Atmospheric temperature at all altitudes. Composition of the earth's atmosphere
The gaseous envelope surrounding our planet Earth, known as the atmosphere, consists of five main layers. These layers originate on the surface of the planet, from sea level (sometimes below) and rise to outer space in the following sequence:
- Troposphere;
- Stratosphere;
- Mesosphere;
- Thermosphere;
- Exosphere.
Diagram of the main layers of the Earth's atmosphere
In between each of these main five layers are transition zones called "pauses" where changes in air temperature, composition and density occur. Together with pauses, the Earth's atmosphere includes a total of 9 layers.
Troposphere: where weather occurs
Of all the layers of the atmosphere, the troposphere is the one with which we are most familiar (whether you realize it or not), since we live on its bottom - the surface of the planet. It envelops the surface of the Earth and extends upward for several kilometers. The word troposphere means "change of the globe." A very appropriate name, since this layer is where our everyday weather occurs.
Starting from the surface of the planet, the troposphere rises to a height of 6 to 20 km. The lower third of the layer, closest to us, contains 50% of all atmospheric gases. This is the only part of the entire atmosphere that breathes. Due to the fact that the air is heated from below earth's surface, absorbing thermal energy The sun, with increasing altitude, the temperature and pressure of the troposphere decrease.
At the top there is a thin layer called the tropopause, which is just a buffer between the troposphere and the stratosphere.
Stratosphere: home of the ozone
The stratosphere is the next layer of the atmosphere. It extends from 6-20 km to 50 km above the Earth's surface. This is the layer in which most commercial airliners fly and hot air balloons travel.
Here the air does not flow up and down, but moves parallel to the surface in very fast air currents. As you climb, the temperature increases, thanks to the abundance of natural ozone (O3) byproduct solar radiation and oxygen, which has the ability to absorb harmful ultraviolet rays from the sun (any increase in temperature with height in meteorology is known as an "inversion").
Since the stratosphere has more warm temperatures below and cooler above, convection (vertical movement of air masses) is rare in this part of the atmosphere. In fact, you can view a storm raging in the troposphere from the stratosphere because the layer acts as a convection cap that prevents storm clouds from penetrating.
After the stratosphere there is again a buffer layer, this time called the stratopause.
Mesosphere: middle atmosphere
The mesosphere is located approximately 50-80 km from the Earth's surface. The upper region of the mesosphere is the coldest natural place on Earth, where temperatures can drop below -143°C.
Thermosphere: upper atmosphere
After the mesosphere and mesopause comes the thermosphere, located between 80 and 700 km above the surface of the planet, and contains less than 0.01% of the total air in the atmospheric envelope. Temperatures here reach up to +2000° C, but due to the strong rarefaction of the air and the lack of gas molecules to transfer heat, these high temperatures are perceived as very cold.
Exosphere: the boundary between the atmosphere and space
![](https://i1.wp.com/natworld.info/wp-content/uploads/2017/08/sloi-atmosfery.jpg)
At an altitude of about 700-10,000 km above the earth's surface is the exosphere - the outer edge of the atmosphere, bordering space. Here weather satellites orbit the Earth.
What about the ionosphere?
The ionosphere is not a separate layer, but in fact the term is used to refer to the atmosphere between 60 and 1000 km altitude. It includes the uppermost parts of the mesosphere, the entire thermosphere and part of the exosphere. The ionosphere gets its name because it is in this part of the atmosphere that radiation from the Sun is ionized as it passes through magnetic fields Lands on and. This phenomenon is observed from the ground as the northern lights.
The stratosphere (from Latin stratum - flooring, layer) is a layer of the atmosphere with a height from 11 to 50 km located above the troposphere. The transition from the troposphere to the stratosphere occurs smoothly, since between them there is a thin intermediate layer called the tropopause, in which the temperature does not decrease with height. The main feature of the stratosphere is the increase in temperature with height. In the lower part of this layer (up to a height of 25 km) the temperature is stable or increases slowly with height, but from the level of 34 - 36 km the temperature rise begins to increase. The increase in temperature lasts until the stratopause - upper limit the stratosphere, which is as warm as the air masses near the Earth's surface.
Compound
The high stability of the stratosphere is due to the increase in temperature with height. Unlike the troposphere, in this layer there is no ordered vertical movement of air and its mixing, but there are small vertical movements in the form of slow subsidence or rise, covering the layers of the stratosphere over vast areas. Air heating in the stratosphere occurs due to the absorption of ultraviolet radiation by ozone, and cooling occurs due to long-wave radiation from H2O and CO2 molecules. Therefore, in low latitudes, where the content of H2O and CO2 is increased and O3 is lower, is colder than above the high latitudes of the stratosphere. In the stratosphere at an altitude of 20 - 25 km in summer the wind direction changes from western to eastern, and in winter it constantly blows westerly winds. At the upper boundary of the stratosphere, maximum high speeds winds and jet streams.
At the bottom of the stratosphere at an altitude of up to 20 - 25 km There is an increased content of aerosol particles, especially sulfate particles, which are brought here during volcanic eruptions. Here they persist longer than in the troposphere due to low turbulent exchange and lack of washout by precipitation.
There is very little water vapor in the stratosphere, but pearlescent clouds are sometimes observed at high latitudes at an altitude of 22 - 24 km . They are especially visible at night, illuminated by the Sun below the horizon. It is assumed that these clouds are formed from supercooled drops or ice crystals.
In the stratosphere gas composition air is practically no different from that in the troposphere, but has a difference, namely, an increased content of ozone (O3). The stratosphere can be called the ozonosphere, due to the presence of an ozone layer in it. The ozone layer was formed and preserved due to the interaction of the sun's ultraviolet rays with oxygen molecules, and serves as a reliable barrier to ultraviolet radiation, which is harmful to all living organisms. When absorbed solar energy The ozone layer increases the temperature of the atmosphere, and therefore the ozone layer is a kind of heat reservoir in the atmosphere. Up to an altitude of 10 km and more than 60 km, the atmosphere is almost completely devoid of ozone, and its maximum concentration is concentrated at an altitude of 20 - 30 km. In the stratosphere, the thermal regime is mainly determined by radiant heat transfer. Ozone is destroyed when interacting with NO, free radicals, and halogen-containing compounds.
The main share of the short-wave part of ultraviolet radiation (180 - 200 nm) remains in the stratosphere and the energy of short waves is transformed. Under the influence of ultraviolet rays, magnetic fields change, molecules disintegrate, ionize, and new gases and other chemical compounds are formed. In nature, these processes are observed as northern lights, lightning and other glows.
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). 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 area constant temperature called the stratopause and is the boundary between the stratosphere and mesosphere. The air density in the stratosphere is tens and hundreds of times less than at ground level.
It is in the stratosphere that the ozone layer (“ozone layer”) is located (at an altitude of 15-20 to 55-60 km), which determines the upper limit of life in the biosphere. Ozone (O 3) is formed as a result of photo chemical reactions most intense at an altitude of ~30 km. total weight O 3 would constitute a layer 1.7-4.0 mm thick at normal pressure, but this is enough to absorb life-destructive ultraviolet radiation from the Sun. The destruction of O 3 occurs when it interacts with free radicals, halogen-containing compounds (including “freons”).
Lingers in the stratosphere most of short-wave part of ultraviolet radiation (180-200 nm) and the transformation of short-wave energy occurs. Under the influence of these rays, magnetic fields change, molecules disintegrate, ionization occurs, and new formation of gases and other chemical compounds occurs. These processes can be observed in the form of northern lights, lightning and other glows.
In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate into atoms (above 80 km CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - N 2). At an altitude of 200-500 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O − 2, N + 2) is ~ 1/300 of the concentration of neutral particles. In the upper layers of the atmosphere there are free radicals - OH, HO 2, etc.
There is almost no water vapor in the stratosphere.
Flights in the stratosphere
Flights into the stratosphere began in the 1930s. The flight on the first stratospheric balloon (FNRS-1), which was made by Auguste Picard and Paul Kipfer on May 27, 1931 to an altitude of 16.2 km, is widely known. Modern combat and supersonic commercial aircraft fly in the stratosphere at altitudes generally up to 20 km (although the dynamic ceiling can be much higher). High-altitude weather balloons rise up to 40 km; the record for an unmanned balloon is 51.8 km.
IN Lately in US military circles great attention pay attention to the development of layers of the stratosphere above 20 km, often called “pre-space” (eng. "near space" ). It is assumed that unmanned airships and solar-powered aircraft (like NASA's Pathfinder) will be able to long time be at an altitude of about 30 km and provide surveillance and communications very large areas, while remaining slightly vulnerable to air defense systems; Such devices will be many times cheaper than satellites.
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2010.:Synonyms
See what "Stratosphere" is in other dictionaries: Stratosphere...
Spelling dictionary-reference book stratosphere - y, w. stratosphere lat. stratum flooring, layer. + gr. sphaire sphere. The layer of the atmosphere located above the troposphere, at an altitude of 8-12 to 80 km. above sea level. BAS 1. Established the existence of the stratosphere and proposed its name in French. meteorologist... ...
Historical Dictionary of Gallicisms of the Russian Language - (from Latin stratum layer and sphere) layer of the atmosphere lying above the troposphere from 8-10 km in high latitudes and from 16-18 km near the equator to 50-55 km. The stratosphere is characterized by an increase in temperature with altitude from 40.C (80.C) to temperatures close to ...
Big Encyclopedic Dictionary STRATOSPHERE, part of the Earth's ATMOSPHERE, located between the TROPOSPHERE and MESOSPHERE. 10 km high, with the temperature of approximately half of this layer remaining constant. The stratosphere contains most of the ozone layer of the atmosphere...
Scientific and technical encyclopedic dictionary STRATOSPHERE, stratosphere, many. no, female (from Latin stratum flooring and Greek sphaira ball). The upper layer of the atmosphere located above the troposphere at an altitude of 11 to 75 km above sea level. Dictionary Ushakova. D.N. Ushakov. 1935 1940 ...
Ushakov's Explanatory Dictionary STRATOSPHERE, s, female. (specialist.). Upper layer earth's atmosphere , lying above the troposphere. | adj. stratospheric, oh, oh. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 …
- (from Latin stratum layer and Greek sphaira ball) see the article Earth's Atmosphere. Aviation: Encyclopedia. M.: Great Russian Encyclopedia. Chief Editor G.P. Svishchev. 1994 ... Encyclopedia of technology
The layer of the atmosphere between the troposphere and mesosphere. The lower boundary of the S. tropopause is located in the polar and temperate latitudes at an altitude of z 8 12 km, in the tropics at z 16 18 km. From winter to summer, the tropopause rises on Wednesday. for 1 2 km. Upper limit N.... ... Physical encyclopedia
The layer of the atmosphere located above 11 km is very rarefied, with a very low atmosphere; bottom layer atmosphere is called the troposphere. There are no vertical currents or cloud formation in the north. The study of S. has practical significance for aviation,... ... Marine dictionary
The stratosphere is one of the upper layers air shell of our planet. It begins at an altitude of approximately 11 km above the ground. Passenger aircraft no longer fly here and clouds rarely form. The Earth's ozone layer is located in the stratosphere - a thin shell that protects the planet from the penetration of harmful ultraviolet radiation.
The air envelope of the planet
The atmosphere is the gaseous envelope of the Earth adjacent to inner surface to the hydrosphere and earth's crust. Its outer border gradually turns into space. The composition of the atmosphere includes gases: nitrogen, oxygen, argon, carbon dioxide, and so on, as well as impurities in the form of dust, water droplets, ice crystals, and combustion products. The ratio of the main elements of the air shell remains constant. The exceptions are carbon dioxide and water - their amount in the atmosphere often changes.
Layers of gas shell
The atmosphere is divided into several layers, located one above the other and having features in their composition:
boundary layer - directly adjacent to the surface of the planet, extending to a height of 1-2 km;
troposphere - the second layer, the outer boundary is located on average at an altitude of 11 km, almost all the water vapor of the atmosphere is concentrated here, clouds form, cyclones and anticyclones arise, and as the altitude increases, the temperature rises;
tropopause - a transition layer characterized by the cessation of temperature decrease;
the stratosphere is a layer that extends to a height of 50 km and is divided into three zones: from 11 to 25 km the temperature changes slightly, from 25 to 40 - the temperature rises, from 40 to 50 - the temperature remains constant (stratopause);
the mesosphere extends to a height of 80-90 km;
the thermosphere reaches 700-800 km above sea level, here at an altitude of 100 km is the Karman line, which is taken as the boundary between the Earth’s atmosphere and space;
The exosphere is also called the scattering zone; particles of matter are greatly lost here, and they fly off into space.
Temperature changes in the stratosphere
So, the stratosphere is the part of the gas shell of the planet that follows the troposphere. Here the air temperature, constant throughout the tropopause, begins to change. The height of the stratosphere is approximately 40 km. The lower limit is 11 km above sea level. Starting from this point, the temperature undergoes minor changes. At an altitude of 25 km, the heating rate begins to slowly increase. At 40 km above sea level, the temperature rises from -56.5º to +0.8ºС. Then it remains close to zero degrees up to an altitude of 50-55 km. The zone between 40 and 55 kilometers is called the stratopause because the temperature does not change here. She happens to be transition zone from the stratosphere to the mesosphere.
Features of the stratosphere
The Earth's stratosphere contains about 20% of the mass of the entire atmosphere. The air here is so rarefied that it is impossible for a person to stay without a special spacesuit. This fact is one of the reasons why flights into the stratosphere began to be carried out only relatively recently.
Another feature of the gas shell of the planet at an altitude of 11-50 km is the very small quantity water vapor. For this reason, clouds almost never form in the stratosphere. It's just not for them building material. However, it is rarely possible to observe the so-called mother-of-pearl clouds with which the stratosphere is “decorated” (photo below) at an altitude of 20-30 km above sea level. Thin formations, as if glowing from within, can be observed after sunset or before sunrise. The shape of nacreous clouds is similar to cirrus or cirrocumulus.
Earth's ozone layer
home distinguishing feature The stratosphere is the maximum concentration of ozone in the entire atmosphere. It is formed under the influence sun rays and protects all life on the planet from their destructive radiation. The Earth's ozone layer is located at an altitude of 20-25 km above sea level. O 3 molecules are distributed throughout the stratosphere and even exist near the surface of the planet, but at this level their highest concentration is observed.
It should be noted that the Earth's ozone layer is only 3-4 mm. This will be its thickness if particles of this gas are placed under conditions normal pressure, for example, near the surface of the planet. Ozone is formed as a result of the breakdown of an oxygen molecule under the influence of ultraviolet radiation into two atoms. One of them combines with a “full” molecule and ozone is formed - O 3.
Dangerous Defender
Thus, today the stratosphere is a more explored layer of the atmosphere than at the beginning of the last century. However, the future of the ozone layer, without which life on Earth would not have arisen, remains not very clear. While countries are cutting back on freon production, some scientists say it won't bring much benefit, according to at least, at such a pace, and others that this is not necessary at all, since the bulk of harmful substances are formed naturally. Time will judge who is right.
Earth's atmosphere
Atmosphere(from. other 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 of atmospheric air and about 90% of all water vapor present 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
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, 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- scattering zone, outer part 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 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., pressure carbon dioxide- 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 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 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 resistance and lift air 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).
Composition of dry air |
||
Nitrogen | ||
Oxygen | ||
Argon | ||
Water | ||
Carbon dioxide | ||
Neon | ||
Helium | ||
Methane | ||
Krypton | ||
Hydrogen | ||
Xenon | ||
Nitrous oxide |
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 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. They can oxidize it with low energy consumption and convert it into a biologically active form. cyanobacteria (blue-green algae) And nodule bacteria, forming the 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 content of CO 2 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 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.