What is the structure of the atmosphere? Chemical composition of the Earth's atmosphere

The atmosphere is what makes life possible on Earth. We receive the very first information and facts about the atmosphere back in primary school. In high school, we become more familiar with this concept in geography lessons.

Concept of earth's atmosphere

Not only the Earth, but also other celestial bodies have an atmosphere. This is the name given to the gaseous shell surrounding the planets. The composition of this gas layer varies significantly between planets. Let's look at the basic information and facts about otherwise called air.

Its most important component is oxygen. Some people mistakenly think that the earth's atmosphere consists entirely of oxygen, but in fact, air is a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, and water vapor. Even though the percentage of these gases is small, they perform an important function - they absorb a significant part of the solar radiant energy, thereby preventing the luminary from turning all life on our planet into ashes. The properties of the atmosphere change depending on altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.

Composition of the Earth's atmosphere

• Carbon dioxide necessary for plant nutrition. It appears in the atmosphere as a result of the process of respiration of living organisms, rotting, and combustion. Its absence in the atmosphere would make the existence of any plants impossible.
• Oxygen- a vital component of the atmosphere for humans. Its presence is a condition for the existence of all living organisms. It makes up about 20% of the total volume atmospheric gases.
• Ozone is a natural absorber of solar ultraviolet radiation, which has a detrimental effect on living organisms. Most of it forms a separate layer of the atmosphere - the ozone screen. IN Lately Human activity leads to the fact that it begins to gradually collapse, but since it is of great importance, active work is being carried out to preserve and restore it.
• water vapor determines air humidity. Its content may vary depending on various factors: air temperature, territorial location, season. At low temperatures there is very little water vapor in the air, maybe less than one percent, and at high temperatures its amount reaches 4%.
• In addition to all of the above, the composition of the earth’s atmosphere always contains a certain percentage solid and liquid impurities. These are soot, ash, sea salt, dust, water drops, microorganisms. They can get into the air both naturally and anthropogenically.

Layers of the atmosphere

And temperature, and density, and high-quality composition air is not the same different heights. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristics. Let's find out what layers of the atmosphere are distinguished:

• Troposphere - this layer of the atmosphere is closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. 90% of all water vapor in the atmosphere is located here, so active cloud formation occurs. Also in this layer processes such as air (wind) movement, turbulence, and convection are observed. Temperatures range from +45 degrees at midday in the warm season in the tropics to -65 degrees at the poles.
• The stratosphere is the second most distant layer of the atmosphere. Located at an altitude of 11 to 50 km. In the lower layer of the stratosphere the temperature is approximately -55; moving away from the Earth it rises to +1˚С. This region is called an inversion and is the boundary of the stratosphere and mesosphere.
• The mesosphere is located at an altitude of 50 to 90 km. The temperature at its lower boundary is about 0, at the upper it reaches -80...-90 ˚С. Meteorites entering the Earth's atmosphere completely burn up in the mesosphere, causing airglows to occur here.
• The thermosphere is approximately 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the influence of cosmic radiation and radiation emanating from the Sun.
• The exosphere is the zone of air dispersion. Here the concentration of gases is small and they gradually escape into interplanetary space.

The boundary between the earth's atmosphere and outer space is considered to be 100 km. This line is called the Karman line.

Atmospheric pressure

When listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how can it affect us?

We figured out that air consists of gases and impurities. Each of these components has its own weight, which means that the atmosphere is not weightless, as was believed until the 17th century. Atmospheric pressure is the force with which all layers of the atmosphere press on the surface of the Earth and on all objects.

Scientists carried out complex calculations and proved that one square meter area the atmosphere presses with a force of 10,333 kg. This means that the human body is subject to air pressure, the weight of which is 12-15 tons. Why don't we feel this? It is our internal pressure that saves us, which balances the external. You can feel the pressure of the atmosphere while on an airplane or high in the mountains, since the atmospheric pressure at altitude is much less. In this case, physical discomfort, blocked ears, and dizziness are possible.

A lot can be said about the surrounding atmosphere. We know many interesting facts about her, and some of them may seem surprising:

• The weight of the earth's atmosphere is 5,300,000,000,000,000 tons.
• It promotes sound transmission. At an altitude of more than 100 km, this property disappears due to changes in the composition of the atmosphere.
• The movement of the atmosphere is provoked by uneven heating of the Earth's surface.
• A thermometer is used to determine the air temperature, and a barometer is used to determine the pressure of the atmosphere.
• The presence of an atmosphere saves our planet from 100 tons of meteorites every day.
• The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
• The atmosphere is believed to extend upward to a height of 3000 km.

The importance of the atmosphere for humans

The physiological zone of the atmosphere is 5 km. At an altitude of 5000 m above sea level, a person begins to experience oxygen starvation, which is expressed in a decrease in his performance and deterioration in well-being. This shows that a person cannot survive in a space where there is no this amazing mixture of gases.

All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, it became possible to develop life on Earth. Already today, having assessed the scale of harm that humanity is capable of causing through its actions to the life-giving air, we should think about further measures to preserve and restore the atmosphere.

Changing the earth's surface. No less important was the activity of the wind, which carried small fractions of rocks over long distances. Temperature fluctuations and other atmospheric factors significantly influenced the destruction of rocks. Along with this, A. protects the Earth's surface from the destructive effects of falling meteorites, most of which burn up when entering the dense layers of the atmosphere.

The activity of living organisms, which has had a strong influence on the development of oxygen, itself depends to a very large extent on atmospheric conditions. A. delays most of the ultraviolet radiation from the Sun, which has a detrimental effect on many organisms. Atmospheric oxygen is used in the process of respiration by animals and plants, atmospheric carbon dioxide is used in the process of plant nutrition. Climatic factors, especially thermal and moisture regimes, affect health and human activity. Agriculture is especially dependent on climatic conditions. In turn, human activity has an ever-increasing influence on the composition of the atmosphere and the climate regime.

The structure of the atmosphere

Vertical distribution of temperature in the atmosphere and related terminology.

Numerous observations show that A. has a clearly defined layered structure (see figure). The main features of the layered structure of aluminum are determined primarily by the characteristics of the vertical temperature distribution. In the lowest part of the atmosphere—the troposphere, where intense turbulent mixing is observed (see Turbulence in the atmosphere and hydrosphere), the temperature decreases with increasing altitude, and the vertical decrease in temperature averages 6° per 1 km. The height of the troposphere varies from 8-10 km at polar latitudes to 16-18 km at the equator. Due to the fact that air density quickly decreases with height, about 80% of the total mass of air is concentrated in the troposphere. Above the troposphere there is a transition layer - the tropopause with a temperature of 190-220, above which the stratosphere begins. In the lower part of the stratosphere, the decrease in temperature with height stops, and the temperature remains approximately constant up to an altitude of 25 km - the so-called. isothermal region(lower stratosphere); higher the temperature begins to increase - the inversion region (upper stratosphere). Temperatures reach a maximum of ~270 K at the level of the stratopause, located at an altitude of about 55 km. The A layer, located at altitudes from 55 to 80 km, where the temperature again decreases with height, is called the mesosphere. Above it there is a transition layer - mesopause, above which is the thermosphere, where the temperature, increasing with height, reaches very high values ​​(over 1000 K). Even higher (at altitudes of ~ 1000 km or more) is the exosphere, from where atmospheric gases are dispersed into space due to dissipation and where a gradual transition from atmospheric to interplanetary space occurs. Usually, all layers of the atmosphere located above the troposphere are called upper, although sometimes the stratosphere or its lower part is also referred to as the lower layers of the atmosphere.

All structural parameters of Africa (temperature, pressure, density) have significant spatiotemporal variability (latitudinal, annual, seasonal, daily, etc.). Therefore, the data in Fig. reflect only the average state of the atmosphere.

Atmospheric structure diagram:
1 - sea level; 2 - the highest point of the Earth - Mount Chomolungma (Everest), 8848 m; 3 - fair weather cumulus clouds; 4 - powerful cumulus clouds; 5 - shower (thunderstorm) clouds; 6 - nimbostratus clouds; 7 - cirrus clouds; 8 - airplane; 9 - layer of maximum ozone concentration; 10 - mother-of-pearl clouds; 11 - stratospheric balloon; 12 - radiosonde; 1З - meteors; 14 - noctilucent clouds; 15 - auroras; 16 - American X-15 rocket aircraft; 17, 18, 19 - radio waves reflected from ionized layers and returning to Earth; 20 - sound wave reflected from the warm layer and returning to Earth; 21 - the first Soviet artificial Earth satellite; 22 - intercontinental ballistic missile; 23 - geophysical research rockets; 24 - meteorological satellites; 25 - spacecraft Soyuz-4 and Soyuz-5; 26 - space rockets, leaving the atmosphere, as well as a radio wave penetrating the ionized layers and leaving the atmosphere; 27, 28 - dissipation (slippage) of H and He atoms; 29 - trajectory of solar protons P; 30 - penetration ultraviolet rays(wavelength l > 2000 and l< 900).

The layered structure of the atmosphere has many other diverse manifestations. The chemical composition of the atmosphere is heterogeneous over altitude. If at altitudes up to 90 km, where there is intense mixing of the atmosphere, the relative composition of the permanent components of the atmosphere remains practically unchanged (this entire thickness of the atmosphere is called the homosphere), then above 90 km - in heterosphere- under the influence of the dissociation of molecules of atmospheric gases by ultraviolet radiation from the sun, a strong change in the chemical composition of the atmosphere occurs with altitude. Typical features of this part of Africa are layers of ozone and the atmosphere's own glow. A complex layered structure is characteristic of atmospheric aerosol—solid particles of terrestrial and cosmic origin suspended in air. The most common aerosol layers are found below the tropopause and at an altitude of about 20 km. The vertical distribution of electrons and ions in the atmosphere is layered, which is expressed in the existence of D-, E-, and F-layers of the ionosphere.

Atmospheric composition

One of the most optically active components- atmospheric aerosol - particles suspended in the air ranging in size from several nm to several tens of microns, formed during the condensation of water vapor and entering the air. earth's surface as a result of industrial pollution, volcanic eruptions, and also from space. Aerosol is observed both in the troposphere and in the upper layers of A. The aerosol concentration quickly decreases with height, but this variation is superimposed by numerous secondary maxima associated with the existence of aerosol layers.

Upper atmosphere

Above 20-30 km, as a result of dissociation, the molecules of atoms disintegrate to one degree or another into atoms, and free atoms and new, more complex molecules appear in the atom. Somewhat higher, ionization processes become significant.

The most unstable region is the heterosphere, where the processes of ionization and dissociation give rise to numerous photochemical reactions that determine changes in the composition of air with height. Gravitational separation of gases also occurs here, which is expressed in the gradual enrichment of Africa with lighter gases as the altitude increases. According to rocket measurements, gravitational separation of neutral gases - argon and nitrogen - is observed above 105-110 km. The main components of oxygen in the 100-210 km layer are molecular nitrogen, molecular oxygen and atomic oxygen (the concentration of the latter at the level of 210 km reaches 77 ± 20% of the concentration of molecular nitrogen).

The upper part of the thermosphere consists mainly of atomic oxygen and nitrogen. At an altitude of 500 km, molecular oxygen is practically absent, but molecular nitrogen, the relative concentration of which greatly decreases, still dominates over atomic nitrogen.

In the thermosphere, tidal movements (see Ebb and flow), gravitational waves, photochemical processes, an increase in the mean free path of particles, and other factors play an important role. The results of observations of satellite braking at altitudes of 200-700 km led to the conclusion that there is a relationship between density, temperature and solar activity, which is associated with the existence of daily, semi-annual and annual variations in structural parameters. It is possible that diurnal variations are largely due to atmospheric tides. During periods of solar flares, temperatures at an altitude of 200 km in low latitudes can reach 1700-1900°C.

Above 600 km, helium becomes the predominant component, and even higher, at altitudes of 2-20 thousand km, the Earth’s hydrogen corona extends. At these altitudes, the Earth is surrounded by a shell of charged particles, the temperature of which reaches several tens of thousands of degrees. The Earth's inner and outer radiation belts are located here. The inner belt, filled mainly with protons with energies of hundreds of MeV, is limited to altitudes of 500-1600 km at latitudes from the equator to 35-40°. The outer belt consists of electrons with energies of the order of hundreds of keV. Beyond the outer belt there is an "outermost belt" in which the concentration and flow of electrons is much higher. The intrusion of solar corpuscular radiation (solar wind) into the upper layers of the sun gives rise to auroras. Under the influence of this bombardment of the upper atmosphere by electrons and protons of the solar corona, the atmosphere’s own glow, which was previously called glow of the night sky. When the solar wind interacts with the Earth's magnetic field, a zone is created, called. Earth's magnetosphere, where solar plasma streams do not penetrate.

For upper layers A. characteristic existence strong winds, the speed of which reaches 100-200 m/sec. Wind speed and direction within the troposphere, mesosphere and lower thermosphere have great spatiotemporal variability. Although the mass of the upper layers of the sky is insignificant compared to the mass of the lower layers and the energy of atmospheric processes in the high layers is relatively small, apparently there is some influence of the high layers of the sky on the weather and climate in the troposphere.

Radiation, heat and water balances of the atmosphere

Practically the only source of energy for all physical processes developing in Africa is solar radiation. main feature radiation regime of A. - so-called. greenhouse effect: A. weakly absorbs short-wave solar radiation (most of it reaches the earth's surface), but retains long-wave (entirely infrared) thermal radiation from the earth's surface, which significantly reduces the heat transfer of the Earth into outer space and increases its temperature.

Solar radiation arriving in Africa is partially absorbed in Africa, mainly by water vapor, carbon dioxide, ozone, and aerosols and is scattered on aerosol particles and on fluctuations in the density of Africa. Due to the dispersion of the radiant energy of the Sun in Africa, not only direct solar radiation is observed, but also scattered radiation, together they make up the total radiation. Reaching the earth's surface, the total radiation is partially reflected from it. The amount of reflected radiation is determined by the reflectivity of the underlying surface, the so-called. albedo Due to the absorbed radiation, the earth's surface heats up and becomes a source of its own long-wave radiation directed towards the earth. In turn, the earth also emits long-wave radiation directed towards the earth's surface (the so-called anti-radiation of the earth) and into outer space (the so-called outgoing radiation). Rational heat exchange between the earth's surface and the earth is determined by effective radiation - the difference between the intrinsic radiation of the earth's surface and the counter-radiation absorbed by it. The difference between the short-wave radiation absorbed by the earth's surface and the effective radiation is called radiation balance.

The transformation of the energy of solar radiation after its absorption on the earth's surface and in the atmosphere constitutes the heat balance of the earth. The main source of heat for the atmosphere is the earth's surface, which absorbs the bulk of solar radiation. Since the absorption of solar radiation in the Earth is less than the loss of heat from the Earth into the world space by long-wave radiation, the radiation heat consumption is replenished by the influx of heat to the Earth from the earth’s surface in the form of turbulent heat exchange and the arrival of heat as a result of condensation of water vapor in the Earth. Since the total The amount of condensation throughout Africa is equal to the amount of precipitation, as well as the amount of evaporation from the earth's surface; the arrival of condensation heat in Africa is numerically equal to the heat lost for evaporation on the Earth's surface (see also Water balance).

Some of the energy of solar radiation is spent on maintaining the general circulation of the atmosphere and on other atmospheric processes, but this part is insignificant compared to the main components of the heat balance.

Air movement

Due to high mobility atmospheric air Winds are observed at all heights of A. Air movements depend on many factors, the main one being the uneven heating of air in different regions of the globe.

Particularly large temperature contrasts at the Earth's surface exist between the equator and the poles due to differences in the arrival solar energy at different latitudes. Along with this, the distribution of temperature is influenced by the location of continents and oceans. Due to the high heat capacity and thermal conductivity of ocean waters, the oceans significantly attenuate temperature fluctuations that arise as a result of changes in the arrival of solar radiation throughout the year. In this regard, in temperate and high latitudes, the air temperature over the oceans in summer is noticeably lower than over the continents, and higher in winter.

The uneven heating of the atmosphere contributes to the development of a system of large-scale air currents - the so-called. general atmospheric circulation, which creates horizontal heat transfer in the atmosphere, as a result of which differences in the heating of atmospheric air in individual areas are noticeably smoothed out. Along with this, the general circulation carries out moisture circulation in Africa, during which water vapor is transferred from the oceans to land and the continents are moistened. The movement of air in the general circulation system is closely related to the distribution of atmospheric pressure and also depends on the rotation of the Earth (see Coriolis force). At sea level, the pressure distribution is characterized by a decrease near the equator and an increase in the subtropics (belt high pressure) and decrease in temperate and high latitudes. At the same time, over the continents of extratropical latitudes, the pressure is usually increased in winter and decreased in summer.

Associated with planetary pressure distribution a complex system air currents, some of them are relatively stable, while others are constantly changing in space and time. Stable air currents include trade winds, which are directed from the subtropical latitudes of both hemispheres to the equator. Monsoons are also relatively stable - air currents that arise between the ocean and the mainland and are seasonal. In temperate latitudes, westerly air currents predominate (from west to east). These currents include large eddies - cyclones and anticyclones, usually extending over hundreds and thousands of km. Cyclones are also observed in tropical latitudes, where they are distinguished by their smaller sizes, but especially high wind speeds, often reaching the strength of a hurricane (so-called tropical cyclones). In the upper troposphere and lower stratosphere there are relatively narrow (hundreds of kilometers wide) jet streams that have sharply defined boundaries, within which the wind reaches enormous speeds - up to 100-150 m/sec. Observations show that the features of atmospheric circulation in the lower part of the stratosphere are determined by processes in the troposphere.

In the upper half of the stratosphere, where temperature increases with altitude, wind speed increases with altitude, with eastern winds dominating in summer and westerly winds in winter. The circulation here is determined by a stratospheric heat source, the existence of which is associated with the intense absorption of ultraviolet solar radiation by ozone.

In the lower part of the mesosphere in temperate latitudes, the speed of the winter westerly transport increases to maximum values ​​- about 80 m/sec, and the summer eastern transport - up to 60 m/sec at a level of about 70 km. Research in recent years has clearly shown that the features of the temperature field in the mesosphere cannot be explained only by the influence of radiation factors. Dynamic factors (in particular, heating or cooling when air descends or rises) are of primary importance, and heat sources resulting from the photo are also possible. chemical reactions(for example, recombination of atomic oxygen).

Above the cold mesopause layer (in the thermosphere), the air temperature begins to increase rapidly with altitude. In many respects, this region of Africa is similar to the lower half of the stratosphere. It is likely that the circulation in the lower part of the thermosphere is determined by processes in the mesosphere, and the dynamics of the upper layers of the thermosphere is determined by the absorption of solar radiation here. However, it is difficult to study atmospheric motion at these altitudes due to their significant complexity. Tidal movements (mainly solar semidiurnal and diurnal tides) become of great importance in the thermosphere, under the influence of which wind speeds at altitudes of more than 80 km can reach 100-120 m/sec. Characteristic atmospheric tides - their strong variability depending on latitude, time of year, altitude above sea level and time of day. In the thermosphere, significant changes in wind speed with height are also observed (mainly near the 100 km level), attributed to the influence of gravitational waves. Located in the altitude range of 100-110 km so-called. The turbopause sharply separates the region above from the zone of intense turbulent mixing.

Along with large-scale air currents, numerous local air circulations are observed in the lower layers of the atmosphere (breeze, bora, mountain-valley winds, etc.; see Local winds). In all air currents, wind pulsations are usually observed, corresponding to the movement of air vortices of medium and small sizes. Such pulsations are associated with atmospheric turbulence, which significantly affects many atmospheric processes.

Climate and weather

Differences in the amount of solar radiation arriving at different latitudes of the earth's surface and the complexity of its structure, including the distribution of oceans, continents and major mountain systems, determine the diversity of the Earth's climates (see Climate).

Literature

• Meteorology and hydrology for 50 years of Soviet power, ed. E. K. Fedorova, L., 1967;
• Khrgian A. Kh., Atmospheric Physics, 2nd ed., M., 1958;
• Zverev A.S., Synoptic meteorology and fundamentals of weather prediction, Leningrad, 1968;
• Khromov S.P., Meteorology and climatology for geographical faculties, Leningrad, 1964;
• Tverskoy P.N., Course of Meteorology, Leningrad, 1962;
• Matveev L. T., Fundamentals of general meteorology. Atmospheric Physics, Leningrad, 1965;
• Budyko M.I., Thermal balance of the earth's surface, Leningrad, 1956;
• Kondratyev K. Ya., Actinometry, Leningrad, 1965;
• Khvostikov I. A., High layers of the atmosphere, Leningrad, 1964;
• Moroz V.I., Physics of Planets, M., 1967;
• Tverskoy P.N., Atmospheric electricity, Leningrad, 1949;
• Shishkin N. S., Clouds, precipitation and thunderstorm electricity, M., 1964;
• Ozone in the Earth's Atmosphere, ed. G. P. Gushchina, Leningrad, 1966;
• Imyanitov I.M., Chubarina E.V., Electricity of the free atmosphere, Leningrad, 1965.

M. I. Budyko, K. Ya. Kondratiev.

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Atmospheric boundary

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

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

Physical properties

In addition to the gases indicated in the table, the atmosphere contains Cl 2, SO 2, NH 3, CO, O 3, NO 2, hydrocarbons, HCl, HBr, vapors, I 2, Br 2, as well as many other gases in minor amounts quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is radon (Rn).

The structure of the atmosphere

Atmospheric boundary layer

The lower layer of the troposphere (1-2 km thick), in which the state and properties of the Earth's surface directly affect the dynamics 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. Turbulence and convection are highly developed in the troposphere, clouds appear, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 meters.

Tropopause

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

Stratosphere

A layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and an increase in temperature in the 25-40 km layer from −56.5 to +0.8 ° (upper layer of the stratosphere or inversion region). Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and mesosphere.

Stratopause

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

Mesosphere

Thermosphere

The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values ​​of the order of 1500 K, after which it remains almost constant to high altitudes. Under the influence of solar radiation and cosmic radiation, ionization of the air (“auroras”) occurs - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity - for example, in 2008-2009 - there is a noticeable decrease in the size of this layer.

Thermopause

The region of the atmosphere adjacent above the thermosphere. In this area the absorption solar radiation insignificantly and the temperature does not actually change with altitude.

Exosphere (scattering sphere)

Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular weights; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200-250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed.

At an altitude of about 2000-3500 km, the exosphere gradually turns into the so-called near space vacuum, which is filled with rare particles of interplanetary gas, mainly hydrogen atoms. But this gas represents only part of the interplanetary matter. The other part consists of dust particles of cometary and meteoric origin. In addition to extremely rarefied dust particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

Review

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere.

Based on electrical properties in the atmosphere, they distinguish neutrosphere And ionosphere .

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

Other properties of the atmosphere and effects on the human body

Already at an altitude of 5 km above sea level, an untrained person begins to experience oxygen starvation and without adaptation, a person’s performance is significantly reduced. The physiological zone of the atmosphere ends here. Human breathing becomes impossible at an altitude of 9 km, although up to approximately 115 km the atmosphere contains oxygen.

The atmosphere supplies us with the oxygen necessary for breathing. However, due to the drop in the total pressure of the atmosphere, as you rise to altitude, the partial pressure of oxygen decreases accordingly.

History of atmospheric formation

According to the most common theory, the Earth's atmosphere has had three different compositions throughout its history. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This is the so-called primary atmosphere. On next stage active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). This is how it was formed secondary atmosphere. This atmosphere was restorative. Further, the process of atmosphere formation was determined by the following factors:

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

Gradually these factors led to the formation tertiary atmosphere, characterized by a much lower content of hydrogen and a much higher content of nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).

Nitrogen

Education large quantity nitrogen N 2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O 2, which began to come from the surface of the planet as a result of photosynthesis, starting 3 billion years ago. Nitrogen N2 is also released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO in the upper atmosphere.

Nitrogen N 2 reacts only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen by ozone at electrical discharges used in small quantities in the industrial production of nitrogen fertilizers. Oxidize it with low energy consumption and convert it into biological active form Cyanobacteria (blue-green algae) and nodule bacteria can form rhizobial symbiosis with leguminous plants, which can be effective green manures - plants that do not deplete, but enrich the soil with natural fertilizers.

Oxygen

The composition of the atmosphere began to change radically with the appearance of living organisms on Earth as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, hydrocarbons, ferrous form of iron contained in the oceans and others. At the end of this stage, the oxygen content in the atmosphere began to increase. Gradually, a modern atmosphere with oxidizing properties formed. Since this caused serious and abrupt changes in many processes occurring in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe.

Noble gases

Air pollution

Recently, humans have begun to influence the evolution of the atmosphere. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological eras. Enormous 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 200-300 years the amount of CO 2 in the atmosphere will double and could lead to global climate change.

Fuel combustion is the main source of polluting gases (CO, SO2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3, and nitrogen oxide to NO 2 in the upper layers of the atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H 2 SO 4 and nitric acid HNO 3 fall to the surface of the Earth in the form so-called acid rain. Usage

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

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

Basic elements of atmosphere

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

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

Nitrogen - about 78 percent;

Oxygen - almost 21 percent;

Argon - about one percent;

Carbon dioxide - less than 0.05%.

Single composition up to an altitude of 90 kilometers

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

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

Physical properties of different atmospheric layers

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

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

The atmosphere protects from solar radiation

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

Zero Celsius at the stratopause

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

In the thermosphere - plus 2000 K!

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

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

How was the earth's atmosphere formed?

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

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

Experiment at IDG RAS

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

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

Minimum oxygen

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

Revolutionary change in air composition

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

The Earth's atmosphere is the gaseous shell of the planet. The lower boundary of the atmosphere passes near the earth's surface (hydrosphere and Earth's crust), and the upper limit is the region of contiguous outer space (122 km). The atmosphere contains many different elements. The main ones are: 78% nitrogen, 20% oxygen, 1% argon, carbon dioxide, neon gallium, hydrogen, etc. Interesting Facts You can look at the end of the article or by clicking on.

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. 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 it is 16 - 18 km, and in polar latitudes it is 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 arise, cyclones form and 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, a layer that absorbs ultraviolet 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 loses its meaning sound barrier. 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 low air rarefaction, flights above the Karman line are only possible along 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 there will be an area of ​​high pressure on the right and low pressure on the left. In the Southern Hemisphere, everything will be the other way around.

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