How is the composition of the atmosphere determined? Atmosphere - the air shell of the Earth

The world It is formed from three very different parts: earth, 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 is it made of and what parts is it divided into? All these questions are extremely interesting.

The very name "atmosphere" is formed from two words Greek origin, translated into Russian they mean "steam" and "ball". And if you look precise definition, then 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 the 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 is the atmosphere and what elements are included in it has interested people for a long time. The main components of this shell were already known in 1774. They were installed by Antoine Lavoisier. He discovered that atmospheric composition mostly formed from nitrogen and oxygen. Over time, its components have been refined. And now we know that it contains many more gases, as well as water and dust.

Let us consider in more detail what the Earth's atmosphere near its surface consists of. The most common gas is nitrogen. It contains a little more than 78 percent. But, despite such a large amount, nitrogen in the air is practically not active.

The next largest and most important element is oxygen. This gas contains almost 21%, and it just shows 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. Its slightly less than one percent. It is followed by carbon dioxide with neon, helium with methane, krypton with hydrogen, xenon, ozone and even ammonia. But they are contained so little that the percentage of such components is equal to hundredths, thousandths and millionths. Of these, only carbon dioxide plays a significant role, since it is the building material that plants need for photosynthesis. Its other important function is to keep out radiation and absorb part of the sun's heat.

Another rare 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 is heated.

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

What else is in the air?

It should be noted that steam and dust can be detected in the airspace. The latter consists of pollen and soil particles, in the city they are joined by impurities of particulate 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 fact, this is the same thing, only the first ones appear high above the surface of the Earth, and the last one spreads along it. Clouds take on a variety of 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 falls on the ground or snow falls. Cumulus clouds form above them up to a height of 8 km. They are always the most beautiful and picturesque. It is they who are examined and wondered what they look like. If such formations appear in the next 10 km, they will be very light and airy. Their name is cirrus.

What are the layers of the atmosphere?

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

The most Bottom part air envelope is called the troposphere. Its thickness increases when moving from the poles to the equator from 8 to 18 km. This is the warmest part of the atmosphere, since the air in it is heated from the earth's surface. Most of the water vapor is concentrated in the troposphere, so clouds form in it, precipitation falls, thunderstorms rumble and winds blow.

The next layer is about 40 km thick and is called the stratosphere. If the observer moves to this part of the air, he will find that the sky has become purple. This is due to the low density of the substance, which practically does not scatter the sun's rays. It is in this layer that jet planes fly. For them, all open spaces are open there, since there are practically no clouds. Inside the stratosphere there is a layer consisting of a large amount of ozone.

It is followed by the stratopause and the mesosphere. The latter has a thickness of about 30 km. 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 with little to 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 characterized by a huge temperature, which can reach 1700 ° C.

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

The next 50 km from the Earth are reserved for the exosphere. This is the outer shell of the atmosphere. In it, air particles are scattered into space. Weather satellites usually move in this layer.

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

After all that has been said, there should be no question about what the atmosphere is. If there are doubts about its necessity, then it is easy to dispel them.

The value of the atmosphere

The main function of the atmosphere is to protect the surface of the planet from overheating during the day and excessive cooling at night. The next importance of this shell, which no one will dispute, is to supply oxygen to all living beings. Without it, 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 about protection from solar radiation has already been mentioned above.

How does a person affect the atmosphere?

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

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

The industry accounts for the following chemical elements: sulfur dioxide, hydrocarbons 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.

Every literate person should know not only that the planet is surrounded by an atmosphere of a mixture of various gases, but also that there are different layers of the atmosphere that are located at unequal distances from the surface of the Earth.

Observing the sky, we absolutely do not see either its complex structure, or its heterogeneous composition, or other things hidden from the eyes. But it is precisely thanks to the complex and multicomponent composition of the air layer that around the planet on it there are such conditions that allowed life to arise here, vegetation to flourish, and everything that has ever been here to appear.

Knowledge about the subject of conversation is given to people already in the 6th grade at school, but some have not yet finished their studies, and some have been there so long that they have already forgotten everything. Nevertheless, every educated person should know what the world around him consists of, especially that part of it on which the very possibility of his normal life directly depends.

What is the name of each of the layers of the atmosphere, at what height is it located, what role does it play? All these questions will be discussed below.

The structure of the Earth's atmosphere

Looking at the sky, especially when it is completely cloudless, it is very difficult to even imagine that it has such a complex and multi-layered structure that the temperature there at different altitudes is very different, and that it is there, at altitude, that the most important processes for all flora and fauna take place. on the ground.

If not for such complex composition gas cover of the planet, then there simply would not be any life and even the possibility for its origin.

The first attempts to study this part of the surrounding world were made by the ancient Greeks, but they could not go too far in their conclusions, since they did not have the necessary technical base. They did not see the boundaries of different layers, could not measure their temperature, study the component composition, etc.

In the main, it was only weather phenomena that prompted the most progressive minds to think that the visible sky is not as simple as it seems.

It is believed that the structure of the modern gaseous envelope around the Earth was formed in three stages. First there was a primary atmosphere of hydrogen and helium captured from outer space.

Then the eruption of volcanoes filled the air with a mass of other particles, and a secondary atmosphere arose. After passing all the main chemical reactions and particle relaxation processes, the current situation has arisen.

Layers of the atmosphere in order from the surface of the earth and their characteristics

The structure of the planet's gaseous envelope is quite complex and diverse. Let's consider it in more detail, gradually reaching the highest levels.

Troposphere

Apart from the boundary layer, the troposphere is the lowest layer of the atmosphere. It extends to a height of approximately 8-10 km above the earth's surface in the polar regions, 10-12 km in temperate climate, and in the tropical parts - by 16-18 kilometers.

Interesting fact: this distance may vary depending on the season - in winter it is somewhat less than in summer.

The air of the troposphere contains the main life-giving force for all life on earth. It contains about 80% of all available atmospheric air, more than 90% of water vapor, it is here that clouds, cyclones and other atmospheric phenomena form.

It is interesting to note the gradual decrease in temperature as you rise from the surface of the planet. Scientists have calculated that for every 100 m of altitude, the temperature decreases by about 0.6-0.7 degrees.

Stratosphere

The next most important layer is the stratosphere. The height of the stratosphere is approximately 45-50 kilometers. It starts from 11 km and negative temperatures already prevail here, reaching as much as -57 ° С.

Why is this layer important for humans, all animals and plants? It is here, at an altitude of 20-25 kilometers, that the ozone layer is located - it traps the ultraviolet rays emanating from the sun and reduces their destructive effect on flora and fauna to an acceptable value.

It is very interesting to note that the stratosphere absorbs many types of radiation that come to earth from the sun, other stars and outer space. The energy received from these particles goes to the ionization of the molecules and atoms located here, various chemical compounds appear.

All this leads to such a famous and colorful phenomenon as the northern lights.

Mesosphere

The mesosphere starts at about 50 and extends up to 90 kilometers. The gradient, or temperature drop with a change in altitude, is not as large here as in the lower layers. In the upper boundaries of this shell, the temperature is about -80°C. The composition of this region includes approximately 80% nitrogen, as well as 20% oxygen.

It is important to note that the mesosphere is a kind of dead zone for any flying devices. Airplanes cannot fly here, because the air is extremely rarefied, while satellites cannot fly at such a low altitude, since the available air density is very high for them.

Another interesting characteristic of the mesosphere is it is here that meteorites that hit the planet burn up. The study of such layers remote from the earth is carried out with the help of special rockets, but the efficiency of the process is low, so the knowledge of the region leaves much to be desired.

Thermosphere

Immediately after the considered layer comes thermosphere, the height in km of which extends for as much as 800 km. In a way, it's almost outer space. There is an aggressive impact of cosmic radiation, radiation, solar radiation.

All this gives rise to such a wonderful and beautiful phenomenon as the aurora borealis.

The lowest layer of the thermosphere heats up to a temperature of about 200 K or more. This happens due to elementary processes between atoms and molecules, their recombination and radiation.

The upper layers are heated due to the magnetic storms flowing here, the electric currents that are generated at the same time. The bed temperature is not uniform and can fluctuate very significantly.

Most artificial satellites, ballistic bodies, manned stations, etc. fly in the thermosphere. It also tests the launches of various weapons and missiles.

Exosphere

The exosphere, or as it is also called the sphere of dispersion, is the most upper level our atmosphere, its limit, followed by interplanetary outer space. The exosphere begins from a height of about 800-1000 kilometers.

The dense layers are left behind and here the air is extremely rarefied, any particles that fall from the side are simply carried away into space due to the very weak action of gravity.

This shell ends at an altitude of approximately 3000-3500 km, and there are almost no particles here. This zone is called the near space vacuum. It is not individual particles in their usual state that prevail here, but plasma, most often completely ionized.

The importance of the atmosphere in the life of the Earth

This is how all the main levels of the structure of the atmosphere of our planet look like. Its detailed scheme may include other regions, but they are already of secondary importance.

It is important to note that The atmosphere plays a crucial role for life on Earth. A lot of ozone in its stratosphere allows flora and fauna to escape from the deadly effects of radiation and radiation from space.

Also, it is here that the weather is formed, all atmospheric phenomena occur, cyclones, winds arise and die, this or that pressure is established. All this has a direct impact on the state of man, all living organisms and plants.

The nearest layer, the troposphere, gives us the opportunity to breathe, saturates all life with oxygen and allows it to live. Even small deviations in the structure and composition of the atmosphere can have the most detrimental effect on all living things.

That is why such a campaign is now launched against harmful emissions from auto and manufacturing, environmentalists are sounding the alarm about the thickness of the ozone layer, the Green Party and its ilk stand up for the maximum conservation of nature. This is the only way to prolong normal life on earth and not make it unbearable in terms of climate.

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.

According to the influx solar energy temperature decreases from the equator to the poles. So, average temperature air at the earth's surface 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 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 from radiosondes and meteorological rockets have shown that the stratosphere, like the upper troposphere, is subject to intense air circulation with large variations 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 formed under the action of the ultraviolet rays of the sun and, although its total amount is insignificant, plays a role important role in the atmosphere. Ozone has the ability to absorb ultraviolet radiation from the sun and thus protects animals and vegetable world from its destructive effect. 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 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 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 believed that they are composed of volcanic dust. However, the absence optical phenomena characteristic of real volcanic clouds led to the rejection of this hypothesis. It was then suggested that the noctilucent clouds are composed of space 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 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 average speed molecular movements. 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. Most interesting feature 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. those who received 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. These layers have 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 increases sharply, leading to strong disturbances of the ionosphere and magnetic field Earth - 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 tropics. 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 speeds 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 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. but modern methods her research allows us to hope that in the coming years man 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 altitude. 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.