What is the composition of the earth's atmosphere. Vertical structure of the atmosphere

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 weight of air (about 29) is constant in it. 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). V 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 to high latitudes. An essential variable component of the atmosphere is carbon dioxide, the content of which in the atmosphere has increased by 35% over the past 200 years, 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).

An important role in the formation of the planet's climate is played by atmospheric aerosol - solid and liquid particles suspended in the air, ranging in size 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 human economic activities, 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 amount of 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 regions composition of the atmosphere differs markedly from ordinary air, which required the creation of a special observation service and control over 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, into outer space; release of gases from the lithosphere as a result of volcanic activity; chemical reactions between the components of the atmosphere and the rocks that make up the earth's 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. For most of this 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 the oxidation reactions of 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 the solar radiation, which is harmful to life. 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 amount and chemical composition of atmospheric gases dissolved in water. Since the chemical composition of the atmosphere significantly depends on the activity of organisms, the biosphere and atmosphere can be considered as part of a single system, the maintenance and evolution of which (see Biogeochemical cycles) was of great importance for changing the composition of the atmosphere throughout the history of the Earth as a planet.

Radiation, heat and water balances of the atmosphere... Solar radiation is practically the only source of energy for all physical processes in the atmosphere. The main feature of 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 heat loss 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). The total radiation, reaching the earth's surface, is partially (about 23%) 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. The main source of heat for the atmosphere is 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 of 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, effective temperature outgoing thermal long-wave radiation 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 the 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 of oceanic waters and the high heat capacity of water, seasonal fluctuations in the temperature of the ocean surface are much less than that of 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 regions of the globe causes a non-uniform spatial distribution 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. Moving air masses are also affected by the deflecting force of the Earth's rotation (Coriolis force), a friction force that decreases with height, and with curvilinear trajectories, and centrifugal force. Turbulent mixing of air is of great importance (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. The monsoons of the Indian Ocean are especially regular. In mid-latitudes, the movement of air masses is mainly westerly (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, jet streams with sharply delineated boundaries are often observed, within which the wind reaches 100-150 and even 200 m / with.

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. In the equatorial zone, there is usually a lot of precipitation, which creates conditions for excessive moisture there. In 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 widespread ice cover on the oceans and land and permafrost, occupying 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, ships and aircraft, from meteorological satellites. See also Meteorology.

Optical, acoustic and electrical phenomena in the atmosphere... With the propagation of 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: rainbows, crowns, halos, mirage, etc. Light scattering determines the apparent height of the sky 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 from spacecraft makes it possible to detect aerosol layers. The features of the propagation of electromagnetic radiation in the atmosphere determine the accuracy of methods for remote sensing of 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 a sharp increase in tension electric field luminous discharges occurring 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, depending on specific conditions, the amount of light and heavy ions, which determine the electrical conductivity of the atmosphere. The main air ionizers near the earth's surface are the radiation of radioactive substances contained in the earth's crust and in the 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 activities. 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 provide information on air temperature and humidity, 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. A number of stations are monitoring atmospheric ozone, electrical phenomena in the atmosphere, and 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.

An increasing amount of information about the atmosphere in recent decades has been obtained with the help of meteorological satellites, which are equipped with instruments for photographing clouds and measuring fluxes of ultraviolet, infrared and microwave radiation from the Sun. Satellites make it possible to obtain information about the vertical profiles of temperature, cloudiness and its water content, elements of the radiation balance of the atmosphere, the temperature of the ocean surface, 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 density, pressure and temperature, and moisture content. With the help of satellites, it became possible to clarify the value of the solar constant and planetary albedo of the Earth, build maps of the radiation balance of the Earth-atmosphere system, measure the content and variability of trace atmospheric impurities, and 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.

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

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

The structure of the atmosphere

Vertical temperature distribution in the atmosphere and related terminology.

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

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

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

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

Atmosphere composition

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

Upper atmosphere

Above 20-30 km, the molecules of A., as a result of dissociation, to one degree or another break down into atoms, and free atoms and new more complex molecules appear in A.. The ionization processes become somewhat higher.

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

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

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

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

The upper layers of A. are characterized by the existence strong winds, the speed of which reaches 100-200 m / s. The speed and direction of the wind within the troposphere, mesosphere and lower thermosphere are highly variable in space and time. Although the mass of the upper layers of the arctic is insignificant in comparison with the mass of the lower layers, and the energy of atmospheric processes in the higher layers is comparatively small, apparently there is some influence of the high layers of the arctic on the weather and climate in the troposphere.

Radiation, heat and water balances of the atmosphere

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

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

The transformations of solar radiation energy after it has been absorbed on the earth's surface and in artillery constitute the earth's heat balance. The main source of heat for the atmosphere is the earth's surface, which absorbs the bulk of solar radiation. Since the absorption of solar radiation in A. is less than the loss of heat from A. to world space by long-wave radiation, the radiative heat consumption is replenished by the influx of heat to A. from the earth's surface in the form of turbulent heat exchange and the arrival of heat as a result of condensation of water vapor in A. Since the final the amount of condensation in the whole arctic is equal to the amount of precipitation falling and also to the amount of evaporation from the earth's surface; the arrival of condensation heat in arctic is numerically equal to the heat consumption for evaporation on the earth's surface (see also Water Balance).

Some of the energy of solar radiation is spent on maintaining the general circulation of A. and on other atmospheric processes, but this part is insignificant in comparison with the main components of the heat balance.

Air movement

Because of the great mobility of the atmospheric air, winds are observed at all altitudes of the Atlantic. Air movements depend on many factors, of which the main one is the uneven heating of A. in different regions of the globe.

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

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

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

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

In the lower part of the mesosphere in temperate latitudes, the rate of winter westerly transport increases to maximum values- about 80 m / s, and the summer eastern transfer - up to 60 m / s at a level of about 70 km. Recent studies have clearly shown that the features of the temperature field in the mesosphere cannot be explained solely by the influence of radiation factors. Dynamic factors are of prime importance (in particular, heating or cooling when air is lowered or raised), as well as heat sources arising as a result of photochemical reactions (for example, atomic oxygen recombination) are possible.

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

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

Climate and weather

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

Literature

Meteorology and Hydrology for 50 Years of Soviet Power, ed. E.K. Fedorova, L., 1967;
Khrgian A. Kh., Physics of the atmosphere, 2nd ed., Moscow, 1958;
Zverev AS, Synoptic meteorology and the basics of weather prediction, L., 1968;
Khromov S. P., Meteorology and climatology for geographical faculties, L., 1964;
Tverskoy P. N., Course of meteorology, L., 1962;
Matveev L.T., Fundamentals of General Meteorology. Physics of the atmosphere, L., 1965;
Budyko MI, Thermal balance of the earth's surface, L., 1956;
Kondratyev K. Ya., Actinometry, L., 1965;
Khvostikov I. A., High layers of the atmosphere, L., 1964;
V. I. Frost, Physics of planets, M., 1967;
Tverskoy P. N., Atmospheric electricity, L., 1949;
Shishkin NS, Clouds, precipitation and thunderstorm electricity, M., 1964;
Ozone in the Earth's Atmosphere, ed. G.P. Gushchina, L., 1966;
Imyanitov I.M., Chubarina E.V., Electricity of a free atmosphere, L., 1965.

M.I.Budyko, K. Ya.Kondratyev.

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The atmosphere extends upwards for many hundreds of kilometers. Its upper border, at an altitude of about 2000-3000 km, to a certain extent it is conditional, since the gases, its constituents, gradually thinning out, pass into the world space. The chemical composition of the atmosphere, pressure, density, temperature and its other physical properties change with height. As mentioned earlier, the chemical composition of air up to a height of 100 km does not change significantly. The atmosphere slightly higher also consists mainly of nitrogen and oxygen. But at heights of 100-110 km, under the influence of ultraviolet radiation from the sun, oxygen molecules are split into atoms and atomic oxygen appears. Above 110-120 km almost all oxygen becomes atomic. It is assumed that above 400-500 km the gases that make up the atmosphere are also in an atomic state.

Air pressure and density rapidly decrease with height. Although the atmosphere extends upwards for hundreds of kilometers, its bulk is located in a rather thin layer adjacent to the earth's surface in its lowest parts. So, in the layer between sea level and heights of 5-6 km half the mass of the atmosphere is concentrated, in the layer 0-16 km-90%, and in the layer 0-30 km- 99%. The same rapid decrease in air mass occurs above 30 km. If the weight is 1 m 3 air at the surface of the earth is 1033 g, then at an altitude of 20 km it is equal to 43 g, and at a height of 40 km only 4 g

At an altitude of 300-400 km and above, the air is so rarefied that its density changes many times during the day. Research has shown that this change in density is related to the position of the Sun. The highest air density is around noon, the lowest at night. This is explained in part by the fact that the upper layers of the atmosphere react to changes in the electromagnetic radiation of the Sun.

The change in air temperature with height also occurs unevenly. By the nature of the change in temperature with height, the atmosphere is divided into several spheres, between which there are transition layers, the so-called pauses, where the temperature changes little with height.

Here are the names and main characteristics of the spheres and transition layers.

Here are the basic data on the physical properties of these spheres.

Troposphere. The physical properties of the troposphere are largely determined by the influence of the earth's surface, which is its lower boundary. The highest tropospheric height is observed in the equatorial and tropical zones. Here she reaches 16-18 km and relatively little is subject to diurnal and seasonal changes. Above the polar and adjacent regions, the upper boundary of the troposphere lies on average at a level of 8-10 km. In middle latitudes, it ranges from 6-8 to 14-16 km.

The vertical thickness of the troposphere depends significantly on the nature of atmospheric processes. Often, during the day, the upper border of the troposphere over a given point or area drops or rises by several kilometers. This is mainly due to changes in air temperature.

More than 4/5 of the mass of the earth's atmosphere and almost all of the water vapor contained in it are concentrated in the troposphere. In addition, from the surface of the earth to the upper border of the troposphere, the temperature decreases by an average of 0.6 ° for every 100 m, or 6 ° per 1 km uplifting . This is due to the fact that the air in the troposphere is heated and cooled primarily from the earth's surface.

In accordance with the influx of solar energy, the temperature decreases from the equator to the poles. So, the average air temperature near the earth's surface at the equator reaches + 26 °, over the polar regions in winter -34 °, -36 °, and in summer about 0 °. Thus, the temperature difference between the equator and the pole is 60 ° in winter and only 26 ° in summer. True, such low temperatures in the Arctic in winter are observed only near the surface of the earth due to the cooling of air over the icy expanses.

In winter, in Central Antarctica, the air temperature on the surface of the ice sheet is even lower. At Vostok station in August 1960, the lowest temperature on the globe was recorded - -88.3 °, and most often in Central Antarctica it is equal to -45 °, -50 °.

From the height, the temperature difference between the equator and the pole decreases. For example, at a height of 5 km at the equator, the temperature reaches - 2 °, -4 °, and at the same altitude in the Central Arctic -37 °, -39 ° in winter and -19 °, -20 ° in summer; therefore, the temperature difference in winter is 35-36 °, and in summer 16-17 °. In the southern hemisphere, these differences are somewhat larger.

The energy of atmospheric circulation can be determined by equator-pole temperature contracts. Since the magnitude of temperature contrasts is greater in winter, atmospheric processes are more intense than in summer. This also explains the fact that the prevailing westerly winds in winter in the troposphere have higher speeds than in summer. In this case, the wind speed, as a rule, increases with height, reaching a maximum at the upper boundary of the troposphere. Horizontal transport is accompanied by vertical air movements and turbulent (disordered) movement. As a result of the rise and fall of large volumes of air, clouds are formed and dispersed, precipitation appears and stops. The transition layer between the troposphere and the overlying sphere is tropopause. Above it lies the stratosphere.

Stratosphere stretches from heights 8-17 to 50-55 km. It was discovered at the beginning of our century. In terms of physical properties, the stratosphere differs sharply from the troposphere in that the air temperature here, as a rule, rises by an average of 1 - 2 ° per kilometer of rise and at the upper boundary, at an altitude of 50-55 km, even becomes positive. The rise in temperature in this area is caused by the presence of ozone (O 3) here, which is formed under the influence of ultraviolet radiation from the Sun. The ozone layer occupies almost the entire stratosphere. The stratosphere is very poor in water vapor. There are no violent cloud formation processes and no precipitation.

More recently, it was assumed that the stratosphere is a relatively calm environment, where there is no mixing of air, as in the troposphere. Therefore, it was believed that the gases in the stratosphere are divided into layers, in accordance with their specific weights... Hence the name of the stratosphere ("stratus" - layered). It was also assumed that the temperature in the stratosphere is formed under the influence of radiative equilibrium, that is, when the absorbed and reflected solar radiation is equal.

New data obtained with the help of radiosondes and meteorological rockets showed that in the stratosphere, as in the upper troposphere, there is intense air circulation with large changes in temperature and wind. Here, as in the troposphere, the air experiences significant vertical displacements, turbulent movements with strong horizontal air currents. All this is the result of a non-uniform temperature distribution.

The transition layer between the stratosphere and the overlying sphere is stratopause. However, before proceeding to characterize the higher layers of the atmosphere, let us familiarize ourselves with the so-called ozonosphere, the boundaries of which approximately correspond to the boundaries of the stratosphere.

Ozone in the atmosphere. Ozone plays an important role in creating the temperature regime and air currents in the stratosphere. Ozone (O 3) is felt by us after a thunderstorm when we inhale clean air with a pleasant aftertaste. However, here we are not talking about this ozone formed after a thunderstorm, but about the ozone contained in the 10-60 layer. km with a maximum at a height of 22-25 km. Ozone is produced by the sun's ultraviolet rays and, although the total is negligible, plays an important role in the atmosphere. Ozone has the ability to absorb ultraviolet radiation from the Sun and thus protects the animal and vegetable world from its destructive action. Even that negligible fraction of ultraviolet rays that reaches the surface of the earth burns the body severely when a person is overly addicted to sunbathing.

The amount of ozone is not the same over various parts Earth. There is more ozone in high latitudes, less in middle and low latitudes, and this amount changes depending on the change of seasons. More ozone in spring, less ozone in autumn. In addition, its non-periodic fluctuations occur depending on the horizontal and vertical circulation of the atmosphere. Many atmospheric processes are closely related to ozone content, as it directly affects the temperature field.

In winter, under polar night conditions, at high latitudes in the ozone layer, air is emitted and cooled. As a result, in the stratosphere of high latitudes (in the Arctic and Antarctic) in winter, a cold region forms, a stratospheric cyclonic vortex with large horizontal temperature and pressure gradients, causing westerly winds over the middle latitudes of the globe.

In summer, during a polar day, at high latitudes, the ozone layer absorbs solar heat and warms up the air. As a result of an increase in temperature in the stratosphere of high latitudes, a heat region and a stratospheric anticyclonic vortex are formed. Therefore, above the middle latitudes of the globe above 20 km in summer, easterly winds prevail in the stratosphere.

Mesosphere. Observations using meteorological rockets and other methods have established that the general increase in temperature observed in the stratosphere ends at heights of 50-55 km. Above this layer, the temperature again decreases and at the upper boundary of the mesosphere (about 80 km) reaches -75 °, -90 °. Further, the temperature rises again with height.

It is interesting to note that the decrease in temperature with altitude, characteristic of the mesosphere, occurs differently at different latitudes and throughout the year. At low latitudes, the temperature drop occurs more slowly than at high latitudes: the average vertical temperature gradient for the mesosphere is 0.23 ° - 0.31 ° per 100, respectively. m or 2.3 ° -3.1 ° per 1 km. In summer, it is much larger than in winter. As shown by the latest research in high latitudes, the temperature at the upper boundary of the mesosphere in summer is several tens of degrees lower than in winter. In the upper mesosphere at an altitude of about 80 km in the mesopause layer, the decrease in temperature with height stops and begins to rise. Here, under the inversion layer at dusk or before sunrise, in clear weather, there are shining thin clouds illuminated by the sun below the horizon. Against the dark background of the sky, they glow with a silvery-blue light. Therefore, these clouds are called silvery.

The nature of noctilucent clouds is still not well understood. Long time believed to be composed of volcanic dust. However, the absence of optical phenomena inherent in real volcanic clouds led to the rejection of this hypothesis. Then it was suggested that noctilucent clouds are composed of cosmic dust. V last years a hypothesis has been proposed that these clouds are composed of ice crystals, like ordinary cirrus clouds. The location of noctilucent clouds is determined by the retarding layer due to temperature inversion during the transition from the mesosphere to the thermosphere at an altitude of about 80 km. Since in the sub-inversion layer the temperature reaches -80 ° and below, the most favorable conditions are created here for condensation of water vapor, which gets here from the stratosphere as a result vertical movement or by turbulent diffusion. Noctilucent clouds are usually observed during the summer, sometimes in very large numbers and for several months.

Observations of noctilucent clouds have established that in summer, at their level, the winds are highly variable. Wind speeds vary widely: from 50-100 to several hundred kilometers per hour.

Temperature at heights. A visual representation of the nature of the temperature distribution with height, between the earth's surface and heights of 90-100 km, in winter and summer in the northern hemisphere, is given in Figure 5. The surfaces separating the spheres are shown here by bold dashed lines. At the very bottom, the troposphere stands out well with a characteristic decrease in temperature with height. Above the tropopause, in the stratosphere, on the contrary, the temperature generally rises with altitude and at heights of 50-55 km reaches + 10 °, -10 °. Pay attention to important detail... In winter, in the stratosphere of high latitudes, the temperature above the tropopause decreases from -60 to -75 ° and only above 30 km increases again to -15 °. In summer, starting from the tropopause, the temperature rises with altitude and by 50 km reaches + 10 °. Above the stratopause, the temperature again begins to decrease with altitude, and at a level of 80 km it does not exceed -70 °, -90 °.

Figure 5 shows that in layer 10-40 km the air temperature in winter and summer in high latitudes is sharply different. In winter, under polar night conditions, the temperature here reaches -60 °, -75 °, and in summer, a minimum of -45 ° is near the tropopause. Above the tropopause, the temperature rises and at altitudes of 30-35 km is only -30 °, -20 °, which is caused by the warming up of the air in the ozone layer in the conditions of a polar day. It also follows from the figure that even in the same season and at the same level, the temperature is not the same. Their difference between different latitudes exceeds 20-30 °. At the same time, the heterogeneity is especially significant in the layer of low temperatures (18-30 km) and in the layer of maximum temperatures (50-60 km) in the stratosphere, as well as in the layer of low temperatures in the upper mesosphere (75-85km).

The average temperatures shown in Figure 5 were obtained from observations in the northern hemispheres, however, judging by the available information, they can be attributed to the southern hemisphere. Some differences are found mainly at high latitudes. Over Antarctica in winter, the air temperature in the troposphere and lower stratosphere is noticeably lower than over the Central Arctic.

Winds at heights. The seasonal temperature distribution is responsible for a rather complex system of air currents in the stratosphere and mesosphere.

Figure 6 shows a vertical section of the wind field in the atmosphere between the earth's surface and a height of 90 km in winter and summer over the northern hemisphere. Isolines show the average speeds of the prevailing wind (in m / s). It follows from the figure that the wind regime in winter and summer in the stratosphere is sharply different. In winter, both in the troposphere and in the stratosphere, westerly winds prevail with maximum speeds equal to about

100 m / sec at a height of 60-65 km. In summer, westerly winds prevail only up to heights of 18-20 km. Above they become eastern, with maximum speeds of up to 70 m / sec at a height of 55-60km.

In summer, above the mesosphere, the winds become westerly, and in winter - easterly.

Thermosphere. The thermosphere is located above the mesosphere, which is characterized by an increase in temperature with height. According to the data obtained, mainly with the help of rockets, it was found that in the thermosphere already at the level of 150 km air temperature reaches 220-240 °, and at 200 km more than 500 °. Above, the temperature continues to rise and at the level of 500-600 km exceeds 1500 °. Based on the data obtained during the launches of artificial earth satellites, it was found that in the upper thermosphere the temperature reaches about 2000 ° and fluctuates significantly during the day. The question arises how to explain such a high temperature in the high layers of the atmosphere. Recall that the temperature of a gas is a measure of the average speed of movement of molecules. In the lower, densest part of the atmosphere, the molecules of the gases that make up the air, when moving, often collide with each other and instantly transfer kinetic energy to each other. Therefore, the kinetic energy in a dense medium is on average the same. In high layers, where the air density is very low, collisions between molecules located at large distances are less frequent. When energy is absorbed, the velocity of the molecules in the interval between collisions changes greatly; in addition, molecules of lighter gases move at a higher speed than molecules of heavy gases. As a result, the temperature of the gases can be different.

In rarefied gases, there are relatively few molecules of very small sizes (light gases). If they move at high speeds, then the temperature in a given volume of air will be high. In the thermosphere, each cubic centimeter of air contains tens and hundreds of thousands of molecules of various gases, while at the surface of the earth there are about hundreds of millions of billions. Therefore, excessively high temperatures in high layers of the atmosphere, showing the speed of movement of molecules in this very loose environment, cannot cause even a slight heating of the body located here. Just as a person does not feel the high temperature under the dazzling illumination of electric lamps, although the filaments in a rarefied environment instantly heat up to several thousand degrees.

In the lower thermosphere and mesosphere, the main part of the meteor showers burns up before reaching the earth's surface.

Available information on atmospheric layers above 60-80 km are still insufficient for final conclusions about the structure, regime and processes developing in them. However, it is known that in the upper mesosphere and lower thermosphere, the temperature regime is created as a result of the conversion of molecular oxygen (O 2) into atomic (O), which occurs under the action of ultraviolet solar radiation. In the thermosphere, the temperature regime is greatly influenced by corpuscular, X-ray, etc. ultraviolet radiation from the sun. Here, even during the day, there are sharp changes in temperature and wind.

Ionization of the atmosphere. Most interesting feature atmosphere above 60-80 km is her ionization, that is, the process of formation of a huge amount of electrically charged particles - ions. Since the ionization of gases is characteristic of the lower thermosphere, it is also called the ionosphere.

Gases in the ionosphere are mostly in the atomic state. Under the influence of ultraviolet and corpuscular radiation of the Sun, which have high energy, the process of splitting off electrons from neutral atoms and molecules of air takes place. Such atoms and molecules that have lost one or more electrons become positively charged, and a free electron can attach again to a neutral atom or molecule and endow them with its negative charge. Such positively and negatively charged atoms and molecules are called ions, and gases - ionized that is, received an electric charge. At a higher concentration of ions, the gases become electrically conductive.

The ionization process occurs most intensively in thick layers, limited by heights of 60-80 and 220-400 km. In these layers there are optimal conditions for ionization. Here the air density is noticeably higher than in the upper atmosphere, and the influx of ultraviolet and corpuscular radiation from the Sun is sufficient for the ionization process.

The discovery of the ionosphere is one of the most important and brilliant achievements of science. After all distinctive feature the ionosphere is its influence on the propagation of radio waves. In the ionized layers, radio waves are reflected, and therefore long-range radio communication becomes possible. Charged atoms-ions reflect short radio waves, and they return to the earth's surface again, but already at a considerable distance from the place of radio transmission. Obviously, short radio waves make this path several times, and thus long-distance radio communication is provided. If it were not for the ionosphere, expensive radio relay lines would have to be built to transmit signals from radio stations over long distances.

However, it is known that sometimes radio communications at short wavelengths are disrupted. This occurs as a result of chromospheric flares on the Sun, due to which the ultraviolet radiation of the Sun is sharply increased, leading to strong disturbances of the ionosphere and magnetic field Earths - to magnetic storms. During magnetic storms, radio communication is disrupted, since the movement of charged particles depends on the magnetic field. During magnetic storms, the ionosphere is less likely to reflect radio waves or transmit them into space. Mainly with a change in solar activity, accompanied by an increase in ultraviolet radiation, the electron density of the ionosphere and the absorption of radio waves in the daytime increase, leading to disruption of radio communication at short waves.

According to new studies, there are zones in a powerful ionized layer where the concentration of free electrons reaches a slightly higher concentration than in neighboring layers. There are four known such zones, which are located at heights of about 60-80, 100-120, 180-200 and 300-400 km and denoted by letters D, E, F 1 and F 2 ... With the increasing radiation of the Sun, charged particles (corpuscles) are deflected towards high latitudes under the influence of the Earth's magnetic field. Entering the atmosphere, the corpuscles intensify the ionization of gases to such an extent that they begin to glow. This is how polar lights- in the form of beautiful multicolored arcs that light up in the night sky mainly in the high latitudes of the Earth. Auroras are accompanied by strong magnetic storms. In such cases, auroras become visible in mid-latitudes, and in rare cases, even in the tropics. For example, the intense aurora observed on January 21-22, 1957, was visible in almost all southern regions of our country.

By photographing auroras from two points located at a distance of several tens of kilometers, the height of the aurora is determined with great accuracy. Usually auroras are located at an altitude of about 100 km, they are often found at an altitude of several hundred kilometers, and sometimes at a level of about 1000 km. Although the nature of the aurora has been clarified, there are still many unresolved issues related to this phenomenon. The reasons for the variety of forms of auroras are still unknown.

According to the third Soviet satellite, between altitudes 200 and 1000 km during the day, positive ions of split molecular oxygen, i.e., atomic oxygen (O), prevail. Soviet scientists are exploring the ionosphere using artificial satellites of the Cosmos series. American scientists are also studying the ionosphere using satellites.

The surface separating the thermosphere from the exosphere undergoes fluctuations depending on changes in solar activity and other factors. Vertically, these fluctuations reach 100-200 km and more.

Exosphere (sphere of dispersion) - the uppermost part of the atmosphere, located above 800 km. It has been little studied. According to observational data and theoretical calculations, the temperature in the exosphere with height increases presumably up to 2000 °. Unlike the lower ionosphere, gases in the exosphere are so rarefied that their particles, moving at tremendous speeds, hardly meet each other.

More recently, it was assumed that the conditional boundary of the atmosphere is at an altitude of about 1000 km. However, based on the deceleration of artificial earth satellites, it was found that at altitudes of 700-800 km in 1 cm 3 contains up to 160 thousand positive ions of atomic oxygen and nitrogen. This suggests that the charged layers of the atmosphere extend into space for a much greater distance.

At high temperatures at the conventional boundary of the atmosphere, the velocities of gas particles reach approximately 12 km / sec. At these velocities, gases gradually leave the area of gravity into interplanetary space. This has been happening for a long time. For example, particles of hydrogen and helium are removed into interplanetary space over several years.

In the study of high layers of the atmosphere, rich data were obtained both from satellites of the "Cosmos" and "Electron" series, and from geophysical rockets and space stations "Mars-1", "Luna-4", etc. Direct observations of astronauts were also valuable. So, according to photographs taken in space by V. Nikolaeva-Tereshkova, it was found that at an altitude of 19 km there is a dust layer from the Earth. This was confirmed by the data received by the crew. spaceship"Sunrise". Apparently, there is a close connection between the dust layer and the so-called mother-of-pearl clouds sometimes observed at altitudes of about 20-30km.

From the atmosphere to outer space. Previous assumptions that outside the Earth's atmosphere, in the interplanetary

space, gases are very rarefied and the concentration of particles does not exceed several units per 1 cm 3, did not come true. Studies have shown that near-Earth space is filled with charged particles. On this basis, a hypothesis was put forward about the existence of zones around the Earth with a noticeably increased content of charged particles, i.e. radiation belts- internal and external. The new data helped to clarify. It turned out that there are also charged particles between the inner and outer radiation belts. Their number varies depending on geomagnetic and solar activity. Thus, according to the new assumption, instead of radiation belts, there are radiation zones without clearly defined boundaries. The boundaries of the radiation zones change depending on solar activity. When it intensifies, that is, when spots and jets of gas appear on the Sun, ejected for hundreds of thousands of kilometers, the flow of cosmic particles increases, which feed the radiation zones of the Earth.

Radiation zones are dangerous for people flying in spaceships. Therefore, before the flight into space, the state and position of the radiation zones are determined, and the orbit of the spacecraft is chosen so that it passes outside the areas of increased radiation. However, the high layers of the atmosphere, as well as the outer space close to the Earth, are still poorly explored.

In the study of the high layers of the atmosphere and near-earth space, use is made of the rich data obtained from the "Cosmos" series satellites and space stations.

The high layers of the atmosphere are the least studied. but modern methods her research allows us to hope that in the coming years a person will know many details of the structure of the atmosphere at the bottom of which he lives.

In conclusion, we present a schematic vertical section of the atmosphere (Fig. 7). Here vertical heights are plotted in kilometers and air pressure in millimeters, and horizontally - temperature. The solid curve shows the change in air temperature with height. The most important phenomena observed in the atmosphere, as well as the maximum heights reached by radiosondes and other means of sounding the atmosphere, are also noted at the corresponding altitudes.

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 upper layers, a living organism can receive a lethal dose of the 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 changes in climatic weather conditions occur. 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 for the launch of 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 of a sound barrier loses its meaning. Here it is possible to control the aircraft 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.
The Buys-Balllot law states that if you are in the Northern Hemisphere and stand with your back to the wind, then there will be a high pressure zone on the right, and low pressure on the left. In the Southern Hemisphere, the opposite will be true.

Atmosphere(from the Greek atmos - steam and spharia - ball) - the air shell of the Earth, rotating with it. The development of the atmosphere was closely associated with the geological and geochemical processes taking place on our planet, as well as with the activities of living organisms.

The lower boundary of the atmosphere coincides with the surface of the Earth, since air penetrates into the smallest pores in the soil and is dissolved even in water.

The upper boundary at an altitude of 2000-3000 km gradually passes into outer space.

Thanks to the atmosphere, which contains oxygen, life on Earth is possible. Atmospheric oxygen is used in the process of respiration by humans, animals, and plants.

If there was no atmosphere, the earth would be as quiet as the moon. After all, sound is the vibration of air particles. The blue color of the sky is explained by the fact that the sun's rays, passing through the atmosphere, as through a lens, decompose into their constituent colors. At the same time, the rays of blue and blue colors are scattered most of all.

The atmosphere traps most of the sun's ultraviolet radiation, which has a detrimental effect on living organisms. It also retains heat at the surface of the Earth, preventing our planet from cooling.

The structure of the atmosphere

Several layers can be distinguished in the atmosphere, differing in density and density (Fig. 1).

Troposphere

Troposphere- the lowest layer of the atmosphere, the thickness of which is 8-10 km above the poles, 10-12 km in temperate latitudes, and 16-18 km above the equator.

Rice. 1. The structure of the Earth's atmosphere

The air in the troposphere is heated from the earth's surface, that is, from land and water. Therefore, the air temperature in this layer decreases with height by an average of 0.6 ° C for every 100 m. At the upper border of the troposphere, it reaches -55 ° C. At the same time, in the equatorial region at the upper border of the troposphere, the air temperature is -70 ° С, and in the North Pole area -65 ° С.

In the troposphere, about 80% of the mass of the atmosphere is concentrated, almost all water vapor is located, thunderstorms, storms, clouds and precipitation occur, and vertical (convection) and horizontal (wind) air movement also occurs.

We can say that the weather is mainly formed in the troposphere.

Stratosphere

Stratosphere- the layer of the atmosphere located above the troposphere at an altitude of 8 to 50 km. The color of the sky in this layer appears purple, which is explained by the rarefaction of the air, due to which the sun's rays are almost not scattered.

The stratosphere contains 20% of the mass of the atmosphere. The air in this layer is rarefied, there is practically no water vapor, and therefore almost no clouds and precipitation are formed. However, stable air currents are observed in the stratosphere, the speed of which reaches 300 km / h.

This layer is concentrated ozone(ozone screen, ozonosphere), a layer that absorbs ultraviolet rays, preventing them from reaching the Earth and thereby protecting living organisms on our planet. Thanks to ozone, the air temperature at the upper boundary of the stratosphere is in the range from -50 to 4-55 ° С.

Between the mesosphere and the stratosphere, there is a transition zone - the stratopause.

Mesosphere

Mesosphere- the layer of the atmosphere located at an altitude of 50-80 km. The density of air here is 200 times less than at the surface of the Earth. The sky in the mesosphere appears to be black, and stars are visible during the day. The air temperature drops to -75 (-90) ° С.

At an altitude of 80 km begins thermosphere. The air temperature in this layer rises sharply to an altitude of 250 m, and then becomes constant: at an altitude of 150 km, it reaches 220-240 ° C; at an altitude of 500-600 km, it exceeds 1500 ° C.

In the mesosphere and thermosphere, under the action of cosmic rays, gas molecules decay into charged (ionized) particles of atoms, therefore this part of the atmosphere is called ionosphere- a layer of very rarefied air, located at an altitude of 50 to 1000 km, consisting mainly of ionized oxygen atoms, nitrogen oxide molecules and free electrons. This layer is characterized by a high electrification, and long and medium radio waves are reflected from it, as from a mirror.

In the ionosphere, auroras arise - the glow of rarefied gases under the influence of electrically charged particles flying from the Sun - and sharp fluctuations in the magnetic field are observed.

Exosphere

Exosphere- the outer layer of the atmosphere, located above 1000 km. This layer is also called the scattering sphere, since gas particles move here with high speed and can be scattered into outer space.

Atmosphere composition

The atmosphere is a mixture of gases, consisting of nitrogen (78.08%), oxygen (20.95%), carbon dioxide (0.03%), argon (0.93%), a small amount of helium, neon, xenon, krypton (0.01%), ozone and other gases, but their content is negligible (Table 1). The modern composition of the Earth's air was established more than a hundred million years ago, but the dramatically increased production activity of man still led to its change. Currently, an increase in the content of CO 2 by about 10-12% is noted.

The gases in the atmosphere have different functional roles. However, the main significance of these gases is determined primarily by the fact that they very strongly absorb radiant energy and thus have a significant effect on temperature regime surface of the Earth and atmosphere.

Table 1. Chemical composition of dry atmospheric air near the earth's surface

	Volume concentration. %	Molecular weight, units

Oxygen

Carbon dioxide





Nitrous oxide
	from 0 to 0.00001
Sulfur dioxide	from 0 to 0.000007 in summer; from 0 to 0.000002 in winter
	From 0 to 0.000002	46,0055/17,03061
Azog dioxide

Carbon monoxide

Nitrogen, the most widespread gas in the atmosphere, it is not chemically active.

Oxygen, unlike nitrogen, it is a very active chemical element. The specific function of oxygen is the oxidation of organic matter of heterotrophic organisms, rocks and under-oxidized gases emitted into the atmosphere by volcanoes. Without oxygen, there would be no decomposition of dead organic matter.

The role of carbon dioxide in the atmosphere is extremely great. It enters the atmosphere as a result of combustion processes, respiration of living organisms, decay and is, first of all, the main building material for the creation of organic matter during photosynthesis. Besides, great value has the property of carbon dioxide to transmit short-wave solar radiation and absorb part of the thermal long-wave radiation, which will create the so-called greenhouse effect, which will be discussed below.

The influence on atmospheric processes, especially on the thermal regime of the stratosphere, is also exerted by ozone. This gas serves as a natural absorber of ultraviolet radiation from the sun, and absorption of solar radiation leads to heating of the air. The average monthly values of the total ozone content in the atmosphere vary depending on the latitude of the area and the time of year in the range of 0.23-0.52 cm (this is the thickness of the ozone layer at ground pressure and temperature). An increase in ozone content from the equator to the poles and an annual variation with a minimum in autumn and maximum in spring are observed.

A characteristic property of the atmosphere is that the content of the main gases (nitrogen, oxygen, argon) changes insignificantly with altitude: at an altitude of 65 km in the atmosphere, the content of nitrogen is 86%, oxygen is 19, argon is 0.91, and at an altitude of 95 km - nitrogen 77, oxygen - 21.3, argon - 0.82%. The constancy of the composition of atmospheric air vertically and horizontally is maintained by mixing it.

In addition to gases, the air contains water vapor and solid particles. The latter can be of both natural and artificial (anthropogenic) origin. These are pollen, tiny salt crystals, road dust, aerosol impurities. When the sun's rays enter the window, they can be seen with the naked eye.

Particles are especially abundant in the air of cities and large industrial centers, where emissions are added to aerosols. harmful gases, their impurities formed during fuel combustion.

The concentration of aerosols in the atmosphere determines the transparency of the air, which affects the solar radiation reaching the Earth's surface. The largest aerosols are condensation nuclei (from lat. condensatio- compaction, thickening) - contribute to the transformation of water vapor into water droplets.

The value of water vapor is determined primarily by the fact that it delays the long-wave thermal radiation of the earth's surface; represents the main link of large and small moisture cycles; increases the air temperature during condensation of water beds.

The amount of water vapor in the atmosphere changes over time and space. Thus, the concentration of water vapor at the earth's surface ranges from 3% in the tropics to 2-10 (15)% in Antarctica.

The average content of water vapor in the vertical column of the atmosphere in temperate latitudes is about 1.6-1.7 cm (this is the thickness of a layer of condensed water vapor). Information on water vapor in different layers of the atmosphere is contradictory. It was assumed, for example, that in the altitude range from 20 to 30 km, the specific humidity increases strongly with height. However, subsequent measurements indicate a greater dryness of the stratosphere. Apparently, the specific humidity in the stratosphere depends little on the height and amounts to 2-4 mg / kg.

The variability of the water vapor content in the troposphere is determined by the interaction of the processes of evaporation, condensation and horizontal transport. As a result of condensation of water vapor, clouds are formed and precipitation falls in the form of rain, hail and snow.

The processes of phase transitions of water occur mainly in the troposphere, which is why clouds in the stratosphere (at altitudes of 20-30 km) and the mesosphere (near the mesopause), called nacreous and silvery, are observed relatively rarely, while tropospheric clouds often cover about 50% of the entire earth surface.

The amount of water vapor that can be contained in the air depends on the air temperature.

1 m 3 of air at a temperature of -20 ° C can contain no more than 1 g of water; at 0 ° С - no more than 5 g; at +10 ° С - no more than 9 g; at +30 ° С - no more than 30 g of water.

Output: the higher the air temperature, the more water vapor it can contain.

The air can be saturated and not saturated water vapor. So, if at a temperature of +30 ° C 1 m 3 of air contains 15 g of water vapor, the air is not saturated with water vapor; if 30 g is saturated.

Absolute humidity Is the amount of water vapor contained in 1 m 3 of air. It is expressed in grams. For example, if they say "the absolute humidity is 15", then this means that 1 m L contains 15 g of water vapor.

Relative humidity Is the ratio (in percent) of the actual water vapor content in 1 m 3 of air to the amount of water vapor that can be contained in 1 ml L at a given temperature. For example, if the radio during the broadcast of the weather report said that the relative humidity is 70%, this means that the air contains 70% of the water vapor that it can hold at a given temperature.

The higher the relative humidity of the air, i.e. the closer the air is to saturation, the more likely precipitation is.

Always high (up to 90%) relative air humidity is observed in the equatorial zone, since there is a high air temperature throughout the year and there is a lot of evaporation from the surface of the oceans. The same high relative humidity in the polar regions, but already because at low temperatures even a small amount of water vapor makes the air saturated or close to saturation. In temperate latitudes, the relative humidity changes with the seasons - in winter it is higher, in summer it is lower.

Especially low relative humidity in deserts: 1 m 1 of air there contains two to three times less than the amount of water vapor possible at a given temperature.

To measure the relative humidity, use a hygrometer (from the Greek. Hygros - wet and metreco - I measure).

When cooled, saturated air cannot retain the same amount of water vapor; it thickens (condenses), turning into fog droplets. Fog can be observed in the summer on a clear cool night.

Clouds- this is the same fog, only it is formed not at the earth's surface, but at a certain height. Rising up, the air is cooled, and the water vapor in it condenses. The resulting tiny droplets of water make up the clouds.

In the formation of clouds are involved and solid particles suspended in the troposphere.

The clouds can have different shape, which depends on the conditions of their formation (Table 14).

The lowest and heaviest clouds are stratus. They are located at an altitude of 2 km from the earth's surface. At an altitude of 2 to 8 km, more picturesque cumulus clouds can be observed. The highest and lightest are cirrus clouds. They are located at an altitude of 8 to 18 km above the earth's surface.

Families	Clouds birth	External appearance
A. Clouds of the upper layer - above 6 km	I. Cirrus	Filiform, fibrous, white
	II. Cirrocumulus	Layers and ridges of fine flakes and curls, white
	III. Cirrostratus	Transparent whitish veil
B. Middle clouds - above 2 km	IV. Altocumulus	Seams and ridges of white and gray color
B. Middle clouds - above 2 km	V. Highly layered	Smooth shroud of milky gray
B. Low-tier clouds - up to 2 km	Vi. Nimbostratus	Solid shapeless gray layer
	Vii. Stratocumulus	Non-translucent gray layers and ridges
	VIII. Layered	An opaque shroud of gray
D. Clouds of vertical development - from the lower to the upper tier	IX. Cumulus	Clubs and domes are bright white, with ripped edges in wind
	X. Cumulonimbus	Powerful cumulus masses, dark leaden in color

Protection of the atmosphere

The main source is industrial plants and automobiles. In big cities, the problem of gas pollution on the main transport routes is very acute. That is why in many large cities of the world, including in our country, environmental control of the toxicity of vehicle exhaust gases has been introduced. According to experts, smoke and dustiness of the air can halve the supply of solar energy to the earth's surface, which will lead to a change in natural conditions.