Troposphere

Its upper boundary is at an altitude of 8-10 km in polar regions, 10-12 km in temperate regions and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass of atmospheric air and about 90% of the total water vapor present in the atmosphere. Turbulence and convection are highly developed in the troposphere, clouds arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m

Tropopause

The transition layer from the troposphere to the stratosphere, a layer of the atmosphere in which the decrease in temperature with height stops.

Stratosphere

A layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and an increase in temperature in the 25-40 km layer from −56.5 to 0.8 ° C (upper layer of the stratosphere or inversion region). Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and mesosphere.

Stratopause

The boundary layer of the atmosphere between the stratosphere and mesosphere. In the vertical temperature distribution there is a maximum (about 0 °C).

Mesosphere

The mesosphere begins at an altitude of 50 km and extends to 80-90 km. Temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc. cause atmospheric luminescence.

Mesopause

Transitional layer between the mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).

Karman Line

The height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. The Karman line is located at an altitude of 100 km above sea level.

Boundary of the Earth's atmosphere

Thermosphere

The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values ​​of the order of 1500 K, after which it remains almost constant to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, ionization of the air (“auroras”) occurs - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity, a noticeable decrease in the size of this layer occurs.

Thermopause

The region of the atmosphere adjacent to the thermosphere. In this region, the absorption of solar radiation is negligible and the temperature does not actually change with altitude.

Exosphere (scattering sphere)

Atmospheric layers up to an altitude of 120 km

The exosphere is a dispersion zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space (dissipation).

Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular weights; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However kinetic energy individual particles at altitudes of 200-250 km correspond to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed.

At an altitude of about 2000-3500 km, the exosphere gradually turns into the so-called near-space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas represents only part of the interplanetary matter. The other part consists of dust particles of cometary and meteoric origin. In addition to extremely rarefied dust particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutronosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. This implies a variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere called the homosphere. The boundary between these layers is called the turbopause; it lies at an altitude of about 120 km.

The atmosphere extends upward for many hundreds of kilometers. Its upper limit, at an altitude of about 2000-3000 km, to a certain extent, it is conditional, since the gases that make it up, gradually becoming rarefied, pass into cosmic space. Chemical composition changes with altitude atmospheric composition, pressure, density, temperature and its other physical properties. As mentioned earlier, the chemical composition of air up to a height of 100 km does not change significantly. Slightly higher, the atmosphere also consists mainly of nitrogen and oxygen. But at altitudes 100-110 km, Under the influence of ultraviolet radiation from the sun, oxygen molecules are split into atoms and atomic oxygen appears. Above 110-120 km almost all oxygen becomes atomic. Supposedly above 400-500 km The gases that make up the atmosphere are also in an atomic state.

Air pressure and density decrease rapidly with altitude. Although the atmosphere extends upward for hundreds of kilometers, the bulk of it is located in a rather thin layer adjacent to the surface of the earth in its lowest parts. So, in the layer between sea level and heights 5-6 km half the mass of the atmosphere is concentrated in the layer 0-16 km-90%, and in the layer 0-30 km- 99%. The same rapid decrease in air mass occurs above 30 km. If weight 1 m 3 air at the surface of the earth is 1033 g, then at a height of 20 km it is equal to 43 g, and at a height of 40 km only 4 years

At an altitude of 300-400 km and above, the air is so rarefied that during the day its density changes many times. Research has shown that this change in density is related to the position of the Sun. The highest air density is around noon, the lowest at night. This is partly explained by the fact that the upper layers of the atmosphere react to changes in the electromagnetic radiation of the Sun.

Air temperature also varies unequally with altitude. According to the nature of temperature changes with altitude, the atmosphere is divided into several spheres, between which there are transition layers, so-called pauses, where the temperature changes little with altitude.

Here are the names and main characteristics of the spheres and transition layers.

Let us present basic data on the physical properties of these spheres.

Troposphere. The physical properties of the troposphere are largely determined by the influence earth's surface, which is its lower limit. The highest altitude of the troposphere is observed in the equatorial and tropical zones. Here it reaches 16-18 km and is subject to relatively little daily and seasonal changes. Over the polar and adjacent regions, the upper boundary of the troposphere lies on average at a level of 8-10 km. In middle latitudes it ranges from 6-8 to 14-16 km.

The vertical thickness of the troposphere depends significantly on the nature of atmospheric processes. Often during the day the upper boundary of the troposphere above a given point or area falls or rises by several kilometers. This is mainly due to changes in air temperature.

More than 4/5 of the mass is concentrated in the troposphere earth's atmosphere and almost all the water vapor it contains. In addition, from the surface of the earth to the upper boundary of the troposphere, the temperature decreases by an average of 0.6° for every 100 m, or 6° per 1 km raising . This is explained by the fact that the air in the troposphere is heated and cooled primarily by the earth's surface.

According to the influx solar energy temperature decreases from the equator to the poles. So, average temperature air near the surface of the earth at the equator reaches +26°, over the polar regions in winter -34°, -36°, and in summer about 0°. Thus, the temperature difference between the equator and the pole in winter is 60°, and in summer only 26°. True, such low temperatures in the Arctic in winter are observed only near the surface of the earth due to cooling of the air above the icy expanses.

In winter in Central Antarctica, the air temperature on the surface of the ice sheet is even lower. At Vostok station in August 1960, the lowest temperature on the globe was recorded -88.3°, and most often in Central Antarctica it is -45°, -50°.

With height, the temperature difference between the equator and the pole decreases. For example, at an altitude of 5 km at the equator the temperature reaches -2°, -4°, and at the same altitude in the Central Arctic -37°, -39° in winter and -19°, -20° in summer; therefore, the temperature difference in winter is 35-36°, and in summer 16-17°. In the southern hemisphere these differences are somewhat larger.

The energy of atmospheric circulation can be determined by equator-pole temperature contracts. Since the magnitude of temperature contrasts is greater in winter, atmospheric processes occur more intensely than in summer. This also explains the fact that the predominant westerly winds in winter they have higher speeds in the troposphere than in summer. In this case, the wind speed, as a rule, increases with height, reaching a maximum at the upper boundary of the troposphere. Horizontal transfer is accompanied by vertical movements of air and turbulent (disordered) movement. Due to the rise and fall of large volumes of air, clouds form and dissipate, precipitation occurs and ceases. The transition layer between the troposphere and the overlying sphere is tropopause. Above it lies the stratosphere.

Stratosphere extends from heights 8-17 to 50-55 km. It was discovered at the beginning of our century. In terms of physical properties, the stratosphere differs sharply from the troposphere in that the air temperature here, as a rule, increases by an average of 1 - 2 ° per kilometer of elevation and at the upper boundary, at an altitude of 50-55 km, even becomes positive. The increase in temperature in this area is caused by the presence of ozone (O 3), which is formed under the influence of ultraviolet radiation from the Sun. The ozone layer occupies almost the entire stratosphere. The stratosphere is very poor in water vapor. There are no violent processes of cloud formation and no precipitation.

More recently, it was assumed that the stratosphere is a relatively calm environment where air mixing does not occur, as in the troposphere. Therefore, it was believed that gases in the stratosphere are divided into layers in accordance with their specific gravities. Hence the name stratosphere (“stratus” - layered). It was also believed that the temperature in the stratosphere is formed under the influence of radiative equilibrium, i.e., when absorbed and reflected solar radiation is equal.

New data obtained from radiosondes and weather rockets have shown that the stratosphere, like the upper troposphere, experiences intense air circulation with large changes in temperature and wind. Here, as in the troposphere, the air experiences significant vertical movements and turbulent movements with strong horizontal air currents. All this is the result of a non-uniform temperature distribution.

The transition layer between the stratosphere and the overlying sphere is stratopause. However, before moving on to the characteristics of higher layers of the atmosphere, let us become familiar with the so-called ozonosphere, the boundaries of which approximately correspond to the boundaries of the stratosphere.

Ozone in the atmosphere. Ozone plays a large role in creating temperature regimes and air currents in the stratosphere. Ozone (O 3) is felt by us after a thunderstorm when inhaled clean air with a pleasant aftertaste. However, here we will not talk about this ozone formed after a thunderstorm, but about the ozone contained in the 10-60 layer km with a maximum at an altitude of 22-25 km. Ozone is formed under the influence of ultraviolet rays from the Sun and, although total its insignificant, plays important role in the atmosphere. Ozone has the ability to absorb ultraviolet radiation from the Sun and thereby protects animals and vegetable world from its destructive effects. Even that insignificant fraction of ultraviolet rays that reaches the surface of the earth severely burns the body when a person is overly keen on sunbathing.

The amount of ozone varies over various parts Earth. There is more ozone in high latitudes, less in middle and low latitudes and this amount changes depending on the changing seasons of the year. There is more ozone in spring, less in autumn. In addition, non-periodic fluctuations occur depending on the horizontal and vertical circulation of the atmosphere. Many atmospheric processes are closely related to the ozone content, since it has a direct effect on the temperature field.

In winter, under polar night conditions, at high latitudes, radiation and cooling of the air occurs in the ozone layer. As a result, in the stratosphere of high latitudes (in the Arctic and Antarctic), a cold region is formed in winter, a stratospheric cyclonic vortex with large horizontal temperature and pressure gradients, causing westerly winds over mid-latitudes globe.

In summer, under polar day conditions, at high latitudes, the ozone layer absorbs solar heat and warms the air. As a result of an increase in temperature in the stratosphere at high latitudes, a heat region and a stratospheric anticyclonic vortex are formed. Therefore, above the middle latitudes of the globe above 20 km In summer, easterly winds predominate in the stratosphere.

Mesosphere. Observations using meteorological rockets and other methods have established that the general increase in temperature observed in the stratosphere ends at altitudes of 50-55 km. Above this layer, the temperature decreases again and at the upper boundary of the mesosphere (about 80 km) reaches -75°, -90°. Then the temperature increases again with height.

It is interesting to note that the decrease in temperature with height characteristic of the mesosphere occurs differently at different latitudes and throughout the year. In low latitudes, the temperature drop occurs more slowly than in high latitudes: the average vertical temperature gradient for the mesosphere is respectively 0.23° - 0.31° per 100 m or 2.3°-3.1° per 1 km. In summer it is much larger than in winter. As shown latest research in high latitudes, the temperature at the upper boundary of the mesosphere in summer is several tens of degrees lower than in winter. In the upper mesosphere at an altitude of about 80 km In the mesopause layer, the decrease in temperature with height stops and its increase begins. Here, under the inversion layer at dusk or before sunrise at clear weather shiny thin clouds are observed, illuminated by the sun below the horizon. Against the dark background of the sky they glow with a silvery-blue light. That's why these clouds are called noctilucent.

The nature of noctilucent clouds has not yet been sufficiently studied. For a long time it was believed that they consisted of volcanic dust. However, the absence of optical phenomena characteristic of real volcanic clouds led to the abandonment of this hypothesis. It was then proposed that noctilucent clouds were composed of cosmic dust. IN last years a hypothesis has been proposed that these clouds consist of ice crystals, like ordinary cirrus clouds. The level of noctilucent clouds is determined by the blocking layer due to temperature inversion during the transition from the mesosphere to the thermosphere at an altitude of about 80 km. Since the temperature in the sub-inversion layer reaches -80° and below, the most favorable conditions are created here for the condensation of water vapor, which enters here from the stratosphere as a result of vertical movement or by turbulent diffusion. Noctilucent clouds are usually observed in summer period, sometimes in very large quantities and for several months.

Observations of noctilucent clouds have established that in summer the winds at their level are highly variable. Wind speeds vary widely: from 50-100 to several hundred kilometers per hour.

Temperature at altitudes. A visual representation of the nature of the temperature distribution with height, between the earth's surface and altitudes of 90-100 km, in winter and summer in the northern hemisphere, is given by Figure 5. The surfaces separating the spheres are depicted here with thick dashed lines. At the very bottom, the troposphere is clearly visible with a characteristic decrease in temperature with height. Above the tropopause, in the stratosphere, on the contrary, the temperature generally increases with height and at altitudes of 50-55 km reaches + 10°, -10°. Let's pay attention to important detail. In winter, in the stratosphere of high latitudes, the temperature above the tropopause drops from -60 to -75° and only above 30 km again increases to -15°. In summer, starting from the tropopause, the temperature rises with altitude by 50 km reaches + 10°. Above the stratopause, the temperature decreases again with height, and at a level of 80 km it does not exceed -70°, -90°.

From Figure 5 it follows that in the layer 10-40 km The air temperature in winter and summer at high latitudes is sharply different. In winter, under polar night conditions, the temperature here reaches -60°, -75°, and in summer a minimum of -45° is near the tropopause. Above the tropopause, the temperature increases at altitudes of 30-35 km is only -30°, -20°, which is caused by the heating of the air in the ozone layer under polar day conditions. It also follows from the figure that even in the same season and at the same level, the temperature is not the same. Their difference between different latitudes exceeds 20-30°. In this case, the heterogeneity is especially significant in the layer of low temperatures (18-30 km) and in the layer of maximum temperatures (50-60 km) in the stratosphere, as well as in the layer of low temperatures in the upper mesosphere (75-85km).

The average temperature values ​​shown in Figure 5 are obtained from observational data in the northern hemisphere, however, judging by the available information, they can also be attributed to southern hemisphere. Some differences exist mainly at high latitudes. Over Antarctica in winter, the air temperature in the troposphere and lower stratosphere is noticeably lower than over the Central Arctic.

Winds at heights. The seasonal distribution of temperature is determined by quite a complex system air currents in the stratosphere and mesosphere.

Figure 6 shows a vertical section of the wind field in the atmosphere between the earth's surface and a height of 90 km winter and summer over the northern hemisphere. The isolines depict the average speeds of the prevailing wind (in m/sec). It follows from the figure that the wind regime in the stratosphere in winter and summer is sharply different. In winter, westerly winds prevail in both the troposphere and stratosphere. maximum speeds, equal to about

100 m/sec at an altitude of 60-65 km. In summer, westerly winds prevail only up to heights of 18-20 km. Higher up they become eastern, with maximum speeds up to 70 m/sec at an altitude of 55-60km.

In summer, above the mesosphere, the winds become westerly, and in winter - eastern.

Thermosphere. Above the mesosphere is the thermosphere, which is characterized by an increase in temperature With height. According to the data obtained, mainly with the help of rockets, it was established that in the thermosphere already at a level of 150 km air temperature reaches 220-240°, and at 200 km more than 500°. Above the temperature continues to rise and at the level of 500-600 km exceeds 1500°. Based on data obtained from launches artificial satellites Earth, it was found that in the upper thermosphere the temperature reaches about 2000° and fluctuates significantly during the day. The question arises as to how to explain such high temperatures in the high layers of the atmosphere. Recall that gas temperature is a measure average speed molecular movements. In the lower, densest part of the atmosphere, the molecules of the gases that make up the air often collide with each other when moving and instantly transfer kinetic energy to each other. Therefore, the kinetic energy in a dense medium is on average the same. In high layers, where the air density is very low, collisions between molecules located at large distances occur less frequently. When energy is absorbed, the speed of molecules changes greatly between collisions; in addition, molecules of lighter gases move at higher speeds than molecules of heavy gases. As a result, the temperature of the gases may be different.

In rarefied gases there are relatively few molecules of very small sizes (light gases). If they move at high speeds, then the temperature in a given volume of air will be high. In the thermosphere, every cubic centimeter of air contains tens and hundreds of thousands of molecules of various gases, while at the surface of the earth there are about hundreds of millions of billions of them. Therefore it is excessive high values temperatures in the high layers of the atmosphere, showing the speed of movement of molecules in this very loose environment, cannot cause even slight heating of the body located here. Just as a person does not feel high temperature under the dazzling light of electric lamps, although the filaments in a rarefied environment instantly heat up to several thousand degrees.

In the lower thermosphere and mesosphere, the main part of meteor showers burns up before reaching the earth's surface.

Available information about atmospheric layers above 60-80 km are still insufficient for final conclusions about the structure, regime and processes developing in them. However, it is known that in the upper mesosphere and lower thermosphere the temperature regime is created as a result of the transformation of molecular oxygen (O 2) into atomic oxygen (O), which occurs under the influence of ultraviolet solar radiation. In the thermosphere to temperature regime big influence provides corpuscular, x-ray, etc. ultraviolet radiation from the sun. Here, even during the day, there are sharp changes in temperature and wind.

Ionization of the atmosphere. Most interesting feature atmosphere above 60-80 km is hers ionization, i.e. the process of education huge amount electrically charged particles - ions. Since the ionization of gases is characteristic of the lower thermosphere, it is also called the ionosphere.

Gases in the ionosphere are for the most part in an atomic state. Under the influence of ultraviolet and corpuscular radiation from the Sun, which have high energy, the process of splitting off electrons from neutral atoms and air molecules occurs. Such atoms and molecules that have lost one or more electrons become positively charged, and the free electron can rejoin a neutral atom or molecule and endow it with its negative charge. Such positively and negatively charged atoms and molecules are called ions, and gases - ionized, i.e. those who received electric charge. At higher concentrations of ions, gases become electrically conductive.

The ionization process occurs most intensively in thick layers limited by heights of 60-80 and 220-400 km. In these layers there are optimal conditions for ionization. Here, the air density is noticeably greater than in the upper atmosphere, and the supply of ultraviolet and corpuscular radiation from the Sun is sufficient for the ionization process.

The discovery of the ionosphere is one of the important and brilliant achievements of science. After all distinctive feature The ionosphere is its influence on the propagation of radio waves. In the ionized layers, radio waves are reflected, and therefore long-distance radio communication becomes possible. Charged atoms-ions reflect short radio waves, and they return to the earth's surface again, but at a considerable distance from the place of radio transmission. Obviously, short radio waves make this path several times, and thus long-distance radio communication is ensured. If it were not for the ionosphere, then it would be necessary to build expensive radio relay lines to transmit radio signals over long distances.

However, it is known that sometimes radio communications on short waves are disrupted. This occurs as a result of chromospheric flares on the Sun, due to which the ultraviolet radiation of the Sun sharply increases, leading to strong disturbances of the ionosphere and the Earth's magnetic field - magnetic storms. During magnetic storms, radio communications are disrupted, since the movement of charged particles depends on the magnetic field. During magnetic storms, the ionosphere reflects radio waves worse or transmits them into space. Mainly with changes in solar activity, accompanied by increased ultraviolet radiation, the electron density of the ionosphere and the absorption of radio waves during the daytime increase, leading to disruption of short-wave radio communications.

According to new research, in a powerful ionized layer there are zones where the concentration of free electrons reaches a slightly higher concentration than in neighboring layers. Four such zones are known, which are located at altitudes of about 60-80, 100-120, 180-200 and 300-400 km and are designated by letters D, E, F 1 And F 2 . With increasing radiation from the Sun, charged particles (corpuscles) under the influence of the Earth's magnetic field are deflected towards high latitudes. Upon entering the atmosphere, the corpuscles increase the ionization of gases so much that they begin to glow. This is how they arise auroras- in the form of beautiful multicolored arcs that light up in the night sky mainly in the high latitudes of the Earth. Auroras are accompanied by strong magnetic storms. In such cases, auroras become visible at mid-latitudes, and at in rare cases even in the tropical zone. For example, the intense aurora observed on January 21-22, 1957, was visible in almost all southern regions of our country.

By photographing auroras from two points located at a distance of several tens of kilometers, the height of the auroras is determined with great accuracy. Usually auroras are located at an altitude of about 100 km, They are often found at an altitude of several hundred kilometers, and sometimes at a level of about 1000 km. Although the nature of the auroras has been clarified, there are still many unresolved questions related to this phenomenon. The reasons for the diversity of forms of auroras are still unknown.

According to the third Soviet satellite, between altitudes 200 and 1000 km During the day, positive ions of split molecular oxygen, i.e., atomic oxygen (O), predominate. Soviet scientists are exploring the ionosphere using artificial satellites of the Cosmos series. American scientists also study the ionosphere using satellites.

The surface separating the thermosphere from the exosphere fluctuates depending on changes in solar activity and other factors. Vertically, these fluctuations reach 100-200 km and more.

Exosphere (scattering sphere) - the uppermost part of the atmosphere, located above 800 km. It has been little studied. According to observational data and theoretical calculations, the temperature in the exosphere increases with altitude, presumably up to 2000°. Unlike the lower ionosphere, in the exosphere the gases are so rarefied that their particles, moving with enormous speeds, almost never meet each other.

Until relatively recently, it was assumed that the conventional boundary of the atmosphere is at an altitude of about 1000 km. However, based on the braking of artificial Earth satellites, it has been established that at altitudes of 700-800 km in 1 cm 3 contains up to 160 thousand positive ions of atomic oxygen and nitrogen. This suggests that the charged layers of the atmosphere extend into space over a much greater distance.

At high temperatures at the conventional boundary of the atmosphere, the speeds of gas particles reach approximately 12 km/sec. At these speeds, gases gradually escape from the region of gravity into interplanetary space. This happens over a long period of time. For example, particles of hydrogen and helium are removed into interplanetary space over several years.

In the study of high layers of the atmosphere, rich data was obtained both from satellites of the Cosmos and Electron series, and from geophysical rockets and space stations Mars-1, Luna-4, etc. Direct observations of astronauts also turned out to be valuable. Thus, according to photographs taken in space by V. Nikolaeva-Tereshkova, it was established that at an altitude of 19 km There is a dust layer from the Earth. This was confirmed by the data received by the crew spaceship"Sunrise". Apparently, there is a close connection between the dust layer and the so-called pearly clouds, sometimes observed at altitudes of about 20-30km.

From the atmosphere to outer space. Previous assumptions that beyond the Earth's atmosphere, in the interplanetary

space, gases are very rarefied and the concentration of particles does not exceed several units in 1 cm 3, didn't come true. Research has shown that near-Earth space is filled with charged particles. On this basis, a hypothesis was put forward about the existence of zones around the Earth with noticeably increased content charged particles, i.e. radiation belts- internal and external. New data helped clarify things. It turned out that there are also charged particles between the inner and outer radiation belts. Their number varies depending on geomagnetic and solar activity. Thus, according to the new assumption, instead of radiation belts, there are radiation zones without clearly defined boundaries. The boundaries of radiation zones change depending on solar activity. When it intensifies, that is, when spots and jets of gas appear on the Sun, ejected over hundreds of thousands of kilometers, the flow of cosmic particles increases, which feed the Earth's radiation zones.

Radiation zones are dangerous for people flying on spacecraft. Therefore, before a flight into space, the state and position of radiation zones are determined, and the orbit of the spacecraft is chosen so that it passes outside areas of increased radiation. However, the high layers of the atmosphere, as well as outer space close to the Earth, have still been little explored.

The study of the high layers of the atmosphere and near-Earth space uses rich data obtained from Cosmos satellites and space stations.

The high layers of the atmosphere are the least studied. However, modern methods of its research allow us to hope that in the coming years people will know many details of the structure of the atmosphere at the bottom of which they live.

In conclusion, we present a schematic vertical section of the atmosphere (Fig. 7). Here, altitudes in kilometers and air pressure in millimeters are plotted vertically, and temperature is plotted horizontally. The solid curve shows the change in air temperature with height. At the corresponding altitudes, the most important phenomena observed in the atmosphere are noted, as well as maximum heights, achieved by radiosondes and other means of sensing the atmosphere.

STRUCTURE OF THE ATMOSPHERE

Atmosphere(from ancient Greek ἀτμός - steam and σφαῖρα - ball) - the gas shell (geosphere) surrounding planet Earth. Its inner surface covers the hydrosphere and partly the earth's crust, while its outer surface borders the near-Earth part of outer space.

Physical properties

The thickness of the atmosphere is approximately 120 km from the Earth's surface. The total mass of air in the atmosphere is (5.1-5.3) 10 18 kg. Of these, the mass of dry air is (5.1352 ± 0.0003) 10 18 kg, the total mass of water vapor is on average 1.27 10 16 kg.

The molar mass of clean dry air is 28.966 g/mol, and the density of air at the sea surface is approximately 1.2 kg/m3. The pressure at 0 °C at sea level is 101.325 kPa; critical temperature - −140.7 °C; critical pressure - 3.7 MPa; C p at 0 °C - 1.0048·10 3 J/(kg·K), C v - 0.7159·10 3 J/(kg·K) (at 0 °C). Solubility of air in water (by mass) at 0 °C - 0.0036%, at 25 °C - 0.0023%.

The following are accepted as “normal conditions” at the Earth’s surface: density 1.2 kg/m3, barometric pressure 101.35 kPa, temperature plus 20 °C and relative humidity 50%. These conditional indicators have purely engineering significance.

The structure of the atmosphere

The atmosphere has a layered structure. The layers of the atmosphere differ from each other in air temperature, its density, the amount of water vapor in the air and other properties.

Troposphere(ancient Greek τρόπος - “turn”, “change” and σφαῖρα - “ball”) - the lower, most studied layer of the atmosphere, 8-10 km high in the polar regions, in temperate latitudes up to 10-12 km, at the equator - 16-18 km.

When rising in the troposphere, the temperature decreases by an average of 0.65 K every 100 m and reaches 180-220 K in the upper part. This upper layer of the troposphere, in which the decrease in temperature with height stops, is called the tropopause. The next layer of the atmosphere, located above the troposphere, is called the stratosphere.

More than 80% of the total mass of atmospheric air is concentrated in the troposphere, turbulence and convection are highly developed, the predominant part of water vapor is concentrated, clouds arise, atmospheric fronts form, cyclones and anticyclones develop, as well as other processes that determine weather and climate. The processes occurring in the troposphere are caused primarily by convection.

The part of the troposphere within which the formation of glaciers on the earth's surface is possible is called chionosphere.

Tropopause(from the Greek τροπος - turn, change and παῦσις - stop, termination) - a layer of the atmosphere in which the decrease in temperature with height stops; transition layer from the troposphere to the stratosphere. In the earth's atmosphere, the tropopause is located at altitudes from 8-12 km (above sea level) in the polar regions and up to 16-18 km above the equator. The height of the tropopause also depends on the time of year (in summer the tropopause is located higher than in winter) and cyclonic activity (in cyclones it is lower, and in anticyclones it is higher)

The thickness of the tropopause ranges from several hundred meters to 2-3 kilometers. In the subtropics, tropopause breaks are observed due to powerful jet currents. The tropopause over certain areas is often destroyed and re-formed.

Stratosphere(from Latin stratum - flooring, layer) - a layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and an increase in temperature in the 25-40 km layer from −56.5 to 0.8 ° C (upper layer of the stratosphere or inversion region). Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and mesosphere. The air density in the stratosphere is tens and hundreds of times less than at sea level.

It is in the stratosphere that the ozone layer (“ozone layer”) is located (at an altitude of 15-20 to 55-60 km), which determines the upper limit of life in the biosphere. Ozone (O 3) is formed as a result of photochemical reactions most intensively at an altitude of ~30 km. The total mass of O 3 would be at normal pressure a layer 1.7-4.0 mm thick, but this is enough to absorb life-destructive ultraviolet radiation from the Sun. The destruction of O 3 occurs when it interacts with free radicals, NO, and halogen-containing compounds (including “freons”).

In the stratosphere, most of the short-wave part of ultraviolet radiation (180-200 nm) is retained and the energy of short waves is transformed. Under the influence of these rays, magnetic fields change, molecules disintegrate, ionization occurs, and new formation of gases and other chemical compounds occurs. These processes can be observed in the form of northern lights, lightning and other glows.

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate into atoms (above 80 km CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - N 2). At an altitude of 200-500 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O − 2, N + 2) is ~ 1/300 of the concentration of neutral particles. In the upper layers of the atmosphere there are free radicals - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

Flights into the stratosphere began in the 1930s. The flight on the first stratospheric balloon (FNRS-1), which was made by Auguste Picard and Paul Kipfer on May 27, 1931 to an altitude of 16.2 km, is widely known. Modern combat and supersonic commercial aircraft fly in the stratosphere at altitudes generally up to 20 km (although the dynamic ceiling can be much higher). High-altitude weather balloons rise up to 40 km; the record for an unmanned balloon is 51.8 km.

Recently, in US military circles, much attention has been paid to the development of layers of the stratosphere above 20 km, often called “pre-space”. « near space» ). It is assumed that unmanned airships and solar-powered aircraft (like NASA Pathfinder) will be able to stay at an altitude of about 30 km for a long time and provide surveillance and communications to very large areas, while remaining low-vulnerable to air defense systems; Such devices will be many times cheaper than satellites.

Stratopause- a layer of the atmosphere that is the boundary between two layers, the stratosphere and the mesosphere. In the stratosphere, temperature increases with increasing altitude, and the stratopause is the layer where the temperature reaches its maximum. The temperature of the stratopause is about 0 °C.

This phenomenon is observed not only on Earth, but also on other planets that have an atmosphere.

On Earth, the stratopause is located at an altitude of 50 - 55 km above sea level. Atmospheric pressure is about 1/1000 that of sea level.

Mesosphere(from the Greek μεσο- - “middle” and σφαῖρα - “ball”, “sphere”) - a layer of the atmosphere at altitudes from 40-50 to 80-90 km. Characterized by an increase in temperature with altitude; the maximum (about +50°C) temperature is located at an altitude of about 60 km, after which the temperature begins to decrease to −70° or −80°C. This decrease in temperature is associated with the vigorous absorption of solar radiation (radiation) by ozone. The term was adopted by the Geographical and Geophysical Union in 1951.

The gas composition of the mesosphere, as well as those located below atmospheric layers, is constant and contains about 80% nitrogen and 20% oxygen.

The mesosphere is separated from the underlying stratosphere by the stratopause, and from the overlying thermosphere by the mesopause. Mesopause basically coincides with turbopause.

Meteors begin to glow and, as a rule, completely burn up in the mesosphere.

Noctilucent clouds may appear in the mesosphere.

For flights, the mesosphere is a kind of “dead zone” - the air here is too rarefied to support airplanes or balloons (at an altitude of 50 km the air density is 1000 times less than at sea level), and at the same time too dense for artificial flights satellites in such low orbit. Direct studies of the mesosphere are carried out mainly using suborbital weather rockets; In general, the mesosphere has been studied less well than other layers of the atmosphere, which is why scientists have nicknamed it the “ignorosphere.”

Mesopause

Mesopause- a layer of the atmosphere that separates the mesosphere and thermosphere. On Earth it is located at an altitude of 80-90 km above sea level. At the mesopause there is a temperature minimum, which is about −100 °C. Below (starting from an altitude of about 50 km) the temperature drops with height, higher (up to an altitude of about 400 km) it rises again. The mesopause coincides with the lower boundary of the region of active absorption of X-ray and short-wave ultraviolet radiation from the Sun. At this altitude noctilucent clouds are observed.

Mesopause occurs not only on Earth, but also on other planets that have an atmosphere.

Karman Line- altitude above sea level, which is conventionally accepted as the boundary between the Earth’s atmosphere and space.

According to the Fédération Aéronautique Internationale (FAI) definition, the Karman line is located at an altitude of 100 km above sea level.

The height was named after Theodore von Karman, an American scientist of Hungarian origin. He was the first to determine that at approximately this altitude the atmosphere becomes so rarefied that aeronautics becomes impossible, since the speed of the aircraft required to create sufficient lift becomes greater than the first cosmic speed, and therefore, to achieve higher altitudes it is necessary to use astronautics.

The Earth's atmosphere continues beyond the Karman line. The outer part of the earth's atmosphere, the exosphere, extends to an altitude of 10 thousand km or more; at this altitude, the atmosphere consists mainly of hydrogen atoms that are capable of leaving the atmosphere.

Achieving the Karman Line was the first condition for receiving the Ansari X Prize, as this is the basis for recognizing the flight as a space flight.

The world around us is formed from three very different parts: land, water and air. Each of them is unique and interesting in its own way. Now we will talk only about the last of them. What is atmosphere? How did it come about? What does it consist of and into what parts is it divided? All these questions are extremely interesting.

The name “atmosphere” itself is formed from two words Greek origin, translated into Russian they mean “steam” and “ball”. And if you look at the exact definition, you can read the following: “The atmosphere is the air shell of the planet Earth, which rushes along with it in outer space.” It developed in parallel with the geological and geochemical processes that took place on the planet. And today all processes occurring in living organisms depend on it. Without an atmosphere, the planet would become a lifeless desert, like the Moon.

What does it consist of?

The question of what the atmosphere is and what elements are included in it has interested people for a long time. The main components of this shell were known already in 1774. They were installed by Antoine Lavoisier. He discovered that the composition of the atmosphere was largely composed of nitrogen and oxygen. Over time, its components were refined. And now it is known that it contains many other gases, as well as water and dust.

Let's take a closer look at what makes up the Earth's atmosphere near its surface. The most common gas is nitrogen. It contains slightly more than 78 percent. But, despite such a large amount, nitrogen is practically inactive in the air.

The next element in quantity and very important in importance is oxygen. This gas contains almost 21%, and it exhibits very high activity. Its specific function is to oxidize dead organic matter, which decomposes as a result of this reaction.

Low but important gases

The third gas that is part of the atmosphere is argon. It's a little less than one percent. After it come carbon dioxide with neon, helium with methane, krypton with hydrogen, xenon, ozone and even ammonia. But there are so few of them that the percentage of such components is equal to hundredths, thousandths and millionths. Of these only carbon dioxide plays a significant role because it is building material, which plants need for photosynthesis. Its other important function is to block radiation and absorb some of the sun's heat.

Another small but important gas, ozone exists to trap ultraviolet radiation coming from the Sun. Thanks to this property, all life on the planet is reliably protected. On the other hand, ozone affects the temperature of the stratosphere. Due to the fact that it absorbs this radiation, the air heats up.

The constancy of the quantitative composition of the atmosphere is maintained by non-stop mixing. Its layers move both horizontally and vertically. Therefore, anywhere on the globe there is enough oxygen and no excess carbon dioxide.

What else is in the air?

It should be noted that steam and dust can be found in the airspace. The latter consists of pollen and soil particles; in the city they are joined by impurities of solid emissions from exhaust gases.

But there is a lot of water in the atmosphere. Under certain conditions, it condenses and clouds and fog appear. In essence, these are the same thing, only the first ones appear high above the surface of the Earth, and the last one spreads along it. Clouds take different shapes. This process depends on the height above the Earth.

If they formed 2 km above land, then they are called layered. It is from them that rain pours on the ground or snow falls. Above them, cumulus clouds form up to a height of 8 km. They are always the most beautiful and picturesque. They are the ones who look at them and wonder what they look like. If such formations appear in the next 10 km, they will be very light and airy. Their name is feathery.

What layers is the atmosphere divided into?

Although they have very different temperatures from each other, it is very difficult to tell at what specific height one layer begins and the other ends. This division is very conditional and is approximate. However, the layers of the atmosphere still exist and perform their functions.

The lowest part of the air shell is called the troposphere. Its thickness increases as it moves from the poles to the equator from 8 to 18 km. This is the warmest part of the atmosphere because the air in it is heated by the earth's surface. Most of the water vapor is concentrated in the troposphere, which is why clouds form, precipitation falls, thunderstorms rumble and winds blow.

The next layer is about 40 km thick and is called the stratosphere. If an observer moves into this part of the air, he will find that the sky has turned purple. This is explained by the low density of the substance, which practically does not scatter the sun's rays. It is in this layer that they fly jet planes. All open spaces are open for them, since there are practically no clouds. Inside the stratosphere there is a layer consisting of large amounts of ozone.

After it come the stratopause and mesosphere. The latter is about 30 km thick. It is characterized by a sharp decrease in air density and temperature. The sky appears black to the observer. Here you can even watch the stars during the day.

Layers in which there is practically no air

The structure of the atmosphere continues with a layer called the thermosphere - the longest of all the others, its thickness reaches 400 km. This layer is distinguished by its enormous temperature, which can reach 1700 °C.

The last two spheres are often combined into one and called the ionosphere. This is due to the fact that reactions occur in them with the release of ions. It is these layers that make it possible to observe such a natural phenomenon as the northern lights.

The next 50 km from the Earth are allocated to the exosphere. This is the outer shell of the atmosphere. It disperses air particles into space. Weather satellites usually move in this layer.

The Earth's atmosphere ends with the magnetosphere. It is she who sheltered most of the planet’s artificial satellites.

After all that has been said, there should be no questions left about what the atmosphere is. If you have doubts about its necessity, they can be easily dispelled.

The meaning of atmosphere

The main function of the atmosphere is to protect the planet's surface from overheating during the day and excessive cooling at night. Following important this shell, which no one will dispute, is to supply oxygen to all living beings. Without this they would suffocate.

Most meteorites burn up in the upper layers, never reaching the Earth's surface. And people can admire the flying lights, mistaking them for shooting stars. Without an atmosphere, the entire Earth would be littered with craters. And protection from solar radiation has already been discussed above.

How does a person influence the atmosphere?

Very negative. This is due to the growing activity of people. The main share of all negative aspects falls on industry and transport. By the way, it is cars that emit almost 60% of all pollutants that penetrate into the atmosphere. The remaining forty are divided between energy and industry, as well as waste disposal industries.

List harmful substances, which daily replenish the composition of the air, is very long. Due to transport in the atmosphere there are: nitrogen and sulfur, carbon, blue and soot, as well as a strong carcinogen that causes skin cancer - benzopyrene.

The industry accounts for such chemical elements: sulfur dioxide, hydrocarbon and hydrogen sulfide, ammonia and phenol, chlorine and fluorine. If the process continues, then soon the answers to the questions: “What is the atmosphere? What does it consist of? will be completely different.

The structure and composition of the Earth’s atmosphere, it must be said, were not always constant values ​​in one or another period of the development of our planet. Today, the vertical structure of this element, which has a total “thickness” of 1.5-2.0 thousand km, is represented by several main layers, including:

1. Troposphere.
2. Tropopause.
3. Stratosphere.
4. Stratopause.
5. Mesosphere and mesopause.
6. Thermosphere.
7. Exosphere.

Basic elements of atmosphere

The troposphere is a layer in which strong vertical and horizontal movements are observed; it is here that weather, sedimentary phenomena, and climatic conditions are formed. It extends 7-8 kilometers from the surface of the planet almost everywhere, with the exception of the polar regions (up to 15 km there). In the troposphere, there is a gradual decrease in temperature, approximately by 6.4 ° C with each kilometer of altitude. This indicator may differ for different latitudes and seasons.

The composition of the Earth's atmosphere in this part is represented by the following elements and their percentages:

Nitrogen - about 78 percent;

Oxygen - almost 21 percent;

Argon - about one percent;

Carbon dioxide - less than 0.05%.

Single composition up to an altitude of 90 kilometers

In addition, you can find dust, water droplets, water vapor, combustion products, ice crystals, sea ​​salts, a lot of aerosol particles, etc. This composition of the Earth’s atmosphere is observed up to approximately ninety kilometers in altitude, so the air is approximately the same in chemical composition, not only in the troposphere, but also in the overlying layers. But there the atmosphere has fundamentally different physical properties. The layer that has a general chemical composition is called the homosphere.

What other elements make up the Earth's atmosphere? In percentage (by volume, in dry air) gases such as krypton (about 1.14 x 10 -4), xenon (8.7 x 10 -7), hydrogen (5.0 x 10 -5), methane (about 1.7 x 10 -5) are represented here. 4), nitrous oxide (5.0 x 10 -5), etc. As a percentage by mass, the most of the listed components are nitrous oxide and hydrogen, followed by helium, krypton, etc.

Physical properties of different atmospheric layers

The physical properties of the troposphere are closely related to its proximity to the surface of the planet. Hence the reflected solar heat in the form of infrared rays is directed back upward, including the processes of thermal conduction and convection. That is why the temperature drops with distance from the earth's surface. This phenomenon is observed up to the height of the stratosphere (11-17 kilometers), then the temperature becomes almost unchanged up to 34-35 km, and then the temperature rises again to altitudes of 50 kilometers (the upper limit of the stratosphere). Between the stratosphere and the troposphere there is a thin intermediate layer tropopause (up to 1-2 km), where constant temperatures are observed above the equator - about minus 70 ° C and below. Above the poles, the tropopause “warms up” in summer to minus 45°C; in winter, temperatures here fluctuate around -65°C.

The gas composition of the Earth's atmosphere includes the following important element, like ozone. There is relatively little of it at the surface (ten to the minus sixth power of one percent), since the gas is formed under the influence sun rays from atomic oxygen to upper parts atmosphere. In particular, the most ozone is at an altitude of about 25 km, and the entire “ozone screen” is located in areas from 7-8 km at the poles, from 18 km at the equator and up to fifty kilometers in total above the surface of the planet.

The atmosphere protects from solar radiation

The composition of the air in the Earth's atmosphere plays a very important role in the preservation of life, since individual chemical elements and compositions successfully limit the access of solar radiation to the earth's surface and the people, animals, and plants living on it. For example, water vapor molecules effectively absorb almost all ranges of infrared radiation, with the exception of lengths in the range from 8 to 13 microns. Ozone absorbs ultraviolet radiation up to a wavelength of 3100 A. Without its thin layer (only 3 mm on average if placed on the surface of the planet), only water at a depth of more than 10 meters and underground caves where solar radiation does not reach can be inhabited. .

Zero Celsius at the stratopause

Between the next two levels of the atmosphere, the stratosphere and mesosphere, there is a remarkable layer - the stratopause. It approximately corresponds to the height of ozone maxima and the temperature here is relatively comfortable for humans - about 0°C. Above the stratopause, in the mesosphere (starts somewhere at an altitude of 50 km and ends at an altitude of 80-90 km), a drop in temperature is again observed with increasing distance from the Earth's surface (to minus 70-80 ° C). Meteors usually burn up completely in the mesosphere.

In the thermosphere - plus 2000 K!

Chemical composition The atmosphere of the Earth in the thermosphere (begins after the mesopause from altitudes of about 85-90 to 800 km) determines the possibility of such a phenomenon as gradual heating of layers of very rarefied “air” under the influence of solar radiation. In this part of the “air blanket” of the planet, temperatures range from 200 to 2000 K, which are obtained due to the ionization of oxygen (atomic oxygen is located above 300 km), as well as the recombination of oxygen atoms into molecules, accompanied by the release of a large amount of heat. The thermosphere is where auroras occur.

Above the thermosphere is the exosphere - the outer layer of the atmosphere, from which light and rapidly moving hydrogen atoms can escape into outer space. The chemical composition of the Earth's atmosphere here is represented more by individual oxygen atoms in lower layers, helium atoms in the middle ones, and almost exclusively hydrogen atoms in the upper ones. Here they dominate high temperatures- about 3000 K and there is no atmospheric pressure.

How was the earth's atmosphere formed?

But, as mentioned above, the planet did not always have such an atmospheric composition. In total, there are three concepts of the origin of this element. The first hypothesis suggests that the atmosphere was taken through the process of accretion from a protoplanetary cloud. However, today this theory is subject to significant criticism, since such a primary atmosphere should have been destroyed by the solar “wind” from a star in our planetary system. In addition, it is assumed that volatile elements could not be retained in the formation zone of terrestrial planets due to too high temperatures.

The composition of the Earth's primary atmosphere, as suggested by the second hypothesis, could have been formed due to the active bombardment of the surface by asteroids and comets that arrived from the vicinity of the Solar system in the early stages of development. It is quite difficult to confirm or refute this concept.

Experiment at IDG RAS

The most plausible seems to be the third hypothesis, which believes that the atmosphere appeared as a result of the release of gases from the mantle of the earth's crust approximately 4 billion years ago. This concept was tested at the Institute of Geography of the Russian Academy of Sciences during an experiment called “Tsarev 2”, when a sample of a substance of meteoric origin was heated in a vacuum. Then the release of gases such as H 2, CH 4, CO, H 2 O, N 2, etc. was recorded. Therefore, scientists rightly assumed that the chemical composition of the Earth’s primary atmosphere included water and carbon dioxide, hydrogen fluoride (HF) vapor, carbon monoxide(CO), hydrogen sulfide (H 2 S), nitrogen compounds, hydrogen, methane (CH 4), ammonia vapor (NH 3), argon, etc. Water vapor from the primary atmosphere participated in the formation of the hydrosphere, carbon dioxide appeared to a greater extent in bound state in organic substances and rocks, nitrogen passed into the composition of modern air, and also again into sedimentary rocks and organic substances.

The composition of the Earth's primary atmosphere would not allow modern people to be in it without breathing apparatus, since there was no oxygen in the required quantities then. This element appeared in significant quantities one and a half billion years ago, believed to be due to the development of the process of photosynthesis in blue-green and other algae, which are the oldest inhabitants of our planet.

Minimum oxygen

The fact that the composition of the Earth's atmosphere was initially almost oxygen-free is indicated by the fact that easily oxidized, but not oxidized graphite (carbon) is found in the oldest (Catarchaean) rocks. Subsequently, the so-called banded iron ores, which included layers of enriched iron oxides, which means the appearance on the planet of a powerful source of oxygen in molecular form. But these elements were found only periodically (perhaps the same algae or other oxygen producers appeared in small islands in an anoxic desert), while the rest of the world was anaerobic. The latter is supported by the fact that easily oxidized pyrite was found in the form of pebbles processed by the current without traces chemical reactions. Since flowing waters cannot be poorly aerated, the view has developed that the atmosphere before the Cambrian contained less than one percent of the oxygen composition of today.

Revolutionary change in air composition

Approximately in the middle of the Proterozoic (1.8 billion years ago), an “oxygen revolution” occurred when the world switched to aerobic respiration, during which 38 can be obtained from one molecule of a nutrient (glucose), and not two (as with anaerobic respiration) units of energy. The composition of the Earth's atmosphere, in terms of oxygen, began to exceed one percent of what it is today, and an ozone layer began to appear, protecting organisms from radiation. It was from her that, for example, such ancient animals as trilobites “hid” under thick shells. From then until our time, the content of the main “respiratory” element gradually and slowly increased, ensuring the diversity of development of life forms on the planet.