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 there are conditions on it that allowed life to arise here, vegetation to flourish, 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 multilayered 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 it were not for such a complex composition of the gas cover of the planet, then there would simply be no life here 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.

It was mostly weather events that led 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 climates, and 16-18 km in tropical parts.

Interesting fact: this distance may vary depending on the time of year - 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.

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 one interesting feature mesosphere - 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, this is almost open 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 flows flowing here. magnetic storms, electric currents, which are then generated. The bed temperature is not uniform and can fluctuate very significantly.

In the thermosphere, the flight of most artificial satellites, ballistic bodies, manned stations, etc. It also tests the launches of various weapons and missiles.

Exosphere

The exosphere, or as it is also called the scattering sphere, is the highest level of our atmosphere, its limit, followed by the interplanetary 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.

Everyone who has flown on an airplane is used to this kind of message: "our flight is at an altitude of 10,000 m, the temperature overboard is 50 ° C." It seems nothing special. The farther from the surface of the Earth heated by the Sun, the colder. Many people think that the decrease in temperature with height goes on continuously and gradually the temperature drops, approaching the temperature of space. By the way, scientists thought so until the end of the 19th century.

Let's take a closer look at the distribution of air temperature over the Earth. The atmosphere is divided into several layers, which primarily reflect the nature of temperature changes.

The lower layer of the atmosphere is called troposphere, which means "sphere of rotation". All changes in weather and climate are the result of physical processes occurring in this layer. The upper boundary of this layer is located where the decrease in temperature with height is replaced by its increase, approximately at a height of 15-16 km above the equator and 7-8 km above the poles. Like the Earth itself, the atmosphere, under the influence of the rotation of our planet, is also somewhat flattened over the poles and swells over the equator. However, this effect is much stronger in the atmosphere than in the solid shell of the Earth. In the direction from the Earth's surface to the upper boundary of the troposphere, the air temperature decreases. Over the equator, the minimum air temperature is about -62°C, and over the poles, about -45°C. In temperate latitudes, more than 75% of the mass of the atmosphere is in the troposphere. In the tropics, about 90% of the mass of the atmosphere is within the troposphere.

In 1899, a minimum was found in the vertical temperature profile at a certain altitude, and then the temperature slightly increased. The beginning of this increase means the transition to the next layer of the atmosphere - to stratosphere, which means "layer sphere". The term stratosphere means and reflects the former idea of ​​​​the uniqueness of the layer lying above the troposphere. The stratosphere extends to a height of about 50 km above the earth's surface. Its feature is, in particular, a sharp increase in air temperature. This increase in temperature is explained ozone formation reaction - one of the main chemical reactions occurring in the atmosphere.

The bulk of the ozone is concentrated at altitudes of about 25 km, but in general the ozone layer is a shell strongly stretched along the height, covering almost the entire stratosphere. The interaction of oxygen with ultraviolet rays is one of the favorable processes in the earth's atmosphere that contribute to the maintenance of life on earth. The absorption of this energy by ozone prevents its excessive flow to the earth's surface, where exactly such a level of energy is created that is suitable for the existence of terrestrial life forms. The ozonosphere absorbs some of the radiant energy passing through the atmosphere. As a result, a vertical air temperature gradient of approximately 0.62 ° C per 100 m is established in the ozonosphere, i.e., the temperature rises with height up to the upper limit of the stratosphere - the stratopause (50 km), reaching, according to some data, 0 ° C.

At altitudes from 50 to 80 km there is a layer of the atmosphere called mesosphere. The word "mesosphere" means "intermediate sphere", here the air temperature continues to decrease with height. Above the mesosphere, in a layer called thermosphere, the temperature rises again with altitude up to about 1000°C, and then drops very quickly to -96°C. However, it does not fall indefinitely, then the temperature rises again.

Thermosphere is the first layer ionosphere. Unlike the previously mentioned layers, the ionosphere is not distinguished by temperature. The ionosphere is a region of an electrical nature that makes many types of radio communications possible. The ionosphere is divided into several layers, designating them with the letters D, E, F1 and F2. These layers also have special names. The division into layers is caused by several reasons, among which the most important is the unequal influence of the layers on the passage of radio waves. The lowest layer, D, mainly absorbs radio waves and thus prevents their further propagation. The best studied layer E is located at an altitude of about 100 km above the earth's surface. It is also called the Kennelly-Heaviside layer after the names of the American and English scientists who simultaneously and independently discovered it. Layer E, like a giant mirror, reflects radio waves. Thanks to this layer, long radio waves travel farther distances than would be expected if they propagated only in a straight line, without being reflected from the E layer. The F layer also has similar properties. It is also called the Appleton layer. Together with the Kennelly-Heaviside layer, it reflects radio waves to terrestrial radio stations. Such reflection can occur at various angles. The Appleton layer is located at an altitude of about 240 km.

The outermost region of the atmosphere, the second layer of the ionosphere, is often called exosphere. This term indicates the existence of the outskirts of space near the Earth. It is difficult to determine exactly where the atmosphere ends and space begins, since the density of atmospheric gases gradually decreases with height and the atmosphere itself gradually turns into an almost vacuum, in which only individual molecules meet. Already at an altitude of about 320 km, the density of the atmosphere is so low that molecules can travel more than 1 km without colliding with each other. The outermost part of the atmosphere serves as its upper boundary, which is located at altitudes from 480 to 960 km.

More information about the processes in the atmosphere can be found on the website "Earth climate"

At 0 °C - 1.0048 10 3 J / (kg K), C v - 0.7159 10 3 J / (kg K) (at 0 °C). The solubility of air in water (by mass) at 0 ° C - 0.0036%, at 25 ° C - 0.0023%.

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 atmosphere adjacent to the Earth's surface (1-2 km thick) in which the influence of this surface directly affects its dynamics.

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 m

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

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

Mesopause

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

Karman Line

Altitude above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. According to the FAI definition, the Karman Line is at an altitude of 100 km above sea level.

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 1226.85 C, after which it remains almost constant up to high altitudes. Under the influence of solar radiation and cosmic radiation, air is ionized (“ auroras”) - 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 highly rarefied 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 drop in the total pressure of the atmosphere, as you rise to a height, respectively, decreases and partial pressure oxygen.

In rarefied layers of air, the propagation of sound is impossible. Up to altitudes of 60-90 km, it is still possible to use air resistance and lift for controlled aerodynamic flight. But starting from altitudes of 100-130 km, the concepts of the M number and the sound barrier familiar to every pilot lose their meaning: there passes the conditional Karman line, beyond which the area of ​​​​purely ballistic flight begins, which can only be controlled using reactive forces.

At altitudes above 100 km, the atmosphere is also deprived of another remarkable property - the ability to absorb, conduct and transfer thermal energy by convection (that is, by mixing air). It means that various elements equipment, orbital equipment space station they will not be able to be cooled from the outside in the way it is usually done on an airplane - with the help of air jets and air radiators. At such a height, as in space in general, the only way to transfer heat is thermal radiation.

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 that take place 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

Education a large number 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, etc. 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

IN Lately man began to influence the evolution of the atmosphere. result human activity became constant growth 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 matter 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 change.

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. The use of internal combustion engines leads to significant air pollution with nitrogen oxides, hydrocarbons and lead compounds (tetraethyl lead Pb (CH 3 CH 2) 4).

Aerosol pollution of the atmosphere is caused both by natural causes (volcanic eruption, dust storms, entrainment of sea water droplets and plant pollen, etc.) and by human economic activity (mining of ores and building materials, fuel combustion, cement production, etc.). Intensive large-scale removal of particulate matter into the atmosphere is one of the possible causes planetary climate change.

see also

• Jacchia (atmosphere model)

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Notes

1. M. I. Budyko , K. Ya. Kondratiev Atmosphere of the Earth // Great Soviet Encyclopedia. 3rd ed. / Ch. ed. A. M. Prokhorov. - M.: Soviet Encyclopedia, 1970. - T. 2. Angola - Barzas. - pp. 380-384.
2. - article from the Geological Encyclopedia
4. Gribbin, John. Science. A History (1543-2001). - L. : Penguin Books, 2003. - 648 p. - ISBN 978-0-140-29741-6.
5. Tans, Pieter. Globally averaged marine surface annual mean data . NOAA/ESRL. Retrieved February 19, 2014.(English) (for 2013)
6. IPCC (English) (for 1998).
7. S. P. Khromov Air humidity // Great Soviet Encyclopedia. 3rd ed. / Ch. ed. A. M. Prokhorov. - M .: Soviet Encyclopedia, 1971. - T. 5. Veshin - Gazli. - S. 149.
8. (English) , SpaceDaily, 07/16/2010

Literature

1. V. V. Parin, F. P. Kosmolinsky, B. A. Dushkov"Space biology and medicine" (2nd edition, revised and supplemented), M .: "Prosveshchenie", 1975, 223 pages.
2. N. V. Gusakova"Chemistry environment", Rostov-on-Don: Phoenix, 2004, 192 with ISBN 5-222-05386-5
3. Sokolov V. A. Geochemistry natural gases, M., 1971;
4. McEwen M, Phillips L. Chemistry of the atmosphere, M., 1978;
5. Wark K., Warner S. Air pollution. Sources and control, trans. from English, M.. 1980;
6. Monitoring of background pollution of natural environments. V. 1, L., 1982.

Links

• // December 17, 2013, FOBOS Center

History of the Earth Physical properties of the Earth Shells of the Earth Geography and geology Environment see also

An excerpt characterizing the Earth's atmosphere

When Pierre approached them, he noticed that Vera was in the self-satisfied enthusiasm of the conversation, Prince Andrei (which rarely happened to him) seemed embarrassed.
- What do you think? Vera said with a thin smile. - You, prince, are so insightful and understand the character of people at once. What do you think of Natalie, can she be constant in her affections, can she, like other women (Vera understood herself), love a person once and remain faithful to him forever? This is what I consider true love. What do you think, prince?
“I know your sister too little,” answered Prince Andrei with a mocking smile, under which he wanted to hide his embarrassment, “to solve such a delicate question; and then I noticed that the less a woman likes, the more constant she is, ”he added and looked at Pierre, who had approached them at that time.
- Yes, it's true, prince; in our time, - continued Vera (referring to our time, as limited people generally like to mention, believing that they have found and appreciated the features of our time and that the properties of people change with time), in our time the girl has so much freedom that le plaisir d "etre courtisee [the pleasure of having fans] often drowns out the true feeling in her. Et Nathalie, il faut l" avouer, y est tres sensible. [And Natalya, it must be confessed, is very sensitive to this.] The return to Natalya again made Prince Andrei frown unpleasantly; he wanted to get up, but Vera continued with an even more refined smile.
“I don’t think anyone was as courtisee [object of courtship] as she was,” Vera said; - but never, until very recently, did she seriously like anyone. You know, count, - she turned to Pierre, - even our dear cousin Boris, who was, entre nous [between us], very, very dans le pays du tendre ... [in the land of tenderness ...]
Prince Andrei frowned silently.
Are you friends with Boris? Vera told him.
- Yes, I know him…
- Did he tell you right about his childhood love for Natasha?
Was there childhood love? - suddenly suddenly blushing, asked Prince Andrei.
- Yes. Vous savez entre cousin et cousine cette intimate mene quelquefois a l "amour: le cousinage est un dangereux voisinage, N" est ce pas? [You know, between cousin and sister, this closeness sometimes leads to love. Such kinship is a dangerous neighborhood. Is not it?]
“Oh, without a doubt,” said Prince Andrei, and suddenly, unnaturally animated, he began to joke with Pierre about how careful he should be in his treatment of his 50-year-old Moscow cousins, and in the middle of a joking conversation, he got up and, taking under the arm of Pierre, took him aside.
- Well? - said Pierre, looking with surprise at the strange animation of his friend and noticing the look that he threw at Natasha getting up.
“I need, I need to talk to you,” said Prince Andrei. - You know our women's gloves (he talked about those Masonic gloves that were given to the newly elected brother to present to his beloved woman). - I ... But no, I'll talk to you later ... - And with a strange gleam in his eyes and restlessness in his movements, Prince Andrei went up to Natasha and sat down beside her. Pierre saw how Prince Andrei asked her something, and she, flushing, answered him.
But at this time, Berg approached Pierre, urging him to take part in a dispute between the general and the colonel about Spanish affairs.
Berg was pleased and happy. The smile of joy never left his face. The evening was very good and exactly like the other evenings he had seen. Everything was similar. And ladylike, subtle conversations, and cards, and behind the cards a general raising his voice, and a samovar, and cookies; but one thing was still missing, that which he always saw at parties, which he wished to imitate.
There was a lack of loud conversation between men and an argument about something important and clever. The general started this conversation and Berg brought Pierre to it.

The next day, Prince Andrei went to the Rostovs for dinner, as Count Ilya Andreich called him, and spent the whole day with them.
Everyone in the house felt for whom Prince Andrei went, and he, without hiding, tried all day to be with Natasha. Not only in the soul of Natasha, frightened, but happy and enthusiastic, but in the whole house, fear was felt before something important that had to happen. The countess looked at Prince Andrei with sad and seriously stern eyes when he spoke with Natasha, and timidly and feigningly began some kind of insignificant conversation, as soon as he looked back at her. Sonya was afraid to leave Natasha and was afraid to be a hindrance when she was with them. Natasha turned pale with fear of anticipation when she remained face to face with him for minutes. Prince Andrei struck her with his timidity. She felt that he needed to tell her something, but that he could not bring himself to do so.
When Prince Andrei left in the evening, the countess went up to Natasha and said in a whisper:
- Well?
- Mom, for God's sake don't ask me anything now. You can’t say that,” Natasha said.
But despite the fact that that evening Natasha, now agitated, now frightened, with stopping eyes, lay for a long time in her mother's bed. Now she told her how he praised her, then how he said that he would go abroad, then how he asked where they would live this summer, then how he asked her about Boris.
“But this, this… has never happened to me!” she said. “Only I’m scared around him, I’m always scared around him, what does that mean?” So it's real, right? Mom, are you sleeping?
“No, my soul, I myself am afraid,” answered the mother. - Go.
“I won’t sleep anyway. What's wrong with sleeping? Mommy, mommy, this has never happened to me! she said with astonishment and fear before the feeling that she was aware of in herself. - And could we think! ...
It seemed to Natasha that even when she first saw Prince Andrei in Otradnoye, she fell in love with him. She seemed to be frightened by this strange, unexpected happiness that the one whom she had chosen back then (she was firmly convinced of this), that the same one had now met her again, and, as it seems, was not indifferent to her. “And it was necessary for him, now that we are here, to come to Petersburg on purpose. And we should have met at this ball. All this is fate. It is clear that this is fate, that all this was led to this. Even then, as soon as I saw him, I felt something special.
What else did he tell you? What verses are these? Read it ... - thoughtfully said the mother, asking about the poems that Prince Andrei wrote in Natasha's album.
- Mom, is it not a shame that he is a widower?
- That's it, Natasha. Pray to God. Les Marieiages se font dans les cieux. [Marriages are made in heaven.]
“Darling, mother, how I love you, how good it is for me!” Natasha shouted, crying tears of happiness and excitement and hugging her mother.
At the same time, Prince Andrei was sitting with Pierre and telling him about his love for Natasha and about his firm intention to marry her.

On that day, Countess Elena Vasilievna had a reception, there was a French envoy, there was a prince, who had recently become a frequent visitor to the countess's house, and many brilliant ladies and men. Pierre was downstairs, walked through the halls, and struck all the guests with his concentrated, absent-minded and gloomy look.
From the time of the ball, Pierre felt the approach of fits of hypochondria in himself and with a desperate effort tried to fight against them. From the time of the prince’s rapprochement with his wife, Pierre was unexpectedly granted a chamberlain, and from that time on he began to feel heaviness and shame in a large society, and more often the same gloomy thoughts about the futility of everything human began to come to him. At the same time, the feeling he noticed between Natasha, who was patronized by him, and Prince Andrei, his opposition between his position and the position of his friend, further strengthened this gloomy mood. He equally tried to avoid thoughts about his wife and about Natasha and Prince Andrei. Again everything seemed to him insignificant in comparison with eternity, again the question presented itself: “what for?”. And he forced himself day and night to work on the Masonic works, hoping to drive away the approach of the evil spirit. Pierre at 12 o'clock, having left the Countess's chambers, was sitting upstairs in a smoky, low room, in a worn dressing gown in front of the table and copying genuine Scottish acts, when someone entered his room. It was Prince Andrew.
“Ah, it’s you,” said Pierre with an absent-minded and displeased look. “But I’m working,” he said, pointing to a notebook with that kind of salvation from the hardships of life with which unhappy people look at their work.
Prince Andrei, with a radiant, enthusiastic face renewed to life, stopped in front of Pierre and, not noticing his sad face, smiled at him with egoism of happiness.
“Well, my soul,” he said, “yesterday I wanted to tell you and today I came to you for this. Never experienced anything like it. I'm in love my friend.
Pierre suddenly sighed heavily and sank down with his heavy body on the sofa, next to Prince Andrei.
- To Natasha Rostov, right? - he said.
- Yes, yes, in whom? I would never believe it, but this feeling is stronger than me. Yesterday I suffered, suffered, but I will not give up this torment for anything in the world. I haven't lived before. Now only I live, but I can't live without her. But can she love me?... I'm old for her... What don't you say?...
- I? I? What did I tell you, - Pierre suddenly said, getting up and starting to walk around the room. “I always thought that… This girl is such a treasure, such… This is a rare girl… Dear friend, I beg you, don’t think, don’t hesitate, get married, get married and get married… And I’m sure that no one will be happier than you.
- But she!
- She loves you.
“Don’t talk nonsense ...” said Prince Andrei, smiling and looking into Pierre’s eyes.
“He loves, I know,” Pierre shouted angrily.
“No, listen,” said Prince Andrei, stopping him by the hand. Do you know what position I'm in? I need to tell everything to someone.
“Well, well, say, I’m very glad,” Pierre said, and indeed his face changed, the wrinkle smoothed out, and he joyfully listened to Prince Andrei. Prince Andrei seemed and was a completely different, new person. Where was his anguish, his contempt for life, his disappointment? Pierre was the only person before whom he dared to speak out; but on the other hand, he told him everything that was in his soul. Either he easily and boldly made plans for a long future, talked about how he could not sacrifice his happiness for the whim of his father, how he would force his father to agree to this marriage and love her or do without his consent, then he was surprised how on something strange, alien, independent of him, against the feeling that possessed him.
“I would not believe someone who would tell me that I can love like that,” said Prince Andrei. “It's not the same feeling I had before. The whole world is divided for me into two halves: one is she and there is all the happiness of hope, light; the other half - everything where it is not there, there is all despondency and darkness ...
“Darkness and gloom,” Pierre repeated, “yes, yes, I understand that.
“I can't help but love the light, it's not my fault. And I am very happy. You understand me? I know that you are happy for me.
“Yes, yes,” Pierre confirmed, looking at his friend with touching and sad eyes. The brighter the fate of Prince Andrei seemed to him, the darker his own seemed.

For marriage, the consent of the father was needed, and for this, the next day, Prince Andrei went to his father.
The father, with outward calm, but inward malice, received his son's message. He could not understand that someone wanted to change life, to bring something new into it, when life was already ending for him. “They would only let me live the way I want, and then they would do what they wanted,” the old man said to himself. With his son, however, he used the diplomacy he used on important occasions. Assuming a calm tone, he discussed the whole matter.
Firstly, the marriage was not brilliant in relation to kinship, wealth and nobility. Secondly, Prince Andrei was not the first youth and was in poor health (the old man especially leaned on this), and she was very young. Thirdly, there was a son whom it was a pity to give to a girl. Fourthly, finally, - said the father, looking mockingly at his son, - I beg you, postpone the matter for a year, go abroad, take medical treatment, find, as you like, a German, for Prince Nikolai, and then, if it’s love, passion, stubbornness, whatever you want, so great, then get married.
“And this is my last word, you know, the last ...” the prince finished in such a tone that he showed that nothing would make him change his mind.
Prince Andrei clearly saw that the old man hoped that the feeling of his or his future bride would not stand the test of the year, or that he himself, the old prince, would die by this time, and decided to fulfill the will of his father: to propose and postpone the wedding for a year.
Three weeks after his last evening at the Rostovs, Prince Andrei returned to Petersburg.

The next day after her explanation with her mother, Natasha waited all day for Bolkonsky, but he did not arrive. The next day, the third day, it was the same. Pierre also did not come, and Natasha, not knowing that Prince Andrei had gone to her father, could not explain his absence to herself.
So three weeks passed. Natasha did not want to go anywhere, and like a shadow, idle and despondent, she walked around the rooms, in the evening she secretly cried from everyone and did not appear in the evenings to her mother. She was constantly blushing and irritated. It seemed to her that everyone knew about her disappointment, laughed and regretted her. With all the strength of inner grief, this vainglorious grief increased her misfortune.
One day she came to the countess, wanted to say something to her, and suddenly burst into tears. Her tears were the tears of an offended child who himself does not know why he is being punished.
The Countess began to reassure Natasha. Natasha, who at first listened to her mother's words, suddenly interrupted her:
- Stop it, mom, I don’t think, and I don’t want to think! So, I traveled and stopped, and stopped ...
Her voice trembled, she almost burst into tears, but she recovered herself and calmly continued: “And I don’t want to get married at all. And I'm afraid of him; I am now completely, completely, calmed down ...
The next day after this conversation, Natasha put on that old dress, which she was especially aware of for the cheerfulness it delivered in the morning, and in the morning she began her former way of life, from which she lagged behind after the ball. After drinking tea, she went to the hall, which she especially loved for its strong resonance, and began to sing her solfeji (singing exercises). Having finished the first lesson, she stopped in the middle of the hall and repeated one musical phrase that she especially liked. She listened joyfully to that (as if unexpected for her) charm with which these sounds, shimmering, filled the entire emptiness of the hall and slowly died away, and she suddenly became cheerful. “Why think about it so much and so well,” she said to herself, and began to walk up and down the hall, stepping not with simple steps on the resonant parquet, but at every step stepping from heel (she was wearing new, favorite shoes) to toe, and just as joyfully as to the sounds of his voice, listening to this measured clatter of heels and the creaking of socks. Passing by a mirror, she looked into it. - "Here I am!" as if the expression on her face at the sight of herself spoke. “Well, that's good. And I don't need anyone."
The footman wanted to come in to clean up something in the hall, but she did not let him in, again shutting the door behind him, and continued her walk. She returned that morning again to her beloved state of self-love and admiration for herself. - “What a charm this Natasha is!” she said again to herself in the words of some third, collective, masculine face. - "Good, voice, young, and she does not interfere with anyone, just leave her alone." But no matter how much they left her alone, she could no longer be at peace, and immediately felt it.
In the front door the entrance door opened, someone asked: are you at home? and someone's footsteps were heard. Natasha looked in the mirror, but she did not see herself. She listened to the sounds in the hallway. When she saw herself, her face was pale. It was he. She knew this for sure, although she barely heard the sound of his voice from the closed doors.
Natasha, pale and frightened, ran into the living room.
- Mom, Bolkonsky has arrived! - she said. - Mom, this is terrible, this is unbearable! “I don’t want to… suffer!” What should I do?…
The countess had not yet had time to answer her, when Prince Andrei entered the drawing room with an anxious and serious face. As soon as he saw Natasha, his face lit up. He kissed the hand of the countess and Natasha and sat down beside the sofa.
“For a long time we have not had pleasure ...” the countess began, but Prince Andrei interrupted her, answering her question and obviously in a hurry to say what he needed.
- I have not been with you all this time, because I was with my father: I needed to talk to him about a very important matter. I just got back last night,” he said, looking at Natasha. “I need to talk to you, Countess,” he added after a moment's silence.
The Countess sighed heavily and lowered her eyes.
“I am at your service,” she said.
Natasha knew that she had to leave, but she could not do it: something was squeezing her throat, and she looked impolitely, directly, with open eyes at Prince Andrei.
"Now? This minute!… No, it can't be!” she thought.
He looked at her again, and this look convinced her that she had not been mistaken. - Yes, now, this very minute her fate was being decided.
“Come, Natasha, I will call you,” said the countess in a whisper.
Natasha looked with frightened, pleading eyes at Prince Andrei and at her mother, and went out.
“I have come, Countess, to ask for the hand of your daughter,” said Prince Andrei. The countess's face flushed, but she said nothing.
“Your suggestion…” the Countess began sedately. He remained silent, looking into her eyes. - Your offer ... (she was embarrassed) we are pleased, and ... I accept your offer, I'm glad. And my husband ... I hope ... but it will depend on her ...
- I will tell her when I have your consent ... do you give it to me? - said Prince Andrew.
“Yes,” said the Countess, and held out her hand to him, and with a mixture of aloofness and tenderness pressed her lips to his forehead as he leaned over her hand. She wanted to love him like a son; but she felt that he was a stranger and a terrible person for her. “I'm sure my husband will agree,” said the countess, “but your father ...
- My father, to whom I informed my plans, made it an indispensable condition for consent that the wedding should not be before a year. And this is what I wanted to tell you, - said Prince Andrei.
- It is true that Natasha is still young, but so long.
“It could not be otherwise,” Prince Andrei said with a sigh.
“I will send it to you,” said the countess, and left the room.
“Lord, have mercy on us,” she repeated, looking for her daughter. Sonya said that Natasha was in the bedroom. Natasha sat on her bed, pale, with dry eyes, looked at the icons and, quickly making the sign of the cross, whispered something. Seeing her mother, she jumped up and rushed to her.
- What? Mom?… What?
- Go, go to him. He asks for your hand, - the countess said coldly, as it seemed to Natasha ... - Go ... go, - the mother said with sadness and reproach after the fleeing daughter, and sighed heavily.
Natasha did not remember how she entered the living room. When she entered the door and saw him, she stopped. “Is this stranger really become my everything now?” she asked herself and instantly answered: “Yes, everything: he alone is now dearer to me than everything in the world.” Prince Andrei went up to her, lowering his eyes.
“I fell in love with you from the moment I saw you. Can I hope?
He looked at her, and the earnest passion of her countenance struck him. Her face said: “Why ask? Why doubt that which is impossible not to know? Why talk when you can’t express what you feel in words.
She approached him and stopped. He took her hand and kissed it.
– Do you love me?
“Yes, yes,” Natasha said as if with annoyance, sighed loudly, another time, more and more often, and sobbed.
– About what? What's wrong with you?
“Oh, I’m so happy,” she answered, smiled through her tears, leaned closer to him, thought for a second, as if asking herself if it was possible, and kissed him.
Prince Andrei held her hands, looked into her eyes, and did not find in his soul the former love for her. Something suddenly turned in his soul: there was no former poetic and mysterious charm of desire, but there was pity for her feminine and childish weakness, there was fear of her devotion and gullibility, a heavy and at the same time joyful consciousness of the duty that bound him forever with her. The real feeling, although it was not as light and poetic as the former, was more serious and stronger.

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. WITH general structure 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, depending on geographical latitude varies and ranges from 8 km. in polar up to 20 km. in tropical latitudes. In middle or temperate latitudes, its upper limit lies at altitudes of 10-12 km. During the year, the upper limit of the troposphere experiences fluctuations depending on the influx of solar radiation. Thus, as a result of probing South Pole The US meteorological service has 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 thanks to the accumulation of greenhouse gases ( carbon dioxide, methane, water vapor) reflected from the Earth's surface sun rays the greenhouse effect develops.

WITH greenhouse effect the decrease in air temperature in the troposphere is associated 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.

In contrast to 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 also change magnetic fields, 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.

The air pressure within the mesopause is 200 times less than that of 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 chaotically 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 structure of the Earth's atmosphere

The atmosphere is the gaseous shell of the Earth with aerosol particles contained in it, moving together with the Earth in world space as a whole and at the same time taking part in the rotation of the Earth. At the bottom of the atmosphere, most of our lives take place.

Almost all of our planets have their own atmospheres. solar system, but only the Earth's atmosphere is capable of supporting life.

When our planet formed 4.5 billion years ago, it was apparently devoid of an atmosphere. The atmosphere was formed as a result of volcanic emissions of water vapor mixed with carbon dioxide, nitrogen and other chemicals from the depths of the young planet. But the atmosphere can only contain a limited amount of moisture, so the excess moisture through condensation gave rise to the oceans. But then the atmosphere was devoid of oxygen. The first living organisms that originated and developed in the ocean, as a result of the photosynthesis reaction (H 2 O + CO 2 = CH 2 O + O 2), began to release small portions of oxygen, which began to enter the atmosphere.

The formation of oxygen in the Earth's atmosphere led to the formation of the ozone layer at altitudes of about 8 - 30 km. And, thus, our planet has acquired protection from the harmful effects of ultraviolet study. This circumstance served as an impetus for the further evolution of life forms on Earth, since. as a result of increased photosynthesis, the amount of oxygen in the atmosphere began to grow rapidly, which contributed to the formation and maintenance of life forms, including on land.

Today our atmosphere is 78.1% nitrogen, 21% oxygen, 0.9% argon, 0.04% carbon dioxide. Very small fractions compared to the main gases are neon, helium, methane, krypton.

The particles of gas contained in the atmosphere are affected by the force of gravity of the Earth. And, given that air is compressible, its density gradually decreases with height, passing into outer space without a clear boundary. Half of the entire mass of the earth's atmosphere is concentrated in the lower 5 km, three-quarters - in the lower 10 km, nine-tenths - in the lower 20 km. 99% of the mass of the Earth's atmosphere is concentrated below a height of 30 km, and this is only 0.5% of the equatorial radius of our planet.

At sea level, the number of atoms and molecules per cubic centimeter of air is about 2 * 10 19 , at an altitude of 600 km it is only 2 * 10 7 . At sea level, an atom or molecule travels about 7 * 10 -6 cm before colliding with another particle. At an altitude of 600 km, this distance is about 10 km. And at sea level, about 7 * 10 9 such collisions occur every second, at an altitude of 600 km - only about one per minute!

But not only pressure changes with altitude. The temperature also changes. So, for example, at the foot of a high mountain it can be quite hot, while the top of the mountain is covered with snow and the temperature there is at the same time below zero. And it is worth climbing by plane to a height of about 10-11 km, as you can hear a message that it is -50 degrees overboard, while at the surface of the earth it is 60-70 degrees warmer ...

Initially, scientists assumed that the temperature decreases with height until it reaches absolute zero (-273.16 ° C). But it's not.

The Earth's atmosphere consists of four layers: troposphere, stratosphere, mesosphere, ionosphere (thermosphere). Such a division into layers is taken on the basis of data on temperature changes with height. The lowest layer, where air temperature drops with height, is called the troposphere. The layer above the troposphere, where the temperature drop stops, is replaced by isotherm and, finally, the temperature begins to rise, is called the stratosphere. The layer above the stratosphere where the temperature drops rapidly again is the mesosphere. And, finally, the layer where the temperature rise again begins, called the ionosphere or thermosphere.

The troposphere extends on average in the lower 12 km. This is where our weather is formed. The highest clouds (cirrus) form in the uppermost layers of the troposphere. The temperature in the troposphere decreases adiabatically with height, i.e. The change in temperature is due to the decrease in pressure with height. The temperature profile of the troposphere is largely determined by the incoming to the Earth's surface solar radiation. As a result of the heating of the Earth's surface by the Sun, upward convective and turbulent flows are formed, which form the weather. It is worth noting that the influence of the underlying surface on the lower layers of the troposphere extends to a height of approximately 1.5 km. Of course, excluding mountainous areas.

The upper boundary of the troposphere is the tropopause, the isothermal layer. Recall the characteristic appearance of thunderclouds, the top of which is an "ejection" of cirrus clouds, called "anvil." This "anvil" just "spreads" under the tropopause, because due to isotherm, the ascending air currents are significantly weakened, and the cloud ceases to develop vertically. But in special, rare cases, the tops of cumulonimbus clouds can invade the lower layers of the stratosphere, overcoming the tropopause.

The height of the tropopause depends on the geographic latitude. So, at the equator, it is at an altitude of about 16 km, and its temperature is about -80 ° C. At the poles, the tropopause is located lower - approximately at an altitude of 8 km. Its temperature here is -40°C in summer and -60°C in winter. Thus, despite higher temperatures near the Earth's surface, the tropical tropopause is much colder than at the poles.