Structure of the atmosphere with increasing altitude. Composition and structure of the atmosphere. Changing aurora

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 is the gaseous shell of our blue planet. Everyone knows this name. Why blue? Simply because the “blue” (and blue and violet) component 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. There are practically no adverse weather conditions in it. It is in the stratosphere that the famous ozone layer 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 "" 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...

1 / 5

Encyclopedic YouTube ✪ Earth spaceship

(Episode 14) - Atmosphere

✪ Why wasn’t the atmosphere pulled into the vacuum of space?

✪ Entry of the Soyuz TMA-8 spacecraft into the Earth’s atmosphere

✪ Atmosphere structure, meaning, study

✪ O. S. Ugolnikov "Upper Atmosphere. Meeting of Earth and Space"

Subtitles

Atmospheric boundary

The atmosphere is considered to be that region around the Earth in which the gaseous medium rotates together with the Earth as a single whole. The atmosphere passes into interplanetary space gradually, in the exosphere, starting at an altitude of 500-1000 km from the Earth's surface.

According to the definition proposed by the International Aviation Federation, the boundary of the atmosphere and space is drawn along the Karman line, located at an altitude of about 100 km, above which aviation flights become completely impossible. NASA uses the 122 kilometers (400,000 ft) mark as the atmospheric limit, where the shuttles switch from powered maneuvering to aerodynamic maneuvering.

Physical properties In addition to the gases indicated in the table, the atmosphere contains , Cl 2 (\displaystyle (\ce (Cl2))) , SO 2 (\displaystyle (\ce (SO2))) , NH 3 (\displaystyle (\ce (NH3))) , CO (\displaystyle ((\ce (CO)))) , O 3 (\displaystyle ((\ce (O3)))) NO 2 (\displaystyle (\ce (NO2))) , hydrocarbons, , HCl (\displaystyle (\ce (HCl))) , HF (\displaystyle (\ce (HF))) , HBr (\displaystyle (\ce (HBr))) HI (\displaystyle ((\ce (HI)))) , couples , Hg (\displaystyle (\ce (Hg))) , I 2 (\displaystyle (\ce (I2))) Br 2 (\displaystyle (\ce (Br2))) , as well as many other gases in small quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is .

Rn (\displaystyle (\ce (Rn)))

The structure of the atmosphere

Atmospheric boundary layer

The lower layer of the troposphere (1-2 km thick), in which the state and properties of the Earth's surface directly affect the dynamics of the atmosphere.

Troposphere Her upper limit
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 arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 meters.

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 the 25-40 km layer from minus 56.5 to plus 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.

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

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 1500 K, 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 minus 110 °C in the mesosphere. However kinetic energy individual particles at altitudes of 200-250 km correspond 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 rare 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.

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 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 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O 2 (\displaystyle (\ce (O2))), which began to come from the surface of the planet as a result of photosynthesis, starting 3 billion years ago. Also nitrogen N 2 (\displaystyle (\ce (N2))) released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO (\displaystyle ((\ce (NO)))) V upper layers atmosphere.

Nitrogen N 2 (\displaystyle (\ce (N2))) 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. Oxidize it with low energy consumption and convert it into biological active form Cyanobacteria (blue-green algae) and nodule bacteria can form rhizobial symbiosis with leguminous plants, which can be effective green manures - plants that do not deplete, but enrich the soil with natural fertilizers.

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 and others. At the end of this stage, the oxygen content in the atmosphere began to increase. Gradually a modern atmosphere emerged, possessing oxidizing properties. Since this caused serious and sudden changes 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. Enormous quantities are consumed during photosynthesis and are 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 human industrial activity. Over the last 100 years content CO 2 (\displaystyle (\ce (CO2))) in the atmosphere 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 CO 2 (\displaystyle (\ce (CO2))) in the atmosphere will double and may lead to

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 arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m

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.

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

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.

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 1500 K, after which it remains almost constant to high altitudes. Under the influence of ultraviolet and x-ray 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.

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 ~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 extremely rarefied dust 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.

According to the definition proposed by the International Aviation Federation, the boundary of the atmosphere and space is drawn along the Karman line, located at an altitude of about 100 km, above which aviation flights become completely impossible. NASA uses the 122 kilometers (400,000 ft) mark as the atmospheric limit, where the shuttles switch from powered maneuvering to aerodynamic maneuvering.

The thickness of the atmosphere is approximately 2000 - 3000 km from the Earth's surface. The total air mass is (5.1-5.3)?10 18 kg. The molar mass of clean dry air is 28.966. Pressure at 0 °C at sea level 101.325 kPa; critical temperature ?140.7 °C; critical pressure 3.7 MPa; C p 1.0048?10? J/(kg K)(at 0 °C), C v 0.7159 10? J/(kg K) (at 0 °C). The solubility of air in water at 0°C is 0.036%, at 25°C - 0.22%.

Physiological and other properties of the atmosphere

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. 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.

As we rise to an ever greater height above the Earth's surface, such familiar phenomena observed in the lower layers of the atmosphere as sound propagation, the occurrence of aerodynamic lift and drag, heat transfer by convection, etc., gradually weaken and then completely disappear.

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 sphere 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 (i.e. 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 such a height, as in general in space, the only way heat transfer is thermal radiation.

Atmospheric composition

The Earth's atmosphere consists mainly of gases and various impurities (dust, water droplets, ice crystals, sea salts, combustion products).

The concentration of gases that make up the atmosphere is almost constant, with the exception of water (H 2 O) and carbon dioxide (CO 2).

Composition of dry air

Gas	Content by volume,%	Content by weight,%
Nitrogen	78,084	75,50
Oxygen	20,946	23,10
Argon	0,932	1,286
Water	0,5-4	-
Carbon dioxide	0,032	0,046
Neon	1.818×10 −3	1.3×10 −3
Helium	4.6×10 −4	7.2×10 −5
Methane	1.7×10 −4	-
Krypton	1.14×10 −4	2.9×10 −4
Hydrogen	5×10 −5	7.6×10 −5
Xenon	8.7×10 −6	-
Nitrous oxide	5×10 −5	7.7×10 −5

In addition to the gases indicated in the table, the atmosphere contains SO 2, NH 3, CO, ozone, hydrocarbons, HCl, vapors, I 2, as well as many other gases in small quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol).

History of atmospheric formation

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(about four billion years ago). 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(about three billion years before the present day). 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 N 2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular O 2, which began to come from the surface of the planet as a result of photosynthesis, starting 3 billion years ago. 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 the industrial production of nitrogen fertilizers. Cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with leguminous plants, the so-called, can oxidize it with low energy consumption and convert it into a biologically active form. green manure.

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. Because it caused major and abrupt changes in many processes occurring in the atmosphere, lithosphere, and biosphere, the event was called the Oxygen Disaster.

Carbon dioxide

The CO 2 content in the atmosphere depends on volcanic activity and chemical processes in the earth's shells, but most of all - on the intensity of biosynthesis and decomposition of organic matter in the Earth's biosphere. Almost the entire current biomass of the planet (about 2.4 × 10 12 tons) is formed due to carbon dioxide, nitrogen and water vapor contained in the atmospheric air. Organics buried in the ocean, swamps and forests turn into coal, oil and natural gas. (see Geochemical carbon cycle)

Noble gases

Air pollution

Recently, humans have begun to influence the evolution of the atmosphere. The result of his activities was a constant significant 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 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 50-60 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 in the upper layers of the atmosphere, which in turn interacts with water and ammonia vapor, and the resulting sulfuric acid (H 2 SO 4) and ammonium sulfate ((NH 4) 2 SO 4) are returned to the surface of the Earth in the form of the 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: natural causes(volcanic eruption, dust storms, carryover of drops of 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.

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. Background pollution monitoring natural environments. V. 1, L., 1982.

see also

Links

Earth's atmosphere

>> Earth's atmosphere

Description Earth's atmosphere for children of all ages: what air is made of, the presence of gases, layers with photos, climate and weather of the third planet solar system.

For the little ones it is already known that the Earth protrudes the only planet in our system, which has a viable atmosphere. The gas blanket is not only rich in air, but also protects us from excessive heat and solar radiation. Important explain to the children that the system is designed incredibly well, because it allows the surface to warm up during the day and cool down at night, maintaining an acceptable balance.

Begin explanation for children It is possible from the fact that the globe of the earth's atmosphere extends over 480 km, but most of it is located 16 km from the surface. The higher the altitude, the lower the pressure. If we take sea level, then the pressure there is 1 kg per square centimeter. But at an altitude of 3 km, it will change - 0.7 kg per square centimeter. Of course, in such conditions it is more difficult to breathe ( children you could feel this if you ever went hiking in the mountains).

Composition of the Earth's air - explanation for children

Among the gases there are:

• Nitrogen – 78%.
• Oxygen – 21%.
• Argon – 0.93%.
• Carbon dioxide – 0.038%.
• There is also water vapor and other gas impurities in small quantities.

Atmospheric layers of the Earth - explanation for children

Parents or teachers At school We should remind you that the earth's atmosphere is divided into 5 levels: exosphere, thermosphere, mesosphere, stratosphere and troposphere. With each layer, the atmosphere dissolves more and more until the gases finally disperse into space.

The troposphere is closest to the surface. With a thickness of 7-20 km, it makes up half of the earth's atmosphere. The closer to Earth, the more the air warms up. Almost all water vapor and dust are collected here. Children may not be surprised that it is at this level that clouds float.

The stratosphere starts from the troposphere and rises 50 km above the surface. There is a lot of ozone here, which heats the atmosphere and protects from harmful solar radiation. The air is 1000 times thinner than above sea level and unusually dry. That is why airplanes feel great here.

Mesosphere: 50 km to 85 km above the surface. The peak is called the mesopause and is the coolest place in the earth's atmosphere (-90°C). It is very difficult to explore because jet planes cannot get there, and the orbital altitude of the satellites is too high. Scientists only know that this is where meteors burn up.

Thermosphere: 90 km and between 500-1000 km. The temperature reaches 1500°C. It is considered part of the earth's atmosphere, but it is important explain to the children that the air density here is so low that most of it is already perceived as outer space. In fact, this is where the space shuttles and the International space station. In addition, auroras are formed here. Charged cosmic particles come into contact with atoms and molecules of the thermosphere, transferring them to a higher energy level. Thanks to this, we see these photons of light in the form of the aurora.

The exosphere is the highest layer. An incredibly thin line of merging the atmosphere with space. Consists of widely scattered hydrogen and helium particles.

Earth's climate and weather - explanation for children

For the little ones need to explain that the Earth manages to support many living species thanks to a regional climate that is represented by extreme cold at the poles and tropical warmth at the equator. Children should know that regional climate is the weather that in a particular area remains unchanged for 30 years. Of course, sometimes it can change for a few hours, but for the most part it remains stable.

In addition, the global earth climate is distinguished - the average of the regional one. It has changed throughout human history. Today there is rapid warming. Scientists are sounding the alarm as greenhouse gases caused by human activity, retain heat in the atmosphere, risking turning our planet into Venus.

The structure and composition of the Earth's atmosphere, it must be said, was not always constant values at one time or another in the development of our planet. Today, the vertical structure of this element, which has a total “thickness” of 1.5-2.0 thousand km, is represented by several main layers, including:

1. Troposphere.
2. Tropopause.
3. Stratosphere.
4. Stratopause.
5. Mesosphere and mesopause.
6. Thermosphere.
7. Exosphere.

Basic elements of atmosphere

The troposphere is a layer in which strong vertical and horizontal movements are observed; it is here that weather, sedimentary phenomena, and climatic conditions are formed. It extends 7-8 kilometers from the surface of the planet almost everywhere, with the exception of the polar regions (up to 15 km there). In the troposphere, there is a gradual decrease in temperature, approximately by 6.4 ° C with each kilometer of altitude. This indicator may differ for different latitudes and seasons.

The composition of the Earth's atmosphere in this part is represented by the following elements and their percentages:

Nitrogen - about 78 percent;

Oxygen - almost 21 percent;

Argon - about one percent;

Carbon dioxide - less than 0.05%.

Single composition up to an altitude of 90 kilometers

In addition, here you can find dust, water droplets, water vapor, combustion products, ice crystals, sea salts, many aerosol particles, etc. This composition of the Earth’s atmosphere is observed up to approximately ninety kilometers in altitude, so the air is approximately the same in chemical composition, not only in the troposphere, but also in the overlying layers. But there the atmosphere has fundamentally different physical properties. The layer that has a common chemical composition, is called the homosphere.

What other elements make up the Earth's atmosphere? In percentage (by volume, in dry air) gases such as krypton (about 1.14 x 10 -4), xenon (8.7 x 10 -7), hydrogen (5.0 x 10 -5), methane (about 1.7 x 10 -5) are represented here. 4), nitrous oxide (5.0 x 10 -5), etc. As a percentage by mass, the most of the listed components are nitrous oxide and hydrogen, followed by helium, krypton, etc.

Physical properties of different atmospheric layers

The physical properties of the troposphere are closely related to its proximity to the surface of the planet. From here, reflected solar heat in the form of infrared rays is directed back upward, involving the processes of conduction and convection. That is why, with distance from earth's surface the temperature drops. This phenomenon is observed up to the height of the stratosphere (11-17 kilometers), then the temperature becomes almost unchanged up to 34-35 km, and then the temperature rises again to altitudes of 50 kilometers (the upper limit of the stratosphere). Between the stratosphere and the troposphere there is a thin intermediate layer of the tropopause (up to 1-2 km), where constant temperatures are observed above the equator - about minus 70 ° C and below. Above the poles, the tropopause “warms up” in summer to minus 45°C; in winter, temperatures here fluctuate around -65°C.

The gas composition of the Earth's atmosphere includes such an important element as ozone. There is relatively little of it at the surface (ten to the minus sixth power of one percent), since the gas is formed under the influence of sunlight from atomic oxygen in the upper parts of the atmosphere. In particular, the most ozone is at an altitude of about 25 km, and all “ ozone screen"located in areas from 7-8 km at the poles, from 18 km at the equator and up to fifty kilometers in total above the surface of the planet.

The atmosphere protects from solar radiation

The composition of the air in the Earth's atmosphere plays a very important role in preserving life, since individual chemical elements and compositions successfully limit the access of solar radiation to the earth's surface and the people, animals, and plants living on it. For example, water vapor molecules effectively absorb almost all ranges of infrared radiation, with the exception of lengths in the range from 8 to 13 microns. Ozone absorbs ultraviolet radiation up to a wavelength of 3100 A. Without its thin layer (only 3 mm on average if placed on the surface of the planet), only water at a depth of more than 10 meters and underground caves where solar radiation does not reach can be inhabited. .

Zero Celsius at the stratopause

Between the next two levels of the atmosphere, the stratosphere and mesosphere, there is a remarkable layer - the stratopause. It approximately corresponds to the height of ozone maxima and the temperature here is relatively comfortable for humans - about 0°C. Above the stratopause, in the mesosphere (starts somewhere at an altitude of 50 km and ends at an altitude of 80-90 km), a drop in temperature is again observed with increasing distance from the Earth's surface (to minus 70-80 ° C). Meteors usually burn up completely in the mesosphere.

In the thermosphere - plus 2000 K!

The chemical composition of the Earth's atmosphere in the thermosphere (begins after the mesopause from altitudes of about 85-90 to 800 km) determines the possibility of such a phenomenon as gradual heating of layers of very rarefied “air” under the influence of solar radiation. In this part of the “air blanket” of the planet, temperatures range from 200 to 2000 K, which are obtained due to the ionization of oxygen (atomic oxygen is located above 300 km), as well as the recombination of oxygen atoms into molecules, accompanied by the release of a large amount of heat. The thermosphere is where auroras occur.

Above the thermosphere is the exosphere - the outer layer of the atmosphere, from which light and rapidly moving hydrogen atoms can escape into outer space. The chemical composition of the Earth's atmosphere here is represented mostly by individual oxygen atoms in the lower layers, helium atoms in the middle layers, and almost exclusively hydrogen atoms in the upper layers. High temperatures prevail here - about 3000 K and there is no atmospheric pressure.

How was the earth's atmosphere formed?

But, as mentioned above, the planet did not always have such an atmospheric composition. In total, there are three concepts of the origin of this element. The first hypothesis suggests that the atmosphere was taken through the process of accretion from a protoplanetary cloud. However, today this theory is subject to significant criticism, since such a primary atmosphere should have been destroyed by the solar “wind” from a star in our planetary system. In addition, it is assumed that volatile elements could not be retained in the zone of planet formation according to the type terrestrial group due to too high temperatures.

The composition of the Earth's primary atmosphere, as suggested by the second hypothesis, could have been formed due to the active bombardment of the surface by asteroids and comets that arrived from the vicinity of the Solar system in the early stages of development. It is quite difficult to confirm or refute this concept.

Experiment at IDG RAS

The most plausible seems to be the third hypothesis, which believes that the atmosphere appeared as a result of the release of gases from the mantle earth's crust approximately 4 billion years ago. This concept was tested at the Institute of Geography of the Russian Academy of Sciences during an experiment called “Tsarev 2”, when a sample of a substance of meteoric origin was heated in a vacuum. Then the release of such gases as H 2, CH 4, CO, H 2 O, N 2, etc. was recorded. Therefore, scientists rightly assumed that the chemical composition of the Earth’s primary atmosphere included water and carbon dioxide, hydrogen fluoride (HF) vapor, carbon monoxide (CO), hydrogen sulfide (H 2 S), nitrogen compounds, hydrogen, methane (CH 4), ammonia vapor (NH 3), argon, etc. Water vapor from the primary atmosphere participated in the formation hydrosphere, carbon dioxide appeared to a greater extent in a bound state in organic substances and rocks, nitrogen passed into the composition of modern air, and also again into sedimentary rocks and organic substances.

The composition of the Earth's primary atmosphere would not have allowed modern people to be in it without breathing apparatus, since there was no oxygen in the required quantities then. This element appeared in significant quantities one and a half billion years ago, believed to be in connection with the development of the process of photosynthesis in blue-green and other algae, which are the oldest inhabitants of our planet.

Minimum oxygen

The fact that the composition of the Earth's atmosphere was initially almost oxygen-free is indicated by the fact that easily oxidized, but not oxidized graphite (carbon) is found in the oldest (Catarchaean) rocks. Subsequently, so-called banded iron ores appeared, which included layers of enriched iron oxides, which means the appearance on the planet of a powerful source of oxygen in molecular form. But these elements were found only periodically (perhaps the same algae or other oxygen producers appeared in small islands in an oxygen-free desert), while the rest of the world was anaerobic. The latter is supported by the fact that easily oxidized pyrite was found in the form of pebbles processed by flow without traces of chemical reactions. Since flowing waters cannot be poorly aerated, the view has developed that the atmosphere before the Cambrian contained less than one percent of the oxygen composition of today.

Revolutionary change in air composition

Approximately in the middle of the Proterozoic (1.8 billion years ago), an “oxygen revolution” occurred when the world switched to aerobic respiration, during which 38 can be obtained from one molecule of a nutrient (glucose), and not two (as with anaerobic respiration) units of energy. The composition of the Earth's atmosphere, in terms of oxygen, began to exceed one percent of what it is today, and an ozone layer began to appear, protecting organisms from radiation. It was from her that, for example, such ancient animals as trilobites “hid” under thick shells. From then until our time, the content of the main “respiratory” element gradually and slowly increased, ensuring the diversity of development of life forms on the planet.