At what altitude are the dense layers of the atmosphere. Information and facts about the atmosphere. Atmosphere of the Earth. Composition of the Earth's atmosphere
Earth's atmosphere
Atmosphere(from. Old Greekἀτμός - steam and σφαῖρα - ball) - gas shell ( geosphere), surrounding the planet Earth. Its inner surface covers hydrosphere and partially bark, the outer one borders on the near-Earth part of outer space.
The set of branches of physics and chemistry that study the atmosphere is usually called atmospheric physics. The atmosphere determines weather on the surface of the Earth, studying weather meteorology, and long-term variations climate - climatology.
The structure of the atmosphere
The structure of the atmosphere
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 atmospheric air and about 90% of all water vapor available in the atmosphere. In the troposphere are highly developed turbulence And convection, arise clouds, are developing cyclones And anticyclones. Temperature decreases with increasing altitude with average vertical gradient 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 the 25-40 km layer from −56.5 to 0.8 ° WITH(upper layer of the stratosphere or region inversions). 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 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
Earth's atmosphere
Mesosphere begins at an altitude of 50 km and extends to 80-90 km. Temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc., cause the glow of the atmosphere.
Mesopause
Transitional layer between the mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).
Karman Line
The height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space.
Thermosphere
Main article: Thermosphere
Upper limit- 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, air ionization occurs (“ auroras") - main areas ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates.
Atmospheric layers up to an altitude of 120 km
Exosphere (scattering sphere)
Exosphere- dispersion zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space ( dissipation).
Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases over 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 kinetic energy individual particles at altitudes of 200-250 km correspond 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 homosphere. The boundary between these layers is called turbo pause, it lies at an altitude of about 120 km.
Physical properties
The thickness of the atmosphere is approximately 2000 - 3000 km from the Earth's surface. Total mass air- (5.1-5.3)×10 18 kg. Molar mass 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 3 J/(kg K) (at 0 °C), C v 0.7159×10 3 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 develops 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 oxygen in alveolar air at normal atmospheric pressure is 110 mm Hg. 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 agents have an intense effect on the body. radiation- primary cosmic rays; at altitudes of more than 40 km, the ultraviolet part is dangerous to humans solar spectrum.
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 the propagation of sound, the emergence of aerodynamic lift and resistance, heat transfer convection and etc.
In rarefied layers of air, distribution sound turns out to be 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, concepts familiar to every pilot numbers M And sound barrier lose their meaning, there is a conditional Karman Line beyond which begins the sphere of purely ballistic flight, which can only be controlled using reactive forces.
At altitudes above 100 km, the atmosphere is deprived 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 space generally, the only way to transfer heat is thermal radiation.
Atmospheric composition
Composition of dry air
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).
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Composition of dry air |
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Nitrogen |
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Oxygen |
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Argon |
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Water |
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Carbon dioxide |
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Neon |
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Helium |
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Methane |
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Krypton |
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Hydrogen |
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Xenon |
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Nitrous oxide |
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In addition to the gases indicated in the table, the atmosphere contains SO 2, NH 3, CO, ozone, hydrocarbons, HCl, HF, couples Hg, I 2 , and also NO and many other gases in small quantities. Constantly located in the troposphere a large number 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 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 upper layers atmosphere.
Nitrogen N 2 reacts only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen by ozone at electrical discharges used in the industrial production of nitrogen fertilizers. They can oxidize it with low energy consumption and convert it into a biologically active form. cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis With legumes plants, so-called green manure.
Oxygen
The composition of the atmosphere began to change radically with the appearance on Earth living organisms, as a result photosynthesis accompanied by the release of oxygen and absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, hydrocarbons, nitrous form gland 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 atmosphere, lithosphere And biosphere, this event was called Oxygen disaster.
During Phanerozoic the composition of the atmosphere and oxygen content underwent changes. They correlated primarily with the rate of deposition of organic sediment. Thus, during periods of coal accumulation, the oxygen content in the atmosphere apparently significantly exceeded the modern level.
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 - from the intensity of biosynthesis and decomposition of organic matter in biosphere Earth. 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. Buried in ocean, V swamps and in forests organic matter turns into coal, oil And natural gas. (cm. Geochemical carbon cycle)
Noble gases
Source of inert gases - argon, helium And krypton- volcanic eruptions and decay of radioactive elements. The Earth in general and the atmosphere in particular are depleted of inert gases compared to space. It is believed that the reason for this lies in the continuous leakage of gases into interplanetary space.
Air pollution
Recently, the evolution of the atmosphere has begun to be influenced by Human. 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, NO, SO 2 ). 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 ) return to the surface of the Earth in the form of the so-called. acid rain. Usage internal combustion engines leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and lead compounds ( tetraethyl lead Pb(CH 3 CH 2 ) 4 ) ).
Aerosol pollution of the atmosphere is due to both natural causes (volcanic eruptions, dust storms, carryover 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.
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 arise, 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 ° 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
The mesosphere begins at an altitude of 50 km and extends to 80-90 km. Temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc. cause atmospheric luminescence.
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. The Karman line is located at an altitude of 100 km above sea level.
Boundary of the Earth's atmosphere
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. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity, a noticeable decrease in the size of this layer occurs.
Thermopause
The region of the atmosphere adjacent to the thermosphere. In this area the absorption solar radiation insignificantly and the temperature does not actually change with altitude.
Exosphere (scattering sphere)
Atmospheric layers up to an altitude of 120 km
The exosphere is a dispersion zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space (dissipation).
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.
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, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity affects the separation of gases, since their mixing at such a height 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.
The atmosphere has a layered structure. The boundaries between layers are not sharp and their height depends on latitude and time of year. The layered structure is the result of temperature changes at different altitudes. Weather is formed in the troposphere (lower about 10 km: about 6 km above the poles and more than 16 km above the equator). And the upper boundary of the troposophere is higher in summer than in winter.
From the surface of the Earth upward these layers are:
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Troposphere
The lower part of the atmosphere, up to a height of 10-15 km, in which 4/5 of the total mass of atmospheric air is concentrated, is called the troposphere. It is characteristic that the temperature here drops with height by an average of 0.6°/100 m (in some cases, the vertical temperature distribution varies widely). The troposphere contains almost all of the atmospheric water vapor and produces almost all of the clouds. Turbulence is also highly developed here, especially near the earth's surface, as well as in the so-called jet streams in the upper part of the troposphere.
The height to which the troposphere extends over each location on Earth varies from day to day. In addition, even on average it varies at different latitudes and in different seasons of the year. On average, the annual troposphere extends over the poles to a height of about 9 km, over temperate latitudes up to 10-12 km and above the equator up to 15-17 km. The average annual air temperature at the earth's surface is about +26° at the equator and about -23° at the north pole. At the upper boundary of the troposphere above the equator average temperature about -70°, above north pole in winter about -65°, and in summer about -45°.
The air pressure at the upper boundary of the troposphere, corresponding to its height, is 5-8 times less than at the earth's surface. Consequently, the bulk of atmospheric air is located in the troposphere. The processes occurring in the troposphere are directly and decisively important for the weather and climate at the earth's surface.
All water vapor is concentrated in the troposphere and that is why all clouds form within the troposphere. Temperature decreases with altitude.
The sun's rays easily pass through the troposphere, and the heat that radiates from the Earth, heated by the sun's rays, accumulates in the troposphere: gases such as carbon dioxide, methane and water vapor retain heat. This mechanism of warming the atmosphere from the Earth, heated by solar radiation, is called the greenhouse effect. Precisely because the source of heat for the atmosphere is the Earth, the air temperature decreases with height
The boundary between the turbulent troposphere and the calm stratosphere is called the tropopause. This is where fast-moving winds called "jet streams" form.
It was once assumed that the temperature of the atmosphere falls above the troposophere, but measurements in the high layers of the atmosphere have shown that this is not so: immediately above the tropopause the temperature is almost constant, and then begins to increase. Strong horizontal winds blow in the stratosphere without forming turbulence. The air in the stratosphere is very dry and therefore clouds are rare. So-called nacreous clouds are formed.
The stratosphere is very important for life on Earth, because it is in this layer that a small amount of ozone, which absorbs strong ultraviolet radiation that is harmful to life. By absorbing ultraviolet radiation, ozone heats the stratosphere.
Stratosphere
Above the troposphere to an altitude of 50-55 km lies the stratosphere, characterized by the fact that the temperature in it, on average, increases with height. The transition layer between the troposphere and stratosphere (1-2 km thick) is called the tropopause.
Above were data on the temperature at the upper boundary of the troposphere. These temperatures are also typical for the lower stratosphere. Thus, the air temperature in the lower stratosphere above the equator is always very low; Moreover, in summer it is much lower than above the pole.
The lower stratosphere is more or less isothermal. But, starting from an altitude of about 25 km, the temperature in the stratosphere quickly increases with altitude, reaching maximum positive values at an altitude of about 50 km (from +10 to +30°). Due to the increase in temperature with altitude, turbulence in the stratosphere is low.
There is negligible water vapor in the stratosphere. However, at altitudes of 20-25 km they are sometimes observed in high latitudes very thin, so-called nacreous clouds. During the day they are not visible, but at night they appear to glow, as they are illuminated by the sun below the horizon. These clouds are made up of supercooled water droplets. The stratosphere is also characterized by the fact that it mainly contains atmospheric ozone, as mentioned above
Mesosphere
Above the stratosphere lies the mesosphere layer, up to approximately 80 km. Here the temperature drops with altitude to several tens of degrees below zero. Due to the rapid drop in temperature with height, turbulence is highly developed in the mesosphere. At altitudes close to the upper boundary of the mesosphere (75-90 km), another special kind of clouds are observed, also illuminated by the sun at night, the so-called noctilucent ones. They are most likely composed of ice crystals.
At the upper boundary of the mesosphere, air pressure is 200 times less than at the earth's surface. Thus, in the troposphere, stratosphere and mesosphere together, up to an altitude of 80 km, lies more than 99.5% of the total mass of the atmosphere. The overlying layers account for a negligible amount of air
At an altitude of about 50 km above the Earth, the temperature begins to fall again, marking the upper limit of the stratosphere and the beginning of the next layer, the mesosphere. The mesosphere has the coldest temperature in the atmosphere: from -2 to -138 degrees Celsius. The highest clouds are also located here: in clear weather they can be seen at sunset. They are called noctilucent (glowing at night).
Thermosphere
The upper part of the atmosphere, above the mesosphere, is characterized by very high temperatures and is therefore called the thermosphere. However, two parts are distinguished in it: the ionosphere, extending from the mesosphere to altitudes of the order of a thousand kilometers, and the outer part lying above it - the exosphere, which turns into the earth's corona.
The air in the ionosphere is extremely rarefied. We have already indicated that at altitudes of 300-750 km its average density is about 10-8-10-10 g/m3. But even with such a low density, each cubic centimeter of air at an altitude of 300 km still contains about one billion (109) molecules or atoms, and at an altitude of 600 km - over 10 million (107). This is several orders of magnitude greater than the content of gases in interplanetary space.
The ionosphere, as its name suggests, is characterized by very strong degree air ionization - the ion content here is many times higher than in the underlying layers, despite the strong general rarefaction of the air. These ions are mainly charged oxygen atoms, charged nitric oxide molecules, and free electrons. Their content at altitudes of 100-400 km is about 1015-106 per cubic centimeter.
Several layers, or regions, with maximum ionization are distinguished in the ionosphere, especially at altitudes of 100-120 km and 200-400 km. But even in the spaces between these layers, the degree of ionization of the atmosphere remains very high. The position of the ionospheric layers and the concentration of ions in them change all the time. Sporadic collections of electrons with particularly high concentrations are called electron clouds.
The electrical conductivity of the atmosphere depends on the degree of ionization. Therefore, in the ionosphere, the electrical conductivity of air is generally 1012 times greater than that of the earth’s surface. Radio waves experience absorption, refraction and reflection in the ionosphere. Waves with a length of more than 20 m cannot pass through the ionosphere at all: they are reflected by electron layers of low concentration in the lower part of the ionosphere (at altitudes of 70-80 km). Medium and short waves are reflected by the overlying ionospheric layers.
It is due to reflection from the ionosphere that long-distance communication on short waves is possible. Multiple reflections from the ionosphere and the earth's surface allow short waves to travel in a zigzag manner over long distances, bending around the surface Globe. Since the position and concentration of ionospheric layers are constantly changing, the conditions for absorption, reflection and propagation of radio waves also change. Therefore, for reliable radio communications, continuous study of the state of the ionosphere is necessary. Observations of the propagation of radio waves are precisely the means for such research.
In the ionosphere, auroras and the glow of the night sky, which is close in nature to them in nature, are observed - constant luminescence of atmospheric air, as well as sharp fluctuations in the magnetic field - ionospheric magnetic storms.
Ionization in the ionosphere owes its existence to the action of ultraviolet radiation from the Sun. Its absorption by molecules of atmospheric gases leads to the formation of charged atoms and free electrons, as discussed above. Magnetic field fluctuations in the ionosphere and auroras depend on fluctuations in solar activity. Changes in solar activity are associated with changes in the flow of corpuscular radiation coming from the Sun into the earth's atmosphere. Namely, corpuscular radiation is of primary importance for these ionospheric phenomena.
The temperature in the ionosphere increases with altitude to very high values. At altitudes of about 800 km it reaches 1000°.
When we talk about high temperatures in the ionosphere, we mean that particles of atmospheric gases move there at very high speeds. However, the air density in the ionosphere is so low that a body located in the ionosphere, for example a flying satellite, will not be heated by heat exchange with the air. Temperature the satellite will depend on its direct absorption of solar radiation and on the release of its own radiation into the surrounding space. The thermosphere is located above the mesosphere at an altitude of 90 to 500 km above the Earth's surface. Gas molecules here are highly scattered and absorb X-rays and short-wavelength ultraviolet radiation. Because of this, temperatures can reach 1000 degrees Celsius.
The thermosphere basically corresponds to the ionosphere, where ionized gas reflects radio waves back to Earth, a phenomenon that makes radio communications possible.
Exosphere
Above 800-1000 km, the atmosphere passes into the exosphere and gradually into interplanetary space. The speeds of movement of gas particles, especially light ones, are very high here, and due to the extreme rarefaction of the air at these altitudes, the particles can fly around the Earth in elliptical orbits without colliding with each other. Individual particles can have speeds sufficient to overcome gravity. For uncharged particles, the critical speed will be 11.2 km/sec. Such especially fast particles can, moving along hyperbolic trajectories, fly out of the atmosphere into outer space, “escape”, and dissipate. Therefore, the exosphere is also called the scattering sphere.
Mostly hydrogen atoms, which are the dominant gas in the highest layers of the exosphere, escape.
Recently it was assumed that the exosphere, and with it the Earth’s atmosphere in general, ends at altitudes of about 2000-3000 km. But from observations by rockets and satellites, it appears that hydrogen escaping from the exosphere forms what is called the Earth's corona around the Earth, extending to more than 20,000 km. Of course, the density of gas in the earth's corona is negligible. For every cubic centimeter there are on average only about a thousand particles. But in interplanetary space the concentration of particles (mainly protons and electrons) is at least ten times less.
With the help of satellites and geophysical rockets, the existence in the upper part of the atmosphere and in near-Earth space of the Earth's radiation belt, starting at an altitude of several hundred kilometers and extending tens of thousands of kilometers from the earth's surface, has been established. This belt consists of electrically charged particles - protons and electrons, captured magnetic field Earth and moving at very high speeds. Their energy is on the order of hundreds of thousands of electron volts. The radiation belt is constantly losing particles in earth's atmosphere and is replenished by flows of solar corpuscular radiation.
atmosphere temperature stratosphere troposphere
The role of the atmosphere in the life of the Earth
The atmosphere is the source of oxygen that people breathe. However, as you rise to altitude, the total atmospheric pressure drops, which leads to a decrease in partial oxygen pressure.
The human lungs contain approximately three liters of alveolar air. If atmospheric pressure is normal, then the partial oxygen pressure in the alveolar air will be 11 mm Hg. Art., carbon dioxide pressure - 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. As altitude increases, oxygen pressure decreases, and the total pressure of water vapor and carbon dioxide in the lungs will remain constant - approximately 87 mm Hg. Art. When the air pressure equals this value, oxygen will stop flowing into the lungs.
Due to the decrease atmospheric pressure at an altitude of 20 km, water and interstitial fluid in the human body will boil here. If you do not use a pressurized cabin, at such a height a person will die almost instantly. Therefore, from the point of view physiological characteristics human body, “space” originates from a height of 20 km above sea level.
The role of the atmosphere in the life of the Earth is very great. For example, thanks to dense air layers- the troposphere and stratosphere, people are protected from radiation exposure. In space, in rarefied air, at an altitude of over 36 km, ionizing radiation acts. At an altitude of over 40 km - ultraviolet.
When rising above the Earth's surface to a height of over 90-100 km, a gradual weakening and then complete disappearance of phenomena familiar to humans observed in the lower atmospheric layer will be observed:
No sound travels.
There is no aerodynamic force or drag.
Heat is not transferred by convection, etc.
The atmospheric layer protects the Earth and all living organisms from cosmic radiation, from meteorites, is responsible for regulating seasonal temperature fluctuations, balancing and leveling daily rates. In the absence of an atmosphere on Earth daily temperature would fluctuate within +/-200С˚. The atmospheric layer is a life-giving “buffer” between the earth’s surface and space, a carrier of moisture and heat; the processes of photosynthesis and energy exchange take place in the atmosphere - the most important biosphere processes.
Layers of the atmosphere in order from the Earth's surface
The atmosphere is a layered structure consisting of the following layers of the atmosphere in order from the Earth's surface:
Troposphere.
Stratosphere.
Mesosphere.
Thermosphere.
Exosphere
Each layer does not have sharp boundaries between each other, and their height is affected by latitude and seasons. This layered structure was formed as a result of temperature changes at different altitudes. It is thanks to the atmosphere that we see twinkling stars.
Structure of the Earth's atmosphere by layers: 
What does the Earth's atmosphere consist of?
Each atmospheric layer differs in temperature, density and composition. The total thickness of the atmosphere is 1.5-2.0 thousand km. What does the Earth's atmosphere consist of? Currently, it is a mixture of gases with various impurities.
Troposphere
The structure of the Earth's atmosphere begins with the troposphere, which is bottom part atmosphere at a height of approximately 10-15 km. The bulk of atmospheric air is concentrated here. Characteristic troposphere - temperature drops by 0.6 ˚C as you rise upward for every 100 meters. The troposphere concentrates almost all atmospheric water vapor, and this is where clouds form.
The height of the troposphere changes daily. In addition, her average value varies depending on latitude and season of the year. The average height of the troposphere above the poles is 9 km, above the equator - about 17 km. Average indicators annual temperature air above the equator is close to +26 ˚C, and above the North Pole -23 ˚C. The upper line of the troposphere boundary above the equator is average annual temperature about -70 ˚C, and above the North Pole at summer time-45 ˚C and -65 ˚C in winter. Thus, the higher the altitude, the lower the temperature. The sun's rays pass unhindered through the troposphere, heating the Earth's surface. The heat emitted by the sun is retained by carbon dioxide, methane and water vapor.
Stratosphere
Above the troposphere layer is the stratosphere, which is 50-55 km in height. The peculiarity of this layer is that the temperature increases with height. Between the troposphere and the stratosphere lies a transition layer called the tropopause.
From approximately 25 kilometers the temperature of the stratospheric layer begins to increase and, upon reaching maximum height 50 km takes on values from +10 to +30 ˚C.
There is very little water vapor in the stratosphere. Sometimes at an altitude of about 25 km you can find rather thin clouds, which are called “pearl clouds”. In the daytime they are not noticeable, but at night they glow due to the illumination of the sun, which is below the horizon. The composition of nacreous clouds consists of supercooled water droplets. The stratosphere consists mainly of ozone.
Mesosphere
The height of the mesosphere layer is approximately 80 km. Here, as it rises upward, the temperature decreases and at the very top reaches values of several tens of C˚ below zero. In the mesosphere, clouds can also be observed, which are presumably formed from ice crystals. These clouds are called "noctilucent." The mesosphere is characterized by the coldest temperature in the atmosphere: from -2 to -138 ˚C.
Thermosphere
This atmospheric layer acquired its name thanks to high temperatures. The thermosphere consists of:
Ionosphere.
Exosphere.
The ionosphere is characterized by rarefied air, each centimeter of which at an altitude of 300 km consists of 1 billion atoms and molecules, and at an altitude of 600 km - more than 100 million.
The ionosphere is also characterized by high air ionization. These ions are made up of charged oxygen atoms, charged molecules of nitrogen atoms, and free electrons.
Exosphere
The exospheric layer begins at an altitude of 800-1000 km. Gas particles, especially light ones, move here at tremendous speed, overcoming the force of gravity. Such particles, due to their rapid movement, fly out of the atmosphere into outer space and are scattered. Therefore, the exosphere is called the sphere of dispersion. Mostly hydrogen atoms, which make up the highest layers of the exosphere, fly into space. Thanks to particles in the upper atmosphere and particles from the solar wind, we can see the northern lights.
Satellites and geophysical rockets have made it possible to establish the presence in the upper layers of the atmosphere of the planet’s radiation belt, consisting of electrically charged particles - electrons and protons.
The atmosphere has clearly defined layers of air. The layers of air differ from each other in temperature, difference in gases and their density and pressure. It should be noted that the layers of the stratosphere and troposphere protect the Earth from solar radiation. In the higher layers, a living organism can receive lethal dose ultraviolet solar spectrum. To quickly jump to the desired atmosphere layer, click on the corresponding layer:
Troposphere and tropopause
Troposphere - temperature, pressure, altitude
The upper limit is approximately 8 - 10 km. IN temperate latitudes 16 - 18 km, and in the polar 10 - 12 km. Troposphere- This is the lower main layer of the atmosphere. This layer contains more than 80% of the total mass of atmospheric air and close to 90% of all water vapor. It is in the troposphere that convection and turbulence occur, clouds form, and cyclones occur. Temperature decreases with increasing altitude. Gradient: 0.65°/100 m. Heated earth and water heat the surrounding air. The heated air rises, cools and forms clouds. The temperature in the upper boundaries of the layer can reach – 50/70 °C.
It is in this layer that climate changes occur weather conditions. The lower boundary of the troposphere is called ground level, since it has a lot of volatile microorganisms and dust. Wind speed increases with increasing height in this layer.
Tropopause
This is the transition layer of the troposphere to the stratosphere. Here the dependence of temperature decrease with increasing altitude stops. Tropopause is the minimum altitude where the vertical temperature gradient drops to 0.2°C/100 m. The height of the tropopause depends on strong climatic events such as cyclones. The height of the tropopause decreases above cyclones, and increases above anticyclones.
Stratosphere and Stratopause
The height of the stratosphere layer is approximately 11 to 50 km. There is a slight change in temperature at an altitude of 11 - 25 km. At an altitude of 25 - 40 km it is observed inversion temperatures, from 56.5 rises to 0.8°C. From 40 km to 55 km the temperature stays at 0°C. This area is called - Stratopause.
In the Stratosphere, the effect of solar radiation on gas molecules is observed; they dissociate into atoms. There is almost no water vapor in this layer. Modern supersonic commercial aircraft fly at altitudes of up to 20 km due to stable flight conditions. High-altitude weather balloons rise to a height of 40 km. There are stable air currents here, their speed reaches 300 km/h. Also concentrated in this layer ozone, the layer that absorbs ultra-violet rays.
Mesosphere and Mesopause - composition, reactions, temperature
The mesosphere layer begins at approximately 50 km altitude and ends at 80 - 90 km. Temperatures decrease with increasing altitude by approximately 0.25-0.3°C/100 m. The main energetic effect here is radiant heat exchange. Complex photochemical processes involving free radicals (has 1 or 2 unpaired electrons) because they implement glow atmosphere.
Almost all meteors burn up in the mesosphere. Scientists named this zone - Ignorosphere. This zone is difficult to explore, since aerodynamic aviation here is very poor due to the air density, which is 1000 times less than on Earth. And for launching artificial satellites, the density is still very high. Research is carried out using weather rockets, but this is a perversion. Mesopause transition layer between the mesosphere and thermosphere. Has a temperature of at least -90°C.
Karman Line
Pocket line called the boundary between the Earth's atmosphere and space. According to the International Aviation Federation (FAI), the height of this border is 100 km. This definition was given in honor of the American scientist Theodore Von Karman. He determined that at approximately this altitude the density of the atmosphere is so low that aerodynamic aviation becomes impossible here, since the speed of the aircraft must be greater escape velocity. At such a height, the concept of a sound barrier loses its meaning. Here to manage aircraft is possible only due to reactive forces.
Thermosphere and Thermopause
The upper boundary of this layer is approximately 800 km. The temperature rises to approximately an altitude of 300 km where it reaches about 1500 K. Above the temperature remains unchanged. In this layer occurs Polar Lights- Occurs as a result of the effect of solar radiation on the air. This process is also called the ionization of atmospheric oxygen.
Due to the low air rarefaction, flights above the Karman line are only possible by ballistic trajectories. All manned orbital flights (except flights to the Moon) take place in this layer of the atmosphere.
Exosphere - density, temperature, height
The height of the exosphere is above 700 km. Here the gas is very rarefied, and the process takes place dissipation— leakage of particles into interplanetary space. The speed of such particles can reach 11.2 km/sec. An increase in solar activity leads to an expansion of the thickness of this layer.
- The gas shell does not fly into space due to gravity. Air consists of particles that have their own mass. From the law of gravity we can conclude that every object with mass is attracted to the Earth.
- Buys-Ballot's Law states that if you are in the Northern Hemisphere and stand with your back to the wind, then the zone will be located on the right high pressure, and on the left - low. In the Southern Hemisphere, everything will be the other way around.
