoa at the end of the Early Vendian, i.e., about 650 million years ago, the oxygen concentration in the atmosphere should have been much higher. After all, Metazoa used oxygen respiration and this required that the partial pressure of oxygen reach a critical level - the Pasteur point. In this case, the anaerobic fermentation process was replaced by an energetically more promising and progressive oxygen metabolism.

After that, the further accumulation of oxygen in the earth's atmosphere occurred rather rapidly. The progressive increase in the volume of blue-green algae contributed to the achievement in the atmosphere of the oxygen level necessary for the life support of the animal world. A certain stabilization of the oxygen content in the atmosphere has occurred since the moment when the plants came to land - about 450 million years ago. The emergence of plants on land, which occurred in the Silurian period, led to the final stabilization of the level of oxygen in the atmosphere. Since that time, its concentration began to fluctuate within rather narrow limits, never going beyond the existence of life. The concentration of oxygen in the atmosphere has completely stabilized since the appearance of flowering plants. This event took place in the middle of the Cretaceous period, i.e. about 100 million years ago.

The bulk of nitrogen was formed in the early stages of the Earth's development, mainly due to the decomposition of ammonia. With the advent of organisms, the process of binding atmospheric nitrogen into organic matter and burying it in marine sediments began. After the release of organisms on land, nitrogen began to be buried in continental sediments. The processes of processing free nitrogen were especially intensified with the advent of terrestrial plants.

At the turn of the Cryptozoic and Phanerozoic, i.e., about 650 million years ago, the carbon dioxide content in the atmosphere decreased to tenths of a percent, and it reached a content close to the current level only quite recently, about 10-20 million years ago.

Thus, the gas composition of the atmosphere not only provided living space for organisms, but also determined the characteristics of their vital activity, promoted settlement and evolution. The resulting failures in the distribution of the gas composition of the atmosphere favorable for organisms, both due to cosmic and planetary causes, led to mass extinctions of the organic world, which repeatedly occurred during the Cryptozoic and at certain boundaries of the Phanerozoic history.

Ethnospheric functions of the atmosphere

The Earth's atmosphere provides the necessary substance, energy and determines the direction and speed of metabolic processes. The gas composition of the modern atmosphere is optimal for the existence and development of life. As an area of ​​weather and climate formation, the atmosphere must create comfortable conditions for the life of people, animals and vegetation. Deviations in one direction or another in the quality of atmospheric air and weather conditions create extreme conditions for the life of the animal and plant world, including humans.

The atmosphere of the Earth not only provides the conditions for the existence of mankind, being the main factor in the evolution of the ethnosphere. At the same time, it turns out to be an energy and raw material resource for production. In general, the atmosphere is a factor that preserves human health, and some areas, due to physical and geographical conditions and atmospheric air quality, serve as recreational areas and are areas intended for sanatorium treatment and recreation for people. Thus, the atmosphere is a factor of aesthetic and emotional impact.

The ethnospheric and technospheric functions of the atmosphere, determined quite recently (E. D. Nikitin, N. A. Yasamanov, 2001), need an independent and in-depth study. Thus, the study of atmospheric energy functions is very relevant both from the point of view of the occurrence and operation of processes that damage the environment, and from the point of view of the impact on human health and well-being. In this case, we are talking about the energy of cyclones and anticyclones, atmospheric vortices, atmospheric pressure and other extreme atmospheric phenomena, the effective use of which will contribute to the successful solution of the problem of obtaining alternative energy sources that do not pollute the environment. After all, the air environment, especially that part of it that is located above the World Ocean, is an area for the release of a colossal amount of free energy.

For example, it has been established that tropical cyclones of average strength release energy equivalent to the energy of 500,000 atomic bombs dropped on Hiroshima and Nagasaki in just a day. For 10 days of the existence of such a cyclone, enough energy is released to meet all the energy needs of a country like the United States for 600 years.

In recent years, a large number of works by natural scientists have been published, to some extent related to various aspects of activity and the influence of the atmosphere on earth processes, which indicates the intensification of interdisciplinary interactions in modern natural science. At the same time, the integrating role of certain of its directions is manifested, among which it is necessary to note the functional-ecological direction in geoecology.

This direction stimulates the analysis and theoretical generalization of the ecological functions and the planetary role of various geospheres, and this, in turn, is an important prerequisite for the development of methodology and scientific foundations for a holistic study of our planet, the rational use and protection of its natural resources.

The Earth's atmosphere consists of several layers: troposphere, stratosphere, mesosphere, thermosphere, ionosphere and exosphere. In the upper part of the troposphere and the lower part of the stratosphere there is a layer enriched with ozone, called the ozone layer. Certain (daily, seasonal, annual, etc.) regularities in the distribution of ozone have been established. Since its inception, the atmosphere has influenced the course of planetary processes. The primary composition of the atmosphere was completely different than at present, but over time the proportion and role of molecular nitrogen steadily increased, about 650 million years ago free oxygen appeared, the amount of which continuously increased, but the concentration of carbon dioxide correspondingly decreased. The high mobility of the atmosphere, its gas composition and the presence of aerosols determine its outstanding role and active participation in various geological and biospheric processes. The role of the atmosphere in the redistribution of solar energy and the development of catastrophic natural phenomena and disasters is great. Atmospheric whirlwinds - tornadoes (tornadoes), hurricanes, typhoons, cyclones and other phenomena have a negative impact on the organic world and natural systems. The main sources of pollution, along with natural factors, are various forms of human economic activity. Anthropogenic impacts on the atmosphere are expressed not only in the appearance of various aerosols and greenhouse gases, but also in an increase in the amount of water vapor, and manifest themselves in the form of smog and acid rain. Greenhouse gases change the temperature regime of the earth's surface, emissions of certain gases reduce the volume of the ozone screen and contribute to the formation of ozone holes. The ethnospheric role of the Earth's atmosphere is great.

The role of the atmosphere in natural processes

The surface atmosphere in its intermediate state between the lithosphere and outer space and its gas composition creates conditions for the life of organisms. At the same time, the weathering and intensity of destruction of rocks, the transfer and accumulation of detrital material depend on the amount, nature and frequency of precipitation, on the frequency and strength of winds, and especially on air temperature. The atmosphere is the central component of the climate system. Air temperature and humidity, cloudiness and precipitation, wind - all this characterizes the weather, that is, the continuously changing state of the atmosphere. At the same time, these same components also characterize the climate, i.e., the average long-term weather regime.

The composition of gases, the presence of clouds and various impurities, which are called aerosol particles (ash, dust, particles of water vapor), determine the characteristics of the passage of solar radiation through the atmosphere and prevent the escape of the Earth's thermal radiation into outer space.

The Earth's atmosphere is very mobile. The processes arising in it and changes in its gas composition, thickness, cloudiness, transparency and the presence of various aerosol particles in it affect both the weather and the climate.

The action and direction of natural processes, as well as life and activity on Earth, are determined by solar radiation. It gives 99.98% of the heat coming to the earth's surface. Annually it makes 134*1019 kcal. This amount of heat can be obtained by burning 200 billion tons of coal. The reserves of hydrogen, which creates this flow of thermonuclear energy in the mass of the Sun, will be enough for at least another 10 billion years, i.e., for a period twice as long as our planet itself exists.

About 1/3 of the total amount of solar energy entering the upper boundary of the atmosphere is reflected back into the world space, 13% is absorbed by the ozone layer (including almost all ultraviolet radiation). 7% - the rest of the atmosphere and only 44% reaches the earth's surface. The total solar radiation reaching the Earth in a day is equal to the energy that humanity has received as a result of burning all types of fuel over the past millennium.

The amount and nature of the distribution of solar radiation on the earth's surface are closely dependent on the cloudiness and transparency of the atmosphere. The amount of scattered radiation is affected by the height of the Sun above the horizon, the transparency of the atmosphere, the content of water vapor, dust, the total amount of carbon dioxide, etc.

The maximum amount of scattered radiation falls into the polar regions. The lower the Sun is above the horizon, the less heat enters a given area.

Atmospheric transparency and cloudiness are of great importance. On a cloudy summer day, it is usually colder than on a clear one, since daytime clouds prevent the earth's surface from heating.

The dust content of the atmosphere plays an important role in the distribution of heat. The finely dispersed solid particles of dust and ash in it, which affect its transparency, adversely affect the distribution of solar radiation, most of which is reflected. Fine particles enter the atmosphere in two ways: they are either ash emitted during volcanic eruptions, or desert dust carried by winds from arid tropical and subtropical regions. Especially a lot of such dust is formed during droughts, when it is carried into the upper layers of the atmosphere by streams of warm air and can stay there for a long time. After the eruption of the Krakatoa volcano in 1883, dust thrown tens of kilometers into the atmosphere remained in the stratosphere for about 3 years. As a result of the 1985 eruption of the El Chichon volcano (Mexico), dust reached Europe, and therefore there was a slight decrease in surface temperatures.

The Earth's atmosphere contains a variable amount of water vapor. In absolute terms, by weight or volume, its amount ranges from 2 to 5%.

Water vapor, like carbon dioxide, enhances the greenhouse effect. In the clouds and fogs that arise in the atmosphere, peculiar physicochemical processes take place.

The primary source of water vapor in the atmosphere is the surface of the oceans. A layer of water 95 to 110 cm thick annually evaporates from it. Part of the moisture returns to the ocean after condensation, and the other is directed towards the continents by air currents. In regions with a variable-humid climate, precipitation moistens the soil, and in humid regions it creates groundwater reserves. Thus, the atmosphere is an accumulator of humidity and a reservoir of precipitation. and fogs that form in the atmosphere provide moisture to the soil cover and thus play a decisive role in the development of the animal and plant world.

Atmospheric moisture is distributed over the earth's surface due to the mobility of the atmosphere. It has a very complex system of winds and pressure distribution. Due to the fact that the atmosphere is in continuous motion, the nature and extent of the distribution of wind flows and pressure are constantly changing. The scales of circulation vary from micrometeorological, with a size of only a few hundred meters, to a global one, with a size of several tens of thousands of kilometers. Huge atmospheric vortices are involved in the creation of systems of large-scale air currents and determine the general circulation of the atmosphere. In addition, they are sources of catastrophic atmospheric phenomena.

The distribution of weather and climatic conditions and the functioning of living matter depend on atmospheric pressure. In the event that atmospheric pressure fluctuates within small limits, it does not play a decisive role in the well-being of people and the behavior of animals and does not affect the physiological functions of plants. As a rule, frontal phenomena and weather changes are associated with pressure changes.

Atmospheric pressure is of fundamental importance for the formation of wind, which, being a relief-forming factor, has the strongest effect on flora and fauna.

The wind is able to suppress the growth of plants and at the same time promotes the transfer of seeds. The role of the wind in the formation of weather and climatic conditions is great. He also acts as a regulator of sea currents. Wind as one of the exogenous factors contributes to the erosion and deflation of weathered material over long distances.

Ecological and geological role of atmospheric processes

The decrease in the transparency of the atmosphere due to the appearance of aerosol particles and solid dust in it affects the distribution of solar radiation, increasing the albedo or reflectivity. Various chemical reactions lead to the same result, causing the decomposition of ozone and the generation of "pearl" clouds, consisting of water vapor. Global change in reflectivity, as well as changes in the gas composition of the atmosphere, mainly greenhouse gases, are the cause of climate change.

Uneven heating, which causes differences in atmospheric pressure over different parts of the earth's surface, leads to atmospheric circulation, which is the hallmark of the troposphere. When there is a difference in pressure, air rushes from areas of high pressure to areas of low pressure. These movements of air masses, together with humidity and temperature, determine the main ecological and geological features of atmospheric processes.

Depending on the speed, the wind produces various geological work on the earth's surface. At a speed of 10 m/s, it shakes thick branches of trees, picks up and carries dust and fine sand; breaks tree branches at a speed of 20 m/s, carries sand and gravel; at a speed of 30 m/s (storm) tears off the roofs of houses, uproots trees, breaks poles, moves pebbles and carries small gravel, and a hurricane at a speed of 40 m/s destroys houses, breaks and demolishes power line poles, uproots large trees.

Squall storms and tornadoes (tornadoes) have a great negative environmental impact with catastrophic consequences - atmospheric vortices that occur in the warm season on powerful atmospheric fronts with a speed of up to 100 m/s. Squalls are horizontal whirlwinds with hurricane wind speeds (up to 60-80 m/s). They are often accompanied by heavy showers and thunderstorms lasting from a few minutes to half an hour. The squalls cover areas up to 50 km wide and travel a distance of 200-250 km. A heavy storm in Moscow and the Moscow region in 1998 damaged the roofs of many houses and knocked down trees.

Tornadoes, called tornadoes in North America, are powerful funnel-shaped atmospheric eddies often associated with thunderclouds. These are columns of air narrowing in the middle with a diameter of several tens to hundreds of meters. The tornado has the appearance of a funnel, very similar to an elephant's trunk, descending from the clouds or rising from the surface of the earth. Possessing a strong rarefaction and high rotation speed, the tornado travels up to several hundred kilometers, drawing in dust, water from reservoirs and various objects. Powerful tornadoes are accompanied by thunderstorms, rain and have great destructive power.

Tornadoes rarely occur in subpolar or equatorial regions, where it is constantly cold or hot. Few tornadoes in the open ocean. Tornadoes occur in Europe, Japan, Australia, the USA, and in Russia they are especially frequent in the Central Black Earth region, in the Moscow, Yaroslavl, Nizhny Novgorod and Ivanovo regions.

Tornadoes lift and move cars, houses, wagons, bridges. Particularly destructive tornadoes (tornadoes) are observed in the United States. From 450 to 1500 tornadoes are recorded annually, with an average of about 100 victims. Tornadoes are fast-acting catastrophic atmospheric processes. They are formed in just 20-30 minutes, and their existence time is 30 minutes. Therefore, it is almost impossible to predict the time and place of occurrence of tornadoes.

Other destructive, but long-term atmospheric vortices are cyclones. They are formed due to a pressure drop, which, under certain conditions, contributes to the occurrence of a circular movement of air currents. Atmospheric vortices originate around powerful ascending currents of humid warm air and rotate at high speed clockwise in the southern hemisphere and counterclockwise in the northern hemisphere. Cyclones, unlike tornadoes, originate over the oceans and produce their destructive actions over the continents. The main destructive factors are strong winds, intense precipitation in the form of snowfall, downpours, hail and surge floods. Winds with speeds of 19 - 30 m / s form a storm, 30 - 35 m / s - a storm, and more than 35 m / s - a hurricane.

Tropical cyclones - hurricanes and typhoons - have an average width of several hundred kilometers. The wind speed inside the cyclone reaches hurricane force. Tropical cyclones last from several days to several weeks, moving at a speed of 50 to 200 km/h. Mid-latitude cyclones have a larger diameter. Their transverse dimensions range from a thousand to several thousand kilometers, the wind speed is stormy. They move in the northern hemisphere from the west and are accompanied by hail and snowfall, which are catastrophic. Cyclones and their associated hurricanes and typhoons are the largest natural disasters after floods in terms of the number of victims and damage caused. In densely populated areas of Asia, the number of victims during hurricanes is measured in the thousands. In 1991, in Bangladesh, during a hurricane that caused the formation of sea waves 6 m high, 125 thousand people died. Typhoons cause great damage to the United States. As a result, dozens and hundreds of people die. In Western Europe, hurricanes cause less damage.

Thunderstorms are considered a catastrophic atmospheric phenomenon. They occur when warm, moist air rises very quickly. On the border of the tropical and subtropical zones, thunderstorms occur for 90-100 days a year, in the temperate zone for 10-30 days. In our country, the largest number of thunderstorms occurs in the North Caucasus.

Thunderstorms usually last less than an hour. Intense downpours, hailstorms, lightning strikes, gusts of wind, and vertical air currents pose a particular danger. The hail hazard is determined by the size of the hailstones. In the North Caucasus, the mass of hailstones once reached 0.5 kg, and in India, hailstones weighing 7 kg were noted. The most hazardous areas in our country are located in the North Caucasus. In July 1992, hail damaged 18 aircraft at the Mineralnye Vody airport.

Lightning is a hazardous weather phenomenon. They kill people, livestock, cause fires, damage the power grid. About 10,000 people die every year from thunderstorms and their consequences worldwide. Moreover, in some parts of Africa, in France and the United States, the number of victims from lightning is greater than from other natural phenomena. The annual economic damage from thunderstorms in the United States is at least $700 million.

Droughts are typical for desert, steppe and forest-steppe regions. The lack of precipitation causes drying up of the soil, lowering the level of groundwater and in reservoirs until they dry up completely. Moisture deficiency leads to the death of vegetation and crops. Droughts are especially severe in Africa, the Near and Middle East, Central Asia and southern North America.

Droughts change the conditions of human life, have an adverse impact on the natural environment through processes such as salinization of the soil, dry winds, dust storms, soil erosion and forest fires. Fires are especially strong during drought in taiga regions, tropical and subtropical forests and savannahs.

Droughts are short-term processes that last for one season. When droughts last more than two seasons, there is a threat of starvation and mass mortality. Typically, the effect of drought extends to the territory of one or more countries. Especially often prolonged droughts with tragic consequences occur in the Sahel region of Africa.

Atmospheric phenomena such as snowfalls, intermittent heavy rains and prolonged prolonged rains cause great damage. Snowfalls cause massive avalanches in the mountains, and the rapid melting of the fallen snow and prolonged heavy rains lead to floods. A huge mass of water falling on the earth's surface, especially in treeless areas, causes severe erosion of the soil cover. There is an intensive growth of ravine-beam systems. Floods occur as a result of large floods during a period of heavy precipitation or floods after a sudden warming or spring snowmelt and, therefore, are atmospheric phenomena in origin (they are discussed in the chapter on the ecological role of the hydrosphere).

Anthropogenic changes in the atmosphere

Currently, there are many different sources of anthropogenic nature that cause atmospheric pollution and lead to serious violations of the ecological balance. In terms of scale, two sources have the greatest impact on the atmosphere: transport and industry. On average, transport accounts for about 60% of the total amount of atmospheric pollution, industry - 15%, thermal energy - 15%, technologies for the destruction of household and industrial waste - 10%.

Transport, depending on the fuel used and the types of oxidizing agents, emits into the atmosphere nitrogen oxides, sulfur, oxides and dioxides of carbon, lead and its compounds, soot, benzopyrene (a substance from the group of polycyclic aromatic hydrocarbons, which is a strong carcinogen that causes skin cancer).

Industry emits sulfur dioxide, carbon oxides and dioxides, hydrocarbons, ammonia, hydrogen sulfide, sulfuric acid, phenol, chlorine, fluorine and other compounds and chemicals into the atmosphere. But the dominant position among emissions (up to 85%) is occupied by dust.

As a result of pollution, the transparency of the atmosphere changes, aerosols, smog and acid rains appear in it.

Aerosols are dispersed systems consisting of solid particles or liquid droplets suspended in a gaseous medium. The particle size of the dispersed phase is usually 10 -3 -10 -7 cm Depending on the composition of the dispersed phase, aerosols are divided into two groups. One includes aerosols consisting of solid particles dispersed in a gaseous medium, the second - aerosols, which are a mixture of gaseous and liquid phases. The first are called smokes, and the second - fogs. Condensation centers play an important role in the process of their formation. Volcanic ash, cosmic dust, products of industrial emissions, various bacteria, etc. act as condensation nuclei. The number of possible sources of concentration nuclei is constantly growing. So, for example, when dry grass is destroyed by fire on an area of ​​4000 m 2, an average of 11 * 10 22 aerosol nuclei is formed.

Aerosols began to form from the moment of the emergence of our planet and influenced natural conditions. However, their number and actions, balanced with the general circulation of substances in nature, did not cause deep ecological changes. Anthropogenic factors of their formation shifted this balance towards significant biospheric overloads. This feature has been especially pronounced since mankind began to use specially created aerosols both in the form of toxic substances and for plant protection.

The most dangerous for vegetation cover are aerosols of sulfur dioxide, hydrogen fluoride and nitrogen. When in contact with a wet leaf surface, they form acids that have a detrimental effect on living things. Acid mists, together with the inhaled air, enter the respiratory organs of animals and humans, and aggressively affect the mucous membranes. Some of them decompose living tissue, and radioactive aerosols cause cancer. Among radioactive isotopes, SG 90 is of particular danger not only because of its carcinogenicity, but also as an analogue of calcium, replacing it in the bones of organisms, causing their decomposition.

During nuclear explosions, radioactive aerosol clouds form in the atmosphere. Small particles with a radius of 1 - 10 microns fall not only into the upper layers of the troposphere, but also into the stratosphere, in which they are able to stay for a long time. Aerosol clouds are also formed during the operation of reactors of industrial plants that produce nuclear fuel, as well as as a result of accidents at nuclear power plants.

Smog is a mixture of aerosols with liquid and solid dispersed phases that form a foggy curtain over industrial areas and large cities.

There are three types of smog: ice, wet and dry. Ice smog is called Alaskan. This is a combination of gaseous pollutants with the addition of dusty particles and ice crystals that occur when fog droplets and steam from heating systems freeze.

Wet smog, or London-type smog, is sometimes called winter smog. It is a mixture of gaseous pollutants (mainly sulfur dioxide), dust particles and fog droplets. The meteorological prerequisite for the appearance of winter smog is calm weather, in which a layer of warm air is located above the surface layer of cold air (below 700 m). At the same time, not only horizontal, but also vertical exchange is absent. Pollutants, which are usually dispersed in high layers, in this case accumulate in the surface layer.

Dry smog occurs during the summer and is often referred to as LA-type smog. It is a mixture of ozone, carbon monoxide, nitrogen oxides and acid vapors. Such smog is formed as a result of the decomposition of pollutants by solar radiation, especially its ultraviolet part. The meteorological prerequisite is atmospheric inversion, which is expressed in the appearance of a layer of cold air above the warm one. Gases and solid particles usually lifted by warm air currents are then dispersed in the upper cold layers, but in this case they accumulate in the inversion layer. In the process of photolysis, nitrogen dioxides formed during the combustion of fuel in car engines decompose:

NO 2 → NO + O

Then ozone synthesis occurs:

O + O 2 + M → O 3 + M

NO + O → NO 2

Photodissociation processes are accompanied by a yellow-green glow.

In addition, reactions occur according to the type: SO 3 + H 2 0 -> H 2 SO 4, i.e. strong sulfuric acid is formed.

With a change in meteorological conditions (the appearance of wind or a change in humidity), the cold air dissipates and the smog disappears.

The presence of carcinogens in smog leads to respiratory failure, irritation of the mucous membranes, circulatory disorders, asthmatic suffocation, and often death. Smog is especially dangerous for young children.

Acid rain is atmospheric precipitation acidified by industrial emissions of sulfur oxides, nitrogen oxides and vapors of perchloric acid and chlorine dissolved in them. In the process of burning coal and gas, most of the sulfur in it, both in the form of oxide and in compounds with iron, in particular in pyrite, pyrrhotite, chalcopyrite, etc., turns into sulfur oxide, which, together with carbon dioxide, is released into atmosphere. When atmospheric nitrogen and technical emissions are combined with oxygen, various nitrogen oxides are formed, and the volume of nitrogen oxides formed depends on the combustion temperature. The bulk of nitrogen oxides occurs during the operation of vehicles and diesel locomotives, and a smaller part occurs in the energy sector and industrial enterprises. Sulfur and nitrogen oxides are the main acid formers. When reacting with atmospheric oxygen and the water vapor in it, sulfuric and nitric acids are formed.

It is known that the alkaline-acid balance of the medium is determined by the pH value. A neutral environment has a pH value of 7, an acidic environment has a pH value of 0, and an alkaline environment has a pH value of 14. In the modern era, the pH value of rainwater is 5.6, although in the recent past it was neutral. A decrease in pH value by one corresponds to a tenfold increase in acidity and, therefore, at present, rains with increased acidity fall almost everywhere. The maximum acidity of rains recorded in Western Europe was 4-3.5 pH. It should be taken into account that the pH value equal to 4-4.5 is fatal for most fish.

Acid rains have an aggressive effect on the Earth's vegetation cover, on industrial and residential buildings and contribute to a significant acceleration of the weathering of exposed rocks. An increase in acidity prevents the self-regulation of neutralization of soils in which nutrients are dissolved. In turn, this leads to a sharp decrease in yields and causes degradation of the vegetation cover. The acidity of the soil contributes to the release of heavy, which are in a bound state, which are gradually absorbed by plants, causing serious tissue damage in them and penetrating into the human food chain.

A change in the alkaline-acid potential of sea waters, especially in shallow waters, leads to the cessation of the reproduction of many invertebrates, causes the death of fish and disrupts the ecological balance in the oceans.

As a result of acid rain, the forests of Western Europe, the Baltic States, Karelia, the Urals, Siberia and Canada are under the threat of death.

ATMOSPHERE OF THE EARTH(Greek atmos steam + sphaira ball) - gaseous shell surrounding the Earth. The mass of the atmosphere is about 5.15·10 15 The biological significance of the atmosphere is enormous. In the atmosphere, there is a mass-energy exchange between animate and inanimate nature, between flora and fauna. Atmospheric nitrogen is assimilated by microorganisms; plants synthesize organic substances from carbon dioxide and water due to the energy of the sun and release oxygen. The presence of the atmosphere ensures the preservation of water on Earth, which is also an important condition for the existence of living organisms.

Studies carried out with the help of high-altitude geophysical rockets, artificial earth satellites and interplanetary automatic stations have established that the earth's atmosphere extends for thousands of kilometers. The boundaries of the atmosphere are unstable, they are influenced by the gravitational field of the moon and the pressure of the flow of sunlight. Above the equator in the region of the earth's shadow, the atmosphere reaches heights of about 10,000 km, and above the poles, its boundaries are 3,000 km from the earth's surface. The main mass of the atmosphere (80-90%) is within altitudes up to 12-16 km, which is explained by the exponential (non-linear) nature of the decrease in the density (rarefaction) of its gaseous medium as the height above sea level increases.

The existence of most living organisms in natural conditions is possible in even narrower boundaries of the atmosphere, up to 7-8 km, where a combination of such atmospheric factors as gas composition, temperature, pressure, and humidity, necessary for the active course of biological processes, takes place. The movement and ionization of air, atmospheric precipitation, and the electrical state of the atmosphere are also of hygienic importance.

Gas composition

The atmosphere is a physical mixture of gases (Table 1), mainly nitrogen and oxygen (78.08 and 20.95 vol. %). The ratio of atmospheric gases is almost the same up to altitudes of 80-100 km. The constancy of the main part of the gas composition of the atmosphere is due to the relative balancing of the processes of gas exchange between animate and inanimate nature and the continuous mixing of air masses in the horizontal and vertical directions.

Table 1. CHARACTERISTICS OF THE CHEMICAL COMPOSITION OF DRY ATMOSPHERIC AIR NEAR THE EARTH'S SURFACE

Gas composition	Volume concentration, %
Oxygen
Carbon dioxide
Nitrous oxide
Sulfur dioxide	0 to 0.0001
	0 to 0.000007 in summer, 0 to 0.000002 in winter
nitrogen dioxide	0 to 0.000002
Carbon monoxide

At altitudes above 100 km, the percentage of individual gases changes due to their diffuse stratification under the influence of gravity and temperature. In addition, under the action of the short-wavelength part of ultraviolet and X-rays at an altitude of 100 km or more, oxygen, nitrogen and carbon dioxide molecules dissociate into atoms. At high altitudes, these gases are in the form of highly ionized atoms.

The content of carbon dioxide in the atmosphere of different regions of the Earth is less constant, which is partly due to the uneven distribution of large industrial enterprises that pollute the air, as well as the uneven distribution of vegetation and water basins that absorb carbon dioxide on the Earth. Also variable in the atmosphere is the content of aerosols (see) - particles suspended in the air ranging in size from several millimicrons to several tens of microns - formed as a result of volcanic eruptions, powerful artificial explosions, pollution by industrial enterprises. The concentration of aerosols decreases rapidly with altitude.

The most unstable and important of the variable components of the atmosphere is water vapor, the concentration of which at the earth's surface can vary from 3% (in the tropics) to 2 × 10 -10% (in Antarctica). The higher the air temperature, the more moisture, ceteris paribus, can be in the atmosphere and vice versa. The bulk of water vapor is concentrated in the atmosphere up to altitudes of 8-10 km. The content of water vapor in the atmosphere depends on the combined influence of the processes of evaporation, condensation and horizontal transport. At high altitudes, due to a decrease in temperature and condensation of vapors, the air is practically dry.

The Earth's atmosphere, in addition to molecular and atomic oxygen, contains a small amount of ozone (see), the concentration of which is very variable and varies depending on the height and season. Most of the ozone is contained in the region of the poles by the end of the polar night at an altitude of 15-30 km with a sharp decrease up and down. Ozone arises as a result of the photochemical action of ultraviolet solar radiation on oxygen, mainly at altitudes of 20-50 km. In this case, diatomic oxygen molecules partially decompose into atoms and, joining undecomposed molecules, form triatomic ozone molecules (polymeric, allotropic form of oxygen).

The presence in the atmosphere of a group of so-called inert gases (helium, neon, argon, krypton, xenon) is associated with the continuous flow of natural radioactive decay processes.

The biological significance of gases the atmosphere is very large. For most multicellular organisms, a certain content of molecular oxygen in a gaseous or aqueous medium is an indispensable factor in their existence, which during respiration determines the release of energy from organic substances created initially during photosynthesis. It is no coincidence that the upper boundaries of the biosphere (the part of the surface of the globe and the lower part of the atmosphere where life exists) are determined by the presence of a sufficient amount of oxygen. In the process of evolution, organisms have adapted to a certain level of oxygen in the atmosphere; changing the oxygen content in the direction of decreasing or increasing has an adverse effect (see Altitude sickness, Hyperoxia, Hypoxia).

The ozone-allotropic form of oxygen also has a pronounced biological effect. At concentrations not exceeding 0.0001 mg / l, which is typical for resort areas and sea coasts, ozone has a healing effect - it stimulates breathing and cardiovascular activity, improves sleep. With an increase in the concentration of ozone, its toxic effect is manifested: eye irritation, necrotic inflammation of the mucous membranes of the respiratory tract, exacerbation of pulmonary diseases, autonomic neuroses. Entering into combination with hemoglobin, ozone forms methemoglobin, which leads to a violation of the respiratory function of the blood; the transfer of oxygen from the lungs to the tissues becomes difficult, the phenomena of suffocation develop. Atomic oxygen has a similar adverse effect on the body. Ozone plays a significant role in creating the thermal regimes of various layers of the atmosphere due to the extremely strong absorption of solar radiation and terrestrial radiation. Ozone absorbs ultraviolet and infrared rays most intensively. Solar rays with a wavelength of less than 300 nm are almost completely absorbed by atmospheric ozone. Thus, the Earth is surrounded by a kind of "ozone screen" that protects many organisms from the harmful effects of ultraviolet radiation from the sun. Nitrogen in atmospheric air is of great biological importance, primarily as a source of so-called. fixed nitrogen - a resource of plant (and ultimately animal) food. The physiological significance of nitrogen is determined by its participation in creating the level of atmospheric pressure necessary for life processes. Under certain conditions of pressure changes, nitrogen plays a major role in the development of a number of disorders in the body (see Decompression sickness). Assumptions that nitrogen weakens the toxic effect of oxygen on the body and is absorbed from the atmosphere not only by microorganisms, but also by higher animals, are controversial.

The inert gases of the atmosphere (xenon, krypton, argon, neon, helium) at the partial pressure they create under normal conditions can be classified as biologically indifferent gases. With a significant increase in partial pressure, these gases have a narcotic effect.

The presence of carbon dioxide in the atmosphere ensures the accumulation of solar energy in the biosphere due to the photosynthesis of complex carbon compounds, which continuously arise, change and decompose in the course of life. This dynamic system is maintained as a result of the activity of algae and land plants that capture the energy of sunlight and use it to convert carbon dioxide (see) and water into a variety of organic compounds with the release of oxygen. The upward extension of the biosphere is partially limited by the fact that at altitudes of more than 6-7 km, chlorophyll-containing plants cannot live due to the low partial pressure of carbon dioxide. Carbon dioxide is also very active in physiological terms, as it plays an important role in the regulation of metabolic processes, the activity of the central nervous system, respiration, blood circulation, and the oxygen regime of the body. However, this regulation is mediated by the influence of carbon dioxide produced by the body itself, and not from the atmosphere. In the tissues and blood of animals and humans, the partial pressure of carbon dioxide is approximately 200 times higher than its pressure in the atmosphere. And only with a significant increase in the content of carbon dioxide in the atmosphere (more than 0.6-1%), there are violations in the body, denoted by the term hypercapnia (see). The complete elimination of carbon dioxide from the inhaled air cannot directly have an adverse effect on the human and animal organisms.

Carbon dioxide plays a role in absorbing long-wavelength radiation and maintaining the "greenhouse effect" that raises the temperature near the Earth's surface. The problem of the influence on thermal and other regimes of the atmosphere of carbon dioxide, which enters the air in huge quantities as a waste product of industry, is also being studied.

Atmospheric water vapor (air humidity) also affects the human body, in particular, heat exchange with the environment.

As a result of the condensation of water vapor in the atmosphere, clouds form and precipitation (rain, hail, snow) falls. Water vapor, scattering solar radiation, participate in the creation of the thermal regime of the Earth and the lower layers of the atmosphere, in the formation of meteorological conditions.

Atmosphere pressure

Atmospheric pressure (barometric) is the pressure exerted by the atmosphere under the influence of gravity on the surface of the Earth. The value of this pressure at each point in the atmosphere is equal to the weight of the overlying column of air with a unit base, extending above the place of measurement to the boundaries of the atmosphere. Atmospheric pressure is measured with a barometer (see) and expressed in millibars, in newtons per square meter or the height of the mercury column in the barometer in millimeters, reduced to 0 ° and the normal value of the acceleration of gravity. In table. 2 shows the most commonly used units of atmospheric pressure.

The change in pressure occurs due to uneven heating of air masses located above land and water at different geographical latitudes. As the temperature rises, the density of air and the pressure it creates decrease. A huge accumulation of fast-moving air with reduced pressure (with a decrease in pressure from the periphery to the center of the vortex) is called a cyclone, with increased pressure (with an increase in pressure towards the center of the vortex) - an anticyclone. For weather forecasting, non-periodic changes in atmospheric pressure are important, which occur in moving vast masses and are associated with the emergence, development and destruction of anticyclones and cyclones. Especially large changes in atmospheric pressure are associated with the rapid movement of tropical cyclones. At the same time, atmospheric pressure can vary by 30-40 mbar per day.

The drop in atmospheric pressure in millibars over a distance of 100 km is called the horizontal barometric gradient. Typically, the horizontal barometric gradient is 1–3 mbar, but in tropical cyclones it sometimes rises to tens of millibars per 100 km.

As the altitude rises, atmospheric pressure decreases in a logarithmic relationship: at first very sharply, and then less and less noticeably (Fig. 1). Therefore, the barometric pressure curve is exponential.

The decrease in pressure per unit vertical distance is called the vertical barometric gradient. Often they use the reciprocal of it - the barometric step.

Since the barometric pressure is the sum of the partial pressures of the gases that form the air, it is obvious that with the rise to a height, along with a decrease in the total pressure of the atmosphere, the partial pressure of the gases that make up the air also decreases. The value of the partial pressure of any gas in the atmosphere is calculated by the formula

where P x ​​is the partial pressure of the gas, P z is the atmospheric pressure at altitude Z, X% is the percentage of gas whose partial pressure is to be determined.

Rice. 1. Change in barometric pressure depending on the height above sea level.

Rice. 2. Change in the partial pressure of oxygen in the alveolar air and saturation of arterial blood with oxygen depending on the change in altitude when breathing air and oxygen. Oxygen breathing starts from a height of 8.5 km (experiment in a pressure chamber).

Rice. 3. Comparative curves of the average values ​​of active consciousness in a person in minutes at different heights after a quick rise while breathing air (I) and oxygen (II). At altitudes above 15 km, active consciousness is equally disturbed when breathing oxygen and air. At altitudes up to 15 km, oxygen breathing significantly prolongs the period of active consciousness (experiment in a pressure chamber).

Since the percentage composition of atmospheric gases is relatively constant, to determine the partial pressure of any gas, it is only necessary to know the total barometric pressure at a given altitude (Fig. 1 and Table 3).

Table 3. TABLE OF STANDARD ATMOSPHERE (GOST 4401-64) 1

Geometric height (m)	Temperature		barometric pressure			Partial pressure of oxygen (mmHg)
				mmHg Art.

1 Given in abbreviated form and supplemented by the column "Partial pressure of oxygen".

When determining the partial pressure of a gas in humid air, subtract the pressure (elasticity) of saturated vapors from the barometric pressure.

The formula for determining the partial pressure of a gas in moist air will be slightly different than for dry air:

where pH 2 O is the elasticity of water vapor. At t° 37°, the elasticity of saturated water vapor is 47 mm Hg. Art. This value is used in calculating the partial pressures of gases in alveolar air in ground and high-altitude conditions.

Effects of high and low blood pressure on the body. Changes in barometric pressure upwards or downwards have a variety of effects on the organism of animals and humans. The effect of increased pressure is associated with the mechanical and penetrating physical and chemical action of the gaseous medium (the so-called compression and penetrating effects).

The compression effect is manifested by: general volumetric compression, due to a uniform increase in the forces of mechanical pressure on organs and tissues; mechanonarcosis due to uniform volumetric compression at very high barometric pressure; local uneven pressure on tissues that limit gas-containing cavities when there is a broken connection between the outside air and the air in the cavity, for example, the middle ear, the accessory cavities of the nose (see Barotrauma); an increase in gas density in the external respiration system, which causes an increase in resistance to respiratory movements, especially during forced breathing (exercise, hypercapnia).

The penetrating effect can lead to the toxic effect of oxygen and indifferent gases, an increase in the content of which in the blood and tissues causes a narcotic reaction, the first signs of a cut when using a nitrogen-oxygen mixture in humans occur at a pressure of 4-8 atm. An increase in the partial pressure of oxygen initially reduces the level of functioning of the cardiovascular and respiratory systems due to the shutdown of the regulatory effect of physiological hypoxemia. With an increase in the partial pressure of oxygen in the lungs more than 0.8-1 ata, its toxic effect is manifested (damage to the lung tissue, convulsions, collapse).

The penetrating and compressive effects of the increased pressure of the gaseous medium are used in clinical medicine in the treatment of various diseases with general and local impairment of oxygen supply (see Barotherapy, Oxygen therapy).

Lowering the pressure has an even more pronounced effect on the body. Under conditions of an extremely rarefied atmosphere, the main pathogenetic factor leading to loss of consciousness in a few seconds, and to death in 4-5 minutes, is a decrease in the partial pressure of oxygen in the inhaled air, and then in the alveolar air, blood and tissues (Fig. 2 and 3). Moderate hypoxia causes the development of adaptive reactions of the respiratory system and hemodynamics, aimed at maintaining oxygen supply primarily to vital organs (brain, heart). With a pronounced lack of oxygen, oxidative processes are inhibited (due to respiratory enzymes), and aerobic processes of energy production in mitochondria are disrupted. This leads first to a breakdown in the functions of vital organs, and then to irreversible structural damage and death of the body. The development of adaptive and pathological reactions, a change in the functional state of the body and human performance with a decrease in atmospheric pressure is determined by the degree and rate of decrease in the partial pressure of oxygen in the inhaled air, the duration of stay at a height, the intensity of the work performed, the initial state of the body (see Altitude sickness).

A decrease in pressure at altitudes (even with the exclusion of lack of oxygen) causes serious disorders in the body, united by the concept of "decompression disorders", which include: high-altitude flatulence, barotitis and barosinusitis, high-altitude decompression sickness and high-altitude tissue emphysema.

High-altitude flatulence develops due to the expansion of gases in the gastrointestinal tract with a decrease in barometric pressure on the abdominal wall when ascending to altitudes of 7-12 km or more. Of certain importance is the release of gases dissolved in the intestinal contents.

Expansion of gases leads to stretching of the stomach and intestines, raising the diaphragm, changing the position of the heart, irritating the receptor apparatus of these organs and causing pathological reflexes that disrupt breathing and blood circulation. Often there are sharp pains in the abdomen. Similar phenomena sometimes occur in divers when ascending from depth to the surface.

The mechanism of development of barotitis and barosinusitis, manifested by a feeling of congestion and pain, respectively, in the middle ear or accessory cavities of the nose, is similar to the development of high-altitude flatulence.

The decrease in pressure, in addition to expanding the gases contained in the body cavities, also causes the release of gases from liquids and tissues in which they were dissolved under pressure at sea level or at depth, and the formation of gas bubbles in the body.

This process of an exit of the dissolved gases (first of all nitrogen) causes development of a decompression sickness (see).

Rice. 4. Dependence of the boiling point of water on altitude and barometric pressure. The pressure numbers are located below the corresponding altitude numbers.

With a decrease in atmospheric pressure, the boiling point of liquids decreases (Fig. 4). At an altitude of more than 19 km, where the barometric pressure is equal to (or less than) the elasticity of saturated vapors at body temperature (37 °), “boiling” of the interstitial and intercellular fluid of the body can occur, resulting in large veins, in the cavity of the pleura, stomach, pericardium , in loose adipose tissue, that is, in areas with low hydrostatic and interstitial pressure, water vapor bubbles form, high-altitude tissue emphysema develops. Altitude "boiling" does not affect cellular structures, being localized only in the intercellular fluid and blood.

Massive steam bubbles can block the work of the heart and blood circulation and disrupt the functioning of vital systems and organs. This is a serious complication of acute oxygen starvation that develops at high altitudes. Prevention of high-altitude tissue emphysema can be achieved by creating external counterpressure on the body with high-altitude equipment.

The very process of lowering barometric pressure (decompression) under certain parameters can become a damaging factor. Depending on the speed, decompression is divided into smooth (slow) and explosive. The latter proceeds in less than 1 second and is accompanied by a strong bang (as in a shot), the formation of fog (condensation of water vapor due to cooling of expanding air). Typically, explosive decompression occurs at altitudes when the glazing of a pressurized cockpit or pressure suit breaks.

In explosive decompression, the lungs are the first to suffer. A rapid increase in intrapulmonary excess pressure (more than 80 mm Hg) leads to a significant stretching of the lung tissue, which can cause rupture of the lungs (with their expansion by 2.3 times). Explosive decompression can also cause damage to the gastrointestinal tract. The amount of overpressure that occurs in the lungs will largely depend on the rate of air outflow from them during decompression and the volume of air in the lungs. It is especially dangerous if the upper airways at the time of decompression turn out to be closed (when swallowing, holding the breath) or decompression coincides with the phase of deep inspiration, when the lungs are filled with a large amount of air.

Atmospheric temperature

The temperature of the atmosphere initially decreases with increasing altitude (on average, from 15° near the ground to -56.5° at an altitude of 11-18 km). The vertical temperature gradient in this zone of the atmosphere is about 0.6° for every 100 m; it changes during the day and year (Table 4).

Table 4. CHANGES IN THE VERTICAL TEMPERATURE GRADIENT OVER THE MIDDLE STRIP OF THE USSR TERRITORY

Rice. 5. Change in the temperature of the atmosphere at different heights. The boundaries of the spheres are indicated by a dotted line.

At altitudes of 11 - 25 km, the temperature becomes constant and amounts to -56.5 °; then the temperature begins to rise, reaching 30–40° at an altitude of 40 km, and 70° at an altitude of 50–60 km (Fig. 5), which is associated with intense absorption of solar radiation by ozone. From a height of 60-80 km, the air temperature again decreases slightly (up to 60°C), and then progressively increases and reaches 270°C at an altitude of 120 km, 800°C at an altitude of 220 km, 1500°C at an altitude of 300 km, and

on the border with outer space - more than 3000 °. It should be noted that due to the high rarefaction and low density of gases at these heights, their heat capacity and ability to heat colder bodies is very small. Under these conditions, the transfer of heat from one body to another occurs only through radiation. All considered changes in temperature in the atmosphere are associated with the absorption by air masses of the thermal energy of the Sun - direct and reflected.

In the lower part of the atmosphere near the Earth's surface, the temperature distribution depends on the influx of solar radiation and therefore has a mainly latitudinal character, that is, lines of equal temperature - isotherms - are parallel to latitudes. Since the atmosphere in the lower layers is heated from the earth's surface, the horizontal temperature change is strongly influenced by the distribution of continents and oceans, the thermal properties of which are different. Usually, reference books indicate the temperature measured during network meteorological observations with a thermometer installed at a height of 2 m above the soil surface. The highest temperatures (up to 58°C) are observed in the deserts of Iran, and in the USSR - in the south of Turkmenistan (up to 50°), the lowest (up to -87°) in Antarctica, and in the USSR - in the regions of Verkhoyansk and Oymyakon (up to -68° ). In winter, the vertical temperature gradient in some cases, instead of 0.6 °, can exceed 1 ° per 100 m or even take a negative value. During the day in the warm season, it can be equal to many tens of degrees per 100 m. There is also a horizontal temperature gradient, which is usually referred to as a distance of 100 km along the normal to the isotherm. The magnitude of the horizontal temperature gradient is tenths of a degree per 100 km, and in frontal zones it can exceed 10° per 100 m.

The human body is able to maintain thermal homeostasis (see) within a fairly narrow range of outdoor temperature fluctuations - from 15 to 45 °. Significant differences in the temperature of the atmosphere near the Earth and at heights require the use of special protective technical means to ensure the thermal balance between the human body and the environment in high-altitude and space flights.

Characteristic changes in the parameters of the atmosphere (temperature, pressure, chemical composition, electrical state) make it possible to conditionally divide the atmosphere into zones, or layers. Troposphere- the closest layer to the Earth, the upper boundary of which extends at the equator up to 17-18 km, at the poles - up to 7-8 km, in middle latitudes - up to 12-16 km. The troposphere is characterized by an exponential pressure drop, the presence of a constant vertical temperature gradient, horizontal and vertical movements of air masses, and significant changes in air humidity. The troposphere contains the bulk of the atmosphere, as well as a significant part of the biosphere; here all the main types of clouds arise, air masses and fronts are formed, cyclones and anticyclones develop. In the troposphere, due to the reflection of the sun's rays by the snow cover of the Earth and the cooling of the surface layers of air, the so-called inversion takes place, that is, an increase in temperature in the atmosphere from the bottom up instead of the usual decrease.

In the warm season, constant turbulent (random, chaotic) mixing of air masses and heat transfer by air flows (convection) occur in the troposphere. Convection destroys fogs and reduces the dust content of the lower atmosphere.

The second layer of the atmosphere is stratosphere.

It starts from the troposphere as a narrow zone (1-3 km) with a constant temperature (tropopause) and extends to heights of about 80 km. A feature of the stratosphere is the progressive rarefaction of the air, the exceptionally high intensity of ultraviolet radiation, the absence of water vapor, the presence of a large amount of ozone and the gradual increase in temperature. The high content of ozone causes a number of optical phenomena (mirages), causes the reflection of sounds and has a significant effect on the intensity and spectral composition of electromagnetic radiation. In the stratosphere there is a constant mixing of air, so its composition is similar to the air of the troposphere, although its density at the upper boundaries of the stratosphere is extremely low. The prevailing winds in the stratosphere are westerly, and in the upper zone there is a transition to easterly winds.

The third layer of the atmosphere is ionosphere, which starts from the stratosphere and extends to altitudes of 600-800 km.

Distinctive features of the ionosphere are the extreme rarefaction of the gaseous medium, the high concentration of molecular and atomic ions and free electrons, and the high temperature. The ionosphere affects the propagation of radio waves, causing their refraction, reflection and absorption.

The main source of ionization in the high layers of the atmosphere is the ultraviolet radiation of the Sun. In this case, electrons are knocked out of the gas atoms, the atoms turn into positive ions, and the knocked-out electrons remain free or are captured by neutral molecules with the formation of negative ions. The ionization of the ionosphere is influenced by meteors, corpuscular, X-ray and gamma radiation of the Sun, as well as the seismic processes of the Earth (earthquakes, volcanic eruptions, powerful explosions), which generate acoustic waves in the ionosphere, which increase the amplitude and speed of oscillations of atmospheric particles and contribute to the ionization of gas molecules and atoms (see Aeroionization).

The electrical conductivity in the ionosphere, associated with a high concentration of ions and electrons, is very high. The increased electrical conductivity of the ionosphere plays an important role in the reflection of radio waves and the occurrence of auroras.

The ionosphere is the area of ​​flights of artificial earth satellites and intercontinental ballistic missiles. Currently, space medicine is studying the possible effects on the human body of flight conditions in this part of the atmosphere.

Fourth, outer layer of the atmosphere - exosphere. From here, atmospheric gases are scattered into the world space due to dissipation (overcoming the forces of gravity by molecules). Then there is a gradual transition from the atmosphere to interplanetary outer space. The exosphere differs from the latter by the presence of a large number of free electrons that form the 2nd and 3rd radiation belts of the Earth.

The division of the atmosphere into 4 layers is very arbitrary. So, according to electrical parameters, the entire thickness of the atmosphere is divided into 2 layers: the neutrosphere, in which neutral particles predominate, and the ionosphere. The temperature distinguishes the troposphere, stratosphere, mesosphere and thermosphere, separated respectively by tropo-, strato- and mesopauses. The layer of the atmosphere located between 15 and 70 km and characterized by a high content of ozone is called the ozonosphere.

For practical purposes, it is convenient to use the International Standard Atmosphere (MCA), for which the following conditions are accepted: the pressure at sea level at t ° 15 ° is 1013 mbar (1.013 X 10 5 nm 2, or 760 mm Hg); the temperature decreases by 6.5° per 1 km to a level of 11 km (conditional stratosphere), and then remains constant. In the USSR, the standard atmosphere GOST 4401 - 64 was adopted (Table 3).

Precipitation. Since the bulk of the atmospheric water vapor is concentrated in the troposphere, the processes of phase transitions of water, which cause precipitation, proceed mainly in the troposphere. Tropospheric clouds usually cover about 50% of the entire earth's surface, while clouds in the stratosphere (at altitudes of 20-30 km) and near the mesopause, called mother-of-pearl and noctilucent clouds, respectively, are observed relatively rarely. As a result of the condensation of water vapor in the troposphere, clouds form and precipitation occurs.

According to the nature of precipitation, precipitation is divided into 3 types: continuous, torrential, drizzling. The amount of precipitation is determined by the thickness of the layer of fallen water in millimeters; precipitation is measured by rain gauges and precipitation gauges. Precipitation intensity is expressed in millimeters per minute.

The distribution of precipitation in certain seasons and days, as well as over the territory, is extremely uneven, due to the circulation of the atmosphere and the influence of the Earth's surface. Thus, on the Hawaiian Islands, on average, 12,000 mm falls per year, and in the driest regions of Peru and the Sahara, precipitation does not exceed 250 mm, and sometimes does not fall for several years. In the annual dynamics of precipitation, the following types are distinguished: equatorial - with a maximum of precipitation after the spring and autumn equinoxes; tropical - with a maximum of precipitation in summer; monsoon - with a very pronounced peak in summer and dry winter; subtropical - with maximum precipitation in winter and dry summer; continental temperate latitudes - with a maximum of precipitation in summer; marine temperate latitudes - with a maximum of precipitation in winter.

The entire atmospheric-physical complex of climatic and meteorological factors that make up the weather is widely used to promote health, hardening, and for medicinal purposes (see Climatotherapy). Along with this, it has been established that sharp fluctuations in these atmospheric factors can adversely affect the physiological processes in the body, causing the development of various pathological conditions and the exacerbation of diseases, which are called meteotropic reactions (see Climatopathology). Of particular importance in this regard are frequent, long-term disturbances of the atmosphere and abrupt fluctuations in meteorological factors.

Meteotropic reactions are observed more often in people suffering from diseases of the cardiovascular system, polyarthritis, bronchial asthma, peptic ulcer, skin diseases.

Bibliography: Belinsky V. A. and Pobiyaho V. A. Aerology, L., 1962, bibliogr.; Biosphere and its resources, ed. V. A. Kovdy. Moscow, 1971. Danilov A. D. Chemistry of the ionosphere, L., 1967; Kolobkov N. V. Atmosphere and its life, M., 1968; Kalitin H.H. Fundamentals of atmospheric physics as applied to medicine, L., 1935; Matveev L. T. Fundamentals of general meteorology, Physics of the atmosphere, L., 1965, bibliogr.; Minkh A. A. Air ionization and its hygienic value, M., 1963, bibliogr.; it, Methods of hygienic researches, M., 1971, bibliogr.; Tverskoy P. N. Course of meteorology, L., 1962; Umansky S.P. Man in space, M., 1970; Khvostikov I. A. High layers of the atmosphere, L., 1964; X r g and a N A. X. Physics of the atmosphere, L., 1969, bibliogr.; Khromov S.P. Meteorology and climatology for geographical faculties, L., 1968.

Effects of high and low blood pressure on the body- Armstrong G. Aviation medicine, trans. from English, M., 1954, bibliogr.; Saltsman G.L. Physiological bases of a person's stay in conditions of high pressure of the gases of the environment, L., 1961, bibliogr.; Ivanov D. I. and Khromushkin A. I. Human life support systems during high-altitude and space flights, M., 1968, bibliogr.; Isakov P. K., etc. Theory and practice of aviation medicine, M., 1971, bibliogr.; Kovalenko E. A. and Chernyakov I. N. Oxygen of fabrics at extreme factors of flight, M., 1972, bibliogr.; Miles S. Underwater medicine, trans. from English, M., 1971, bibliography; Busby D. E. Space clinical medicine, Dordrecht, 1968.

I. H. Chernyakov, M. T. Dmitriev, S. I. Nepomnyashchy.

Blue planet...

This topic was supposed to appear on the site one of the first. After all, helicopters are atmospheric aircraft. Earth's atmosphere- their, so to speak, habitat :-). BUT physical properties of air just determine the quality of this habitat :-). So that's one of the basics. And the basis is always written first. But I just realized this now. However, it is better, as you know, late than never ... Let's touch on this issue, but without getting into the wilds and unnecessary difficulties :-).

So… Earth's atmosphere. This is the gaseous shell of our blue planet. Everyone knows this name. Why blue? Simply because the "blue" (as well as blue and violet) component of sunlight (spectrum) is most well scattered in the atmosphere, thus coloring it in bluish-bluish, sometimes with a hint of violet (on a sunny day, of course :-)) .

Composition of the Earth's atmosphere.

The composition of the atmosphere is quite wide. I will not list all the components in the text, there is a good illustration for this. The composition of all these gases is almost constant, with the exception of carbon dioxide (CO 2 ). In addition, the atmosphere necessarily contains water in the form of vapors, suspended droplets or ice crystals. The amount of water is not constant and depends on temperature and, to a lesser extent, on air pressure. In addition, the Earth's atmosphere (especially the current one) also contains a certain amount, I would say "all sorts of filth" :-). These are SO 2, NH 3, CO, HCl, NO, in addition there are mercury vapors Hg. True, all this is there in small quantities, thank God :-).

Earth's atmosphere It is customary to divide into several zones following each other in height above the surface.

The first, closest to the earth, is the troposphere. This is the lowest and, so to speak, the main layer for the life of various types. It contains 80% of the mass of all atmospheric air (although by volume it makes up only about 1% of the entire atmosphere) and about 90% of all atmospheric water. The bulk of all winds, clouds, rains and snows 🙂 come from there. The troposphere extends to heights of about 18 km in tropical latitudes and up to 10 km in polar latitudes. The air temperature in it drops with a rise of about 0.65º for every 100 m.

atmospheric zones.

The second zone is the stratosphere. I must say that another narrow zone is distinguished between the troposphere and stratosphere - the tropopause. It stops the temperature drop with height. The tropopause has an average thickness of 1.5-2 km, but its boundaries are indistinct and the troposphere often overlaps the stratosphere.

So the stratosphere has an average height of 12 km to 50 km. The temperature in it up to 25 km remains unchanged (about -57ºС), then somewhere up to 40 km it rises to about 0ºС and further up to 50 km it remains unchanged. The stratosphere is a relatively quiet part of the earth's atmosphere. There are practically no adverse weather conditions in it. It is in the stratosphere that the famous ozone layer is located at altitudes from 15-20 km to 55-60 km.

This is followed by a small boundary layer stratopause, in which the temperature remains around 0ºС, and then the next zone is the mesosphere. It extends to altitudes of 80-90 km, and in it the temperature drops to about 80ºС. In the mesosphere, small meteors usually become visible, which begin to glow in it and burn out there.

The next narrow gap is the mesopause and beyond it the thermosphere zone. Its height is up to 700-800 km. Here the temperature again begins to rise and at altitudes of about 300 km it can reach values ​​of the order of 1200ºС. Thereafter, it remains constant. The ionosphere is located inside the thermosphere up to a height of about 400 km. Here, the air is strongly ionized due to exposure to solar radiation and has a high electrical conductivity.

The next and, in general, the last zone is the exosphere. This is the so-called scatter zone. Here, mainly very rarefied hydrogen and helium (with a predominance of hydrogen) are present. At altitudes of about 3000 km, the exosphere passes into the near space vacuum.

It's like that somewhere. Why about? Because these layers are rather conditional. Various changes in altitude, composition of gases, water, temperature, ionization, and so on are possible. In addition, there are many more terms that define the structure and state of the earth's atmosphere.

For example homosphere and heterosphere. In the first, the atmospheric gases are well mixed and their composition is quite homogeneous. The second is located above the first and there is practically no such mixing there. The gases are separated by gravity. The boundary between these layers is located at an altitude of 120 km, and it is called turbopause.

Let's finish with the terms, but I will definitely add that it is conventionally accepted that the boundary of the atmosphere is located at an altitude of 100 km above sea level. This border is called the Karman Line.

I will add two more pictures to illustrate the structure of the atmosphere. The first, however, is in German, but it is complete and easy enough to understand :-). It can be enlarged and well considered. The second shows the change in atmospheric temperature with altitude.

The structure of the Earth's atmosphere.

Change in air temperature with height.

Modern manned orbital spacecraft fly at altitudes of about 300-400 km. However, this is no longer aviation, although the area, of course, is in a certain sense closely related, and we will certainly talk about it again :-).

The aviation zone is the troposphere. Modern atmospheric aircraft can also fly in the lower layers of the stratosphere. For example, the practical ceiling of the MIG-25RB is 23000 m.

Flight in the stratosphere.

And exactly physical properties of air tropospheres determine how the flight will be, how effective the aircraft control system will be, how turbulence in the atmosphere will affect it, how the engines will work.

The first main property is air temperature. In gas dynamics, it can be determined on the Celsius scale or on the Kelvin scale.

Temperature t1 at a given height H on the Celsius scale is determined:

t 1 \u003d t - 6.5N, where t is the air temperature at the ground.

Temperature on the Kelvin scale is called absolute temperature Zero on this scale is absolute zero. At absolute zero, the thermal motion of molecules stops. Absolute zero on the Kelvin scale corresponds to -273º on the Celsius scale.

Accordingly, the temperature T on high H on the Kelvin scale is determined:

T \u003d 273K + t - 6.5H

Air pressure. Atmospheric pressure is measured in Pascals (N / m 2), in the old system of measurement in atmospheres (atm.). There is also such a thing as barometric pressure. This is the pressure measured in millimeters of mercury using a mercury barometer. Barometric pressure (pressure at sea level) equal to 760 mm Hg. Art. called standard. In physics, 1 atm. just equal to 760 mm Hg.

Air density. In aerodynamics, the most commonly used concept is the mass density of air. This is the mass of air in 1 m3 of volume. The density of air changes with height, the air becomes more rarefied.

Air humidity. Shows the amount of water in the air. There is a concept " relative humidity". This is the ratio of the mass of water vapor to the maximum possible at a given temperature. The concept of 0%, that is, when the air is completely dry, can exist in general only in the laboratory. On the other hand, 100% humidity is quite real. This means that the air has absorbed all the water it could absorb. Something like an absolutely "full sponge". High relative humidity reduces air density, while low relative humidity increases it accordingly.

Due to the fact that aircraft flights take place under different atmospheric conditions, their flight and aerodynamic parameters in one flight mode may be different. Therefore, for a correct assessment of these parameters, we introduced International Standard Atmosphere (ISA). It shows the change in the state of the air with the rise in altitude.

The main parameters of the state of air at zero humidity are taken as:

pressure P = 760 mm Hg. Art. (101.3 kPa);

temperature t = +15°C (288 K);

mass density ρ \u003d 1.225 kg / m 3;

For the ISA, it is assumed (as mentioned above :-)) that the temperature drops in the troposphere by 0.65º for every 100 meters of altitude.

Standard atmosphere (example up to 10000 m).

ISA tables are used for calibrating instruments, as well as for navigational and engineering calculations.

Physical properties of air also include such concepts as inertness, viscosity and compressibility.

Inertia is a property of air that characterizes its ability to resist changes in the state of rest or uniform rectilinear motion. . The measure of inertia is the mass density of air. The higher it is, the higher the inertia and drag force of the medium when the aircraft moves in it.

Viscosity. Determines the frictional resistance against air as the aircraft moves.

Compressibility measures the change in air density as pressure changes. At low speeds of the aircraft (up to 450 km/h), there is no change in pressure when the air flow flows around it, but at high speeds, the effect of compressibility begins to appear. Its influence on supersonic is especially pronounced. This is a separate area of ​​​​aerodynamics and a topic for a separate article :-).

Well, it seems that's all for now ... It's time to finish this slightly tedious enumeration, which, however, cannot be dispensed with :-). Earth's atmosphere, its parameters, physical properties of air are as important for the aircraft as the parameters of the apparatus itself, and it was impossible not to mention them.

For now, until the next meetings and more interesting topics 🙂 …

P.S. For dessert, I suggest watching a video filmed from the cockpit of a MIG-25PU twin during its flight into the stratosphere. Filmed, apparently, by a tourist who has money for such flights :-). Filmed mostly through the windshield. Notice the color of the sky...