At sea level, 1013.25 hPa (about 760 mm Hg). The global average air temperature at the Earth's surface is 15 ° C, while the temperature varies from about 57 ° C in subtropical deserts to -89 ° C in Antarctica. Air density and pressure decrease with height according to a law close to exponential.

The structure of the atmosphere... Vertically, the atmosphere has a layered structure, which is mainly determined by the features of the vertical temperature distribution (figure), which depends on the geographic location, season, time of day, and so on. The lower layer of the atmosphere - the troposphere - is characterized by a drop in temperature with height (by about 6 ° C per 1 km), its height is from 8-10 km in polar latitudes to 16-18 km in the tropics. Due to the rapid decrease in air density with height, about 80% of the total mass of the atmosphere is in the troposphere. Above the troposphere is the stratosphere - a layer that is generally characterized by an increase in temperature with height. The transitional layer between the troposphere and stratosphere is called the tropopause. In the lower stratosphere, up to a level of about 20 km, the temperature changes little with height (the so-called isothermal region) and often even slightly decreases. Above, the temperature rises due to the absorption of UV radiation from the Sun by ozone, at first slowly, and from a level of 34-36 km - faster. The upper boundary of the stratosphere - the stratopause - is located at an altitude of 50-55 km, corresponding to the maximum temperature (260-270 K). The layer of the atmosphere, located at an altitude of 55-85 km, where the temperature again drops with altitude, is called the mesosphere, at its upper border - the mesopause - the temperature reaches 150-160 K in summer, and 200-230 K in winter. Above the mesopause begins the thermosphere - a layer, characterized by a rapid increase in temperature, reaching 800-1200 K at an altitude of 250 km. The thermosphere absorbs corpuscular and X-ray radiation from the Sun, decelerates and burns meteors, therefore it performs the function of a protective layer of the Earth. Even higher is the exosphere, from where atmospheric gases are scattered into world space due to dissipation, and where there is a gradual transition from the atmosphere to interplanetary space.

Atmosphere composition... Up to an altitude of about 100 km, the atmosphere is practically homogeneous in chemical composition and the average molecular mass air (about 29) in it is constant. Near the Earth's surface, the atmosphere consists of nitrogen (about 78.1% by volume) and oxygen (about 20.9%), and also contains small amounts of argon, carbon dioxide (carbon dioxide), neon and other constant and variable components (see Air ).

In addition, the atmosphere contains small amounts of ozone, nitrogen oxides, ammonia, radon, etc. The relative content of the main constituents of the air is constant over time and uniformly in different geographic regions. The content of water vapor and ozone is variable in space and time; despite their low content, their role in atmospheric processes is very significant.

Above 100-110 km, oxygen, carbon dioxide and water vapor molecules dissociate, so the molecular mass of air decreases. At an altitude of about 1000 km, light gases begin to dominate - helium and hydrogen, and even higher, the Earth's atmosphere gradually turns into interplanetary gas.

The most important variable component of the atmosphere is water vapor, which is released into the atmosphere by evaporation from the surface of water and moist soil, as well as by transpiration by plants. The relative content of water vapor near the earth's surface varies from 2.6% in the tropics to 0.2% at polar latitudes. With height, it rapidly falls, decreasing by half already at an altitude of 1.5-2 km. The vertical column of the atmosphere in temperate latitudes contains about 1.7 cm of "precipitated water layer". When water vapor condenses, clouds are formed, from which atmospheric precipitation falls in the form of rain, hail, snow.

An important component of atmospheric air is ozone, which is concentrated 90% in the stratosphere (between 10 and 50 km), about 10% of it is in the troposphere. Ozone ensures the absorption of hard UV radiation (with a wavelength of less than 290 nm), and this is its protective role for the biosphere. The values ​​of the total ozone content vary depending on latitude and season in the range from 0.22 to 0.45 cm (the thickness of the ozone layer at a pressure of p = 1 atm and a temperature of T = 0 ° C). In ozone holes observed in spring in Antarctica since the early 1980s, the ozone content can drop to 0.07 cm.It increases from the equator to the poles and has an annual variation with a maximum in spring and a minimum in autumn, and the amplitude of the annual variation is small in the tropics and grows towards high latitudes. An essential variable component of the atmosphere is carbon dioxide, the content of which in the atmosphere over the past 200 years has increased by 35%, which is mainly explained by an anthropogenic factor. Its latitudinal and seasonal variability is observed, associated with plant photosynthesis and solubility in sea ​​water(according to Henry's law, the solubility of a gas in water decreases with an increase in its temperature).

Important role atmospheric aerosol plays in the formation of the planet's climate - solid and liquid particles sizes from several nm to tens of microns. Aerosols of natural and anthropogenic origin are distinguished. Aerosol is formed in the process of gas-phase reactions from the waste products of plants and economic activity human, volcanic eruptions, as a result of the rise of dust by the wind from the surface of the planet, especially from its desert regions, and is also formed from cosmic dust that falls into the upper atmosphere. Most of the aerosol is concentrated in the troposphere; aerosol from volcanic eruptions forms the so-called Junge layer at an altitude of about 20 km. The largest number anthropogenic aerosol enters the atmosphere as a result of the operation of vehicles and thermal power plants, chemical production, fuel combustion, etc. Therefore, in some areas, the composition of the atmosphere differs markedly from ordinary air, which required the creation of a special service for observing and monitoring the level of atmospheric air pollution.

Evolution of the atmosphere... The modern atmosphere has, apparently, a secondary origin: it was formed from gases released by the solid shell of the Earth after the completion of the formation of the planet about 4.5 billion years ago. During the geological history of the Earth, the atmosphere underwent significant changes in its composition under the influence of a number of factors: dissipation (volatilization) of gases, mainly lighter ones, in space; emission of gases from the lithosphere as a result volcanic activity; chemical reactions between the components of the atmosphere and the rocks that make up earth crust; photochemical reactions in the atmosphere itself under the influence of solar UV radiation; accretion (capture) of matter of the interplanetary medium (for example, meteoric matter). The development of the atmosphere is closely related to geological and geochemical processes, and the last 3-4 billion years also with the activity of the biosphere. A significant part of the gases that make up the modern atmosphere (nitrogen, carbon dioxide, water vapor) arose in the course of volcanic activity and intrusion, which carried them out from the depths of the Earth. Oxygen appeared in noticeable quantities about 2 billion years ago as a result of the activities of photosynthetic organisms that originally originated in surface waters ocean.

Based on the data on the chemical composition of carbonate deposits, estimates of the amount of carbon dioxide and oxygen in the atmosphere of the geological past were obtained. Throughout the Phanerozoic (the last 570 million years of Earth's history), the amount of carbon dioxide in the atmosphere varied widely in accordance with the level of volcanic activity, ocean temperature and the level of photosynthesis. Most At that time, the concentration of carbon dioxide in the atmosphere was significantly higher than today (up to 10 times). The amount of oxygen in the Phanerozoic atmosphere changed significantly, and the tendency to increase it prevailed. In the Precambrian atmosphere, the mass of carbon dioxide was, as a rule, greater, and the mass of oxygen, less than in the Phanerozoic atmosphere. Fluctuations in the amount of carbon dioxide in the past had a significant impact on the climate, intensifying the greenhouse effect with an increase in the concentration of carbon dioxide, due to which the climate during the main part of the Phanerozoic was much warmer than in the modern era.

Atmosphere and life... Without an atmosphere, the Earth would be a dead planet. Organic life takes place in close interaction with the atmosphere and the associated climate and weather. Small in mass compared to the planet as a whole (about a millionth part), the atmosphere is a sine qua non for all life forms. Oxygen, nitrogen, water vapor, carbon dioxide, ozone are of the greatest importance for the vital activity of organisms. When carbon dioxide is absorbed by photosynthetic plants, organic matter is created, which is used as a source of energy by the vast majority of living things, including humans. Oxygen is necessary for the existence of aerobic organisms, for which the flow of energy is provided by oxidation reactions organic matter... Nitrogen, assimilated by some microorganisms (nitrogen fixers), is necessary for the mineral nutrition of plants. Ozone, which absorbs the hard UV radiation of the Sun, significantly attenuates this harmful part of life. solar radiation... Condensation of water vapor in the atmosphere, the formation of clouds and the subsequent precipitation of atmospheric precipitation supply water to land, without which no life forms are possible. The vital activity of organisms in the hydrosphere is largely determined by the number and chemical composition atmospheric gases dissolved in water. Since the chemical composition of the atmosphere significantly depends on the activity of organisms, the biosphere and the atmosphere can be considered as part of the unified system, the maintenance and evolution of which (see Biogeochemical cycles) was of great importance for the change in the composition of the atmosphere throughout the history of the Earth as a planet.

Radiation, heat and water balances atmosphere... Solar radiation is practically the only source of energy for everyone physical processes in the atmosphere. main feature The radiation regime of the atmosphere is the so-called greenhouse effect: the atmosphere transmits solar radiation to the earth's surface quite well, but actively absorbs long-wave thermal radiation from the earth's surface, part of which returns to the surface in the form of counter-radiation, which compensates for the radiation loss of heat by the earth's surface (see Atmospheric radiation). In the absence of the atmosphere, the average temperature of the earth's surface would be -18 ° C, in reality it is 15 ° C. The incoming solar radiation is partially (about 20%) absorbed into the atmosphere (mainly by water vapor, water droplets, carbon dioxide, ozone and aerosols), and is also scattered (about 7%) by aerosol particles and density fluctuations (Rayleigh scattering). Total radiation, reaching the earth's surface, partially (about 23%) is reflected from it. The reflectance is determined by the reflectivity of the underlying surface, the so-called albedo. On average, the Earth's albedo for the integral solar radiation flux is close to 30%. It varies from a few percent (dry soil and chernozem) to 70-90% for freshly fallen snow. Radiation heat exchange between the Earth's surface and the atmosphere depends significantly on the albedo and is determined by the effective radiation of the Earth's surface and the counter-radiation of the atmosphere absorbed by it. The algebraic sum of radiation fluxes entering the Earth's atmosphere from outer space and leaving it back is called the radiation balance.

Transformations of solar radiation after its absorption by the atmosphere and the earth's surface determine the thermal balance of the Earth as a planet. Main source heat for the atmosphere - the earth's surface; heat from it is transferred not only in the form of long-wave radiation, but also by convection, and is also released during condensation of water vapor. The shares of these heat inflows are on average 20%, 7% and 23%, respectively. This also adds about 20% of the heat due to the absorption of direct solar radiation. The solar radiation flux per unit time through a unit area perpendicular to the sun's rays and located outside the atmosphere at an average distance from the Earth to the Sun (the so-called solar constant) is 1367 W / m2, the changes are 1–2 W / m2, depending on cycle solar activity... With a planetary albedo of about 30%, the time-average global inflow of solar energy to the planet is 239 W / m2. Since the Earth as a planet emits into space on average the same amount of energy, then, according to the Stefan-Boltzmann law, the effective temperature of the outgoing thermal long-wave radiation is 255 K (-18 ° C). At the same time, the average temperature of the earth's surface is 15 ° C. The difference of 33 ° C is due to greenhouse effect.

The water balance of the atmosphere as a whole corresponds to the equality of the amount of moisture evaporated from the Earth's surface and the amount of precipitation falling on the Earth's surface. The atmosphere over the oceans receives more moisture from evaporation processes than over land, and loses 90% in the form of precipitation. Excess water vapor over the oceans is carried to the continents by air currents. The amount of water vapor transported into the atmosphere from the oceans to the continents is equal to the volume of the rivers flowing into the oceans.

Air movement... The Earth has a spherical shape, so much less solar radiation comes to its high latitudes than to the tropics. As a result, large temperature contrasts arise between latitudes. The temperature distribution is also significantly influenced by the relative position of the oceans and continents. Due to the large mass ocean waters and high heat capacity water seasonal fluctuations in ocean surface temperature are much less than land. In this regard, in the middle and high latitudes, the air temperature over the oceans is noticeably lower in summer than over the continents, and higher in winter.

Unequal heating of the atmosphere in different areas the globe causes a spatial distribution of atmospheric pressure. At sea level, the pressure distribution is characterized by relatively low values near the equator, an increase in the subtropics (high pressure belts) and a decrease in the middle and high latitudes. At the same time, over the continents of extratropical latitudes, the pressure is usually increased in winter and decreased in summer, which is associated with the temperature distribution. Under the influence of a pressure gradient, the air experiences acceleration from areas of high pressure to areas of low pressure, which leads to the movement of air masses. The moving air masses are also affected by the deflecting force of the Earth's rotation (Coriolis force), the friction force decreasing with height, and with curvilinear trajectories and centrifugal force. Great importance has turbulent mixing of air (see Turbulence in the atmosphere).

A complex system of air currents (general circulation of the atmosphere) is associated with the planetary pressure distribution. In the meridional plane, on average, two or three cells of meridional circulation are traced. Near the equator, heated air rises and falls in the subtropics, forming the Hadley cell. In the same place, the air of the Ferrell return cell is lowered. At high latitudes, a straight polar cell is often traced. The meridional circulation velocities are of the order of 1 m / s or less. Due to the action of the Coriolis force, westerly winds are observed in most of the atmosphere with velocities in the middle troposphere of about 15 m / s. There are relatively stable wind systems. These include the trade winds - winds blowing from high-pressure belts in the subtropics to the equator with a noticeable eastern component (from east to west). Monsoons are fairly stable - air currents that have a clearly pronounced seasonal character: they blow from the ocean to the mainland in summer and in the opposite direction in winter. Monsoons are especially regular Indian Ocean... In middle latitudes, the movement of air masses is mainly western direction(from west to east). This is a zone of atmospheric fronts, on which large eddies arise - cyclones and anticyclones, covering many hundreds and even thousands of kilometers. Cyclones also occur in the tropics; here they are smaller, but very high wind speeds reaching hurricane force (33 m / s and more), the so-called tropical cyclones. In the Atlantic and east Pacific they are called hurricanes, and in the west Pacific they are called typhoons. In the upper troposphere and lower stratosphere, in the regions separating the direct Hadley meridional circulation cell and the inverse Ferrell cell, relatively narrow, hundreds of kilometers wide, are often observed jet streams with sharply defined boundaries, within which the wind reaches 100-150 and even 200 m / s.

Climate and weather... The difference in the amount of solar radiation arriving at different latitudes to different physical properties the earth's surface, determines the diversity of the Earth's climates. From the equator to tropical latitudes, the air temperature near the earth's surface averages 25-30 ° C and varies little throughout the year. V equatorial belt usually there is a lot of precipitation, which creates conditions of excessive moisture there. V tropical zones the amount of precipitation decreases and in some areas becomes very low. The vast deserts of the Earth are located here.

In subtropical and middle latitudes, the air temperature changes significantly throughout the year, and the difference between the temperatures of summer and winter is especially great in areas of continents far from the oceans. Thus, in some regions of Eastern Siberia, the annual amplitude of air temperature reaches 65 ° C. Humidification conditions at these latitudes are very diverse, depend mainly on the general atmospheric circulation regime and vary significantly from year to year.

In polar latitudes, the temperature remains low throughout the year, even if there is a noticeable seasonal variation. This contributes to the widespread distribution of ice cover on the oceans and land and permafrost, which occupy over 65% of its area in Russia, mainly in Siberia.

Over the past decades, changes in the global climate have become more and more noticeable. Temperatures rise more at high latitudes than at low latitudes; more in winter than in summer; more at night than during the day. Over the 20th century, the average annual air temperature near the earth's surface in Russia has increased by 1.5-2 ° C, and in some regions of Siberia there is an increase of several degrees. This is associated with an increase in the greenhouse effect due to an increase in the concentration of trace gases.

The weather is determined by the conditions of atmospheric circulation and geographic location terrain, it is most stable in the tropics and most variable in the middle and high latitudes. Most of all, the weather changes in the zones of change in air masses, caused by the passage of atmospheric fronts, cyclones and anticyclones, carrying precipitation and increased wind. Data for weather forecasting is collected at ground-based weather stations, marine and aircraft, from meteorological satellites. See also Meteorology.

Optical, acoustic and electrical phenomena in the atmosphere... When distributing electromagnetic radiation in the atmosphere as a result of refraction, absorption and scattering of light by air and various particles (aerosol, ice crystals, water droplets), various optical phenomena arise: rainbow, crowns, halo, mirage, etc. apparent height firmament and blue sky. The visibility range of objects is determined by the conditions of light propagation in the atmosphere (see Atmospheric visibility). The communication range and the ability to detect objects by instruments, including the possibility of astronomical observations from the Earth's surface, depend on the transparency of the atmosphere at different wavelengths. The phenomenon of twilight plays an important role in studies of optical inhomogeneities in the stratosphere and mesosphere. For example, photographing twilight with spacecraft allows the detection of aerosol layers. The features of the propagation of electromagnetic radiation in the atmosphere determine the accuracy of the methods. remote sensing its parameters. All these questions, like many others, are studied by atmospheric optics. Refraction and scattering of radio waves determine the possibilities of radio reception (see Propagation of radio waves).

Sound propagation in the atmosphere depends on the spatial distribution of temperature and wind speed (see Atmospheric Acoustics). It is of interest for remote sensing of the atmosphere. Explosions of charges launched by rockets into the upper atmosphere provided a wealth of information about wind systems and the course of temperature in the stratosphere and mesosphere. In a stably stratified atmosphere, when the temperature decreases with altitude more slowly than the adiabatic gradient (9.8 K / km), so-called internal waves arise. These waves can travel upward into the stratosphere and even into the mesosphere, where they attenuate, contributing to increased wind and turbulence.

The negative charge of the Earth and the resulting electric field, the atmosphere, together with the electrically charged ionosphere and magnetosphere, create a global electrical circuit... The formation of clouds and thunderstorm electricity plays an important role in this. The danger of lightning discharges has caused the need to develop methods for lightning protection of buildings, structures, power lines and communications. This phenomenon is especially dangerous for aviation. Lightning discharges cause atmospheric radio interference, called atmospherics (see Whistling atmospherics). During dramatic increase intensity of the electric field, glowing discharges are observed arising at the tips and sharp corners objects protruding above the earth's surface, on individual peaks in the mountains, etc. (Elma lights). The atmosphere always contains highly variable depending on specific conditions the number of light and heavy ions that determine electrical conductivity atmosphere. The main ionizers of air near the earth's surface are radiation radioactive substances contained in the earth's crust and atmosphere, as well as cosmic rays... See also Atmospheric electricity.

Human influence on the atmosphere. Over the past centuries, there has been an increase in the concentration of greenhouse gases in the atmosphere due to human economic activity. The percentage of carbon dioxide increased from 2.8-10 2 two hundred years ago to 3.8-10 2 in 2005, the content of methane - from 0.7-10 1 about 300-400 years ago to 1.8-10 -4 at the beginning of the 21st century; About 20% of the increase in the greenhouse effect over the last century was given by freons, which were practically absent in the atmosphere until the middle of the 20th century. These substances are recognized as stratospheric ozone destructors and their production is prohibited by the 1987 Montreal Protocol. The rising concentration of carbon dioxide in the atmosphere is caused by the burning of increasing amounts of coal, oil, gas and other types of carbon fuels, as well as deforestation, as a result of which the absorption of carbon dioxide through photosynthesis decreases. The concentration of methane increases with the growth of oil and gas production (due to its losses), as well as with the expansion of rice crops and an increase in the number of cattle. All this contributes to the warming of the climate.

Methods of active influence on atmospheric processes have been developed to change the weather. They are used to protect agricultural plants from hail by dispersing special reagents in thunderclouds. There are also methods for dispersing fog at airports, protecting plants from frost, acting on clouds to increase precipitation in the right places, or to dissipate clouds at times of mass events.

Study of the atmosphere... Information about physical processes in the atmosphere is obtained primarily from meteorological observations, which are carried out by a global network of permanent meteorological stations and posts located on all continents and on many islands. Daily observations give information about the temperature and humidity of the air, atmospheric pressure and precipitation, cloudiness, wind, etc. Observations of solar radiation and its transformations are carried out at actinometric stations. Of great importance for the study of the atmosphere are the networks of aerological stations, at which meteorological measurements are carried out using radiosondes up to an altitude of 30-35 km. At a number of stations, observations of atmospheric ozone are carried out, electrical phenomena in the atmosphere, the chemical composition of the air.

The data of the ground stations are supplemented by observations on the oceans, where “weather ships” operate permanently in certain regions of the World Ocean, as well as meteorological information received from research and other vessels.

Everything larger volume In recent decades, information about the atmosphere has been obtained with the help of meteorological satellites equipped with instruments for photographing clouds and measuring fluxes of ultraviolet, infrared and microwave radiation from the Sun. Satellites provide information on the vertical profiles of temperature, cloudiness and its water content, elements radiation balance atmosphere, ocean surface temperature, etc. Using measurements of the refraction of radio signals from a system of navigation satellites, it is possible to determine in the atmosphere vertical profiles of density, pressure and temperature, as well as moisture content. With the help of satellites, it became possible to clarify the value of the solar constant and planetary albedo of the Earth, to build maps of the radiation balance of the Earth-atmosphere system, to measure the content and variability of trace atmospheric impurities, to solve many other problems of atmospheric physics and environmental monitoring.

Lit .: Budyko MI Climate in the past and the future. L., 1980; Matveev L.T. Course of General Meteorology. Physics of the atmosphere. 2nd ed. L., 1984; Budyko M.I., Ronov A. B., Yanshin A. L. History of the atmosphere. L., 1985; Khrgian A. Kh. Atmospheric Physics. M., 1986; Atmosphere: Handbook. L., 1991; Khromov S.P., Petrosyants M.A. Meteorology and climatology. 5th ed. M., 2001.

G. S. Golitsyn, N. A. Zaitseva.

The Earth's atmosphere is a gas envelope of the planet. The lower boundary of the atmosphere runs near the earth's surface (hydrosphere and crust), and the upper boundary is the area of ​​contiguous outer space (122 km). The atmosphere contains many different elements. The main ones are: 78% nitrogen, 20% oxygen, 1% argon, carbon dioxide, gallium neon, hydrogen, etc. Interesting Facts can be viewed at the end of the article or by clicking on.

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

Troposphere and tropopause

Troposphere - temperature, pressure, altitude

The upper border is kept at around 8-10 km. In temperate latitudes 16 - 18 km, and in polar latitudes 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 nearly 90% of all water vapor. It is in the troposphere that convection and turbulence arise, cyclones are formed and occur. Temperature decreases with increasing height. Gradient: 0.65 ° / 100 m. Heated earth and water heat the supplied air. The heated air rises to the top, cools and forms clouds. The temperature in the upper boundaries of the layer can reach - 50/70 ° C.

It is in this layer that climatic changes occur. weather conditions... The lower boundary of the troposphere is called ground as it has many volatile microorganisms and dust. The wind speed increases with increasing height in this layer.

Tropopause

It is a transitional layer of the troposphere to the stratosphere. Here the dependence of the temperature decrease with increasing altitude stops. The tropopause is the minimum altitude where the vertical temperature gradient drops to 0.2 ° C / 100 m. The tropopause height depends on strong climatic events such as cyclones. Above cyclones, the tropopause height decreases, and above anticyclones it increases.

Stratosphere and Stratopause

The height of the stratospheric 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, there is inversion temperature, from 56.5 rises to 0.8 ° C. From 40 km to 55 km, the temperature is kept 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 meteorological balloons rise to an altitude of 40 km. Stable air currents are present 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 starts at about 50 km and ends at 80 - 90 km. Temperatures decrease with an increase in altitude of about 0.25-0.3 ° C / 100 m. The main energetic effect here is radiant heat transfer. Complex photochemical processes with the participation of free radicals (has 1 or 2 unpaired electron) because they implement glow atmosphere.

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

Pocket Line

Pocket line called the border between the Earth's atmosphere and space. According to the International Aeronautical 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 about this altitude, the density of the atmosphere is so low that aerodynamic aviation becomes impossible here, since the speed of the flying device must be greater first space speed... At such a height, the concept loses its meaning sound barrier... Manage here aircraft it is possible only due to the reactive forces.

Thermosphere and Thermopause

The upper boundary of this layer is about 800 km. The temperature rises to about an altitude of 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 exposure to solar radiation on the air. This process is also called atmospheric oxygen ionization.

Due to the low air density, flights above the Karman line are feasible only along ballistic trajectories. All manned orbital flights (except for flights to the Moon) take place in this layer of the atmosphere.

Exosphere - density, temperature, altitude

The exosphere is over 700 km high. Here the gas is very rarefied, and the process takes place dissipation- particle leakage 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 into space due to gravity. Air is made up of particles that have their own mass. From the law of gravitation, one can deduce that every object with mass is attracted to the Earth.
• Buys-Balllot's law says 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, the opposite will be true.

The exact size of the atmosphere is unknown, as its upper limit is not clearly visible. However, the structure of the atmosphere has been studied enough so that everyone can get an idea of ​​how the gas envelope of our planet is arranged.

Scientists studying the physics of the atmosphere define it as the area around the Earth that orbits with the planet. FAI gives the following definition:

• the boundary between space and the atmosphere runs along the Karman line. This line, according to the definition of the same organization, is an altitude above sea level at an altitude of 100 km.

Everything above this line is outer space. The atmosphere passes into interplanetary space gradually, which is why there are different views about its size.

WITH lower bound atmosphere, everything is much simpler - it passes along the surface of the earth's crust and the water surface of the Earth - the hydrosphere. In this case, the border, one might say, merges with the earth and water surfaces, since the particles there are also dissolved air particles.

What layers of the atmosphere are included in the size of the Earth

An interesting fact: in winter it is lower, in summer it is higher.

It is in this layer that turbulence, anticyclones and cyclones arise, clouds are formed. It is this sphere that is responsible for the formation of the weather; approximately 80% of all air masses are located in it.

The tropopause is a layer in which the temperature does not decrease with height. Above the tropopause, at an altitude above 11 and up to 50 km. The stratosphere contains a layer of ozone, which is known to protect the planet from ultraviolet rays. The air in this layer is discharged, these are explained by the characteristic purple tint sky. The air speed here can reach 300 km / h. Between the stratosphere and the mesosphere there is a stratopause - a boundary sphere in which a temperature maximum takes place.

The next layer is. It extends to heights of 85-90 kilometers. The color of the sky in the mesosphere is black, so the stars can be observed even in the morning and afternoon. The most complex photochemical processes take place there, during which the glow of the atmosphere arises.

Between the mesosphere and the next layer, there is a mesopause. It is defined as a transition layer in which a temperature minimum is observed. Above, at an altitude of 100 kilometers above sea level, is the Karman line. Above this line are the thermosphere (altitude limit of 800 km) and the exosphere, which is also called the "dissipation zone". At an altitude of about 2-3 thousand kilometers, it passes into the near-space vacuum.

Given that the upper layer of the atmosphere is not clearly traced, its exact size cannot be calculated. Besides, in different countries there are organizations with different opinions on this matter. It should be noted that Karman's line can be considered the boundary of the earth's atmosphere only conditionally, since different sources use different marks of the boundaries. So, in some sources you can find information that the upper border runs at an altitude of 2500-3000 km.

NASA uses the 122 kilometer mark for calculations. Not so long ago, experiments were carried out that clarified the border as located at the 118 km mark.

Everyone who has flown by plane is accustomed to this kind of message: "Our flight takes place at an altitude of 10,000 m, the temperature overboard is 50 ° C." It seems nothing special. The farther from the Earth's surface heated by the Sun, the colder it is. Many people think that the decrease in temperature with altitude goes on continuously and gradually the temperature drops, approaching the temperature of space. By the way, scientists thought so until the end of the 19th century.

Let's take a closer look at the distribution of air temperature over the Earth. The atmosphere is divided into several layers, which primarily reflect the nature of the temperature change.

The lower atmosphere is called troposphere, which means “sphere of rotation.” All changes in weather and climate are the result of physical processes occurring in this layer. The upper boundary of this layer is located where the decrease in temperature with height gives way to its increase, - approximately at an altitude of 15-16 km above the equator and 7-8 km above the poles. Like the Earth itself, the atmosphere under the influence of the rotation of our planet is also somewhat flattened above the poles and swells above the equator. However, this effect is much more pronounced in the atmosphere than in the solid shell of the Earth. In the direction from the Earth's surface to the upper boundary of the troposphere, the air temperature decreases. Above the equator, the minimum air temperature is about -62 ° C, and above the poles, about -45 ° C. In temperate latitudes, more than 75% of the mass of the atmosphere is in the troposphere. In the tropics, about 90% is within the troposphere. masses of the atmosphere.

In 1899, its minimum was found in the vertical temperature profile at a certain altitude, and then the temperature rose slightly. The beginning of this increase means the transition to the next layer of the atmosphere - to stratosphere, which means "layer sphere". The term stratosphere means and reflects the former idea of ​​the uniqueness of the layer lying above the troposphere. The stratosphere extends up to an altitude of about 50 km above the earth's surface. Its peculiarity is, in particular, a sharp increase in air temperature. the reaction of ozone formation - one of the main chemical reactions taking place in the atmosphere.

The bulk of ozone is concentrated at altitudes of about 25 km, but in general, the ozone layer is a highly stretched shell in height, covering almost the entire stratosphere. The interaction of oxygen with ultraviolet rays is one of the beneficial processes in the earth's atmosphere that contribute to the maintenance of life on earth. The absorption of this energy by ozone prevents its excessive flow to the earth's surface, where exactly such a level of energy is created, which is suitable for the existence of terrestrial life forms. The ozonosphere absorbs part radiant energy passing through the atmosphere. As a result, a vertical air temperature gradient of about 0.62 ° С per 100 m is established in the ozonosphere, i.e., the temperature rises with altitude up to the upper limit of the stratosphere - stratopause (50 km), reaching, according to some data, 0 ° С.

At altitudes from 50 to 80 km, there is a layer of the atmosphere called mesosphere... The word "mesosphere" means "intermediate sphere", here the air temperature continues to decrease with height. Above the mesosphere, in a layer called thermosphere, the temperature rises again with an altitude of about 1000 ° C, and then very quickly drops to -96 ° C. However, it does not fall indefinitely, then the temperature rises again.

Thermosphere is the first layer ionosphere... Unlike the layers mentioned earlier, the ionosphere is not distinguished by temperature. The ionosphere is an area of ​​electrical nature that makes many types of radio communications possible. The ionosphere is divided into several layers, denoted by the letters D, E, F1 and F2 These layers also have special names. The separation into layers is caused by several reasons, among which the most important is the unequal effect of layers on the transmission of radio waves. The lowest layer, D, mainly absorbs radio waves and thus prevents their further propagation. The best-studied E layer is located about 100 km above the earth's surface. It is also called the Kennelly-Heaviside layer after the American and English scientists who simultaneously and independently discovered it. Layer E, like a giant mirror, reflects radio waves. Thanks to this layer, long radio waves travel farther distances than would be expected if they propagated only in a straight line, without being reflected from layer E. The F layer has similar properties. It is also called the Appleton layer. Together with the Kennelly-Heaviside layer, it reflects radio waves to ground-based radio stations. Such reflections can occur at different angles. Appleton's layer is located at an altitude of about 240 km.

The outermost region of the atmosphere, the second layer of the ionosphere, is often called exosphere... This term indicates the existence of the edge of space near the Earth. It is difficult to determine exactly where the atmosphere ends and space begins, since with altitude the density of atmospheric gases gradually decreases and the atmosphere itself smoothly turns almost into a vacuum, in which only individual molecules are found. Already at an altitude of about 320 km, the density of the atmosphere is so low that molecules can travel more than 1 km without colliding with each other. The outermost part of the atmosphere serves as its upper boundary, which is located at altitudes from 480 to 960 km.

More information about the processes in the atmosphere can be found on the website "Earth climate"

STRUCTURE OF THE ATMOSPHERE

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

Physical properties

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

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

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

The structure of the atmosphere

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

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

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

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

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

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

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

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

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

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

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate into atoms (above 80 km CO2 and H2 dissociate, above 150 km - O 2, above 300 km - N 2). At an altitude of 200-500 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O - 2, N + 2) is ~ 1/300 of the concentration of neutral particles. Free radicals are present in the upper layers of the atmosphere - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

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

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

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

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

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

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

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

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

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

Noctilucent clouds may appear in the mesosphere.

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

Mesopause

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

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

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

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

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

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

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