10.045×10 3 J/(kg*K) (in the temperature range from 0-100°C), C v 8.3710*10 3 J/(kg*K) (0-1500°C). The solubility of air in water at 0°C is 0.036%, at 25°C - 0.22%.

Atmospheric composition

History of atmospheric formation

Early history

Currently, science cannot trace all stages of the formation of the Earth with one hundred percent accuracy. According to the most common theory, the Earth's atmosphere has had four different compositions over time. 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 (hydrocarbons, 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:

• constant leakage of hydrogen 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).

The emergence of life and oxygen

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, the composition of the atmosphere began to change. There is, however, data (analysis of the isotopic composition of atmospheric oxygen and that released during photosynthesis) that indicates the geological origin of atmospheric oxygen.

Initially, oxygen was spent on the oxidation of reduced compounds - 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.

In the 1990s, experiments were carried out to create a closed ecological system (“Biosphere 2”), during which it was not possible to create a stable system with a uniform air composition. The influence of microorganisms led to a decrease in oxygen levels and an increase in the amount of carbon dioxide.

Nitrogen

The formation of a large amount of N 2 is due to the oxidation of the primary ammonia-hydrogen atmosphere with molecular O 2, which began to come from the surface of the planet as a result of photosynthesis, supposedly about 3 billion years ago (according to another version, atmospheric oxygen is of geological origin). Nitrogen is oxidized to NO in upper layers atmosphere, is used in industry and is bound by nitrogen-fixing bacteria, at the same time N 2 is released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds.

Nitrogen N 2 is an inert gas and reacts only under specific conditions (for example, during a lightning discharge). Cyanobacteria and some bacteria (for example, nodule bacteria that form rhizobial symbiosis with leguminous plants) can oxidize it and convert it into biological form.

Oxidation of molecular nitrogen by electrical discharges is used in industrial production nitrogen fertilizers, it also led to the formation of unique deposits of nitrate in the Chilean Atacama Desert.

Noble gases

Fuel combustion is the main source of polluting gases (CO, NO, SO2). Sulfur dioxide is oxidized by air O 2 to SO 3 in the upper layers of the atmosphere, which interacts with H 2 O and NH 3 vapors, and the resulting H 2 SO 4 and (NH 4) 2 SO 4 return to the Earth's surface along with precipitation. The use of internal combustion engines leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and Pb compounds.

Aerosol pollution of the atmosphere is caused by: natural causes(volcanic eruptions, dust storms, removal of drops of sea water and particles of plant pollen, etc.), and economic activity humans (mining ores and building materials, burning fuel, making cement, etc.). Intensive large-scale emission of solid particles into the atmosphere is one of the possible reasons changes in the planet's climate.

The structure of the atmosphere and characteristics of individual shells

The physical state of the atmosphere is determined by weather and climate. Basic parameters of the atmosphere: air density, pressure, temperature and composition. As altitude increases, air density and atmospheric pressure decrease. Temperature also changes with changes in altitude. The vertical structure of the atmosphere is characterized by different temperature and electrical properties, and different air conditions. Depending on the temperature in the atmosphere, the following main layers are distinguished: troposphere, stratosphere, mesosphere, thermosphere, exosphere (scattering sphere). The transitional regions of the atmosphere between neighboring shells are called tropopause, stratopause, etc., respectively.

Troposphere

Stratosphere

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, magnetic fields change, 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 - H 2). At an altitude of 100-400 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.

Mesosphere

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 weights; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to a 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 ~1500°C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed.

At an altitude of about 2000-3000 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 these extremely rarefied particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

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, the neutronosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

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.

Atmospheric properties

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 15 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.

The human lungs constantly contain about 3 liters of alveolar air. The partial pressure of oxygen in alveolar air at normal atmospheric pressure is 110 mmHg. Art., carbon dioxide pressure - 40 mm Hg. Art., and water vapor −47 mm Hg. Art. With increasing altitude, oxygen pressure drops, and the total vapor pressure of water and carbon dioxide in the lungs remains almost constant - about 87 mm Hg. Art. The supply of oxygen to the lungs will completely stop when the ambient air pressure becomes equal to this value.

At an altitude of about 19-20 km, the atmospheric pressure drops to 47 mm Hg. Art. Therefore, at this altitude, water and interstitial fluid begin to boil in the human body. Outside the pressurized cabin at these altitudes, death occurs almost instantly. Thus, from the point of view of human physiology, “space” begins already at an altitude of 15-19 km.

Dense layers of air - the troposphere and stratosphere - protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, ionizing radiation - primary cosmic rays - has an intense effect on the body; At altitudes of more than 40 km, the ultraviolet part of the solar spectrum is dangerous for humans.

Blue Planet...

This topic should have been one of the first to appear on the site. After all, helicopters are atmospheric aircraft. Earth's atmosphere– their habitat, so to speak:-). A physical properties air This is precisely what determines the quality of this habitat :-). That is, this is one of the basics. And they always write about the basis first. But I realized this only now. However, as you know, it’s better late than never... Let’s touch on this issue, without getting into the weeds and unnecessary complications :-).

So… Earth's atmosphere. This gas envelope of our blue planet. Everyone knows this name. Why blue? Simply because the “blue” (as well as blue and violet) component of sunlight (spectrum) is most well scattered in the atmosphere, thereby coloring it bluish-bluish, sometimes with a hint of violet tone (on a sunny day, of course :-)) .

Composition of the Earth's atmosphere.

The composition of the atmosphere is quite broad. I will not list all the components in the text; there is a good illustration for this. The composition of all these gases is almost constant, with the exception of carbon dioxide (CO 2 ). In addition, the atmosphere necessarily contains water in the form of vapor, suspended droplets or ice crystals. The amount of water is not constant and depends on temperature and, to a lesser extent, air pressure. In addition, the Earth’s atmosphere (especially the current one) contains a certain amount of, I would say, “all sorts of nasty things” :-). These are SO 2, NH 3, CO, HCl, NO, in addition there are mercury vapors Hg. True, all this is there in small quantities, thank God :-).

Earth's atmosphere It is customary to divide it into several successive zones in height above the surface.

The first, closest to the earth, is the troposphere. This is the lowest and, so to speak, main layer for life. different types. It contains 80% of the mass of all atmospheric air (although by volume it is only about 1% of the entire atmosphere) and about 90% of all atmospheric water. The bulk of all the winds, clouds, rain and snow 🙂 come from there. The troposphere extends to altitudes of about 18 km in tropical latitudes and up to 10 km in polar latitudes. The air temperature in it drops with an increase in height by approximately 0.65º for every 100 m.

Atmospheric zones.

Zone two - stratosphere. It must be said that between the troposphere and the stratosphere there is another narrow zone - the tropopause. It stops the temperature falling with height. The tropopause has an average thickness of 1.5-2 km, but its boundaries are unclear and the troposphere often overlaps the stratosphere.

So the stratosphere has an average height of 12 km to 50 km. The temperature in it remains unchanged up to 25 km (about -57ºС), then somewhere up to 40 km it rises to approximately 0ºС and then remains unchanged up to 50 km. The stratosphere is a relatively calm part of the earth's atmosphere. Unfavorable weather it is practically absent. It is in the stratosphere that the famous ozone layer is located at altitudes from 15-20 km to 55-60 km.

This is followed by a small boundary layer, the stratopause, in which the temperature remains around 0ºC, and then the next zone is the mesosphere. It extends to altitudes of 80-90 km, and in it the temperature drops to about 80ºC. In the mesosphere, small meteors usually become visible, which begin to glow in it and burn up there.

The next narrow interval is the mesopause and beyond it the thermosphere zone. Its height is up to 700-800 km. Here the temperature begins to rise again and at altitudes of about 300 km can reach values ​​of the order of 1200ºС. Then it remains constant. Inside the thermosphere, up to an altitude of about 400 km, is the ionosphere. Here the air is highly ionized due to exposure to solar radiation and has high electrical conductivity.

The next and, in general, the last zone is the exosphere. This is the so-called scattering zone. Here, there is mainly very rarefied hydrogen and helium (with a predominance of hydrogen). At altitudes of about 3000 km, the exosphere passes into the near-space vacuum.

Something like this. Why approximately? Because these layers are quite conventional. Various changes in altitude, composition of gases, water, temperature, ionization, and so on are possible. In addition, there are many more terms that define the structure and state of the earth’s atmosphere.

For example, homosphere and heterosphere. In the first, atmospheric gases are well mixed and their composition is quite homogeneous. The second is located above the first and there is practically no such mixing there. The gases in it are separated by gravity. The boundary between these layers is located at an altitude of 120 km, and it is called turbopause.

Let’s finish with the terms, but I’ll definitely add that it is conventionally accepted that the boundary of the atmosphere is located at an altitude of 100 km above sea level. This border is called the Karman Line.

I will add two more pictures to illustrate the structure of the atmosphere. The first one, however, is in German, but it is complete and quite easy to understand :-). It can be enlarged and seen clearly. The second shows the change in atmospheric temperature with altitude.

The structure of the Earth's atmosphere.

Air temperature changes with altitude.

Modern manned orbital spacecraft fly at altitudes of about 300-400 km. However, this is no longer aviation, although the area, of course, is closely related in a certain sense, and we will certainly talk about it later :-).

The aviation zone is the troposphere. Modern atmospheric aircraft can also fly in the lower layers of the stratosphere. For example, the practical ceiling of the MIG-25RB is 23,000 m.

Flight in the stratosphere.

And exactly physical properties of air The troposphere determines what the flight will be like, how effective the aircraft’s control system will be, how turbulence in the atmosphere will affect it, and how the engines will operate.

The first main property is air temperature. In gas dynamics, it can be determined on the Celsius scale or on the Kelvin scale.

Temperature t 1 at a given height N on the Celsius scale is determined by:

t 1 = t - 6.5N, Where t– air temperature near the ground.

Temperature on the Kelvin scale is called absolute temperature, zero on this scale is absolute zero. At absolute zero, the thermal motion of molecules stops. Absolute zero on the Kelvin scale corresponds to -273º on the Celsius scale.

Accordingly the temperature T on high N on the Kelvin scale is determined by:

T = 273K + t - 6.5H

Air pressure. Atmospheric pressure is measured in Pascals (N/m2), in the old system of measurement in atmospheres (atm.). There is also such a thing as barometric pressure. This is the pressure measured in millimeters of mercury using a mercury barometer. Barometric pressure (pressure at sea level) equal to 760 mmHg. Art. called standard. In physics 1 atm. exactly equal to 760 mm Hg.

Air density. In aerodynamics, the most often used concept is the mass density of air. This is the mass of air in 1 m3 of volume. The density of air changes with altitude, the air becomes more rarefied.

Air humidity. Shows the amount of water in the air. There is a concept " relative humidity " This is the ratio of the mass of water vapor to the maximum possible at a given temperature. The concept of 0%, that is, when the air is completely dry, can only exist in the laboratory. On the other hand, 100% humidity is quite possible. This means that the air has absorbed all the water it could absorb. Something like an absolutely “full sponge”. High relative humidity reduces air density, while low relative humidity increases it.

Due to the fact that aircraft flights occur under different atmospheric conditions, their flight and aerodynamic parameters in the same flight mode may be different. Therefore, to correctly estimate these parameters, we introduced International Standard Atmosphere (ISA). It shows the change in the state of air with increasing altitude.

The basic parameters of the air condition at zero humidity are taken as follows:

pressure P = 760 mm Hg. Art. (101.3 kPa);

temperature t = +15°C (288 K);

mass density ρ = 1.225 kg/m 3 ;

For the ISA it is accepted (as mentioned above :-)) that the temperature drops in the troposphere by 0.65º for every 100 meters of altitude.

Standard atmosphere (example up to 10,000 m).

MSA tables are used for calibrating instruments, as well as for navigational and engineering calculations.

Physical properties of air also include such concepts as inertia, viscosity and compressibility.

Inertia is a property of air that characterizes its ability to resist changes in its state of rest or uniform linear motion. . A measure of inertia is the mass density of air. The higher it is, the higher the inertia and resistance force of the medium when the aircraft moves in it.

Viscosity Determines the air friction resistance when the aircraft is moving.

Compressibility determines the change in air density with changes in pressure. At low speeds of the aircraft (up to 450 km/h), there is no change in pressure when the air flow flows around it, but at high speeds the compressibility effect begins to appear. Its influence is especially noticeable at supersonic speeds. This is a separate area of ​​aerodynamics and a topic for a separate article :-).

Well, that seems to be all for now... It's time to finish this slightly tedious enumeration, which, however, cannot be avoided :-). Earth's atmosphere, its parameters, physical properties of air are as important for the aircraft as the parameters of the device itself, and they could not be ignored.

Bye, until next meetings and more interesting topics :) ...

P.S. For dessert, I suggest watching a video filmed from the cockpit of a MIG-25PU twin during its flight into the stratosphere. Apparently it was filmed by a tourist who has money for such flights :-). Mostly everything was filmed through the windshield. Pay attention to the color of the sky...

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 area that is responsible for the formation of weather; approximately 80% of all air masses.

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 the stratosphere. The stratosphere contains a layer of ozone, 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 the mesosphere. 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, the thermosphere, is the 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. Besides, in different countries there are organizations that adhere to different opinions on this score. 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.

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 the total 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 average vertical gradient(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 weights; 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 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). It means that various elements equipment, orbital equipment space station will not be able to cool outside in the way that is usually done on an airplane - with the help of air jets and air radiators. At such a height, as in general in space, the only way heat transfer 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

The formation of a large amount of nitrogen N2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O2, 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, which 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 substances of plant and animal origin, as well as due to volcanism and production activities person. 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 caused by both natural causes (volcanic eruptions, dust storms, entrainment of drops of sea water and plant pollen, etc.) and human economic activities (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 consider true love. What do you think, prince?
“I know your sister too little,” answered Prince Andrei with a mocking smile, under which he wanted to hide his embarrassment, “to 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 object of courtship] like her,” said Vera; - 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. Is not it?]
“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 in the whole house one could feel the 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? Mom, mom, 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. From the time the prince became close to his wife, Pierre was unexpectedly granted a chamberlain, and from that time on he began to feel heaviness and shame in large society, and more often the old gloomy thoughts about the futility of everything human began to come to him. At the same time, the feeling he noticed between Natasha, whom he protected, and Prince Andrei, the contrast 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 to work day and night on Masonic works, hoping to ward off the approach 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 can't 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 this... This girl is such a treasure, such... This is a 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. 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 traveled 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 I listen to the sounds of my own 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 he. She knew this for sure, although she barely heard the sound of his voice from the closed doors.
Natasha, pale and frightened, ran into the living room.
- Mom, Bolkonsky has arrived! - she said. - Mom, this is terrible, this is unbearable! – I don’t want... to suffer! What should I do?…
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 was discourteously, directly, with open eyes looked 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 for 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,” said Prince Andrei 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 icons 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 structure of the Earth's atmosphere

The atmosphere is the gaseous shell of the Earth with the aerosol particles it contains, moving together with the Earth in space as a single whole and at the same time taking part in the rotation of the Earth. Most of our life takes place at the bottom of the atmosphere.

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

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

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

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

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

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

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

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

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

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

The upper boundary of the troposphere is the tropopause - an isothermal layer. Remember characteristic appearance thunderclouds whose top is a “burst” of cirrus clouds called an “anvil.” This “anvil” just “spreads” under the tropopause, because due to isotherm, the ascending air currents are significantly weakened, and the cloud stops developing vertically. But in special, rare cases, the tops of cumulonimbus clouds can invade the lower layers of the stratosphere, breaking the tropopause.

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