Layers of the atmosphere and their properties. The structure of the atmosphere

The atmosphere extends upward for many hundreds of kilometers. Its upper boundary, at an altitude of about 2000-3000 km, to a certain extent conditional, since the gases that make up it, gradually rarefied, pass into the world space. The chemical composition of the atmosphere, pressure, density, temperature and its other physical properties change with height. As mentioned earlier, the chemical composition of air up to a height of 100 km does not change significantly. Somewhat 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 of the oxygen becomes atomic. It is assumed that above 400-500 km the gases that make up the atmosphere are also in the atomic state.

Air pressure and density decrease rapidly with height. Although the atmosphere extends upwards for hundreds of kilometers, most of it is located in a rather thin layer adjacent to the earth's surface in its lowest parts. So, in the layer between sea level and altitudes 5-6 km half of the mass of the atmosphere is concentrated in 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 earth's surface 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. Studies have 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.

The change in air temperature with height is also uneven. According to the nature of the change in temperature with height, the atmosphere is divided into several spheres, between which there are transitional layers, the so-called pauses, where the temperature changes little with height.

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

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

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

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

More than 4/5 of the mass of the earth's atmosphere and almost all of the water vapor contained in it are concentrated in the troposphere. In addition, from the earth's surface to the upper limit of the troposphere, the temperature drops by an average of 0.6° for every 100 m, or 6° for 1 km uplift . This is due to the fact that the air in the troposphere is heated and cooled mainly from the surface of the earth.

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

From a height, the temperature difference between the equator and the pole decreases. For example, at height 5 km at the equator the temperature reaches -2°, -4°, and at the same height 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 temperature contrasts are greater in winter, atmospheric processes are more intense than in summer. This also explains the fact that the prevailing westerly winds in the troposphere in winter have higher speeds 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 transport is accompanied by vertical air movements and turbulent (disordered) movement. Due to the rise and fall of large volumes of air, clouds form and disperse, precipitation occurs and stops. 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 opened 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, rises by an average of 1–2 ° per kilometer of elevation and at the upper boundary, at a height of 50–55 km, even becomes positive. The increase in temperature in this area is caused by the presence of ozone (O 3) here, which is formed under the influence of ultraviolet radiation from the Sun. The ozone layer covers 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 the gases in the stratosphere are divided into layers, in accordance with their specific gravity. Hence the name of the stratosphere ("stratus" - layered). It was also believed that the temperature in the stratosphere is formed under the influence of radiative equilibrium, i.e., when the absorbed and reflected solar radiation are equal.

New data obtained by radiosondes and meteorological rockets have shown that in the stratosphere, as in the upper troposphere, there is an intense circulation of air with large changes in temperature and wind. Here, as in the troposphere, the air experiences significant vertical movements, 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 proceeding to the characteristics of the higher layers of the atmosphere, let's get acquainted with the so-called ozonosphere, the boundaries of which approximately correspond to the boundaries of the stratosphere.

Ozone in the atmosphere. Ozone plays an important role in creating the temperature regime and air currents in the stratosphere. Ozone (O 3) is felt by us after a thunderstorm when we inhale 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 layer 10-60 km with a maximum at a height of 22-25 km. Ozone is produced by the action of the ultraviolet rays of the sun and, although its total amount is insignificant, plays an important role in the atmosphere. Ozone has the ability to absorb the ultraviolet radiation of the sun and thereby protects the animal and plant world from its harmful effects. Even that tiny fraction of ultraviolet rays that reaches the surface of the earth burns the body badly when a person is excessively fond of sunbathing.

The amount of ozone is not the same over different parts of the Earth. There is more ozone in high latitudes, less in middle and low latitudes, and this amount changes depending on the change of seasons of the year. More ozone in spring, less in autumn. In addition, its 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, during the polar night, at high latitudes, the ozone layer emits and cools the air. As a result, in the stratosphere of high latitudes (in the Arctic and Antarctic), a cold region forms in winter, a stratospheric cyclonic eddy with large horizontal temperature and pressure gradients, which causes westerly winds over the middle latitudes of the globe.

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

Mesosphere. Observations with meteorological rockets and other methods have established that the overall temperature increase observed in the stratosphere ends at altitudes of 50-55 km. Above this layer, the temperature drops again and near the upper boundary of the mesosphere (about 80 km) reaches -75°, -90°. Further, the temperature rises 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. At low latitudes, the temperature drop occurs more slowly than at 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 by the 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 a height 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 twilight or before sunrise in clear weather, brilliant 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. Therefore, these clouds are called silvery.

The nature of noctilucent clouds is not yet well understood. For a long time it was believed that they were composed of volcanic dust. However, the absence of optical phenomena characteristic of real volcanic clouds led to the rejection of this hypothesis. Then it was suggested that noctilucent clouds are composed of cosmic dust. In recent years, a hypothesis has been proposed that these clouds are composed of ice crystals, like ordinary cirrus clouds. The level of location of noctilucent clouds is determined by the delay layer due to temperature inversion during the transition from the mesosphere to the thermosphere at a height of about 80 km. Since the temperature in the subinversion layer reaches -80°C and lower, 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 the summer, sometimes in very large numbers and for several months.

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

Temperature at altitude. 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 in Figure 5. The surfaces separating the spheres are depicted here by bold dashed lines. At the very bottom, the troposphere stands out well, with a characteristic decrease in temperature with height. Above the tropopause, in the stratosphere, on the contrary, the temperature increases with height in general and at heights of 50-55 km reaches + 10°, -10°. Let's pay attention to an 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 rises again to -15°. In summer, starting from the tropopause, the temperature increases with height and by 50 km reaches + 10°. Above the stratopause, the temperature again begins to decrease with height, and at a level of 80 km it does not exceed -70°, -90°.

From figure 5 it follows that in layer 10-40 km the air temperature in winter and summer in high latitudes is sharply different. In winter, during the polar night, the temperature here reaches -60°, -75°, and in summer a minimum of -45° is near the tropopause. Above the tropopause, the temperature increases and at altitudes of 30-35 km is only -30°, -20°, which is caused by the heating of the air in the ozone layer during the polar day. It also follows from the figure that even in one season and at the same level, the temperature is not the same. Their difference between different latitudes exceeds 20-30°. In this case, the inhomogeneity is especially significant in the low-temperature layer (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 mean temperatures shown in Figure 5 are based on observations in the northern hemisphere, but according to the available information, they can also be attributed to the 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 on high. The seasonal distribution of temperature determines a rather complex system of 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 show the average speeds of the prevailing wind (in m/s). It follows from the figure that the wind regime in winter and summer in the stratosphere is sharply different. In winter, both in the troposphere and in the stratosphere, westerly winds prevail with maximum speeds equal to about

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

In summer, above the mesosphere, the winds become westerly, and in winter, they become easterly.

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 found that in the thermosphere it is already at the level of 150 km the air temperature reaches 220-240°, and at the level of 200 km over 500°. Above, the temperature continues to rise and at the level of 500-600 km exceeds 1500°. On the basis of data obtained during launches of artificial earth satellites, it has been found that in the upper thermosphere the temperature reaches about 2000° and fluctuates significantly during the day. The question arises how to explain such a high temperature in the high layers of the atmosphere. Recall that the temperature of a gas is a measure of the average velocity of molecules. In the lower, densest part of the atmosphere, the gas molecules 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 in the interval between collisions changes greatly; in addition, the molecules of lighter gases move at a higher speed than the molecules of heavy gases. As a result, the temperature of the gases can 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, each 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 a hundred million billion of them. Therefore, excessively high temperatures in the high layers of the atmosphere, showing the speed of movement of molecules in this very thin medium, cannot cause even a slight heating of the body located here. Just as a person does not feel heat when dazzling electric lamps, although the filaments in a rarefied medium instantly heat up to several thousand degrees.

In the lower thermosphere and mesosphere, the main part of meteor showers burns out 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 action of ultraviolet solar radiation. In the thermosphere, the temperature regime is greatly influenced by corpuscular, X-ray, and radiation. ultraviolet radiation from the sun. Here, even during the day, there are sharp changes in temperature and wind.

Atmospheric ionization. The most interesting feature of the atmosphere above 60-80 km is her ionization, i.e., the process of formation of a huge number of electrically charged particles - ions. Since the ionization of gases is characteristic of the lower thermosphere, it is also called the ionosphere.

The gases in the ionosphere are mostly in the atomic state. Under the action of ultraviolet and corpuscular radiation of the Sun, which have high energy, the process of splitting off electrons from neutral atoms and air molecules occurs. Such atoms and molecules, having lost one or more electrons, become positively charged, and a free electron can reattach to a neutral atom or molecule and endow them with its negative charge. These positively and negatively charged atoms and molecules are called ions, and the gases ionized, i.e., having received an electric charge. At a higher concentration 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 higher than in the upper atmosphere, and the influx of ultraviolet and corpuscular radiation from the Sun is sufficient for the ionization process.

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

However, it is known that sometimes shortwave radio communications 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 communication is disrupted, since the movement of charged particles depends on the magnetic field. During magnetic storms, the ionosphere reflects radio waves worse or passes them into space. Mainly with a change in solar activity, accompanied by an increase in ultraviolet radiation, the electron density of the ionosphere and the absorption of radio waves in 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 marked with 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, corpuscles intensify the ionization of gases to such an extent that their glow begins. This is how auroras- in the form of beautiful multi-colored 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, the auroras become visible in the middle latitudes, and in rare cases even in the tropical zone. Thus, for example, the intense aurora observed on January 21-22, 1957, was visible in almost all the southern regions of our country.

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

According to the third Soviet satellite, between heights 200 and 1000 km during the day, positive ions of split molecular oxygen, i.e., atomic oxygen (O), predominate. Soviet scientists are studying the ionosphere with the help of artificial satellites of the Kosmos series. American scientists are also studying the ionosphere with the help of 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. She is little studied. According to the data of observations and theoretical calculations, the temperature in the exosphere increases with height presumably up to 2000°. In contrast to the lower ionosphere, in the exosphere the gases are so rarefied that their particles, moving at tremendous speeds, almost never meet each other.

Until relatively recently, it was assumed that the conditional boundary of the atmosphere is located at an altitude of about 1000 km. However, based on the deceleration 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 gives grounds to assume that the charged layers of the atmosphere extend into space for a much greater distance.

At high temperatures, at the conditional boundary of the atmosphere, the velocities of gas particles reach approximately 12 km/s At these velocities, the gases gradually leave the region of the earth's gravity into interplanetary space. This has been going on for a long time. For example, particles of hydrogen and helium are removed into interplanetary space over several years.

In the study of the high layers of the atmosphere, rich data were obtained both from satellites of the Kosmos and Elektron series, and geophysical rockets and space stations Mars-1, Luna-4, etc. Direct observations of astronauts were also valuable. So, according to photographs taken in space by V. Nikolaeva-Tereshkova, it was found that at an altitude of 19 km there is a dust layer from the Earth. This was also confirmed by the data obtained by the crew of the Voskhod spacecraft. Apparently, there is a close relationship between the dust layer and the so-called mother-of-pearl clouds, sometimes observed at altitudes of about 20-30km.

From the atmosphere to outer space. Previous assumptions that outside 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, were not justified. Studies have 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 a markedly increased content of charged particles, i.e. radiation belts- internal and external. New data helped to clarify. 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. With its intensification, i.e., 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 radiation zones of the Earth.

Radiation zones are dangerous for people flying on spacecraft. Therefore, before the flight into space, the state and position of the radiation zones are determined, and the spacecraft orbit is chosen in such a way that it passes outside the regions of increased radiation. However, the high layers of the atmosphere, as well as outer space close to the Earth, have not yet been studied enough.

In the study of the high layers of the atmosphere and near-Earth space, rich data obtained from satellites of the Kosmos series and space stations are used.

The high layers of the atmosphere are the least studied. However, modern methods of studying it allow us to hope that in the coming years a person will know many details of the structure of the atmosphere at the bottom of which he lives.

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

The Earth's atmosphere is heterogeneous: different air densities and pressures are observed at different heights, temperature and gas composition change. Based on the behavior of the ambient temperature (i.e., the temperature rises with height or decreases), the following layers are distinguished in it: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The boundaries between the layers are called pauses: there are 4 of them, because. the upper boundary of the exosphere is very blurred and often refers to the near space. The general structure of the atmosphere can be found in the attached diagram.

Fig.1 The structure of the Earth's atmosphere. Credit: website

The lowest atmospheric layer is the troposphere, the upper boundary of which, called the tropopause, varies depending on the geographical latitude and ranges from 8 km. in polar up to 20 km. in tropical latitudes. In middle or temperate latitudes, its upper boundary lies at altitudes of 10-12 km. During the year, the upper boundary of the troposphere experiences fluctuations depending on the influx of solar radiation. So, as a result of sounding at the South Pole of the Earth by the US meteorological service, it was revealed that from March to August or September there is a steady cooling of the troposphere, as a result of which, for a short period in August or September, its border rises to 11.5 km. Then, between September and December, it drops rapidly and reaches its lowest position - 7.5 km, after which its height remains practically unchanged until March. Those. The troposphere is at its thickest in summer and at its thinnest in winter.

It should be noted that in addition to seasonal variations, there are also daily fluctuations in the height of the tropopause. Also, its position is influenced by cyclones and anticyclones: in the first, it descends, because. the pressure in them is lower than in the surrounding air, and secondly, it rises accordingly.

The troposphere contains up to 90% of the total mass of the earth's air and 9/10 of all water vapor. Turbulence is highly developed here, especially in the near-surface and highest layers, clouds of all tiers develop, cyclones and anticyclones form. And due to the accumulation of greenhouse gases (carbon dioxide, methane, water vapor) of the sun's rays reflected from the Earth's surface, the greenhouse effect develops.

The greenhouse effect is associated with a decrease in air temperature in the troposphere with height (because the heated Earth gives off more heat to the surface layers). The average vertical gradient is 0.65°/100 m (i.e. the air temperature drops by 0.65° C for every 100 meters you rise). So if at the Earth's surface near the equator the average annual air temperature is + 26 °, then at the upper limit -70 °. The temperature in the tropopause region above the North Pole varies throughout the year from -45° in summer to -65° in winter.

As the altitude increases, the air pressure also decreases, amounting to only 12-20% of the near-surface level near the upper troposphere.

On the border of the troposphere and the overlying layer of the stratosphere lies the tropopause layer, 1-2 km thick. The air layer in which the vertical gradient decreases to 0.2°/100 m versus 0.65°/100 m in the underlying regions of the troposphere is usually taken as the lower boundaries of the tropopause.

Within the tropopause, air flows of a strictly defined direction are observed, called high-altitude jet streams or "jet streams", formed under the influence of the Earth's rotation around its axis and heating of the atmosphere with the participation of solar radiation. Currents are observed at the boundaries of zones with significant temperature differences. There are several centers of localization of these currents, for example, arctic, subtropical, subpolar and others. Knowing the localization of jet streams is very important for meteorology and aviation: the first uses streams for more accurate weather forecasting, the second for building aircraft flight routes, because At the flow boundaries there are strong turbulent eddies, similar to small whirlpools, called "clear sky turbulence" due to the absence of clouds at these heights.

Under the influence of high-altitude jet currents, ruptures often form in the tropopause, and at times it disappears altogether, though then it forms again. This is especially often observed in subtropical latitudes over which a powerful subtropical high-altitude current dominates. In addition, the difference in the layers of the tropopause in terms of ambient air temperature leads to the formation of breaks. For example, a wide gap exists between the warm and low polar tropopause and the high and cold tropopause of tropical latitudes. Recently, a layer of the tropopause of temperate latitudes has also been distinguished, which has breaks with the previous two layers: polar and tropical.

The second layer of the earth's atmosphere is the stratosphere. The stratosphere can be conditionally divided into 2 regions. The first of them, lying up to heights of 25 km, is characterized by almost constant temperatures, which are equal to the temperatures of the upper layers of the troposphere over a specific area. The second region, or inversion region, is characterized by an increase in air temperature to altitudes of about 40 km. This is due to the absorption of solar ultraviolet radiation by oxygen and ozone. In the upper part of the stratosphere, due to this heating, the temperature is often positive or even comparable to the surface air temperature.

Above the inversion region is a layer of constant temperatures, which is called the stratopause and is the boundary between the stratosphere and the mesosphere. Its thickness reaches 15 km.

Unlike the troposphere, turbulent disturbances are rare in the stratosphere, but strong horizontal winds or jet streams blowing in narrow zones along the borders of temperate latitudes facing the poles are noted. The position of these zones is not constant: they can shift, expand, or even disappear altogether. Often, jet streams penetrate into the upper layers of the troposphere, or vice versa, air masses from the troposphere penetrate into the lower layers of the stratosphere. Such mixing of air masses in areas of atmospheric fronts is especially characteristic.

Little in the stratosphere and water vapor. The air here is very dry, and therefore there are few clouds. Only at altitudes of 20-25 km, being in high latitudes, one can notice very thin mother-of-pearl clouds, consisting of supercooled water droplets. During the day, these clouds are not visible, but with the onset of darkness, they seem to glow due to their illumination by the Sun that has already set below the horizon.

At the same heights (20-25 km.) in the lower stratosphere there is the so-called ozone layer - the area with the highest ozone content, which is formed under the influence of ultraviolet solar radiation (you can learn more about this process on the page). The ozone layer or ozonosphere is essential to sustain life for all organisms living on land by absorbing deadly ultraviolet rays up to 290 nm. It is for this reason that living organisms do not live above the ozone layer, it is the upper limit of the spread of life on Earth.

Under the influence of ozone, magnetic fields also change, atoms break up molecules, ionization occurs, new formation of gases and other chemical compounds.

The layer of the atmosphere above the stratosphere is called the mesosphere. It is characterized by a decrease in air temperature with height with an average vertical gradient of 0.25-0.3°/100 m, which leads to strong turbulence. At the upper boundaries of the mesosphere in the area called the mesopause, temperatures up to -138 ° C were noted, which is the absolute minimum for the entire atmosphere of the Earth as a whole.

Here, within the mesopause, the lower boundary of the region of active absorption of X-ray and short-wavelength ultraviolet radiation of the Sun passes. This energy process is called radiant heat transfer. As a result, the gas is heated and ionized, which causes the glow of the atmosphere.

At altitudes of 75-90 km near the upper boundaries of the mesosphere, special clouds were noted, occupying vast areas in the polar regions of the planet. These clouds are called silver because of their glow at dusk, which is due to the reflection of sunlight from the ice crystals of which these clouds are composed.

Air pressure within the mesopause is 200 times less than at the earth's surface. This suggests that almost all the air in the atmosphere is concentrated in its 3 lower layers: the troposphere, stratosphere and mesosphere. The overlying layers of the thermosphere and exosphere account for only 0.05% of the mass of the entire atmosphere.

The thermosphere lies at altitudes from 90 to 800 km above the Earth's surface.

The thermosphere is characterized by a continuous increase in air temperature up to altitudes of 200-300 km, where it can reach 2500°C. The increase in temperature occurs due to the absorption by gas molecules of the X-ray and short-wave part of the ultraviolet radiation of the Sun. Above 300 km above sea level, the temperature rise stops.

At the same time as the temperature rises, the pressure decreases, and, consequently, the density of the surrounding air. So if at the lower boundaries of the thermosphere the density is 1.8 × 10 -8 g / cm 3, then at the upper it is already 1.8 × 10 -15 g / cm 3, which approximately corresponds to 10 million - 1 billion particles in 1 cm 3 .

All characteristics of the thermosphere, such as the composition of air, its temperature, density, are subject to strong fluctuations: depending on the geographical location, season of the year and time of day. Even the location of the upper boundary of the thermosphere is changing.

The uppermost layer of the atmosphere is called the exosphere or scattering layer. Its lower limit is constantly changing within very wide limits; the height of 690-800 km was taken as the average value. It is set where the probability of intermolecular or interatomic collisions can be neglected, i.e. the average distance that a randomly moving molecule will cover before colliding with another similar molecule (the so-called free path) will be so large that, in fact, the molecules will not collide with a probability close to zero. The layer where the described phenomenon takes place is called the thermopause.

The upper boundary of the exosphere lies at altitudes of 2-3 thousand km. It is strongly blurred and gradually passes into the near space vacuum. Sometimes, for this reason, the exosphere is considered a part of outer space, and its upper boundary is taken to be a height of 190 thousand km, at which the effect of solar radiation pressure on the speed of hydrogen atoms exceeds the gravitational attraction of the Earth. This is the so-called. the earth's corona, which is made up of hydrogen atoms. The density of the earth's corona is very low: only 1000 particles per cubic centimeter, but even this number is more than 10 times higher than the concentration of particles in interplanetary space.

Due to the extremely rarefied air of the exosphere, particles move around the Earth in elliptical orbits without colliding with each other. Some of them, moving along open or hyperbolic trajectories with cosmic velocities (hydrogen and helium atoms), leave the atmosphere and go into outer space, which is why the exosphere is called the scattering sphere.

The exact size of the atmosphere is unknown, since its upper boundary is not clearly visible. However, the structure of the atmosphere has been studied enough so that everyone can get an idea of \u200b\u200bhow the gaseous shell of our planet is arranged.

Atmospheric physics scientists define it as the area around the Earth that rotates with the planet. The FAI gives the following definition:

The boundary between space and the atmosphere runs along the Karman line. This line, according to the definition of the same organization, is the height above sea level, located at an altitude of 100 km.

Anything above this line is outer space. The atmosphere gradually passes into interplanetary space, which is why there are different ideas about its size.

With the lower boundary of the atmosphere, everything is much simpler - it passes through the surface of the earth's crust and the water surface of the Earth - the hydrosphere. At the same time, the boundary, one might say, merges with the earth and water surfaces, since particles of air are also dissolved there.

What layers of the atmosphere are included in the size of the Earth

Interesting fact: in winter it is lower, in summer it is higher.

It is in this layer that turbulence, anticyclones and cyclones arise, clouds form. It is this sphere that is responsible for the formation of the weather; approximately 80% of all air masses are located in it.

The tropopause is the layer in which temperature does not decrease with height. Above the tropopause, at an altitude above 11 and up to 50 km is located. The stratosphere contains a layer of ozone, which is known to protect the planet from ultraviolet rays. The air in this layer is rarefied, which explains the characteristic purple hue of the sky. The speed of air currents here can reach 300 km/h. Between the stratosphere and the mesosphere is the stratopause - the boundary sphere, in which the temperature maximum takes place.

The next layer is . It extends to heights of 85-90 kilometers. The color of the sky in the mesosphere is black, so the stars can be observed even in the morning and afternoon. The most complex photochemical processes take place there, during which atmospheric glow occurs.

Between the mesosphere and the next layer is the mesopause. It is defined as a transition layer in which a temperature minimum is observed. Above, at an altitude of 100 kilometers above sea level, is the Karman line. Above this line are the thermosphere (altitude limit 800 km) and the exosphere, which is also called the "dispersion zone". At an altitude of about 2-3 thousand kilometers, it passes into the near space vacuum.

Given that the upper layer of the atmosphere is not clearly visible, its exact size cannot be calculated. In addition, there are organizations in different countries with different opinions on this matter. It should be noted that Karman line can be considered the boundary of the earth's atmosphere only conditionally, since different sources use different boundary marks. So, in some sources you can find information that the upper limit passes at an altitude of 2500-3000 km.

NASA uses the 122 kilometer mark for calculations. Not so long ago, experiments were carried out that clarified the border as located at around 118 km.

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 heights, 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 protons with an energy of hundreds of MeV, 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 intense 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.

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Atmosphere boundary

The atmosphere is considered to be that area around the Earth in which the gaseous medium rotates together with the Earth as a whole. The atmosphere passes into interplanetary space gradually, in the exosphere, starting at an altitude of 500-1000 km from the Earth's surface.

According to the definition proposed by the International Aviation Federation, the boundary between the atmosphere and space is drawn along the Karmana line, located at an altitude of about 100 km, above which air flights become completely impossible. NASA uses the 122 kilometers (400,000 ft) mark as the boundary of the atmosphere, where the shuttles switch from propulsion maneuvering to aerodynamic maneuvering.

Physical Properties

In addition to the gases indicated in the table, the atmosphere contains Cl 2, SO 2, NH 3, CO, O 3, NO 2, hydrocarbons, HCl,, HBr, vapors, I 2, Br 2, as well as many other gases in minor quantities. In the troposphere there is constantly a large amount of suspended solid and liquid particles (aerosol). Radon (Rn) is the rarest gas in the Earth's atmosphere.

The structure of the atmosphere

boundary layer of the atmosphere

The lower layer of the troposphere (1-2 km thick), in which the state and properties of the Earth's surface directly affect the dynamics of the atmosphere.

Troposphere

Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate 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 all water vapor present in the atmosphere. Turbulence and convection are strongly developed in the troposphere, clouds appear, cyclones and anticyclones develop. Temperature decreases with altitude with an average vertical gradient of 0.65°/100 meters.

tropopause

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

Stratosphere

The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and its increase in the 25-40 km layer from −56.5 to +0.8 ° (upper stratosphere or inversion region) are typical. 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 the mesosphere.

Stratopause

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

Mesosphere

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 up to high altitudes. Under the action of solar radiation and cosmic radiation, air is ionized (“polar lights”) - 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 - for example, in 2008-2009 - there is a noticeable decrease in the size of this layer.

Thermopause

The region of the atmosphere above the thermosphere. In this region, the absorption of solar radiation is insignificant and the temperature does not actually change with height.

Exosphere (scattering sphere)

Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular masses, 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, the kinetic energy of individual particles at altitudes of 200–250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

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

Review

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for 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, they emit the neutrosphere and ionosphere .

Depending on the composition of the gas in the atmosphere, they emit homosphere and heterosphere. heterosphere- this is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. Hence follows the 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 turbopause, it lies at an altitude of about 120 km.

Other properties of the atmosphere and effects on the human body

Already at an altitude of 5 km above sea level, an untrained person develops oxygen starvation, and without adaptation, a person's performance is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 9 km, although up to about 115 km the atmosphere contains oxygen.

The atmosphere provides us with the oxygen we need to breathe. However, due to the decrease in the total pressure of the atmosphere, as one rises to a height, the partial pressure of oxygen also decreases accordingly.

History of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere has been in three different compositions throughout its history. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This so-called primary atmosphere. At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). This is how secondary atmosphere. This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors:

leakage of light gases (hydrogen and helium) into interplanetary space;
chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.

Gradually, these factors led to the formation tertiary atmosphere, characterized by a much lower content of hydrogen and a much higher content of nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).

Nitrogen

The formation of a large amount of nitrogen N 2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O 2, which began to come from the surface of the planet as a result of photosynthesis, starting from 3 billion years ago. Nitrogen N 2 is also released into the atmosphere as a result of the denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO in the upper atmosphere.

Nitrogen N 2 enters into reactions only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen by ozone during electrical discharges is used in small quantities in the industrial production of nitrogen fertilizers. It can be oxidized with low energy consumption and converted into a biologically active form by cyanobacteria (blue-green algae) and nodule bacteria that form a rhizobial symbiosis with legumes, which can be effective green manure plants that do not deplete, but enrich the soil with natural fertilizers.

Oxygen

The composition of the atmosphere began to change radically with the advent of living organisms on Earth, as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, hydrocarbons, the ferrous form of iron contained in the oceans and others. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties formed. Since this caused serious and abrupt changes in many processes occurring in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe.

noble gases

Air pollution

Recently, man has begun to influence the evolution of the atmosphere. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological epochs. Huge amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic substances of plant and animal origin, as well as due to volcanism and human production activities. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the main part (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the next 200-300 years the amount of CO 2 in the atmosphere will double and may lead to global climate changes.

Fuel combustion is the main source of polluting gases (СО,, SO 2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3, and nitric oxide to NO 2 in the upper atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H 2 SO 4 and nitric acid HNO 3 fall on the Earth's surface in the form so-called acid rain. Usage