How the composition of the atmosphere is determined. Atmosphere - Earth's air envelope

The world formed from three very different parts: earth, water and air. Each of them is unique and interesting in its own way. Now we will only talk about the last of them. What is atmosphere? How did it come about? What does it consist of and what parts is it divided into? All of 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 processes 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 an atmosphere is 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 found that composition of the atmosphere mostly formed from nitrogen and oxygen. Over time, its components have been refined. And now it is known that it contains many other gases, as well as water and dust.

Let us consider in more detail what the Earth's atmosphere consists of near its surface. The most common gas is nitrogen. It contains slightly more than 78 percent. But, despite such a large amount, nitrogen is practically inactive in the air.

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

Gases with a low content, but an important value

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

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

The constancy of the quantitative composition of the atmosphere is maintained by non-stop stirring. 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 vapor and dust can be found in the air. The latter consists of pollen and soil particles, in the city they are joined by impurities of solid emissions from exhaust gases.

But there is a lot of water in the atmosphere. Under certain conditions, it condenses and clouds and fog appear. In fact, they are one and the same, only the former appear high above the surface of the Earth, and the latter creeps along it. Clouds take on a variety of shapes. This process depends on the height above the Earth.

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

What layers is the atmosphere divided into?

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

The most Bottom part the air shell is called the troposphere. Its thickness increases as it moves from the poles to the equator from 8 to 18 km. This is the warmest part of the atmosphere, as the air in it heats up from the earth's surface. Most of the water vapor is concentrated in the troposphere, so clouds form in it, precipitation falls, thunderstorms thunder 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 turned 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. All open spaces are open for them, since there are practically no clouds. Inside the stratosphere, there is a layer of large amounts of ozone.

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

Layers with little or no air

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

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

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

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

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

The meaning of the atmosphere

The main function of the atmosphere is to protect the planet's surface 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 things. Without it, they would suffocate.

Most meteorites burn up in the upper layers, never reaching the Earth's surface. And people can admire flying lights, mistaking them for shooting stars. Without the atmosphere, the entire Earth would be strewn with craters. And the 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 negative aspects falls on industry and transport. By the way, it is cars that emit almost 60% of all pollutants that penetrate into the atmosphere. The remaining forty are divided between energy and industry, as well as waste disposal industries.

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

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

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

Observing in the sky, we absolutely do not see either its complex structure, or its heterogeneous composition, or other things hidden from our eyes. But it is precisely due to the complex and multicomponent composition of the air layer around the planet on it that conditions exist that have allowed life to arise here, vegetation to flourish, and everything that has ever appeared here.

Knowledge about the subject of the conversation is already given to people by the 6th grade at school, but some have not finished their studies yet, and some have been there so long ago 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 issues 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 assume that it has such a complex and multilayered structure that the temperature there at different heights is very different, and that it is there, in altitude, that the most important processes for all flora and fauna take place. on the ground.

If not for this complex composition the 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 undertaken 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.

Basically, only weather phenomena pushed the most progressive minds into thinking that the visible sky is not as simple as it seems.

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

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

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

The structure of the gas envelope of the planet is rather 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 climates, and in the tropical parts - by 16-18 kilometers.

Interesting fact: this distance can vary depending on the season - in winter it is slightly 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 are formed.

It is interesting to note the gradual decrease in temperature as it rises from the planet's surface. 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 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 is used to ionize 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 no longer 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 area 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 device. Airplanes cannot fly here, since the air is excessively rarefied, while satellites do not fly at such a low altitude, since the available air density for them is very high.

Another interesting characteristic of the mesosphere is it is here that the meteorites hitting the planet burn. 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, therefore, the study of the region leaves much to be desired.

Thermosphere

Immediately after the considered layer goes thermosphere, the height in km of which extends as much as 800 km. In a way, it's almost open space... Aggressive effects of cosmic radiation, radiation, solar radiation are observed here.

All this gives rise to such a wonderful and beautiful phenomenon as the polar lights.

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

The upper layers are heated due to magnetic storms flowing here, electric currents, which are generated in this case. The bed temperature is uneven and can fluctuate very significantly.

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

Exosphere

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

Dense layers were left behind and here the air is extremely rarefied, any particles that come from the side are simply carried away into space due to the very weak action of the force 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 predominate 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 decisive role for life on Earth. A lot of ozone in its stratosphere allows flora and fauna to escape the damaging effects of radiation and radiation from space.

It is also 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 ability to breathe, oxygenates all living things and allows them 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 has now been launched against harmful emissions from auto and manufacturing, environmentalists are sounding the alarm about the thickness of the ozone ball, the Green Party and others like it stand up for the maximum preservation of nature. This is the only way to prolong normal life on earth and not make it climatically unbearable.

The atmosphere extends upwards for many hundreds of kilometers. Its upper border, at an altitude of about 2000-3000 km, to a certain extent it is conditional, since the gases, its constituents, gradually thinning out, 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. The atmosphere slightly higher also consists mainly of nitrogen and oxygen. But at heights of 100-110 km, under the influence of ultraviolet radiation from the sun, oxygen molecules are split into atoms and atomic oxygen appears. Above 110-120 km almost all oxygen becomes atomic. It is assumed that above 400-500 km the gases that make up the atmosphere are also in an atomic state.

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

At an altitude of 300-400 km and above, the air is so rarefied that its density changes many times during the day. Research has shown that this change in density is related to the position of the Sun. The highest air density is around noon, the lowest at night. This is explained in part 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 also occurs unevenly. By the nature of the change in temperature with height, the atmosphere is divided into several spheres, between which there are transition layers, the so-called pauses, where the temperature changes little with height.

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

Here are 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 tropospheric height is observed in the equatorial and tropical zones. Here she reaches 16-18 km and relatively little is subject to diurnal 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 middle latitudes, it ranges from 6-8 to 14-16 km.

The vertical thickness of the troposphere depends significantly on the nature of atmospheric processes. Often, during the day, the upper border 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 surface of the earth to the upper border of the troposphere, the temperature decreases by an average of 0.6 ° for every 100 m, or 6 ° per 1 km uplifting . This is due to the fact that the air in the troposphere is heated and cooled primarily from the earth's surface.

According to the inflow solar energy the temperature goes down from the equator to the poles. So, average temperature air at the surface of the earth at the equator reaches + 26 °, over the polar regions in winter -34 °, -36 °, and in summer about 0 °. Thus, the temperature difference between the equator and the pole 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 the cooling of air over the icy expanses.

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

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

The energy of atmospheric circulation can be determined by equator-pole temperature contracts. Since the magnitude of temperature contrasts is greater in winter, atmospheric processes are more intense than in summer. This also explains the fact that the prevailing westerly winds in winter in the troposphere 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. As a result of the rise and fall of large volumes of air, clouds are formed and dispersed, precipitation appears and stops. The transition layer between the troposphere and the overlying sphere is tropopause. Above it lies the stratosphere.

Stratosphere stretches from heights 8-17 to 50-55 km. It was discovered at the beginning of our century. In terms of physical properties, the stratosphere differs sharply from the troposphere in that the air temperature here, as a rule, rises by an average of 1 - 2 ° per kilometer of rise and at the upper boundary, at an altitude of 50-55 km, even becomes positive. The rise 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 occupies almost the entire stratosphere. The stratosphere is very poor in water vapor. There are no violent cloud formation processes and no precipitation.

More recently, it was assumed that the stratosphere is a relatively calm environment, where there is no mixing of air, as in the troposphere. Therefore, it was believed that the gases in the stratosphere are divided into layers, in accordance with their specific weights... Hence the name of the stratosphere ("stratus" - layered). It was also assumed that the temperature in the stratosphere is formed under the influence of radiant equilibrium, that is, when the absorbed and reflected solar radiation is equal.

New data obtained with the help of radiosondes and meteorological rockets showed that in the stratosphere, as in the upper troposphere, there is intense air circulation with large changes in temperature and wind. Here, as in the troposphere, the air experiences significant vertical displacements, 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 characterize the higher layers of the atmosphere, let us familiarize ourselves 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 are not talking about this ozone formed after a thunderstorm, but about the ozone contained in the 10-60 layer. km with a maximum at a height of 22-25 km. Ozone is formed under the influence of the sun's ultraviolet rays and, although its total amount is insignificant, it plays important role in the atmosphere. Ozone has the ability to absorb ultraviolet radiation from the Sun and thus protects the animal and vegetable world from its destructive action. Even that negligible fraction of ultraviolet rays that reaches the surface of the earth burns the body severely when a person is overly addicted to sunbathing.

The amount of ozone is not the same 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. More ozone in spring, less ozone 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 ozone content, as it directly affects the temperature field.

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

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

Mesosphere. Observations using meteorological rockets and other methods have established that the general increase in temperature observed in the stratosphere ends at heights of 50-55 km. Above this layer, the temperature again decreases and at 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 altitude, 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 0.23 ° - 0.31 ° per 100, respectively. 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 an altitude of about 80 km in the mesopause layer, the decrease in temperature with height stops and begins to rise. Here, under the inversion layer at dusk or before sunrise, in clear weather, there are shining thin clouds 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 still not well understood. Long time believed to be 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 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 location of noctilucent clouds is determined by the retarding layer due to temperature inversion during the transition from the mesosphere to the thermosphere at an altitude of about 80 km. Since in the sub-inversion layer the temperature reaches -80 ° and below, the most favorable conditions are created here for condensation of water vapor, which gets here from the stratosphere as a result vertical movement or by turbulent diffusion. Noctilucent clouds are usually observed during 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 heights. A visual representation of the nature of the temperature distribution with height, between the earth's surface and heights of 90-100 km, in winter and summer in the northern hemisphere, is given in Figure 5. The surfaces separating the spheres are shown 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 generally rises with altitude and at heights of 50-55 km reaches + 10 °, -10 °. Pay attention to important detail... In winter, in the stratosphere of high latitudes, the temperature above the tropopause decreases from -60 to -75 ° and only above 30 km increases again to -15 °. In summer, starting from the tropopause, the temperature rises with altitude and by 50 km reaches + 10 °. Above the stratopause, the temperature again begins to decrease with altitude, and at a level of 80 km it does not exceed -70 °, -90 °.

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

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

Winds at heights. The seasonal temperature distribution is responsible for 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 in winter and summer over the northern hemisphere. 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 / sec at a height of 60-65 km. In summer, westerly winds prevail only up to heights of 18-20 km. Above they become eastern, with maximum speeds of up to 70 m / sec at a height of 55-60km.

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

Thermosphere. The thermosphere is located above the mesosphere, 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 already at the level of 150 km air temperature reaches 220-240 °, and at 200 km more than 500 °. Above, the temperature continues to rise and at the level of 500-600 km exceeds 1500 °. Based on the data obtained during the launches of artificial earth satellites, it was 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 gas temperature is a measure average speed movement of molecules. In the lower, densest part of the atmosphere, the molecules of the gases that make up the air, when moving, often collide with each other 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 are less frequent. When energy is absorbed, the velocity of the molecules in the interval between collisions changes greatly; in addition, molecules of lighter gases move at a higher speed than 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 hundreds of millions of billions. Therefore, excessively high temperatures in high layers of the atmosphere, showing the speed of movement of molecules in this very loose environment, cannot cause even a slight heating of the body located here. Just as a person does not feel the high temperature under the dazzling illumination of electric lamps, although the filaments in a rarefied environment instantly heat up to several thousand degrees.

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

Available information on 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 conversion of molecular oxygen (O 2) into atomic (O), which occurs under the action of ultraviolet solar radiation. In the thermosphere, the temperature regime is greatly influenced by corpuscular, X-ray, etc. ultraviolet radiation from the sun. Here, even during the day, there are sharp changes in temperature and wind.

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

Gases in the ionosphere are mostly in the atomic state. Under the influence of ultraviolet and corpuscular radiation of the Sun, which have high energy, the process of splitting off electrons from neutral atoms and molecules of air takes place. Such atoms and molecules that have lost one or more electrons become positively charged, and a free electron can attach again to a neutral atom or molecule and endow them with its negative charge. Such positively and negatively charged atoms and molecules are called ions, and gases - ionized i.e. those who received electric charge... At a higher concentration of ions, the 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. Indeed, 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 return to the earth's surface again, but already at a considerable distance from the place of radio transmission. Obviously, short radio waves make this path several times, and thus long-distance radio communication is provided. If it were not for the ionosphere, expensive radio relay lines would have to be built to transmit signals from radio stations over long distances.

However, it is known that sometimes radio communications at short wavelengths are disrupted. This occurs as a result of chromospheric flares on the Sun, due to which the ultraviolet radiation of the Sun is sharply increased, leading to strong disturbances of the ionosphere and magnetic field Earths - to 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 is less likely to reflect radio waves or transmit 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 radio communication at short waves.

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

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

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

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

Exosphere (sphere of dispersion) - the uppermost part of the atmosphere, located above 800 km. It has been little studied. According to observational data and theoretical calculations, the temperature in the exosphere with height increases presumably up to 2000 °. Unlike the lower ionosphere, gases in the exosphere are so rarefied that their particles, moving at tremendous speeds, hardly meet each other.

More recently, it was assumed that the conditional boundary of the atmosphere is at an altitude of about 1000 km. However, based on the deceleration of artificial earth satellites, it was found that at altitudes of 700-800 km in 1 cm 3 contains up to 160 thousand positive ions of atomic oxygen and nitrogen. This suggests that the charged layers of the atmosphere extend into space for a much greater distance.

At high temperatures at the conventional boundary of the atmosphere, the velocities of gas particles reach approximately 12 km / sec. At these velocities, gases gradually leave the area of gravity into interplanetary space. This has been happening 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 "Cosmos" and "Electron" series, and from 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 connection 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 per 1 cm 3, did not come true. 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 noticeably increased content of charged particles, i.e. radiation belts- internal and external. The 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 the radiation zones change depending on solar activity. When it intensifies, that is, when spots and jets of gas appear on the Sun, ejected for 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 in spaceships. Therefore, before the flight into space, the state and position of the radiation zones are determined, and the orbit of the spacecraft is chosen so that it passes outside the areas of increased radiation. However, the high layers of the atmosphere, as well as the outer space close to the Earth, are still poorly explored.

In the study of the high layers of the atmosphere and near-earth space, use is made of the rich data obtained from the "Cosmos" series satellites and space stations.

The high layers of the atmosphere are the least studied. but modern methods her research allows 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 vertical heights are plotted in kilometers and air pressure in millimeters, and horizontally - temperature. The solid curve shows the change in air temperature with height. The most important phenomena observed in the atmosphere, as well as the maximum heights reached by radiosondes and other means of sounding the atmosphere, are also noted at the corresponding altitudes.