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

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 amounts quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is radon (Rn).

The structure of the atmosphere

Atmospheric boundary layer

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 highly developed in the troposphere, clouds appear, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m

Tropopause

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

Stratosphere

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

Stratopause

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

Mesosphere

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

Mesopause

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

Karman Line

The height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. According to the FAI definition, the Karman line is located 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 to high altitudes. Under the influence of solar radiation and cosmic radiation, ionization of the air (“ auroras”) occurs - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity - for example, in 2008-2009 - there is a noticeable decrease in the size of this layer.

Thermopause

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

Exosphere (scattering sphere)

Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular 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 in time and space are observed.

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

Review

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere.

Based on the electrical properties in the atmosphere, they distinguish neutrosphere And ionosphere .

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

Other properties of the atmosphere and effects on the human body

Already at an altitude of 5 km above sea level, an untrained person begins to experience oxygen starvation and without adaptation, a person’s performance is significantly reduced. The physiological zone of the atmosphere ends here. Human breathing becomes impossible at an altitude of 9 km, although up to approximately 115 km the atmosphere contains oxygen.

The atmosphere supplies us with the oxygen necessary for breathing. However, due to the drop in the total pressure of the atmosphere, as you rise to altitude, the partial pressure of oxygen decreases accordingly.

In rarefied layers of air, sound propagation 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 conventional Karman line, beyond which the region of purely ballistic flight begins, which can only be controlled using reactive forces.

At altitudes above 100 km, the atmosphere is devoid of another remarkable property - the ability to absorb, conduct and transmit thermal energy by convection (that is, by mixing air). This means that various elements of equipment on the orbital space station will not be able to be cooled from the outside in the same way as is usually done on an airplane - with the help of air jets and air radiators. At this altitude, as in space generally, the only way to transfer heat is thermal radiation.

History of atmospheric formation

According to the most common theory, the Earth's atmosphere has had three different compositions throughout its history. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This is the 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 it was formed secondary atmosphere. This atmosphere was restorative. Further, the process of atmosphere formation was determined by the following factors:

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

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

Nitrogen

Education large quantity 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 3 billion years ago. Nitrogen N2 is also released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO in the upper atmosphere.

Nitrogen N 2 reacts only under specific conditions (for example, during a lightning discharge). The oxidation of molecular nitrogen by ozone during electrical discharges is used in small quantities in the industrial production of nitrogen fertilizers. Cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with leguminous plants, which can be effective green manures - plants that do not deplete, but enrich the soil with natural fertilizers, can oxidize it with low energy consumption and convert it into a biologically active form.

Oxygen

The composition of the atmosphere began to change radically with the appearance 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, ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to increase. 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. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological eras. 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 plant and animal origin, as well as due to volcanism and human industrial activity. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the bulk (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 could lead to global climate change.

Fuel combustion is the main source of polluting gases (CO, SO2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3, and nitrogen oxide to NO 2 in the upper layers of the atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H 2 SO 4 and nitric acid HNO 3 fall to the surface of the Earth in the form so-called acid rain. The use of internal combustion engines leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and lead compounds (tetraethyl lead Pb(CH 3 CH 2) 4).

Aerosol pollution of the atmosphere is due to both natural causes (volcanic eruptions, dust storms, entrainment of droplets sea ​​water and plant pollen, etc.), and economic activity humans (mining ores and building materials, burning fuel, making cement, etc.). Intense large-scale release of particulate matter into the atmosphere is one of the possible causes of climate change on the planet.

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) (as of 2013)
6. IPCC (English) (as of 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. - P. 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 expanded), M.: “Prosveshcheniye”, 1975, 223 pp.
2. N. V. Gusakova"Chemistry environment", Rostov-on-Don: Phoenix, 2004, 192 with ISBN 5-222-05386-5
3. Sokolov V. A. Geochemistry of natural gases, M., 1971;
4. McEwen M., Phillips L. Atmospheric Chemistry, 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

Excerpt characterizing the Earth's Atmosphere

When Pierre approached them, he noticed that Vera was in a smug rapture of conversation, Prince Andrei (which rarely happened to him) seemed embarrassed.
– What do you think? – Vera said with a subtle smile. “You, prince, are so insightful and so immediately understand the character of people.” What do you think about Natalie, can she be constant in her affections, can she, like other women (Vera meant herself), love a person once and remain faithful to him forever? This is what I think 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 resolve such a delicate question; and then I noticed that the less I like a woman, the more constant she is,” he added and looked at Pierre, who came up to them at that time.
- Yes, it’s true, prince; in our time,” Vera continued (mentioning our time, as narrow-minded people generally like to mention, believing that they have found and appreciated the features of our time and that the properties of people change over time), in our time a girl has so much freedom that le plaisir d"etre courtisee [the pleasure of having admirers] often drowns out the true feeling in her. Et Nathalie, il faut l"avouer, y est tres sensible. [And Natalya, I must admit, is very sensitive to this.] The return to Natalie again made Prince Andrei frown unpleasantly; he wanted to get up, but Vera continued with an even more refined smile.
“I think no one was courtisee [the subject of courtship] like her,” 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 and remained silent.
– You’re friends with Boris, aren’t you? - Vera told him.
- Yes, I know him...
– Did he tell you correctly about his childhood love for Natasha?
– Was there childhood love? - Prince Andrei suddenly asked, blushing unexpectedly.
- 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 a cousin and sister, this closeness sometimes leads to love. Such kinship is a dangerous neighborhood. Isn't that right?]
“Oh, without a doubt,” said Prince Andrei, and suddenly, unnaturally animated, he began joking with Pierre about how he should be careful in his treatment of his 50-year-old Moscow cousins, and in the middle of the joking conversation he stood up and, taking under Pierre's arm and took him aside.
- Well? - said Pierre, looking with surprise at the strange animation of his friend and noticing the look that he cast at Natasha as he stood up.
“I need, I need to talk to you,” said Prince Andrei. – You know our women’s gloves (he was talking about those Masonic gloves that were given to a newly elected brother to give to his beloved woman). “I... But no, I’ll talk to you later...” And with a strange sparkle in his eyes and anxiety in his movements, Prince Andrei approached Natasha and sat down next to her. Pierre saw Prince Andrei ask her something, and she flushed and answered him.
But at this time Berg approached Pierre, urgently asking him to take part in the dispute between the general and the colonel about Spanish affairs.
Berg was pleased and happy. The smile of joy did not leave his face. The evening was very good and exactly like other evenings he had seen. Everything was similar. And ladies', delicate conversations, and cards, and a general at cards, raising his voice, and a samovar, and cookies; but one thing was still missing, something that he always saw at the evenings, which he wanted to imitate.
There was a lack of loud conversation between men and an argument about something important and smart. The general started this conversation and Berg attracted Pierre to him.

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 was traveling, and he, without hiding, tried to be with Natasha all day. Not only in Natasha’s frightened, but happy and enthusiastic soul, but throughout the whole house there was a sense of fear of something important that was about to happen. The Countess looked at Prince Andrei with sad and seriously stern eyes when he spoke to Natasha, and timidly and feignedly began some 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 alone with him for minutes. Prince Andrei amazed 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 Andrey left in the evening, the Countess came 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 this, that evening Natasha, sometimes excited, sometimes frightened, with fixed eyes, lay for a long time in her mother’s bed. Either 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 in front of him, I’m always scared in front of him, what does that mean?” That means it's real, right? Mom, are you sleeping?
“No, my soul, I’m scared myself,” answered the mother. - Go.
“I won’t sleep anyway.” What nonsense is it to sleep? Mommy, mommy, this has never happened to me! - she said with surprise and fear at the feeling that she recognized in herself. – And could we think!...
It seemed to Natasha that even when she first saw Prince Andrey 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, it seemed, was not indifferent to her. “And he had to come to St. Petersburg on purpose now that we are here. And we had to meet at this ball. It's all fate. It is clear that this is fate, that all this was leading 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... - the mother said thoughtfully, asking about the poems that Prince Andrei wrote in Natasha’s album.
“Mom, isn’t it a shame that he’s a widower?”
- That's enough, 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 makes me feel! – 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 his firm intention to marry her.

On this day, Countess Elena Vasilyevna 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 amazed all the guests with his concentrated, absent-minded and gloomy appearance.
Since the time of the ball, Pierre had felt the approaching attacks of hypochondria and with desperate effort tried to fight against them. Since the prince's rapprochement with his wife, Pierre was unexpectedly granted a chamberlain, and from that time he began to feel heaviness and shame in large society, and the former dark thoughts about the futility of everything human. At the same time, the feeling he noticed between Natasha, whom he protected, and Prince Andrei, his opposition between his position and the position of his friend, further intensified this gloomy mood. He equally tried to avoid thoughts about his wife and about Natasha and Prince Andrei. Again everything seemed insignificant to him in comparison with eternity, again the question presented itself: “why?” And he forced himself day and night to work on Masonic works, hoping to ward off 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, copying out authentic Scottish acts, when someone entered his room. It was Prince Andrei.
“Oh, it’s you,” said Pierre with an absent-minded and dissatisfied look. “And I’m working,” he said, pointing to a notebook with that look of salvation from the hardships of life with which unhappy people look at their work.
Prince Andrei, with a radiant, enthusiastic face and renewed life, stopped in front of Pierre and, not noticing his sad face, smiled at him with the egoism of happiness.
“Well, my soul,” he said, “yesterday I wanted to tell you and today I came to you for this.” I've never experienced anything like it. I'm in love, my friend.
Pierre suddenly sighed heavily and collapsed with his heavy body on the sofa, next to Prince Andrei.
- To Natasha Rostova, right? - he said.
- Yes, yes, who? I would never believe it, but this feeling is stronger than me. Yesterday I suffered, I suffered, but I wouldn’t give up this torment for anything in the world. I haven't lived before. Now only I live, but I cannot live without her. But can she love me?... I'm too old for her... What aren't you saying?...
- 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 rare girl... Dear friend, I ask you, don’t get smart, don’t doubt, get married, get married and get married... And I’m sure that there will be no happier person than you.
- But she!
- She loves you.
“Don’t talk nonsense...” said Prince Andrei, smiling and looking into Pierre’s eyes.
“He loves me, I know,” Pierre shouted angrily.
“No, listen,” said Prince Andrei, stopping him by the hand. – Do you know what situation I’m in? I need to tell everything to someone.
“Well, well, say, I’m very glad,” said Pierre, and indeed his face changed, the wrinkles smoothed out, and he joyfully listened to Prince Andrei. Prince Andrei seemed and was a completely different, new person. Where was his melancholy, his contempt for life, his disappointment? Pierre was the only person, to whom he dared to speak; but he expressed to 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 something strange, alien, independent of him, influenced by the feeling that possessed him.
“I wouldn’t believe anyone who told me that I could love like that,” said Prince Andrei. “This is not at all the feeling that I had before.” The whole world is divided for me into two halves: one - she and there is all the happiness of hope, light; the other half is everything where she 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 world, it’s not my fault. And I'm very happy. Do you understand me? I know you're happy for me.
“Yes, yes,” Pierre confirmed, looking at his friend with tender and sad eyes. The brighter the fate of Prince Andrei seemed to him, the darker his own seemed.

To get married, 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 inner anger, accepted his son's message. He could not understand that anyone would want to change life, to introduce something new into it, when life was already ending for him. “If only they would let me live the way I want, and then we would do what we wanted,” the old man said to himself. With his son, however, he used the diplomacy that he used on important occasions. Taking a calm tone, he discussed the whole matter.
Firstly, the marriage was not brilliant in terms of kinship, wealth and nobility. Secondly, Prince Andrei was not in his first youth and was in poor health (the old man was especially careful about this), and she was very young. Thirdly, there was a son whom it was a pity to give to the girl. Fourthly, finally,” said the father, looking mockingly at his son, “I ask you, postpone the matter for a year, go abroad, get treatment, find, as you want, 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, my last...” the prince finished in a tone that showed that nothing would force him to change his decision.
Prince Andrei clearly saw that the old man hoped that the feeling of him or his future bride would not withstand the test of the year, or that he himself, the old prince, would die by this time, and decided to fulfill his father’s will: to propose and postpone the wedding for a year.
Three weeks after his last evening with the Rostovs, Prince Andrei returned to St. Petersburg.

The next day after her explanation with her mother, Natasha waited the whole day for Bolkonsky, but he did not come. The next, third day the same thing happened. Pierre also did not come, and Natasha, not knowing that Prince Andrei had gone to his father, could not explain his absence.
Three weeks passed like this. Natasha did not want to go anywhere and, like a shadow, idle and sad, she walked from room to room, cried secretly from everyone in the evening and did not appear to her mother in the evenings. She was constantly blushing and irritated. It seemed to her that everyone knew about her disappointment, laughed and felt sorry for her. With all the strength of her inner grief, this vain grief intensified her misfortune.
One day she came to the countess, wanted to tell her something, and suddenly began to cry. Her tears were the tears of an offended child who himself does not know why he is being punished.
The Countess began to calm Natasha down. Natasha, who had been listening at first to her mother’s words, suddenly interrupted her:
- Stop it, mom, I don’t think, and I don’t want to think! So, I drove and stopped, and stopped...
Her voice trembled, she almost cried, but she recovered and calmly continued: “And I don’t want to get married at all.” And I'm afraid of him; I have now completely, completely calmed down...
The next day after this conversation, Natasha put on that old dress, which she was especially famous for the cheerfulness it brought in the morning, and in the morning she began her old way of life, from which she had fallen 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 solfeges (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 the (as if unexpected for her) charm with which these shimmering sounds filled the entire emptiness of the hall and slowly froze, and she suddenly felt cheerful. “It’s good to think about it so much,” she said to herself and began to walk back and forth around the hall, not walking with simple steps on the ringing parquet floor, but at every step shifting from heel (she was wearing her new, favorite shoes) to toe, and just as joyfully as you listen to the sounds of your voice, listening to this measured clatter of a heel and the creaking of a sock. Passing by the mirror, she looked into it. - “Here I am!” as if the expression on her face when she saw herself spoke. - “Well, that’s good. And I don’t need anyone.”
The footman wanted to enter to clean something in the hall, but she did not let him in, again closing the door behind him, and continued her walk. This morning she returned again to her favorite 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, male person. “She’s good, she has a voice, she’s young, and she doesn’t bother anyone, just leave her alone.” But no matter how much they left her alone, she could no longer be calm and she immediately felt it.
The entrance door opened in the hallway, and someone asked: “Are you at home?” and someone's steps were heard. Natasha looked in the mirror, but she did not see herself. She listened to sounds in the hall. When she saw herself, her face was pale. It was him. 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?...
Before the countess even had time to answer her, Prince Andrei entered the living 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 near the sofa.
“We haven’t had the pleasure for a long time...” the countess began, but Prince Andrei interrupted her, answering her question and obviously in a hurry to say what he needed.
“I wasn’t with you all this time because I was with my father: I needed to talk to him about a very important matter.” “I just returned last night,” he said, looking at Natasha. “I need to talk to you, Countess,” he added after a moment of silence.
The Countess, sighing heavily, 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 discourteously, directly, with open eyes at Prince Andrei.
"Now? This minute!... No, this can’t be!” she thought.
He looked at her again, and this look convinced her that she was not mistaken. “Yes, now, this very minute, her fate was being decided.”
“Come, Natasha, I’ll call you,” the countess said in a whisper.
Natasha looked at Prince Andrei and her mother with frightened, pleading eyes, and left.
“I came, Countess, to ask for your daughter’s hand in marriage,” said Prince Andrei. The countess's face flushed, but she said nothing.
“Your proposal...” the countess began sedately. “He was 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’ll tell her when I have your consent... do you give it to me?” - said Prince Andrei.
“Yes,” said the countess and extended her hand to him and, with a mixed feeling 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 communicated my plans, made it an indispensable condition of consent that the wedding should not be before a year. And this is what I wanted to tell you,” said Prince Andrei.
– It’s true that Natasha is still young, but for so long.
“It couldn’t 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 is in the bedroom. Natasha sat on her bed, pale, with dry eyes, looking at the images and, quickly crossing herself, whispering 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... “Come... come,” the mother said with sadness and reproach after her running daughter, and sighed heavily.
Natasha did not remember how she entered the living room. Entering the door and seeing him, she stopped. “Has this stranger really become everything to me now?” she asked herself and instantly answered: “Yes, that’s it: he alone is now dearer to me than everything in the world.” Prince Andrei approached her, lowering his eyes.
“I loved you from the moment I saw you.” Can I hope?
He looked at her, and the serious passion in her expression struck him. Her face said: “Why ask? Why doubt something you can’t help but know? Why talk when you can’t express in words what you feel.”
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, and another time, more and more often, and began to sob.
- 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 this was possible, and kissed him.
Prince Andrei held her hands, looked into her eyes, and did not find in his soul the same 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 forever connected him with her. The real feeling, although it was not as light and poetic as the previous one, was more serious and stronger.

The exact size of the atmosphere is unknown, since its upper boundary is not clearly visible. However, the structure of the atmosphere has been studied enough for everyone to get an idea of ​​how the gaseous envelope of our planet is structured.

Scientists who study the physics of the atmosphere define it as the region around the Earth that rotates with the planet. FAI gives the following definition:

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

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

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

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

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

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

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

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

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

Considering that the upper layer of the atmosphere is not clearly visible, its exact size is impossible to calculate. In addition, in different countries there are organizations that have different opinions on this matter. It should be noted that Karman line can be considered the boundary of the earth’s atmosphere only conditionally, since different sources use different boundary markers. Thus, in some sources you can find information that the upper limit passes at an altitude of 2500-3000 km.

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

STRUCTURE OF THE ATMOSPHERE

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

Physical properties

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

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

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

The structure of the atmosphere

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

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

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

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

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

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

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

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

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

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

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

There is almost no water vapor in the stratosphere.

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

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

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

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

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

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

The gas composition of the mesosphere, like that of the underlying atmospheric layers, is constant and contains about 80% nitrogen and 20% oxygen.

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

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

Noctilucent clouds may appear in the mesosphere.

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

Mesopause

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

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

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

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

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

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

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

The atmosphere began to form along with the formation of the Earth. During the evolution of the planet and as its parameters approach modern meanings fundamentally qualitative changes occurred in its chemical composition and physical properties. According to the evolutionary model, at an early stage the Earth was in a molten state and about 4.5 billion years ago formed as a solid body. This milestone is taken as the beginning of the geological chronology. From that time on, the slow evolution of the atmosphere began. Some geological processes (for example, lava outpourings during volcanic eruptions) were accompanied by the release of gases from the bowels of the Earth. They included nitrogen, ammonia, methane, water vapor, CO oxide and carbon dioxide CO 2. Under the influence of solar ultraviolet radiation, water vapor decomposed into hydrogen and oxygen, but the released oxygen reacted with carbon monoxide to form carbon dioxide. Ammonia decomposed into nitrogen and hydrogen. During the process of diffusion, hydrogen rose upward and left the atmosphere, and heavier nitrogen could not evaporate and gradually accumulated, becoming the main component, although some of it was bound into molecules as a result of chemical reactions ( cm. CHEMISTRY OF THE ATMOSPHERE). Under the influence of ultraviolet rays and electrical discharges, a mixture of gases present in the original atmosphere of the Earth entered into chemical reactions, which resulted in the formation of organic substances, in particular amino acids. With the advent of primitive plants, the process of photosynthesis began, accompanied by the release of oxygen. This gas, especially after diffusion into the upper layers of the atmosphere, began to protect its lower layers and the surface of the Earth from life-threatening ultraviolet and X-ray radiation. According to theoretical estimates, the oxygen content, 25,000 times less than now, could already lead to the formation of an ozone layer with only half the concentration than now. However, this is already enough to provide very significant protection of organisms from the destructive effects of ultraviolet rays.

It is likely that the primary atmosphere contained a lot of carbon dioxide. It was used up during photosynthesis, and its concentration must have decreased as the plant world evolved and also due to absorption during certain geological processes. Since greenhouse effect associated with the presence of carbon dioxide in the atmosphere, fluctuations in its concentration are one of important reasons such large-scale climate changes in Earth's history as ice ages.

Most of the helium present in the modern atmosphere is a product of the radioactive decay of uranium, thorium and radium. These radioactive elements emit a particles, which are the nuclei of helium atoms. Since during radioactive decay an electric charge is neither formed nor destroyed, with the formation of each a-particle two electrons appear, which, recombining with the a-particles, form neutral helium atoms. Radioactive elements are contained in minerals dispersed in rocks, so a significant part of the helium formed as a result of radioactive decay is retained in them, escaping very slowly into the atmosphere. A certain amount of helium rises upward into the exosphere due to diffusion, but due to the constant influx from the earth's surface, the volume of this gas in the atmosphere remains almost unchanged. Based on spectral analysis of starlight and the study of meteorites, it is possible to estimate the relative abundance of various chemical elements in the Universe. The concentration of neon in space is approximately ten billion times higher than on Earth, krypton - ten million times, and xenon - a million times. It follows that the concentration of these inert gases, apparently initially present in the Earth’s atmosphere and not replenished during chemical reactions, decreased greatly, probably even at the stage of the Earth’s loss of its primary atmosphere. An exception is the inert gas argon, since in the form of the 40 Ar isotope it is still formed during the radioactive decay of the potassium isotope.

Barometric pressure distribution.

The total weight of atmospheric gases is approximately 4.5 x 10 15 tons. Thus, the “weight” of the atmosphere per unit area, or atmospheric pressure, at sea level is approximately 11 t/m 2 = 1.1 kg/cm 2 . Pressure equal to P 0 = 1033.23 g/cm 2 = 1013.250 mbar = 760 mm Hg. Art. = 1 atm, taken as the standard average atmospheric pressure. For the atmosphere in a state of hydrostatic equilibrium we have: d P= –rgd h, this means that in the height interval from h to h+d h takes place equality between the change in atmospheric pressure d P and the weight of the corresponding element of the atmosphere with unit area, density r and thickness d h. As a relationship between pressure R and temperature T The equation of state of an ideal gas with density r, which is quite applicable to the earth’s atmosphere, is used: P= r R T/m, where m – molecular weight, and R = 8.3 J/(K mol) is the universal gas constant. Then d log P= – (m g/RT)d h= – bd h= – d h/H, where the pressure gradient is on a logarithmic scale. Its inverse value H is called the atmospheric altitude scale.

When integrating this equation for an isothermal atmosphere ( T= const) or for its part where such an approximation is permissible, the barometric law of pressure distribution with height is obtained: P = P 0 exp(– h/H 0), where the height reference h produced from ocean level, where the standard mean pressure is P 0 . Expression H 0 = R T/ mg, is called the altitude scale, which characterizes the extent of the atmosphere, provided that the temperature in it is the same everywhere (isothermal atmosphere). If the atmosphere is not isothermal, then integration must take into account the change in temperature with height, and the parameter N– some local characteristic of atmospheric layers, depending on their temperature and the properties of the environment.

Standard atmosphere.

Model (table of values ​​of the main parameters) corresponding to standard pressure at the base of the atmosphere R 0 and chemical composition is called a standard atmosphere. More precisely, this is a conditional model of the atmosphere, for which the average values ​​of temperature, pressure, density, viscosity and other air characteristics at altitudes from 2 km below sea level to the outer boundary of the earth’s atmosphere are specified for latitude 45° 32° 33°. The parameters of the middle atmosphere at all altitudes were calculated using the equation of state of an ideal gas and the barometric law assuming that at sea level the pressure is 1013.25 hPa (760 mm Hg) and the temperature is 288.15 K (15.0 ° C). According to the nature of the vertical temperature distribution, the average atmosphere consists of several layers, in each of which the temperature is approximated by a linear function of height. In the lowest layer - the troposphere (h Ј 11 km) the temperature drops by 6.5 ° C with each kilometer of rise. At high altitudes, the value and sign of the vertical temperature gradient changes from layer to layer. Above 790 km the temperature is about 1000 K and practically does not change with altitude.

The standard atmosphere is a periodically updated, legalized standard, issued in the form of tables.

Table 1. Standard model of the earth's atmosphere

Table 1. STANDARD MODEL OF THE EARTH'S ATMOSPHERE. The table shows: h– height from sea level, R- pressure, T– temperature, r – density, N– number of molecules or atoms per unit volume, H– height scale, l– free path length. Pressure and temperature at an altitude of 80–250 km, obtained from rocket data, have lower values. Values ​​for altitudes greater than 250 km obtained by extrapolation are not very accurate.
h(km)	P(mbar)	T(°C)	r (g/cm 3)	N(cm –3)	H(km)	l(cm)
0	1013	288	1.22 10 –3	2.55 10 19	8,4	7.4·10 –6
1	899	281	1.11·10 –3	2.31 10 19		8.1·10 –6
2	795	275	1.01·10 –3	2.10 10 19		8.9·10 –6
3	701	268	9.1·10 –4	1.89 10 19		9.9 10 –6
4	616	262	8.2·10 –4	1.70 10 19		1.1·10 –5
5	540	255	7.4·10 –4	1.53 10 19	7,7	1.2·10 –5
6	472	249	6.6·10 –4	1.37 10 19		1.4·10 –5
8	356	236	5.2·10 -4	1.09 10 19		1.7·10 –5
10	264	223	4.1·10 –4	8.6 10 18	6,6	2.2·10 –5
15	121	214	1.93·10 –4	4.0 10 18		4.6·10 –5
20	56	214	8.9·10 –5	1.85 10 18	6,3	1.0·10 –4
30	12	225	1.9·10 –5	3.9 10 17	6,7	4.8·10 –4
40	2,9	268	3.9·10 –6	7.6 10 16	7,9	2.4·10 –3
50	0,97	276	1.15·10 –6	2.4 10 16	8,1	8.5·10 –3
60	0,28	260	3.9·10 –7	7.7 10 15	7,6	0,025
70	0,08	219	1.1·10 –7	2.5 10 15	6,5	0,09
80	0,014	205	2.7·10 –8	5.0 10 14	6,1	0,41
90	2.8·10 –3	210	5.0·10 –9	9 10 13	6,5	2,1
100	5.8·10 –4	230	8.8·10 –10	1.8 10 13	7,4	9
110	1.7·10 –4	260	2.1·10 –10	5.4 10 12	8,5	40
120	6·10 –5	300	5.6·10 –11	1.8 10 12	10,0	130
150	5·10 –6	450	3.2·10 –12	9 10 10	15	1.8 10 3
200	5·10 –7	700	1.6·10 –13	5 10 9	25	3 10 4
250	9·10 –8	800	3·10 –14	8 10 8	40	3·10 5
300	4·10 –8	900	8·10 –15	3 10 8	50
400	8·10 –9	1000	1·10 –15	5 10 7	60
500	2·10 –9	1000	2·10 –16	1 10 7	70
700	2·10 –10	1000	2·10 –17	1 10 6	80
1000	1·10 –11	1000	1·10 –18	1·10 5	80

Troposphere.

The lowest and most dense layer of the atmosphere, in which the temperature decreases rapidly with height, is called the troposphere. It contains up to 80% of the total mass of the atmosphere and extends in the polar and middle latitudes to altitudes of 8–10 km, and in the tropics up to 16–18 km. Almost all weather-forming processes develop here, heat and moisture exchange occurs between the Earth and its atmosphere, clouds form, and various meteorological phenomena, fog and precipitation occur. These layers of the earth's atmosphere are in convective equilibrium and, thanks to active mixing, have a homogeneous chemical composition, mainly from molecular nitrogen (78%) and oxygen (21%). The vast majority of natural and man-made aerosol and gas air pollutants are concentrated in the troposphere. The dynamics of the lower part of the troposphere, up to 2 km thick, strongly depends on the properties of the underlying surface of the Earth, which determines the horizontal and vertical movements of air (winds) caused by the transfer of heat from warmer land through the infrared radiation of the earth's surface, which is absorbed in the troposphere, mainly by vapors water and carbon dioxide (greenhouse effect). The temperature distribution with height is established as a result of turbulent and convective mixing. On average, it corresponds to a temperature drop with height of approximately 6.5 K/km.

The wind speed in the surface boundary layer initially increases rapidly with height, and above it continues to increase by 2–3 km/s per kilometer. Sometimes narrow planetary flows (with a speed of more than 30 km/s) appear in the troposphere, western in the middle latitudes, and eastern near the equator. They are called jet streams.

Tropopause.

At the upper boundary of the troposphere (tropopause), the temperature reaches its minimum value for the lower atmosphere. This is the transition layer between the troposphere and the stratosphere located above it. The thickness of the tropopause ranges from hundreds of meters to 1.5–2 km, and the temperature and altitude, respectively, range from 190 to 220 K and from 8 to 18 km, depending on the latitude and season. In temperate and high latitudes in winter it is 1–2 km lower than in summer and 8–15 K warmer. In the tropics, seasonal changes are much less (altitude 16–18 km, temperature 180–200 K). Over jet streams tropopause breaks are possible.

Water in the Earth's atmosphere.

The most important feature of the Earth's atmosphere is the presence of significant amounts of water vapor and water in droplet form, which is most easily observed in the form of clouds and cloud structures. The degree of cloud coverage of the sky (at a certain moment or on average over a certain period of time), expressed on a 10-point scale or as a percentage, is called cloudiness. The shape of the clouds is determined by international classification. On average, clouds cover about half of the globe. Cloudiness – important factor characterizing weather and climate. In winter and at night, cloudiness prevents a decrease in the temperature of the earth's surface and the surface layer of air; in summer and during the day, it weakens the heating of the earth's surface by the sun's rays, softening the climate inside the continents.

Clouds.

Clouds are accumulations of water droplets suspended in the atmosphere (water clouds), ice crystals (ice clouds), or both together (mixed clouds). As droplets and crystals become larger, they fall out of the clouds in the form of precipitation. Clouds form mainly in the troposphere. They arise as a result of condensation of water vapor contained in the air. The diameter of cloud drops is on the order of several microns. The content of liquid water in clouds ranges from fractions to several grams per m3. Clouds are distinguished by height: According to the international classification, there are 10 types of clouds: cirrus, cirrocumulus, cirrostratus, altocumulus, altostratus, nimbostratus, stratus, stratocumulus, cumulonimbus, cumulus.

Pearlescent clouds are also observed in the stratosphere, and noctilucent clouds are observed in the mesosphere.

Cirrus clouds are transparent clouds in the form of thin white threads or veils with a silky sheen that do not provide shadows. Cirrus clouds are composed of ice crystals and form in the upper troposphere at very low temperatures. Some types of cirrus clouds serve as harbingers of weather changes.

Cirrocumulus clouds are ridges or layers of thin white clouds in the upper troposphere. Cirrocumulus clouds are built from small elements that look like flakes, ripples, small balls without shadows and consist mainly of ice crystals.

Cirrostratus clouds are a whitish translucent veil in the upper troposphere, usually fibrous, sometimes blurry, consisting of small needle-shaped or columnar ice crystals.

Altocumulus clouds are white, gray or white-gray clouds in the lower and middle layers of the troposphere. Altocumulus clouds have the appearance of layers and ridges, as if built from plates, rounded masses, shafts, flakes lying on top of each other. Altocumulus clouds form during intense convective activity and usually consist of supercooled water droplets.

Altostratus clouds are grayish or bluish clouds with a fibrous or uniform structure. Altostratus clouds are observed in the middle troposphere, extending several kilometers in height and sometimes thousands of kilometers in the horizontal direction. Typically, altostratus clouds are part of frontal cloud systems associated with upward movements of air masses.

Nimbostratus clouds are a low (from 2 km and above) amorphous layer of clouds of a uniform gray color, giving rise to continuous rain or snow. Nimbostratus clouds are highly developed vertically (up to several km) and horizontally (several thousand km), consist of supercooled water droplets mixed with snowflakes, usually associated with atmospheric fronts.

Stratus clouds are clouds of the lower tier in the form of a homogeneous layer without definite outlines, gray in color. The height of stratus clouds above the earth's surface is 0.5–2 km. Occasionally, drizzle falls from stratus clouds.

Cumulus clouds are dense, bright white clouds during the day with significant vertical development (up to 5 km or more). Upper parts cumulus clouds They look like domes or towers with rounded outlines. Typically, cumulus clouds arise as convection clouds in cold air masses.

Stratocumulus clouds are low (below 2 km) clouds in the form of gray or white non-fibrous layers or ridges of round large blocks. The vertical thickness of stratocumulus clouds is small. Occasionally, stratocumulus clouds produce light precipitation.

Cumulonimbus clouds are powerful and dense clouds with strong vertical development (up to a height of 14 km), producing heavy rainfall with thunderstorms, hail, and squalls. Cumulonimbus clouds develop from powerful cumulus clouds, differing from them in the upper part consisting of ice crystals.

Stratosphere.

Through the tropopause, on average at altitudes from 12 to 50 km, the troposphere passes into the stratosphere. In the lower part, for about 10 km, i.e. up to altitudes of about 20 km, it is isothermal (temperature about 220 K). It then increases with altitude, reaching a maximum of about 270 K at an altitude of 50–55 km. Here is the boundary between the stratosphere and the overlying mesosphere, called the stratopause. .

There is significantly less water vapor in the stratosphere. Still, thin translucent pearlescent clouds are sometimes observed, occasionally appearing in the stratosphere at an altitude of 20–30 km. Pearlescent clouds are visible in the dark sky after sunset and before sunrise. In shape, nacreous clouds resemble cirrus and cirrocumulus clouds.

Middle atmosphere (mesosphere).

At an altitude of about 50 km, the mesosphere begins from the peak of the broad temperature maximum . The reason for the increase in temperature in the region of this maximum is an exothermic (i.e. accompanied by the release of heat) photochemical reaction of ozone decomposition: O 3 + hv® O 2 + O. Ozone arises as a result of the photochemical decomposition of molecular oxygen O 2

O 2 + hv® O + O and the subsequent reaction of a triple collision of an oxygen atom and molecule with some third molecule M.

O + O 2 + M ® O 3 + M

Ozone voraciously absorbs ultraviolet radiation in the region from 2000 to 3000 Å, and this radiation heats the atmosphere. Ozone, located in the upper atmosphere, serves as a kind of shield that protects us from the effects of ultraviolet radiation from the Sun. Without this shield, the development of life on Earth in its modern forms would hardly have been possible.

In general, throughout the mesosphere, the atmospheric temperature decreases to its minimum value of about 180 K at the upper boundary of the mesosphere (called mesopause, altitude about 80 km). In the vicinity of the mesopause, at altitudes of 70–90 km, a very thin layer of ice crystals and particles of volcanic and meteorite dust may appear, observed in the form of a beautiful spectacle of noctilucent clouds shortly after sunset.

In the mesosphere, small solid meteorite particles that fall on the Earth, causing the phenomenon of meteors, mostly burn up.

Meteors, meteorites and fireballs.

Flares and other phenomena in the upper atmosphere of the Earth caused by the intrusion of solid cosmic particles or bodies into it at a speed of 11 km/s or higher are called meteoroids. An observable bright meteor trail appears; the most powerful phenomena, often accompanied by the fall of meteorites, are called fireballs; the appearance of meteors is associated with meteor showers.

Meteor shower:

1) the phenomenon of multiple falls of meteors over several hours or days from one radiant.

2) a swarm of meteoroids moving in the same orbit around the Sun.

The systematic appearance of meteors in a certain area of ​​the sky and on certain days of the year, caused by the intersection of the Earth's orbit with the common orbit of many meteorite bodies moving at approximately the same and identically directed speeds, due to which their paths in the sky appear to emerge from a common point (radiant) . They are named after the constellation where the radiant is located.

Meteor showers make a deep impression with their light effects, but individual meteors are rarely visible. Much more numerous are invisible meteors, too small to be visible when they are absorbed into the atmosphere. Some of the smallest meteors probably do not heat up at all, but are only captured by the atmosphere. These small particles with sizes ranging from a few millimeters to ten thousandths of a millimeter are called micrometeorites. The amount of meteoric matter entering the atmosphere every day ranges from 100 to 10,000 tons, with the majority of this material coming from micrometeorites.

Since meteoric matter partially burns in the atmosphere, its gas composition is replenished with traces of various chemical elements. For example, rocky meteors introduce lithium into the atmosphere. The combustion of metal meteors leads to the formation of tiny spherical iron, iron-nickel and other droplets that pass through the atmosphere and settle on the earth's surface. They can be found in Greenland and Antarctica, where ice sheets remain almost unchanged for years. Oceanologists find them in bottom ocean sediments.

Most meteor particles entering the atmosphere settle within approximately 30 days. Some scientists believe that this cosmic dust plays an important role in the formation of such atmospheric phenomena, like rain, because they serve as condensation nuclei for water vapor. Therefore, it is assumed that precipitation is statistically related to large meteor showers. However, some experts believe that since the total supply of meteoric material is many tens of times greater than that of even the largest meteor shower, the change in the total amount of this material resulting from one such rain can be neglected.

However, there is no doubt that the largest micrometeorites and visible meteorites leave long traces of ionization in the high layers of the atmosphere, mainly in the ionosphere. Such traces can be used for long-distance radio communications, as they reflect high-frequency radio waves.

The energy of meteors entering the atmosphere is spent mainly, and perhaps completely, on heating it. This is one of the minor components of the thermal balance of the atmosphere.

A meteorite is a naturally occurring solid body that fell to the surface of the Earth from space. Usually a distinction is made between stony, stony-iron and iron meteorites. The latter mainly consist of iron and nickel. Among the meteorites found, most weigh from a few grams to several kilograms. The largest of those found, the Goba iron meteorite weighs about 60 tons and still lies in the same place where it was discovered, in South Africa. Most meteorites are fragments of asteroids, but some meteorites may have come to Earth from the Moon and even Mars.

A bolide is a very bright meteor, sometimes visible even during the day, often leaving behind a smoky trail and accompanied by sound phenomena; often ends with the fall of meteorites.

Thermosphere.

Above the temperature minimum of the mesopause, the thermosphere begins, in which the temperature, first slowly and then quickly begins to rise again. The reason is the absorption of ultraviolet radiation from the Sun at altitudes of 150–300 km, due to the ionization of atomic oxygen: O + hv® O + + e.

In the thermosphere, the temperature continuously increases to an altitude of about 400 km, where it reaches 1800 K during the day during the epoch of maximum solar activity. During the epoch of minimum solar activity, this limiting temperature can be less than 1000 K. Above 400 km, the atmosphere turns into an isothermal exosphere. The critical level (the base of the exosphere) is at an altitude of about 500 km.

Polar lights and many orbits of artificial satellites, as well as noctilucent clouds - all these phenomena occur in the mesosphere and thermosphere.

Polar lights.

At high latitudes, auroras are observed during magnetic field disturbances. They may last several minutes, but are often visible for several hours. Auroras vary greatly in shape, color and intensity, all of which sometimes change very quickly over time. The spectrum of auroras consists of emission lines and bands. Some of the night sky emissions are enhanced in the aurora spectrum, primarily the green and red lines l 5577 Å and l 6300 Å oxygen. It happens that one of these lines is many times more intense than the other, and this determines visible color aurora: green or red. Magnetic field disturbances are also accompanied by disruptions in radio communications in the polar regions. The cause of the disruption is changes in the ionosphere, which mean that during magnetic storms there is a powerful source of ionization. It has been established that strong magnetic storms occur when there is near the center of the solar disk large groups spots Observations have shown that storms are not associated with the sunspots themselves, but with solar flares that appear during the development of a group of sunspots.

Auroras are a range of light of varying intensity with rapid movements observed in high latitude regions of the Earth. The visual aurora contains green (5577Å) and red (6300/6364Å) atomic oxygen emission lines and molecular N2 bands, which are excited by energetic particles of solar and magnetospheric origin. These emissions usually appear at altitudes of about 100 km and above. The term optical aurora is used to refer to visual auroras and their emission spectrum from the infrared to the ultraviolet region. The radiation energy in the infrared part of the spectrum significantly exceeds the energy in the visible region. When auroras appeared, emissions were observed in the ULF range (

The actual forms of auroras are difficult to classify; The most commonly used terms are:

1. Calm, uniform arcs or stripes. The arc typically extends ~1000 km in the direction of the geomagnetic parallel (toward the Sun in polar regions) and has a width of one to several tens of kilometers. A stripe is a generalization of the concept of an arc, it usually does not have a regular arc-shaped shape, but bends in the form of the letter S or in the form of spirals. Arcs and stripes are located at altitudes of 100–150 km.

2. Rays of the aurora . This term refers to an auroral structure elongated along magnetic field lines, with a vertical extent of several tens to several hundred kilometers. The horizontal extent of the rays is small, from several tens of meters to several kilometers. The rays are usually observed in arcs or as separate structures.

3. Stains or surfaces . These are isolated areas of glow that do not have a specific shape. Individual spots may be connected to each other.

4. Veil. An unusual form of aurora, which is a uniform glow that covers large areas of the sky.

According to their structure, auroras are divided into homogeneous, hollow and radiant. Various terms are used; pulsating arc, pulsating surface, diffuse surface, radiant stripe, drapery, etc. There is a classification of auroras according to their color. According to this classification, auroras of the type A. The upper part or the entire part is red (6300–6364 Å). They usually appear at altitudes of 300–400 km with high geomagnetic activity.

Aurora type IN colored red in the lower part and associated with the glow of the bands of the first positive system N 2 and the first negative system O 2. Such forms of auroras appear during the most active phases of auroras.

Zones polar lights – These are the zones of maximum frequency of auroras at night, according to observers at a fixed point on the Earth's surface. The zones are located at 67° north and south latitude, and their width is about 6°. Maximum occurrence of auroras corresponding to at this moment geomagnetic local time, occurs in oval-like belts (oval auroras), which are located asymmetrically around the north and south geomagnetic poles. The aurora oval is fixed in latitude – time coordinates, and the aurora zone is the geometric locus of the points of the oval’s midnight region in latitude – longitude coordinates. The oval belt is located approximately 23° from the geomagnetic pole in the night sector and 15° in the daytime sector.

Aurora oval and aurora zones. The location of the aurora oval depends on geomagnetic activity. The oval becomes wider with high geomagnetic activity. Auroral zones or auroral oval boundaries are better represented by L 6.4 than by dipole coordinates. Geomagnetic field lines at the boundary of the daytime sector of the aurora oval coincide with magnetopause. A change in the position of the aurora oval is observed depending on the angle between the geomagnetic axis and the Earth-Sun direction. The auroral oval is also determined on the basis of data on precipitation of particles (electrons and protons) of certain energies. Its position can be independently determined from data on Kaspakh on the dayside and in the tail of the magnetosphere.

The daily variation in the frequency of occurrence of auroras in the aurora zone has a maximum at geomagnetic midnight and a minimum at geomagnetic noon. On the near-equatorial side of the oval, the frequency of occurrence of auroras sharply decreases, but the shape of the daily variations is preserved. On the polar side of the oval, the frequency of auroras decreases gradually and is characterized by complex diurnal changes.

Intensity of auroras.

Aurora intensity determined by measuring the apparent surface brightness. Luminosity surface I aurora in a certain direction is determined by the total emission of 4p I photon/(cm 2 s). Since this value is not the true surface brightness, but represents the emission from the column, the unit photon/(cm 2 column s) is usually used when studying auroras. The usual unit for measuring total emission is Rayleigh (Rl) equal to 10 6 photons/(cm 2 column s). More practical units of auroral intensity are determined by the emissions of an individual line or band. For example, the intensity of auroras is determined by the International Luminance Coefficients (IBRs) according to the intensity of the green line (5577 Å); 1 kRl = I MKY, 10 kRl = II MKY, 100 kRl = III MKY, 1000 kRl = IV MKY (maximum intensity of the aurora). This classification cannot be used for red auroras. One of the discoveries of the era (1957–1958) was the establishment of the spatiotemporal distribution of auroras in the form of an oval, shifted relative to the magnetic pole. From simple ideas about the circular shape of the distribution of auroras relative to the magnetic pole there was The transition to modern physics of the magnetosphere has been completed. The honor of the discovery belongs to O. Khorosheva, and the intensive development of ideas for the aurora oval was carried out by G. Starkov, Y. Feldstein, S. I. Akasofu and a number of other researchers. The auroral oval is the region of the most intense influence of the solar wind on the Earth's upper atmosphere. The intensity of the aurora is greatest in the oval, and its dynamics are continuously monitored using satellites.

Stable auroral red arcs.

Steady auroral red arc, otherwise called mid-latitude red arc or M-arc, is a subvisual (below the limit of sensitivity of the eye) wide arc, stretching from east to west for thousands of kilometers and possibly encircling the entire Earth. The latitudinal length of the arc is 600 km. The emission of the stable auroral red arc is almost monochromatic in the red lines l 6300 Å and l 6364 Å. Recently, weak emission lines l 5577 Å (OI) and l 4278 Å (N+2) were also reported. Sustained red arcs are classified as auroras, but they appear at much higher altitudes. The lower limit is located at an altitude of 300 km, the upper limit is about 700 km. The intensity of the quiet auroral red arc in the l 6300 Å emission ranges from 1 to 10 kRl (typical value 6 kRl). The sensitivity threshold of the eye at this wavelength is about 10 kRl, so arcs are rarely observed visually. However, observations have shown that their brightness is >50 kRL on 10% of nights. The usual lifespan of arcs is about one day, and they rarely appear in subsequent days. Radio waves from satellites or radio sources crossing persistent auroral red arcs are subject to scintillation, indicating the existence of electron density inhomogeneities. The theoretical explanation for red arcs is that the heated electrons of the region F The ionosphere causes an increase in oxygen atoms. Satellite observations show an increase in electron temperature along geomagnetic field lines that intersect persistent auroral red arcs. The intensity of these arcs is positively correlated with geomagnetic activity(storms), and the frequency of occurrence of arcs is with solar sunspot activity.

Changing aurora.

Some forms of auroras experience quasiperiodic and coherent temporal variations in intensity. These auroras with approximately stationary geometry and rapid periodic variations occurring in phase are called changing auroras. They are classified as auroras forms r according to the International Atlas of Auroras A more detailed subdivision of the changing auroras:

r 1 (pulsating aurora) is a glow with uniform phase variations in brightness throughout the aurora shape. By definition, in an ideal pulsating aurora, the spatial and temporal parts of the pulsation can be separated, i.e. brightness I(r,t)= I s(r)· I T(t). In a typical aurora r 1 pulsations occur with a frequency from 0.01 to 10 Hz of low intensity (1–2 kRl). Most auroras r 1 – these are spots or arcs that pulsate with a period of several seconds.

r 2 (fiery aurora). The term is usually used to refer to movements like flames filling the sky, rather than to describe a distinct form. The auroras have the shape of arcs and usually move upward from a height of 100 km. These auroras are relatively rare and occur more often outside the aurora.

r 3 (shimmering aurora). These are auroras with rapid, irregular or regular variations in brightness, giving the impression of flickering flames in the sky. They appear shortly before the aurora disintegrates. Typically observed frequency of variation r 3 is equal to 10 ± 3 Hz.

The term streaming aurora, used for another class of pulsating auroras, refers to irregular variations in brightness moving quickly horizontally in auroral arcs and streaks.

The changing aurora is one of the solar-terrestrial phenomena that accompany pulsations of the geomagnetic field and auroral X-ray radiation caused by the precipitation of particles of solar and magnetospheric origin.

The glow of the polar cap is characterized by high intensity of the band of the first negative system N + 2 (l 3914 Å). Typically, these N + 2 bands are five times more intense than the green line OI l 5577 Å; the absolute intensity of the polar cap glow ranges from 0.1 to 10 kRl (usually 1–3 kRl). During these auroras, which appear during periods of PCA, a uniform glow covers the entire polar cap up to a geomagnetic latitude of 60° at altitudes of 30 to 80 km. It is generated predominantly by solar protons and d-particles with energies of 10–100 MeV, creating a maximum ionization at these altitudes. There is another type of glow in aurora zones, called mantle aurora. For this type of auroral glow, the daily maximum intensity, occurring in the morning hours, is 1–10 kRL, and the minimum intensity is five times weaker. Observations of mantle auroras are few and far between; their intensity depends on geomagnetic and solar activity.

Atmospheric glow is defined as radiation produced and emitted by a planet's atmosphere. This is non-thermal radiation of the atmosphere, with the exception of the emission of auroras, lightning discharges and the emission of meteor trails. This term is used in relation to the earth's atmosphere (nightglow, twilight glow and dayglow). Atmospheric glow constitutes only a portion of the light available in the atmosphere. Other sources include starlight, zodiacal light, and daytime diffuse light from the Sun. At times, the atmospheric glow can be up to 40% total number Sveta. Atmospheric glow occurs in atmospheric layers of varying height and thickness. The atmospheric glow spectrum covers wavelengths from 1000 Å to 22.5 microns. The main emission line in the atmospheric glow is l 5577 Å, appearing at an altitude of 90–100 km in a layer 30–40 km thick. The appearance of luminescence is due to the Chapman mechanism, based on the recombination of oxygen atoms. Other emission lines are l 6300 Å, appearing in the case of dissociative recombination of O + 2 and emission NI l 5198/5201 Å and NI l 5890/5896 Å.

The intensity of airglow is measured in Rayleigh. Brightness (in Rayleigh) is equal to 4 rv, where b is the angular surface brightness of the emitting layer in units of 10 6 photons/(cm 2 ster·s). The intensity of the glow depends on latitude (different for different emissions), and also varies throughout the day with a maximum near midnight. A positive correlation was noted for airglow in the l 5577 Å emission with the number of sunspots and solar radiation flux at a wavelength of 10.7 cm. Airglow is observed during satellite experiments. From outer space, it appears as a ring of light around the Earth and has a greenish color.

Ozonosphere.

At altitudes of 20–25 km, the maximum concentration of an insignificant amount of ozone O 3 is reached (up to 2×10 –7 of the oxygen content!), which arises under the influence of solar ultraviolet radiation at altitudes of approximately 10 to 50 km, protecting the planet from ionizing solar radiation. Despite the extremely small number of ozone molecules, they protect all life on Earth from the harmful effects of short-wave (ultraviolet and x-ray) radiation from the Sun. If you deposit all the molecules to the base of the atmosphere, you will get a layer no more than 3–4 mm thick! At altitudes above 100 km, the proportion of light gases increases, and at very high altitudes helium and hydrogen predominate; many molecules dissociate into individual atoms, which, ionized under the influence of hard radiation from the Sun, form the ionosphere. The pressure and density of air in the Earth's atmosphere decrease with altitude. Depending on the temperature distribution, the Earth's atmosphere is divided into the troposphere, stratosphere, mesosphere, thermosphere and exosphere. .

At an altitude of 20–25 km there is ozone layer. Ozone is formed due to the breakdown of oxygen molecules when absorbing ultraviolet radiation from the Sun with wavelengths shorter than 0.1–0.2 microns. Free oxygen combines with O 2 molecules and forms ozone O 3, which greedily absorbs all ultraviolet radiation shorter than 0.29 microns. O3 ozone molecules are easily destroyed by short-wave radiation. Therefore, despite its rarefaction, the ozone layer effectively absorbs ultraviolet radiation from the Sun that passes through higher and more transparent atmospheric layers. Thanks to this, living organisms on Earth are protected from the harmful effects of ultraviolet light from the Sun.

Ionosphere.

Radiation from the sun ionizes the atoms and molecules of the atmosphere. The degree of ionization becomes significant already at an altitude of 60 kilometers and steadily increases with distance from the Earth. At different altitudes in the atmosphere, dissociation processes occur sequentially various molecules and subsequent ionization of various atoms and ions. These are mainly molecules of oxygen O 2, nitrogen N 2 and their atoms. Depending on the intensity of these processes, the various layers of the atmosphere lying above 60 kilometers are called ionospheric layers , and their totality is the ionosphere . The lower layer, the ionization of which is insignificant, is called the neutrosphere.

The maximum concentration of charged particles in the ionosphere is achieved at altitudes of 300–400 km.

History of the study of the ionosphere.

The hypothesis about the existence of a conducting layer in the upper atmosphere was put forward in 1878 by the English scientist Stuart to explain the features of the geomagnetic field. Then in 1902, independently of each other, Kennedy in the USA and Heaviside in England pointed out that to explain the propagation of radio waves over long distances it was necessary to assume the existence of regions of high conductivity in the high layers of the atmosphere. In 1923, academician M.V. Shuleikin, considering the features of the propagation of radio waves of various frequencies, came to the conclusion that there are at least two reflective layers in the ionosphere. Then in 1925, English researchers Appleton and Barnett, as well as Breit and Tuve, first experimentally proved the existence of regions that reflect radio waves, and laid the foundation for their systematic study. Since that time, a systematic study has been carried out of the properties of these layers, generally called the ionosphere, which play a significant role in a number of geophysical phenomena that determine the reflection and absorption of radio waves, which is very important for practical purposes, in particular for ensuring reliable radio communications.

In the 1930s, systematic observations of the state of the ionosphere began. In our country, on the initiative of M.A. Bonch-Bruevich, installations for its pulse probing were created. Many have been studied general properties ionosphere, heights and electron concentration of its main layers.

At altitudes of 60–70 km layer D is observed, at altitudes of 100–120 km layer E, at altitudes, at altitudes of 180–300 km double layer F 1 and F 2. The main parameters of these layers are given in Table 4.

Table 4.

Table 4.
Ionospheric region	Maximum height, km	T i , K	Day		Night n e , cm –3	a΄, ρm 3 s – 1
			min n e , cm –3	Max n e , cm –3
D	70	20	100	200	10	10 –6
E	110	270	1.5 10 5	3·10 5	3000	10 –7
F 1	180	800–1500	3·10 5	5 10 5	–	3·10 –8
F 2 (winter)	220–280	1000–2000	6 10 5	25 10 5	~10 5	2·10 –10
F 2 (summer)	250–320	1000–2000	2·10 5	8 10 5	~3·10 5	10 –10
n e– electron concentration, e – electron charge, T i– ion temperature, a΄ – recombination coefficient (which determines the value n e and its change over time)

Average values ​​are given as they vary for different latitudes, depending on the time of day and seasons. Such data is necessary to ensure long-distance radio communications. They are used in selecting operating frequencies for various shortwave radio links. Knowledge of their changes depending on the state of the ionosphere at different times of the day and in different seasons is extremely important to ensure the reliability of radio communications. The ionosphere is a collection of ionized layers of the earth's atmosphere, starting from altitudes of about 60 km and extending to altitudes of tens of thousands of km. The main source of ionization of the Earth's atmosphere is ultraviolet and X-ray radiation from the Sun, which occurs mainly in the solar chromosphere and corona. In addition, the degree of ionization of the upper atmosphere is influenced by solar corpuscular flows that occur during solar flares, as well as cosmic rays and meteor particles.

Ionospheric layers

- these are areas in the atmosphere in which maximum concentrations of free electrons are reached (i.e., their number per unit volume). Electrically charged free electrons and (to a lesser extent, less mobile ions) resulting from the ionization of atoms of atmospheric gases, interacting with radio waves (i.e., electromagnetic oscillations), can change their direction, reflecting or refracting them, and absorb their energy. As a result, when receiving distant radio stations, various effects may occur, for example, fading of radio communications, increased audibility of remote stations, blackouts etc. phenomena.

Research methods.

Classical methods for studying the ionosphere from Earth come down to pulse sounding - sending radio pulses and observing their reflections from various layers of the ionosphere, measuring the delay time and studying the intensity and shape of the reflected signals. By measuring the heights of reflection of radio pulses at various frequencies, determining the critical frequencies of various areas (the critical frequency is the carrier frequency of a radio pulse, for which a given region of the ionosphere becomes transparent), it is possible to determine the value of the electron concentration in the layers and the effective heights for given frequencies, and select the optimal frequencies for given radio paths. With the development of rocket technology and the advent of the space age of artificial Earth satellites (AES) and other spacecraft, it became possible to directly measure the parameters of near-Earth space plasma, the lower part of which is the ionosphere.

Measurements of electron concentration, carried out on board specially launched rockets and along satellite flight paths, confirmed and clarified data previously obtained by ground-based methods on the structure of the ionosphere, the distribution of electron concentration with height above various regions of the Earth and made it possible to obtain electron concentration values ​​above the main maximum - the layer F. Previously, this was impossible to do using sounding methods based on observations of reflected short-wave radio pulses. It has been discovered that in some areas of the globe there are quite stable areas with reduced electron concentration, regular “ionospheric winds”, peculiar wave processes arise in the ionosphere that carry local ionospheric disturbances thousands of kilometers from the place of their excitation, and much more. The creation of particularly highly sensitive receiving devices made it possible to receive pulse signals partially reflected from the lowest regions of the ionosphere (partial reflection stations) at ionospheric pulse sounding stations. The use of powerful pulsed installations in the meter and decimeter wavelength ranges with the use of antennas that allow for a high concentration of emitted energy made it possible to observe signals scattered by the ionosphere at various altitudes. The study of the features of the spectra of these signals, incoherently scattered by electrons and ions of the ionospheric plasma (for this, stations of incoherent scattering of radio waves were used) made it possible to determine the concentration of electrons and ions, their equivalent temperature at various altitudes up to altitudes of several thousand kilometers. It turned out that the ionosphere is quite transparent for the frequencies used.

The concentration of electric charges (the electron concentration is equal to the ion concentration) in the earth's ionosphere at an altitude of 300 km is about 10 6 cm –3 during the day. Plasma of such density reflects radio waves with a length of more than 20 m, and transmits shorter ones.

Typical vertical distribution of electron concentration in the ionosphere for day and night conditions.

Propagation of radio waves in the ionosphere.

Stable reception of long-distance broadcasting stations depends on the frequencies used, as well as on the time of day, season and, in addition, on solar activity. Solar activity significantly affects the state of the ionosphere. Radio waves emitted by a ground station travel in a straight line, like all types of electromagnetic waves. However, it should be taken into account that both the surface of the Earth and the ionized layers of its atmosphere serve as the plates of a huge capacitor, acting on them like the effect of mirrors on light. Reflecting from them, radio waves can travel many thousands of kilometers, going around globe in huge leaps of hundreds and thousands of km, reflecting alternately from a layer of ionized gas and from the surface of the Earth or water.

In the 20s of the last century, it was believed that radio waves shorter than 200 m were generally not suitable for long-distance communications due to strong absorption. The first experiments on long-distance reception of short waves across the Atlantic between Europe and America were carried out by English physicist Oliver Heaviside and American electrical engineer Arthur Kennelly. Independently of each other, they suggested that somewhere around the Earth there is an ionized layer of the atmosphere capable of reflecting radio waves. It was called the Heaviside-Kennelly layer, and then the ionosphere.

According to modern concepts, the ionosphere consists of negatively charged free electrons and positively charged ions, mainly molecular oxygen O + and nitric oxide NO +. Ions and electrons are formed as a result of the dissociation of molecules and ionization of neutral gas atoms by solar X-rays and ultraviolet radiation. In order to ionize an atom, it is necessary to impart ionization energy to it, the main source of which for the ionosphere is ultraviolet, x-ray and corpuscular radiation from the Sun.

While the gaseous shell of the Earth is illuminated by the Sun, more and more electrons are continuously formed in it, but at the same time some of the electrons, colliding with ions, recombine, again forming neutral particles. After sunset, the formation of new electrons almost stops, and the number of free electrons begins to decrease. The more free electrons there are in the ionosphere, the better high-frequency waves are reflected from it. With a decrease in electron concentration, the passage of radio waves is possible only in low frequency ranges. That is why at night, as a rule, it is possible to receive distant stations only in the ranges of 75, 49, 41 and 31 m. Electrons are distributed unevenly in the ionosphere. At altitudes from 50 to 400 km there are several layers or regions of increased electron concentration. These areas smoothly transition into one another and have different effects on the propagation of HF radio waves. The upper layer of the ionosphere is designated by the letter F. Here the highest degree of ionization (the fraction of charged particles is about 10 –4). It is located at an altitude of more than 150 km above the Earth's surface and plays the main reflective role in the long-distance propagation of high-frequency HF radio waves. In the summer months, region F splits into two layers - F 1 and F 2. Layer F1 can occupy heights from 200 to 250 km, and layer F 2 seems to “float” in the altitude range of 300–400 km. Usually layer F 2 is ionized much stronger than the layer F 1. Night layer F 1 disappears and the layer F 2 remains, slowly losing up to 60% of its degree of ionization. Below layer F at altitudes from 90 to 150 km there is a layer E, the ionization of which occurs under the influence of soft X-ray radiation from the Sun. The degree of ionization of the E layer is lower than that of the F, during the day, reception of stations in the low-frequency HF ranges of 31 and 25 m occurs when signals are reflected from the layer E. Typically these are stations located at a distance of 1000–1500 km. At night in the layer E Ionization decreases sharply, but even at this time it continues to play a significant role in the reception of signals from stations on the 41, 49 and 75 m ranges.

Of great interest for receiving signals of high-frequency HF ranges of 16, 13 and 11 m are those arising in the area E layers (clouds) of highly increased ionization. The area of ​​these clouds can vary from a few to hundreds of square kilometers. This layer of increased ionization is called the sporadic layer E and is designated Es. Es clouds can move in the ionosphere under the influence of wind and reach speeds of up to 250 km/h. In summer in mid-latitudes during the daytime, the origin of radio waves due to Es clouds occurs for 15–20 days per month. Near the equator it is almost always present, and in high latitudes it usually appears at night. Sometimes, during years of low solar activity, when there is no transmission on the high-frequency HF bands, distant stations suddenly appear on the 16, 13 and 11 m bands with good volume, the signals of which are reflected many times from Es.

The lowest region of the ionosphere is the region D located at altitudes between 50 and 90 km. There are relatively few free electrons here. From the area D Long and medium waves are well reflected, and signals from low-frequency HF stations are strongly absorbed. After sunset, ionization disappears very quickly and it becomes possible to receive distant stations in the ranges of 41, 49 and 75 m, the signals of which are reflected from the layers F 2 and E. Individual layers of the ionosphere play an important role in the propagation of HF radio signals. The effect on radio waves occurs mainly due to the presence of free electrons in the ionosphere, although the mechanism of radio wave propagation is associated with the presence of large ions. The latter are also of interest when studying chemical properties atmosphere, since they are more active than neutral atoms and molecules. Chemical reactions occurring in the ionosphere play an important role in its energy and electrical balance.

Normal ionosphere. Observations made using geophysical rockets and satellites have yielded a wealth of new information, indicating that ionization of the atmosphere occurs under the influence of broad-spectrum solar radiation. Its main part (more than 90%) is concentrated in the visible part of the spectrum. Ultraviolet radiation, which has a shorter wavelength and higher energy than violet light rays, is emitted by hydrogen in the Sun's inner atmosphere (the chromosphere), and x-rays, which have even higher energy, are emitted by gases in the Sun's outer shell (the corona).

The normal (average) state of the ionosphere is due to constant powerful radiation. Regular changes occur in the normal ionosphere due to the daily rotation of the Earth and seasonal differences in the angle of incidence of the sun's rays at noon, but unpredictable and abrupt changes in the state of the ionosphere also occur.

Disturbances in the ionosphere.

As is known, powerful cyclically repeating manifestations of activity occur on the Sun, which reach a maximum every 11 years. Observations under the International Geophysical Year (IGY) program coincided with the period of the highest solar activity for the entire period of systematic meteorological observations, i.e. from the beginning of the 18th century. During periods of high activity, the brightness of some areas on the Sun increases several times, and the power of ultraviolet and X-ray radiation increases sharply. Such phenomena are called solar flares. They last from several minutes to one to two hours. During a flare, solar plasma (mostly protons and electrons) is erupted, and elementary particles rush into outer space. Electromagnetic and corpuscular radiation from the Sun during such flares has strong impact to the Earth's atmosphere.

The initial reaction is observed 8 minutes after the flare, when intense ultraviolet and X-ray radiation reaches the Earth. As a result, ionization increases sharply; X-rays penetrate the atmosphere to the lower boundary of the ionosphere; the number of electrons in these layers increases so much that the radio signals are almost completely absorbed (“extinguished”). The additional absorption of radiation causes the gas to heat up, which contributes to the development of winds. Ionized gas is electrical conductor, and when it moves in the Earth's magnetic field, a dynamo effect occurs and an electric current is generated. Such currents can, in turn, cause noticeable disturbances in the magnetic field and manifest themselves in the form of magnetic storms.

The structure and dynamics of the upper atmosphere are significantly determined by non-equilibrium processes in the thermodynamic sense associated with ionization and dissociation solar radiation, chemical processes, excitation of molecules and atoms, their deactivation, collision and other elementary processes. In this case, the degree of nonequilibrium increases with height as the density decreases. Up to altitudes of 500–1000 km, and often higher, the degree of nonequilibrium for many characteristics of the upper atmosphere is quite small, which makes it possible to use classical and hydromagnetic hydrodynamics, taking into account chemical reactions, to describe it.

The exosphere is the outer layer of the Earth's atmosphere, starting at altitudes of several hundred kilometers, from which light, fast-moving hydrogen atoms can escape into outer space.

Edward Kononovich

Literature:

Pudovkin M.I. Fundamentals of Solar Physics. St. Petersburg, 2001
Eris Chaisson, Steve McMillan Astronomy today. Prentice-Hall, Inc. Upper Saddle River, 2002
Materials on the Internet: http://ciencia.nasa.gov/



The gaseous envelope surrounding our planet Earth, known as the atmosphere, consists of five main layers. These layers originate on the surface of the planet, from sea level (sometimes below) and rise to outer space in the following sequence:

• Troposphere;
• Stratosphere;
• Mesosphere;
• Thermosphere;
• Exosphere.

Diagram of the main layers of the Earth's atmosphere

In between each of these main five layers are transition zones called "pauses" where changes in air temperature, composition and density occur. Together with pauses, the Earth's atmosphere includes a total of 9 layers.

Troposphere: where weather occurs

Of all the layers of the atmosphere, the troposphere is the one with which we are most familiar (whether you realize it or not), since we live on its bottom - the surface of the planet. It envelops the surface of the Earth and extends upward for several kilometers. The word troposphere means "change of the globe." A very appropriate name, since this layer is where our everyday weather occurs.

Starting from the surface of the planet, the troposphere rises to a height of 6 to 20 km. The lower third of the layer, closest to us, contains 50% of all atmospheric gases. This is the only part of the entire atmosphere that breathes. Due to the fact that the air is heated from below by the earth's surface, which absorbs the thermal energy of the Sun, the temperature and pressure of the troposphere decrease with increasing altitude.

At the top there is a thin layer called the tropopause, which is just a buffer between the troposphere and the stratosphere.

Stratosphere: home of the ozone

The stratosphere is the next layer of the atmosphere. It extends from 6-20 km to 50 km above the Earth's surface. This is the layer in which most commercial airliners fly and hot air balloons travel.

Here the air does not flow up and down, but moves parallel to the surface in very fast air currents. As you rise, the temperature increases, thanks to the abundance of naturally occurring ozone (O3), a byproduct of solar radiation and oxygen, which has the ability to absorb the sun's harmful ultraviolet rays (any increase in temperature with altitude in meteorology is known as an "inversion") .

Because the stratosphere has warmer temperatures at the bottom and cooler temperatures at the top, convection (vertical movement of air masses) is rare in this part of the atmosphere. In fact, you can view a storm raging in the troposphere from the stratosphere because the layer acts as a convection cap that prevents storm clouds from penetrating.

After the stratosphere there is again a buffer layer, this time called the stratopause.

Mesosphere: middle atmosphere

The mesosphere is located approximately 50-80 km from the Earth's surface. The upper mesosphere is the coldest natural place on Earth, where temperatures can drop below -143°C.

Thermosphere: upper atmosphere

After the mesosphere and mesopause comes the thermosphere, located between 80 and 700 km above the surface of the planet, and contains less than 0.01% of the total air in the atmospheric envelope. Temperatures here reach up to +2000° C, but due to the strong rarefaction of the air and the lack of gas molecules to transfer heat, these high temperatures are perceived as very cold.

Exosphere: the boundary between the atmosphere and space

At an altitude of about 700-10,000 km above the earth's surface is the exosphere - the outer edge of the atmosphere, bordering space. Here weather satellites orbit the Earth.

What about the ionosphere?

The ionosphere is not a separate layer, but in fact the term is used to refer to the atmosphere between 60 and 1000 km altitude. It includes the uppermost parts of the mesosphere, the entire thermosphere and part of the exosphere. The ionosphere gets its name because in this part of the atmosphere the radiation from the Sun is ionized when it passes through the Earth's magnetic fields at and. This phenomenon is observed from the ground as the northern lights.