A layer of gases 100 km from the earth. The structure of the atmosphere. See what "upper layers of the atmosphere" is in other dictionaries

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 are already more familiar with this concept in geography lessons.

The concept of the earth's atmosphere

The atmosphere is present not only in the Earth, but also in other celestial bodies. This is the name of the gaseous shell surrounding the planets. The composition of this gas layer of different planets is significantly different. Let's look at the basic information and facts about otherwise called air.

Its most important component is oxygen. Some mistakenly think that the earth's atmosphere is made entirely of oxygen, but air is actually a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, water vapor. Let the percentage of these gases be small, but 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 with altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.

The composition of the Earth's atmosphere

• Carbon dioxide essential for plant nutrition. In the atmosphere, it appears as a result of the process of respiration of living organisms, rotting, burning. The absence of it in the composition of the atmosphere would make it impossible for any plants to exist.
• Oxygen is 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 of atmospheric gases.
• Ozone It is a natural absorber of solar ultraviolet radiation, which adversely affects 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 underway to preserve and restore it.
• water vapor determines the humidity of the air. Its content may vary depending on various factors: air temperature, geographical 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, in the composition of the earth's atmosphere there is always 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 by anthropogenic means.

Layers of the atmosphere

temperature, density, and qualitative composition air is not the same at different heights. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristic. Let's find out which layers of the atmosphere are distinguished:

• The troposphere is the layer of the atmosphere closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. Here is 90% of all water vapor that is available in the atmosphere, so there is an active formation of clouds. Also in this layer there are such processes as the movement of air (wind), turbulence, convection. The temperature ranges from +45 degrees at noon in the warm season in the tropics to -65 degrees at the poles.
• The stratosphere is the second furthest layer from the atmosphere. It is located at an altitude of 11 to 50 km. In the lower layer of the stratosphere, the temperature is approximately -55, towards the distance from the Earth it rises to +1˚С. This region is called the inversion and is the boundary between the stratosphere and the 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 that enter the Earth's atmosphere burn out completely in the mesosphere, because of this, airglows occur here.
• The thermosphere is about 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the action of cosmic radiation and radiation emanating from the Sun.
• The exosphere is a zone of air dispersion. Here, the concentration of gases is small and their gradual escape into interplanetary space takes place.

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

atmospheric pressure

Listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how might 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 conducted complex calculations and proved that the atmosphere presses on one square meter of area with a force of 10,333 kg. Means, human body subject to air pressure, the weight of which is 12-15 tons. Why don't we feel it? It saves us its internal pressure, which balances the external one. You can feel the pressure of the atmosphere while on an airplane or high in the mountains, as Atmosphere pressure much less at altitude. In this case, physical discomfort, stuffy ears, dizziness are possible.

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

• The weight of the earth's atmosphere is 5,300,000,000,000,000 tons.
• It contributes to the transmission of sound. 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 measure air temperature, and a barometer is used to measure atmospheric pressure.
• The presence of an atmosphere saves our planet from 100 tons of meteorites daily.
• The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
• It is believed that the atmosphere extends upwards to an altitude of 3000 km.

The value 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 show oxygen starvation, which is expressed in a decrease in his working capacity and a deterioration in well-being. This shows that a person cannot survive in a space where this amazing mixture of gases does not exist.

All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, the possibility of the development of life on Earth appeared. Even today, having assessed the extent of the harm that mankind is capable of inflicting with its actions on the life-giving air, we should think about further measures to preserve and restore the atmosphere.

The atmosphere has distinct layers of air. Air layers differ in temperature, difference in gases and their density and pressure. It should be noted that the layers of the stratosphere and troposphere protect the Earth from solar radiation. In the higher layers, a living organism can receive a lethal dose of the ultraviolet solar spectrum. To quickly jump to the desired layer of the atmosphere, click on the corresponding layer:

Troposphere and tropopause

Troposphere - temperature, pressure, altitude

The upper limit is kept at around 8 - 10 km approximately. IN temperate latitudes 16 - 18 km, and in the polar 10 - 12 km. Troposphere It 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 the total water vapor. It is in the troposphere that convection and turbulence arise, clouds form, cyclones occur. Temperature decreases with height. Gradient: 0.65°/100 m. The heated earth and water heat up the enclosing 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 changes in climatic weather conditions occur. The lower limit of the troposphere is called surface since it has a lot of volatile microorganisms and dust. Wind speed increases with height in this layer.

tropopause

This is the transitional layer of the troposphere to the stratosphere. Here, the dependence of the decrease in temperature with an increase in altitude ceases. The tropopause is the minimum height 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 from 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, inversion temperature, from 56.5 rises to 0.8°C. From 40 km to 55 km the temperature stays at around 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 up to 20 km due to stable flight conditions. High-altitude weather balloons rise to a height of 40 km. There are steady air currents here, their speed reaches 300 km/h. Also in this layer is concentrated ozone, a layer that absorbs ultraviolet rays.

Mesosphere and Mesopause - composition, reactions, temperature

The mesosphere layer begins at about 50 km and ends at around 80-90 km. Temperatures decrease with elevation by about 0.25-0.3°C/100 m. Radiant heat exchange is the main energy effect here. Complex photochemical processes involving free radicals (has 1 or 2 unpaired electrons) since they implement glow atmosphere.

Almost all meteors burn up in the mesosphere. Scientists have named this area Ignorosphere. This zone is difficult to explore, as aerodynamic aviation here is very poor due to the air density, which is 1000 times less than on Earth. And to run artificial satellites the density is still very high. Research is carried out with the help of meteorological rockets, but this is a perversion. mesopause transitional layer between mesosphere and thermosphere. Has a minimum temperature of -90°C.

Karman Line

Pocket line called the boundary between the Earth's atmosphere and outer 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 Theodor von Karman. He determined that at about this height the density of the atmosphere is so low that aerodynamic aviation becomes impossible here, since the speed of the aircraft must be greater first space velocity. At such a height, the concept of a sound barrier loses its meaning. Here you can control the aircraft only due to reactive forces.

Thermosphere and Thermopause

The upper boundary of this layer is about 800 km. The temperature rises up to about 300 km, where it reaches about 1500 K. Above, the temperature remains unchanged. In this layer there is Polar Lights- occurs as a result of the effect of solar radiation on the air. This process is also called the ionization of atmospheric oxygen.

Due to the low rarefaction of the air, flights above the Karman line are possible only 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. The growth of solar activity leads to the expansion of the thickness of this layer.

• The gas shell does not fly away into space due to gravity. Air is made up of particles that have their own mass. From the law of gravitation, it can be concluded 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 a high pressure zone on the right, and low pressure on the left. In the Southern Hemisphere, it will be the other way around.

- air shell the globe rotating with the earth. The upper boundary of the atmosphere is conventionally carried out 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: troposphere, stratosphere, mesosphere and thermosphere.

The bottom layer of air is called troposphere. At different latitudes, its power is not the same. 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 varies from 10 to 20 km. At the equator it is greater, and at the poles it is less. The troposphere is characterized by the maximum density of air, 4/5 of the mass of the entire atmosphere is concentrated in it. The troposphere determines weather: various air masses, clouds and precipitation are formed, there is an intense horizontal and vertical movement of air.

Above the troposphere, up to an altitude of 50 km, is located stratosphere. It is characterized by a lower density of air, 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 a high concentration of ozone, which absorbs ultraviolet radiation, which is fatal to organisms.

At an altitude of 50 to 80-90 km extends mesosphere. As the altitude increases, the temperature decreases with an average vertical gradient of (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 due to complex photochemical processes involving radicals, vibrationally excited molecules.

Thermosphere located at an altitude of 80-90 to 800 km. The air density here is minimal, 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 for the nature of the Earth. Without oxygen, living organisms cannot breathe. Its ozone layer protects all living things from harmful ultraviolet rays. The atmosphere smooths out temperature fluctuations: the Earth's surface does not get supercooled at night and does not overheat during the day. In dense layers of atmospheric air, not reaching the surface of the planet, meteorites burn out from thorns.

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

Human activities have 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 global warming climate and amplifies the greenhouse effect. Ozone layer The land is being destroyed due to industrial waste and transport.

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

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Earth's atmosphere

Atmosphere(from. other Greekἀτμός - steam and σφαῖρα - ball) - gas shell ( geosphere) surrounding the planet Earth. Its inner surface is covered hydrosphere and partially bark, the outer one borders on the near-Earth part of outer space.

The totality of sections of physics and chemistry that study the atmosphere is commonly called atmospheric physics. The atmosphere determines weather on the surface of the Earth, is engaged in the study of weather meteorology, and long-term variations climate - climatology.

The structure of the atmosphere

The structure of the atmosphere

Troposphere

Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere. It contains more than 80% of the total mass of atmospheric air and about 90% of all water vapor present in the atmosphere. highly developed in the troposphere turbulence And convection, arise clouds, develop cyclones And anticyclones. The temperature decreases with increasing height with an average vertical gradient 0.65°/100 m

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

Stratosphere

The 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 its increase in the 25-40 km layer from -56.5 to 0.8 ° WITH(upper stratosphere or region inversions). Having reached a value of about 273 K (almost 0 ° C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called stratopause and is the boundary between the stratosphere and mesosphere.

Stratopause

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

Mesosphere

Earth's atmosphere

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 of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc., determine the glow of the atmosphere.

mesopause

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

Karman Line

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

Thermosphere

Main article: Thermosphere

The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values ​​of the order of 1500 K, after which it remains almost constant up to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, air ionization occurs (" auroras”) - main areas ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates.

Atmospheric layers up to a height of 120 km

Exosphere (sphere of dispersion)

Exosphere- scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and hence its particles leak into interplanetary space ( dissipation).

Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in 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 gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200–250 km corresponds to a temperature of ~1500 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

At an altitude of about 2000-3000 km, the exosphere gradually passes 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 part of the interplanetary matter. The other part is composed 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 accounts for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

Depending on the composition of the gas in the atmosphere, they emit homosphere And heterosphere. heterosphere - this is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. Hence follows 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 develops 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 up to about 115 km the atmosphere contains oxygen.

The atmosphere provides us with the oxygen we need to breathe. However, due to the drop in the total pressure of the atmosphere as you rise to a height, the partial pressure of oxygen also decreases accordingly.

The human lungs constantly contain about 3 liters of alveolar air. Partial pressure oxygen in the alveolar air at normal atmospheric pressure is 110 mm Hg. Art., pressure of carbon dioxide - 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 into the lungs will completely stop 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 altitudes, death occurs almost instantly. Thus, from the point of view of human physiology, "space" begins already at an altitude of 15-19 km.

Dense layers of air - the troposphere and stratosphere - protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, an intense effect on the body is exerted by 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, 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, propagation sound turns out to be impossible. Up to altitudes of 60-90 km, it is still possible to use air resistance and lift for controlled aerodynamic flight. But starting from altitudes of 100-130 km, concepts familiar to every pilot numbers M And sound barrier lose their meaning, there passes the conditional Karman Line beyond which begins the sphere of purely ballistic flight, which can be controlled only by using reactive forces.

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

Composition of the atmosphere

Composition of dry air

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

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

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 minor quantities. The troposphere constantly contains a large number of suspended solid and liquid particles ( aerosol).

History of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere has been in four different compositions over time. Initially, it consisted of light gases ( hydrogen And helium) captured from interplanetary space. This so-called primary atmosphere(about four billion years ago). At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, steam). This is how secondary atmosphere(about three billion years before our days). This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors:

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

chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.

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

Nitrogen

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

Nitrogen N 2 enters into reactions only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen by 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 the rhizobial symbiosis With legumes plants, so-called. green manure.

Oxygen

The composition of the atmosphere began to change radically with the advent of living organisms, as a result 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, oxide 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 formed. Since this caused serious and abrupt changes in many processes occurring in atmosphere, lithosphere And biosphere, this event is called Oxygen catastrophe.

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. So, during the periods of coal accumulation, the oxygen content in the atmosphere, apparently, noticeably exceeded the modern level.

Carbon dioxide

The content of CO 2 in the atmosphere depends on volcanic activity and chemical processes in the earth's shells, but most of all - on the intensity of biosynthesis and decomposition of organic matter in biosphere Earth. Almost the entire current biomass of the planet (about 2.4 × 10 12 tons ) is formed due to carbon dioxide, nitrogen and water vapor contained in atmospheric air. Buried in ocean, V swamps and in forests organic matter becomes 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 as a whole 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 epochs. Huge amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic substances of plant and animal origin, as well as due to volcanism and human production activities. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the main part (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the next 50 - 60 years the amount of CO 2 in the atmosphere will double and may lead to global climate change.

Fuel combustion is the main source of both pollutant gases ( SO, NO, SO 2 ). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3 in the upper atmosphere, which in turn interacts with water vapor and ammonia, 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 a so-called. acid rain. Usage internal combustion engines leads to significant air pollution 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 eruption, dust storms, entrainment of sea water droplets and plant pollen, etc.) and by human economic activity (mining of ores and building materials, fuel combustion, cement production, etc.). Intense large-scale removal of solid particles into the atmosphere is one of the possible causes of climate change on the planet.

STRUCTURE OF THE ATMOSPHERE

Atmosphere(from other Greek ἀτμός - steam and σφαῖρα - ball) - a gaseous shell (geosphere) surrounding the planet Earth. Its inner surface covers the hydrosphere and partially the earth's crust, while its outer surface 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 air density 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). The solubility of air in water (by mass) at 0 ° C - 0.0036%, at 25 ° C - 0.0023%.

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

The structure of the atmosphere

The atmosphere has a layered structure. The layers of the atmosphere differ from each other in air temperature, 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, 8-10 km high in the polar regions, up to 10-12 km in temperate latitudes, at the equator - 16-18 km.

When rising in the troposphere, the temperature drops 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 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 arise, atmospheric fronts also form, cyclones and anticyclones develop, as well as other processes that determine weather and climate. The processes occurring in the troposphere are primarily due to convection.

The part of the troposphere within which glaciers can form on the earth's surface is called the chionosphere.

tropopause(from the Greek τροπος - turn, change and παῦσις - stop, cessation) - the layer of the atmosphere in which the decrease in temperature with height stops; transition layer from troposphere to 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 time of year (the tropopause is higher in summer than in winter) and cyclonic activity (it is lower in cyclones and higher in anticyclones)

The thickness of the tropopause ranges from several hundred meters to 2-3 kilometers. In the subtropics, tropopause ruptures are observed due to powerful jet streams. The tropopause over certain areas is often destroyed and re-formed.

Stratosphere(from Latin stratum - flooring, layer) - a layer of the atmosphere, located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from -56.5 to 0.8 °C (the upper stratosphere layer or inversion region) are typical. 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 ozonosphere 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 1.7-4.0 mm thick, but even this is enough to absorb the solar ultraviolet radiation that is harmful to life. The destruction of O 3 occurs when it interacts with free radicals, NO, halogen-containing compounds (including "freons").

Most of the short-wavelength part of ultraviolet radiation (180-200 nm) is retained in the stratosphere and the energy of short waves is transformed. Under the influence of these rays, magnetic fields change, molecules break up, ionization, new formation of gases and other chemical compounds occur. These processes can be observed in the form of northern lights, lightning and other glows.

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate - into atoms (above 80 km, CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - N 2). At an altitude of 200-500 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O - 2, N + 2) is ~ 1/300 of the concentration of neutral particles. In the upper layers of the atmosphere there are free radicals - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

Flights into the stratosphere began in the 1930s. The flight on the first stratospheric balloon (FNRS-1), which Auguste Picard and Paul Kipfer made on May 27, 1931 to a height of 16.2 km, is widely known. Modern combat and supersonic commercial aircraft fly in the stratosphere at altitudes generally up to 20 km (although the dynamic ceiling can be much higher). High-altitude weather balloons rise up to 40 km; the record for an unmanned balloon is 51.8 km.

Recently, in the military circles of the United States, much attention has been paid to the development of layers of the stratosphere above 20 km, often called the "pre-space" (Eng. « near space» ). It is assumed that unmanned airships and solar-powered aircraft (like 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 low-vulnerability to air defense systems; such devices will be many times cheaper than satellites.

Stratopause- the layer of the atmosphere, which is the boundary between two layers, the stratosphere and the mesosphere. In the stratosphere, temperature rises with altitude, and the stratopause is the layer where the temperature reaches its maximum. The temperature of the stratopause 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 of the lower 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, burn up completely 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 rarefied 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 too dense for artificial flights. satellites in such a low orbit. Direct studies 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, in connection with which scientists called it the “ignorosphere”.

mesopause

mesopause The layer of the atmosphere that separates 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 a height of about 50 km) the temperature drops with height, above (up to a height of about 400 km) it rises again. The mesopause coincides with the lower boundary of the region of active absorption of the X-ray and the shortest wavelength ultraviolet radiation of the Sun. Silvery clouds are observed at this altitude.

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

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

As defined by the Fédération Aéronautique Internationale (FAI), the Karman Line is at an altitude of 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 cosmic speed, and therefore, in order to achieve higher altitudes, it is necessary to use the means of astronautics.

The Earth's atmosphere continues beyond the Karman line. The outer part of the earth's atmosphere, the exosphere, extends to an altitude of 10,000 km or more, at such an altitude the atmosphere consists mainly of hydrogen atoms that can leave the atmosphere.

Reaching the Karman Line was the first condition for the Ansari X Prize, as this is the basis for recognizing the flight as a space flight.