Atmosphere of earth

Atmosphere(from. Old Greekἀτμός - steam and σφαῖρα - ball) - gas shell ( geosphere) surrounding the planet Land... Its inner surface covers hydrosphere and partly bark, the outer one is bordered by the near-earth part of outer space.

The set of sections of physics and chemistry that study the atmosphere are usually called physics of the atmosphere... The atmosphere defines the weather on the surface of the earth, studying the weather meteorology, and long-term variations climate - climatology.

The structure of the atmosphere

The structure of the atmosphere

Troposphere

Its upper boundary 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 in the atmosphere. Strongly developed in the troposphere turbulence and convection, arise clouds, develop cyclones and anticyclones... The temperature decreases with increasing altitude with an average vertical gradient 0.65 ° / 100 m

For "normal conditions" at the Earth's surface, the following are taken: density 1.2 kg / m3, barometric pressure 101.35 kPa, temperature plus 20 ° C and relative humidity 50%. These conditional indicators are of purely engineering significance.

Stratosphere

The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the layer 11-25 km (the lower layer of the stratosphere) and its increase in the layer 25-40 km from -56.5 to 0.8 ° are characteristic WITH(the upper layer of the stratosphere or area 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 border between the stratosphere and mesosphere.

Stratopause

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

Mesosphere

Atmosphere of earth

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

Mesopause

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

Pocket Line

Height above sea level, which is conventionally taken as the boundary between the Earth's atmosphere and space.

Thermosphere

Main article: Thermosphere

Atmospheric layers up to a height of 120 km

Exosphere (Orb of Dispersion)

Exosphere- the scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and hence the leakage of its particles 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 along the height depends on their molecular masses, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in the density of gases, 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 the temperature and density of gases are observed in time and space.

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 is only a fraction of the interplanetary matter. Another part is made up of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like 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. On the basis of electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. At present, it is 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. Heterosphere - this is the area where gravity affects the separation of gases, since their mixing at this height is negligible. Hence the 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 turbopause, 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). Solubility of air in water at 0 ° C - 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 has oxygen starvation and without adaptation, human performance is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 15 km, although the atmosphere contains oxygen up to about 115 km.

The atmosphere supplies us with the oxygen we need to breathe. However, due to the drop in the total pressure of the atmosphere as it rises to altitude, the partial pressure of oxygen also 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., the pressure of carbon dioxide is 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. With increasing altitude, the oxygen pressure drops, and the total pressure of water vapor and carbon dioxide in the lungs remains almost constant - about 87 mm Hg. Art. The flow of oxygen to the lungs will stop completely when the pressure of the surrounding air 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 height, water and interstitial fluid begin to boil in the human body. Outside the pressurized cabin, at these heights, 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 - 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; at altitudes of more than 40 km, the ultraviolet part of the solar spectrum, which is dangerous for humans, operates.

As we rise to an ever greater height above the Earth's surface, they gradually weaken, and then completely disappear, such phenomena familiar to us, observed in the lower layers of the atmosphere, such as the propagation of sound, the emergence of aerodynamic lifting force and resistance, heat transfer convection and etc.

In rarefied layers of air, the spread sound turns out to be impossible. Up to heights of 60-90 km, it is still possible to use the resistance and lift of the air for controlled aerodynamic flight. But starting from altitudes of 100-130 km, concepts are familiar to every pilot numbers M and sound barrier lose their meaning, there is a conditional Pocket Line behind which begins the sphere of purely ballistic flight, which can be controlled only using reactive forces.

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

Atmosphere composition

Dry air 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 practically constant, with the exception of water (H 2 O) and carbon dioxide (CO 2).

Dry air composition

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 NO and many other gases in small quantities. In the troposphere, there is constantly a large number of suspended solid and liquid particles ( spray can).

The history of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere over time was in four different compositions. 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 saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, steam). So it was formed secondary atmosphere(about three billion years ago). The atmosphere was restorative. Further, the process of the formation of the atmosphere was determined by the following factors:

leakage of light gases (hydrogen and helium) into interplanetary space;

chemical reactions 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 hydrogen content and a much higher nitrogen and carbon dioxide content (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 with molecular O 2, which began to flow from the planet's surface as a result of photosynthesis, starting from 3 billion years ago. Also, N 2 is 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 strike). Oxidation of molecular nitrogen with ozone during electrical discharges is used in the industrial production of nitrogen fertilizers. It can be oxidized with low energy consumption and converted into a biologically active form. cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis With legumes plants, so-called. siderates.

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 the absorption of carbon dioxide. Initially, oxygen was consumed for the oxidation of reduced compounds - ammonia, hydrocarbons, acidic form gland contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties was formed. Since this caused serious and dramatic changes in many processes taking place in atmosphere, lithosphere and biosphere, this event was named Oxygen disaster.

During phanerozoic the composition of the atmosphere and the oxygen content underwent changes. They correlated primarily with the rate of deposition of organic sedimentary rocks. Thus, during periods of coal accumulation, the oxygen content in the atmosphere, apparently, significantly exceeded the current 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 Of the earth... Almost all of the planet's current biomass (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 turns into coal, oil and natural gas... (cm. Geochemical cycle of carbon)

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 in 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 began 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. Enormous amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic matter of plant and animal origin, as well as due to volcanism and human production activities. 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 CO2 in the atmosphere will double and may lead to global climate change.

Fuel combustion is the main source of pollutant gases ( CO, NO, SO 2 ). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3 in the upper atmosphere, which in turn interacts with water and ammonia vapors, 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 pollution of the atmosphere with nitrogen oxides, hydrocarbons and lead compounds ( tetraethyl lead Pb (CH 3 CH 2 ) 4 ) ).

Aerosol pollution of the atmosphere is caused both by natural causes (volcanic eruptions, dust storms, carry-over of seawater droplets and plant pollen, etc.), and by human economic activities (mining of ores and building materials, burning fuel, making cement, etc.). Intense large-scale removal of solid particles into the atmosphere is one of the possible causes of climate change on the planet.

The role of the atmosphere in the life of the Earth

The atmosphere is the source of oxygen that humans breathe. However, when climbing to altitude, the total atmospheric pressure drops, which leads to a decrease in the partial oxygen pressure.

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., the pressure of carbon dioxide is 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. With increasing altitude, oxygen pressure decreases, and the pressure of water vapor and carbon dioxide in the lungs in total will remain constant - approximately 87 mm Hg. Art. When the air pressure equals this value, oxygen will stop flowing to the lungs.

Due to the decrease in atmospheric pressure at an altitude of 20 km, water and interstitial body fluid in the human body will boil here. If you do not use a pressurized cabin, a person will die almost instantly at this height. Therefore, from the point of view of the physiological characteristics of the human body, "space" originates from an altitude of 20 km above sea level.

The role of the atmosphere in the life of the Earth is very great. So, for example, thanks to the dense air layers - the troposphere and stratosphere, people are protected from radiation exposure. In space, in thin 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 an altitude of more than 90-100 km, a gradual weakening, and then a complete disappearance of the phenomena familiar to humans, observed in the lower atmospheric layer, will be observed:

Sound does not propagate.

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 diurnal. In the absence of an atmosphere on Earth, the daily temperature would fluctuate within +/- 200C˚. 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, the most important biospheric processes, take place in the atmosphere.

Layers of the atmosphere in order from the surface of the Earth

The atmosphere is a layered structure representing the following layers of the atmosphere in order from the surface of the Earth:

Troposphere.

Stratosphere.

Mesosphere.

Thermosphere.

Exosphere

Each layer has no sharp boundaries between each other, and their height is influenced by latitude and seasons. This layered structure was formed as a result of temperature changes at different heights. It is thanks to the atmosphere that we see the twinkling stars.

The structure of the Earth's atmosphere by layers:

What is the Earth's atmosphere made of?

Each atmospheric layer differs in temperature, density and composition. The total thickness of the atmosphere is 1.5-2.0 thousand km. What is the Earth's atmosphere made of? At present, it is a mixture of gases with various impurities.

Troposphere

The structure of the Earth's atmosphere begins with the troposphere, which is the lower part of the atmosphere approximately 10-15 km high. The main part of the atmospheric air is concentrated here. A characteristic feature of the troposphere is a drop in temperature by 0.6 ˚C as it rises upward for every 100 meters. The troposphere has concentrated almost all atmospheric water vapor, and clouds form here.

The height of the troposphere changes daily. In addition, its average value changes depending on the latitude and season of the year. The average height of the troposphere above the poles is 9 km, above the equator - about 17 km. The average annual air temperature above the equator is close to +26 ˚C, and above the North Pole -23 ˚C. The upper line of the tropospheric boundary above the equator is an average annual temperature of about -70 ˚C, and above the North Pole in summer -45 ˚C and in winter -65 ˚C. 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 radiated from the sun is trapped by carbon dioxide, methane and water vapor.

Stratosphere

Above the tropospheric layer is the stratosphere, which is 50-55 km high. The peculiarity of this layer is the rise in temperature with height. Between the troposphere and the stratosphere there is a transitional layer called the tropopause.

From an altitude of about 25 kilometers, the temperature of the stratospheric layer begins to increase and, upon reaching a maximum height of 50 km, it acquires 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 "nacreous". In the daytime they are not noticeable, and at night they glow due to the illumination of the sun, which is below the horizon. The composition of nacreous clouds is supercooled water droplets. The stratosphere is composed primarily of ozone.

Mesosphere

The height of the mesosphere is approximately 80 km. Here, as it rises upward, the temperature decreases and at the uppermost boundary reaches values of several tens of C˚ below zero. Clouds can also be observed in the mesosphere, presumably formed from ice crystals. These clouds are called "silvery". The mesosphere is characterized by the coldest temperature in the atmosphere: from -2 to -138 ˚C.

Thermosphere

This atmospheric layer acquired its name due to the high temperatures. The thermosphere consists of:

Ionosphere.

Exospheres.

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 - of more than 100 million.

Also, the ionosphere is 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. Particles of gas, especially light ones, move here with great speed, overcoming the force of gravity. Such particles, due to their rapid movement, fly out of the atmosphere into outer space and scatter. Therefore, the exosphere is called the sphere of dispersion. Mostly hydrogen atoms, which make up the highest layers of the exosphere, fly out into space. Thanks to particles in the upper atmosphere and particles from the solar wind, we can observe the northern lights.

Satellites and geophysical rockets made it possible to establish the presence in the upper atmosphere of the planet's radiation belt, consisting of electrically charged particles - electrons and protons.

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

Tropopause

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

Stratosphere

The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the layer of 11-25 km (the lower layer of the stratosphere) and its increase in the layer 25-40 km from -56.5 to 0.8 ° (the upper layer of the stratosphere or the inversion region) are characteristic. 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 the mesosphere.

Stratopause

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

Mesosphere

Atmosphere of earth

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 up to high altitudes. Under the influence of ultraviolet and X-ray solar radiation and cosmic radiation, air ionization ("polar lights") occurs - the main areas of the ionosphere lie inside the thermosphere. At altitudes over 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 to the top of the thermosphere. In this area, the absorption of solar radiation is negligible and the temperature does not actually change with altitude.

Exosphere (Orb of Dispersion)

Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases along the height depends on their molecular masses, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in the density of gases, 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 the temperature and density of gases are observed in time and space.

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 is only a fraction of the interplanetary matter. Another part is made up of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

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

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, the person's working capacity is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 9 km, although the atmosphere contains oxygen up to about 115 km.

In rarefied layers of air, the propagation of sound is impossible. Up to heights of 60-90 km, it is still possible to use the resistance and lift of the air for controlled aerodynamic flight. But starting from altitudes of 100-130 km, the concepts of the number M and the sound barrier, familiar to every pilot, lose their meaning: the conditional Karman line passes there, beyond which the area of purely ballistic flight begins, which can only be controlled using reactive forces.

The history of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere over time was in three different compositions. It originally 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 saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). So it was formed secondary atmosphere(about three billion years ago). The atmosphere was restorative. Further, the process of the formation of the atmosphere was determined by the following factors:

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

Nitrogen

The formation of a large amount of nitrogen N 2 is due to the oxidation of the ammonia-hydrogen atmosphere with molecular oxygen O 2, which began to flow from the planet's surface as a result of photosynthesis, starting from 3 billion years ago. Also, nitrogen N 2 is 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 strike). Oxidation of molecular nitrogen by ozone with electrical discharges in small quantities is used in the industrial production of nitrogen fertilizers. It can be oxidized with low energy consumption and converted into a biologically active form by cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with legumes, the so-called. siderates.

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, the ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties was formed. Since this caused serious and abrupt changes in many processes taking place in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe.

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. Enormous amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic matter of plant and animal origin, as well as due to volcanism and human production activities. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the bulk (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the next 200-300 years the amount of СО 2 in the atmosphere will double and may lead to global climate changes.

Fuel combustion is the main source of polluting gases (CO, SO 2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3 in the upper atmosphere, which in turn interacts with water and ammonia vapors, 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. The use of internal combustion engines leads to significant pollution of the atmosphere with nitrogen oxides, hydrocarbons and lead compounds (tetraethyl lead Pb (CH 3 CH 2) 4)).

Notes (edit)

Literature

V. V. Parin, F. P. Kosmolinsky, B. A. Dushkov"Space biology and medicine" (2nd edition, revised and enlarged), M .: "Education", 1975, 223 pages.
N.V. Gusakova"Chemistry of the Environment", Rostov-on-Don: Phoenix, 2004, 192 with ISBN 5-222-05386-5
Sokolov V.A. Geochemistry of natural gases, M., 1971;
McEwen M., Phillips L. Chemistry of the atmosphere, M., 1978;
Work K., Warner S. Air pollution. Sources and Control, trans. from English., M .. 1980;
Monitoring of background pollution of natural environments. v. 1, L., 1982.

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STRUCTURE OF THE ATMOSPHERE

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

Physical properties

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

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

For "normal conditions" at the Earth's surface, the following are taken: density 1.2 kg / m 3, barometric pressure 101.35 kPa, temperature plus 20 ° C and relative humidity 50%. These conditional indicators are of purely engineering significance.

The structure of the atmosphere

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

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

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

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

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

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

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

Stratosphere(from Lat. stratum - flooring, layer) - a layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the layer of 11-25 km (the lower layer of the stratosphere) and its increase in the layer 25-40 km from -56.5 to 0.8 ° C (the upper layer of the stratosphere or the inversion region) are characteristic. 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 the mesosphere. The density of air in the stratosphere is tens and hundreds of times less than at sea level.

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

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

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate into atoms (above 80 km CO2 and H2 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. Free radicals are present in the upper layers of the atmosphere - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

Flights to the stratosphere began in the 1930s. The flight on the first stratospheric balloon (FNRS-1), which was made by Auguste Piccard 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 meteorological balloons rise up to 40 km; the record for an unmanned balloon is 51.8 km.

Recently, in the US military circles, much attention has been paid to the development of stratospheric layers above 20 km, often called "pre-space" (eng. « near space» ). It is assumed that unmanned airships and solar-powered aircraft (like the NASA Pathfinder) will be able to stay at an altitude of about 30 km for a long time and provide observation and communication for very large areas, while remaining slightly vulnerable to air defense systems; such devices will be many times cheaper than satellites.

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

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

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

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

The gas composition of the mesosphere, as well as those located below the atmospheric layers, is constant and contains about 80% nitrogen and 20% oxygen.

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

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

Noctilucent clouds may appear in the mesosphere.

For flights, the mesosphere is a kind of "dead zone" - the air here is too thin to support airplanes or balloons (at an altitude of 50 km, the air density is 1000 times less than at sea level), and at the same time, it is too dense for artificial flights. satellites in such a low orbit. Direct investigations of the mesosphere are carried out mainly with the help of suborbital meteorological rockets; in general, the mesosphere has been studied worse than other layers of the atmosphere, and therefore scientists have called it "ignorosphere".

Mesopause

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

Mesopause exists not only on Earth, but also on other planets with an atmosphere.

Karman line- height above sea level, which is conventionally taken as the boundary between the Earth's atmosphere and space.

The Fédération Aéronautique Internationale (FAI) defines the Karman Line at 100 km above sea level.

The height was named after Theodor von Karman, an American scientist of Hungarian origin. He was the first to determine that at about this altitude, the atmosphere becomes so rarefied that aeronautics becomes impossible, since the speed of the aircraft necessary to create sufficient lift becomes greater than the first space speed, and therefore, to reach higher altitudes, it is necessary to use spacecraft.

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

Reaching the Pocket Line was the first condition for receiving the Ansari X Prize, as this is the basis for the recognition of space flight.

- the air shell of the earth, rotating with the Earth. The upper boundary of the atmosphere is conventionally drawn at altitudes of 150-200 km. The lower boundary is the surface of the Earth.

Atmospheric air is a mixture of gases. Most of its volume in the surface air layer is nitrogen (78%) and oxygen (21%). In addition, the air contains inert gases (argon, helium, neon, etc.), carbon dioxide (0.03), water vapor and various solid particles (dust, soot, salt crystals).

The air is colorless, and the color of the sky is explained by the peculiarities of the scattering of light waves.

The atmosphere consists of several layers: the troposphere, stratosphere, mesosphere and thermosphere.

The lower surface layer of air is called troposphere. Its thickness is not the same at different latitudes. The troposphere repeats the shape of the planet and participates, together with the Earth, in axial rotation. At the equator, the thickness of the atmosphere ranges from 10 to 20 km. It is more at the equator, and less at the poles. The troposphere is characterized by the maximum air density, 4/5 of the mass of the entire atmosphere is concentrated in it. The troposphere determines the weather conditions: here various air masses are formed, clouds and precipitation are formed, there is an intense horizontal and vertical air movement.

Above the troposphere, up to an altitude of 50 km, is stratosphere. It is characterized by a lower air density, there is no water vapor in it. In the lower part of the stratosphere at altitudes of about 25 km. there is an "ozone screen" - a layer of the atmosphere with an increased concentration of ozone, which absorbs ultraviolet radiation, which is fatal to organisms.

At an altitude of 50 to 80-90 km stretches mesosphere. With increasing altitude, the temperature decreases with an average vertical gradient (0.25-0.3) ° / 100 m, and the air density decreases. The main energy process is radiant heat transfer. The glow of the atmosphere is caused by complex photochemical processes involving radicals, vibrationally excited molecules.

Thermosphere is located at an altitude of 80-90 to 800 km. The air density is minimal here, the degree of air ionization is very high. The temperature changes depending on the activity of the Sun. Due to the large number of charged particles, auroras and magnetic storms are observed here.

The atmosphere is of great importance to the nature of the Earth. Breathing of living organisms is impossible without oxygen. Its ozone layer protects all living things from harmful ultraviolet rays. The atmosphere smoothes temperature fluctuations: the Earth's surface does not overcool at night and does not overheat during the day. In dense layers of atmospheric air, before reaching the surface of the planet, meteorites burn out from thorns.

The atmosphere interacts with all the shells of the earth. With its help, heat and moisture are exchanged between the ocean and land. Without the atmosphere, there would be no clouds, precipitation, winds.

Human economic activity has a significant adverse effect on the atmosphere. Air pollution occurs, which leads to an increase in the concentration of carbon monoxide (CO 2). And this contributes to global warming and enhances the "greenhouse effect". The ozone layer of the Earth is being destroyed due to industrial and transport waste.

The atmosphere needs protection. In developed countries, a set of measures is being taken to protect atmospheric air from pollution.

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The atmosphere of the earth is composed of layers. Layers of the atmosphere - troposphere, stratosphere, mesosphere, thermosphere and exosphere. Other properties of the atmosphere and effects on the human body

Tropopause

Stratosphere

Stratopause

Mesosphere

Boundary of the earth's atmosphere

Thermosphere

Thermopause

Exosphere (Orb of Dispersion)

Physiological and other properties of the atmosphere

The history of the formation of the atmosphere

Nitrogen

Oxygen

Noble gases

Air pollution

see also

Notes (edit)

Links

Literature

The structure of the atmosphere