Atmosphere stratosphere troposphere what's next there. Earth atmosphere

The composition of the atmosphere. The air shell of our planet - atmosphere protects the earth's surface from the harmful effects on living organisms of ultraviolet radiation from the Sun. It also protects the Earth from cosmic particles - dust and meteorites.

The atmosphere consists of a mechanical mixture of gases: 78% of its volume is nitrogen, 21% is oxygen, and less than 1% is helium, argon, krypton and other inert gases. The amount of oxygen and nitrogen in the air is practically unchanged, because nitrogen almost does not enter into combinations with other substances, and oxygen, which, although very active and is spent on respiration, oxidation and combustion, is constantly replenished by plants.

Up to a height of about 100 km, the percentage of these gases remains practically unchanged. This is due to the fact that the air is constantly mixed.

In addition to these gases, the atmosphere contains about 0.03% carbon dioxide, which is usually concentrated near the earth's surface and is distributed unevenly: in cities, industrial centers and areas of volcanic activity, its amount increases.

There is always a certain amount of impurities in the atmosphere - water vapor and dust. The content of water vapor depends on the temperature of the air: the higher the temperature, the more vapor the air holds. Due to the presence of vaporous water in the air, atmospheric phenomena such as rainbows, refraction of sunlight, etc. are possible.

Dust enters the atmosphere during volcanic eruptions, sand and dust storms, with incomplete combustion of fuel at thermal power plants, etc.

The structure of the atmosphere. The density of the atmosphere changes with height: it is highest at the Earth's surface, and decreases as it rises. So, at an altitude of 5.5 km, the density of the atmosphere is 2 times, and at an altitude of 11 km - 4 times less than in the surface layer.

Depending on the density, composition and properties of gases, the atmosphere is divided into five concentric layers (Fig. 34).

Rice. 34. Vertical section of the atmosphere (atmospheric stratification)

1. The bottom layer is called troposphere. Its upper boundary runs at an altitude of 8-10 km at the poles and 16-18 km at the equator. The troposphere contains up to 80% of the total mass of the atmosphere and almost all of the water vapor.

The air temperature in the troposphere decreases with height by 0.6 °C every 100 m and at its upper boundary it is -45-55 °C.

The air in the troposphere is constantly mixed, moving in different directions. Only here fogs, rains, snowfalls, thunderstorms, storms and others are observed. weather conditions.

2. Above is located stratosphere, which extends to a height of 50-55 km. Air density and pressure in the stratosphere are negligible. The rarefied air consists of the same gases as in the troposphere, but it contains more ozone. The highest concentration of ozone is observed at an altitude of 15-30 km. The temperature in the stratosphere rises with height and reaches 0 °C or more at its upper boundary. This is due to the fact that ozone absorbs the short-wavelength part of solar energy, as a result of which the air heats up.

3. Above the stratosphere lies mesosphere, extending to a height of 80 km. In it, the temperature drops again and reaches -90 ° C. The air density there is 200 times less than at the surface of the Earth.

4. Above the mesosphere is thermosphere(from 80 to 800 km). The temperature in this layer rises: at an altitude of 150 km to 220 °C; at an altitude of 600 km to 1500 °C. The atmospheric gases (nitrogen and oxygen) are in an ionized state. Under the action of short-wave solar radiation, individual electrons are detached from the shells of atoms. As a result, in this layer - ionosphere layers of charged particles appear. Their densest layer is at an altitude of 300-400 km. Due to the low density, the sun's rays do not scatter there, so the sky is black, stars and planets shine brightly on it.

In the ionosphere there are polar lights, powerful electric currents are generated that cause disturbances in the Earth's magnetic field.

5. Above 800 km, the outer shell is located - exosphere. The speed of movement of individual particles in the exosphere approaches the critical one - 11.2 mm/s, so individual particles can overcome the Earth's gravity and escape into the world space.

The value of the atmosphere. The role of the atmosphere in the life of our planet is exceptionally great. Without it, the Earth would be dead. The atmosphere protects the Earth's surface from intense heating and cooling. Its influence can be likened to the role of glass in greenhouses: to let in the sun's rays and prevent heat from escaping.

The atmosphere protects living organisms from the shortwave and corpuscular radiation of the Sun. The atmosphere is the environment where weather phenomena occur, with which all human activity. The study of this shell is carried out at meteorological stations. Day and night, in any weather, meteorologists monitor the state of the lower atmosphere. Four times a day, and at many stations every hour they measure temperature, pressure, air humidity, note cloudiness, wind direction and speed, precipitation, electrical and sound phenomena in the atmosphere. Meteorological stations are located everywhere: in Antarctica and in tropical rainforests, on high mountains and in the vast expanses of the tundra. Observations are also being made on the oceans from specially built ships.

From the 30s. 20th century observations began in the free atmosphere. They began to launch radiosondes, which rise to a height of 25-35 km, and with the help of radio equipment transmit to Earth information about temperature, pressure, air humidity and wind speed. Nowadays, meteorological rockets and satellites are also widely used. The latter have television installations that transmit images of the earth's surface and clouds.

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5. Air shell of the earth§ 31. Heating of the atmosphere

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 the atmosphere

The troposphere is the layer in which strong vertical and horizontal movements, it is here that the weather, precipitation phenomena, climatic conditions. It extends for 7-8 kilometers from the surface of the planet almost everywhere, with the exception of the polar regions (there - up to 15 km). In the troposphere, there is a gradual decrease in temperature, approximately 6.4 ° C with each kilometer of altitude. This figure 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 a height of 90 kilometers

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

What other elements are in the Earth's atmosphere? As a 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 - 4), nitrous oxide (5.0 x 10 -5), etc. In terms of mass percentage of the listed components, nitrous oxide and hydrogen are the most, followed by helium, krypton, etc.

Physical properties of different atmospheric layers

The physical properties of the troposphere are closely related to its attachment to the surface of the planet. From here, the reflected solar heat in the form of infrared rays is sent back up, including the processes of thermal 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 practically unchanged up to the level of 34-35 km, and then there is again an increase in temperatures up to heights of 50 kilometers (the upper boundary 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 near the surface (ten to the minus sixth power of a percent), since the gas is formed under the influence of sunlight from atomic oxygen in the upper parts of the atmosphere. In particular, most of the ozone is at an altitude of about 25 km, and the entire "ozone screen" is located in areas from 7-8 km in the region of the poles, from 18 km at the equator and up to fifty kilometers in general above the surface of the planet.

Atmosphere protects from solar radiation

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

Zero Celsius at stratopause

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

In the thermosphere - plus 2000 K!

The chemical composition of the Earth's atmosphere in the thermosphere (begins after the mesopause from altitudes of about 85-90 to 800 km) determines the possibility of such a phenomenon as the 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 from 200 to 2000 K occur, which are obtained in connection with the ionization of oxygen (above 300 km is atomic oxygen), as well as the recombination of oxygen atoms into molecules, accompanied by the release of a large amount of heat. The thermosphere is where the auroras originate.

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 more by individual oxygen atoms in the lower layers, helium atoms in the middle, and almost exclusively hydrogen atoms in the upper. 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 a composition of the atmosphere. In total, there are three concepts of the origin of this element. The first hypothesis assumes that the atmosphere was taken in the process of accretion from a protoplanetary cloud. However, today this theory is subject to significant criticism, since such a primary atmosphere must have been destroyed by the solar "wind" from a star in our planetary system. In addition, it is assumed that volatile elements could not stay in the zone of formation of planets like the terrestrial group due to too high temperatures.

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

Experiment at IDG RAS

The most plausible is 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 about 4 billion years ago. This concept was tested at the Institute of Geology and Geochemistry of the Russian Academy of Sciences in the course of an experiment called "Tsarev 2", when a sample of a meteoric substance 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 vapor (HF), carbon monoxide gas (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 turned out to be more in a bound state in organic matter and rocks, nitrogen passed into the composition of modern air, as well as again into sedimentary rocks and organic matter.

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 amounts one and a half billion years ago, as is believed, in connection with the development of the process of photosynthesis in blue-green and other algae, which are the oldest inhabitants of our planet.

Oxygen minimum

The fact that the composition of the Earth's atmosphere was initially almost anoxic is indicated by the fact that easily oxidized, but not oxidized graphite (carbon) is found in the most ancient (Katarchean) rocks. Subsequently, the so-called banded iron ores appeared, which included interlayers of enriched iron oxides, which means the appearance on the planet of a powerful source of oxygen in molecular form. But these elements came across only periodically (perhaps the same algae or other oxygen producers appeared as small islands in an anoxic 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 the flow without traces. chemical reactions. Since flowing waters cannot be poorly aerated, the view has evolved that the pre-Cambrian atmosphere contained less than one percent oxygen of today's composition.

Revolutionary change in air composition

Approximately in the middle of the Proterozoic (1.8 billion years ago), the “oxygen revolution” took place, when the world switched to aerobic respiration, during which 38 can be obtained from one nutrient molecule (glucose), 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 an ozone layer began to appear, protecting organisms from radiation. It was from her that “hidden” under thick shells, for example, such ancient animals as trilobites. From then until our time, the content of the main "respiratory" element has gradually and slowly increased, providing a variety of development of life forms on the planet.

Earth's atmosphere is the gaseous envelope of our planet. Its lower boundary passes at the level of the earth's crust and hydrosphere, and the upper one passes into the near-Earth region of outer space. The atmosphere contains about 78% nitrogen, 20% oxygen, up to 1% argon, carbon dioxide, hydrogen, helium, neon and some other gases.

This earth shell is characterized by clearly defined layering. The layers of the atmosphere are determined by the vertical distribution of temperature and the different density of gases at its different levels. There are such layers of the Earth's atmosphere: troposphere, stratosphere, mesosphere, thermosphere, exosphere. The ionosphere is distinguished separately.

Up to 80% of the total mass of the atmosphere is the troposphere - the lower surface layer of the atmosphere. The troposphere in the polar zones is located at a level of up to 8-10 km above the earth's surface, in the tropical zone - up to a maximum of 16-18 km. Between the troposphere and the overlying stratosphere is the tropopause - the transition layer. In the troposphere, temperature decreases as altitude increases, and atmospheric pressure decreases with altitude. The average temperature gradient in the troposphere is 0.6°C per 100 m. The temperature at different levels of this shell is determined by the absorption of solar radiation and the efficiency of convection. Almost all human activity takes place in the troposphere. Most high mountains do not go beyond the troposphere, only air transport can cross the upper boundary of this shell to a small height and be in the stratosphere. A large proportion of water vapor is contained in the troposphere, which determines the formation of almost all clouds. Also, almost all aerosols (dust, smoke, etc.) that form on the earth's surface are concentrated in the troposphere. In the boundary lower layer of the troposphere, daily fluctuations in temperature and air humidity are expressed, the wind speed is usually reduced (it increases with altitude). In the troposphere, there is a variable division of the air column into air masses in the horizontal direction, which differ in a number of characteristics depending on the zone and the area of ​​their formation. At atmospheric fronts - the boundaries between air masses - cyclones and anticyclones are formed, which determine the weather in a certain area for a specific period of time.

The stratosphere is the layer of the atmosphere between the troposphere and the mesosphere. The limits of this layer range from 8-16 km to 50-55 km above the Earth's surface. In the stratosphere, the gas composition of air is approximately the same as in the troposphere. Distinctive feature– a decrease in the concentration of water vapor and an increase in the content of ozone. The ozone layer of the atmosphere, which protects the biosphere from the aggressive effects of ultraviolet light, is at a level of 20 to 30 km. In the stratosphere, the temperature rises with height, and the temperature values ​​​​are determined by solar radiation, and not by convection (movements of air masses), as in the troposphere. The heating of the air in the stratosphere is due to the absorption of ultraviolet radiation by ozone.

The mesosphere extends above the stratosphere up to a level of 80 km. This layer of the atmosphere is characterized by the fact that the temperature decreases from 0 ° C to - 90 ° C as the height increases. This is the coldest region of the atmosphere.

Above the mesosphere is the thermosphere up to a level of 500 km. From the border with the mesosphere to the exosphere, the temperature varies from approximately 200 K to 2000 K. Up to a level of 500 km, the air density decreases by several hundred thousand times. The relative composition of the atmospheric components of the thermosphere is similar to the surface layer of the troposphere, but with increasing altitude, more oxygen passes into the atomic state. A certain proportion of molecules and atoms of the thermosphere is in an ionized state and distributed in several layers, they are united by the concept of the ionosphere. The characteristics of the thermosphere vary over a wide range depending on the geographic latitude, the amount of solar radiation, the time of year and day.

The upper layer of the atmosphere is the exosphere. This is the thinnest layer of the atmosphere. In the exosphere, the mean free paths of particles are so huge that particles can freely escape into interplanetary space. The mass of the exosphere is one ten millionth of the total mass of the atmosphere. The lower boundary of the exosphere is the level of 450-800 km, and the upper boundary is the area where the concentration of particles is the same as in outer space - several thousand kilometers from the Earth's surface. The exosphere is made up of plasma, an ionized gas. Also in the exosphere are the radiation belts of our planet.

Video presentation - layers of the Earth's atmosphere:

Related content:

Blue planet...

This topic was supposed to appear on the site one of the first. After all, helicopters are atmospheric aircraft. Earth's atmosphere- their, so to speak, habitat :-). A physical properties of air just determine the quality of this habitat :-). So that's one of the basics. And the basis is always written first. But I just realized this now. However, it is better, as you know, late than never ... Let's touch on this issue, but without getting into the wilds and unnecessary difficulties :-).

So… Earth's atmosphere. This is the gaseous shell of our blue planet. Everyone knows this name. Why blue? Simply because the “blue” (as well as blue and violet) component of sunlight (spectrum) is most well scattered in the atmosphere, thus coloring it in bluish-bluish, sometimes with a hint of violet (on a sunny day, of course :-)) .

Composition of the Earth's atmosphere.

The composition of the atmosphere is quite wide. I will not list all the components in the text, there is a good illustration for this. The composition of all these gases is almost constant, with the exception of carbon dioxide (CO 2 ). In addition, the atmosphere necessarily contains water in the form of vapors, suspended droplets or ice crystals. The amount of water is not constant and depends on temperature and, to a lesser extent, on air pressure. In addition, the Earth's atmosphere (especially the current one) also contains a certain amount, I would say "all sorts of filth" :-). These are SO 2, NH 3, CO, HCl, NO, in addition there are mercury vapors Hg. True, all this is there in small quantities, thank God :-).

Earth's atmosphere It is customary to divide into several zones following each other in height above the surface.

The first, closest to the earth, is the troposphere. This is the lowest and, so to speak, the main layer for life. different kind. It contains 80% of the total mass atmospheric air(although by volume it makes up only about 1% of the entire atmosphere) and about 90% of all atmospheric water. The bulk of all winds, clouds, rains and snows 🙂 come from there. The troposphere extends to altitudes of about 18 km. tropical latitudes and up to 10 km in the polar ones. The air temperature in it drops with a rise of about 0.65º for every 100 m.

atmospheric zones.

The second zone is the stratosphere. I must say that another narrow zone is distinguished between the troposphere and stratosphere - the tropopause. It stops the temperature drop with height. The tropopause has an average thickness of 1.5-2 km, but its boundaries are indistinct and the troposphere often overlaps the stratosphere.

So the stratosphere has an average height of 12 km to 50 km. The temperature in it up to 25 km remains unchanged (about -57ºС), then somewhere up to 40 km it rises to about 0ºС and further up to 50 km it remains unchanged. The stratosphere is a relatively quiet part of the earth's atmosphere. There are practically no adverse weather conditions in it. It is in the stratosphere that the famous ozone layer is located at altitudes from 15-20 km to 55-60 km.

This is followed by a small boundary layer stratopause, in which the temperature remains around 0ºС, and then the next zone is the mesosphere. It extends to altitudes of 80-90 km, and in it the temperature drops to about 80ºС. In the mesosphere, small meteors usually become visible, which begin to glow in it and burn out there.

The next narrow gap is the mesopause and beyond it the thermosphere zone. Its height is up to 700-800 km. Here the temperature again begins to rise and at altitudes of about 300 km it can reach values ​​of the order of 1200ºС. Thereafter, it remains constant. The ionosphere is located inside the thermosphere up to a height of about 400 km. Here, the air is strongly ionized due to exposure to solar radiation and has a high electrical conductivity.

The next and, in general, the last zone is the exosphere. This is the so-called scatter zone. Here, mainly very rarefied hydrogen and helium (with a predominance of hydrogen) are present. At altitudes of about 3000 km, the exosphere passes into the near space vacuum.

It's like that somewhere. Why about? Because these layers are rather conditional. Various changes in altitude, composition of gases, water, temperature, ionization, and so on are possible. In addition, there are many more terms that define the structure and state of the earth's atmosphere.

For example homosphere and heterosphere. In the first, the atmospheric gases are well mixed and their composition is quite homogeneous. The second is located above the first and there is practically no such mixing there. The gases are separated by gravity. The boundary between these layers is located at an altitude of 120 km, and it is called turbopause.

Let's finish with the terms, but I will definitely add that it is conventionally accepted that the boundary of the atmosphere is located at an altitude of 100 km above sea level. This border is called the Karman Line.

I will add two more pictures to illustrate the structure of the atmosphere. The first, however, is in German, but it is complete and easy enough to understand :-). It can be enlarged and well considered. The second shows the change in atmospheric temperature with altitude.

The structure of the Earth's atmosphere.

Change in air temperature with altitude.

Modern manned orbital spacecraft fly at altitudes of about 300-400 km. However, this is no longer aviation, although the region, of course, is in in a certain sense closely related, and we will certainly talk about it :-).

The aviation zone is the troposphere. Modern atmospheric aircraft can also fly in the lower layers of the stratosphere. For example, the practical ceiling of the MIG-25RB is 23000 m.

Flight in the stratosphere.

And exactly physical properties of air tropospheres determine how the flight will be, how effective the aircraft control system will be, how the turbulence in the atmosphere will affect it, how the engines will work.

The first main property is air temperature. In gas dynamics, it can be determined on the Celsius scale or on the Kelvin scale.

Temperature t1 at a given height H on the Celsius scale is determined:

t 1 \u003d t - 6.5N, Where t is the air temperature at the ground.

Temperature on the Kelvin scale is called absolute temperature Zero on this scale is absolute zero. At absolute zero, the thermal motion of molecules stops. Absolute zero on the Kelvin scale corresponds to -273º on the Celsius scale.

Accordingly, the temperature T on high H on the Kelvin scale is determined:

T \u003d 273K + t - 6.5H

Air pressure. Atmospheric pressure is measured in Pascals (N / m 2), in the old system of measurement in atmospheres (atm.). There is also such a thing as barometric pressure. This is the pressure measured in millimeters of mercury using a mercury barometer. Barometric pressure (pressure at sea level) equal to 760 mm Hg. Art. called standard. In physics, 1 atm. just equal to 760 mm Hg.

Air density. In aerodynamics, the most commonly used concept is the mass density of air. This is the mass of air in 1 m3 of volume. The density of air changes with height, the air becomes more rarefied.

Air humidity. Shows the amount of water in the air. There is a concept " relative humidity". This is the ratio of the mass of water vapor to the maximum possible at a given temperature. The concept of 0%, that is, when the air is completely dry, can exist in general only in the laboratory. On the other hand, 100% humidity is quite real. This means that the air has absorbed all the water it could absorb. Something like an absolutely "full sponge". High relative humidity reduces air density, while low relative humidity increases it accordingly.

Due to the fact that aircraft flights take place under different atmospheric conditions, their flight and aerodynamic parameters in one flight mode may be different. Therefore, for a correct assessment of these parameters, we introduced International Standard Atmosphere (ISA). It shows the change in the state of the air with the rise in altitude.

The main parameters of the state of air at zero humidity are taken as:

pressure P = 760 mm Hg. Art. (101.3 kPa);

temperature t = +15°C (288 K);

mass density ρ \u003d 1.225 kg / m 3;

For the ISA, it is assumed (as mentioned above :-)) that the temperature drops in the troposphere by 0.65º for every 100 meters of altitude.

Standard atmosphere (example up to 10000 m).

ISA tables are used for calibrating instruments, as well as for navigational and engineering calculations.

Physical properties of air also include such concepts as inertness, viscosity and compressibility.

Inertia is a property of air that characterizes its ability to resist changes in the state of rest or uniform rectilinear motion. . The measure of inertia is the mass density of air. The higher it is, the higher the inertia and drag force of the medium when the aircraft moves in it.

Viscosity. Determines the frictional resistance against air as the aircraft moves.

Compressibility measures the change in air density as pressure changes. At low speeds of the aircraft (up to 450 km/h), there is no change in pressure when the air flow flows around it, but at high speeds, the effect of compressibility begins to appear. Its influence on supersonic is especially pronounced. This is a separate area of ​​​​aerodynamics and a topic for a separate article :-).

Well, it seems that's all for now ... It's time to finish this slightly tedious enumeration, which, however, cannot be dispensed with :-). Earth's atmosphere, its parameters, physical properties of air are as important for the aircraft as the parameters of the apparatus itself, and it was impossible not to mention them.

For now, until the next meetings and more interesting topics 🙂 …

P.S. For dessert, I suggest watching a video filmed from the cockpit of a MIG-25PU twin during its flight into the stratosphere. Filmed, apparently, by a tourist who has money for such flights :-). Shot mostly through Windshield. Notice the color of the sky...

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

tropopause

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

Stratosphere

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

Stratopause

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

Mesosphere

Earth's atmosphere

Earth's atmosphere boundary

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 is ionized ("polar lights") - 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 above the thermosphere. In this region, the absorption of solar radiation is insignificant and the temperature does not actually change with height.

Exosphere (scattering sphere)

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 ~150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

At an altitude of about 2000-3500 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 the homosphere. The boundary between these layers is called turbopause, it lies at an altitude of about 120 km.

Physiological and other properties of the atmosphere

Already at an altitude of 5 km above sea level, an untrained person develops oxygen starvation and, without adaptation, a person's performance is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 9 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.

In rarefied layers of air, the propagation of sound is 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, the concepts of the M number and the sound barrier familiar to every pilot lose their meaning: there passes the conditional Karman line, beyond which the area of ​​\u200b\u200bpurely ballistic flight begins, which can only be controlled 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.

History of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere has been in three 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, water vapor). 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 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 from 3 billion years ago. Nitrogen 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 upper layers 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 small quantities in the industrial production of nitrogen fertilizers. Oxidize it with low energy consumption and convert it into biologically active form can cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with legumes, the so-called. green manure.

Oxygen

The composition of the atmosphere began to change radically with the advent of living organisms on Earth, as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, hydrocarbons, the ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties 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

IN Lately man began to influence the evolution of the atmosphere. The result of his activities was a constant significant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological epochs. Huge amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere through the decomposition of carbonate rocks and organic matter of plant and animal origin, as well as due to volcanism and human production activities. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the main part (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 may lead to global climate change.

Fuel combustion is the main source of polluting gases (СО,, 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. The use of 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 due to both natural causes (volcanic eruptions, dust storms, sea ​​water and plant pollen, etc.), and 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.

see also

• Jacchia (atmosphere model)

Notes

Links

Literature

1. V. V. Parin, F. P. Kosmolinsky, B. A. Dushkov"Space biology and medicine" (2nd edition, revised and supplemented), M .: "Prosveshchenie", 1975, 223 pages.
2. N. V. Gusakova"Chemistry environment", Rostov-on-Don: Phoenix, 2004, 192 with ISBN 5-222-05386-5
3. Sokolov V. A. Geochemistry of natural gases, M., 1971;
4. McEwen M, Phillips L. Chemistry of the atmosphere, M., 1978;
5. Wark K., Warner S. Air pollution. Sources and control, trans. from English, M.. 1980;
6. Background pollution monitoring natural environments. V. 1, L., 1982.

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