Temperature in the layers of the atmosphere. Earth's atmosphere and physical properties of air

ATMOSPHERE of the Earth(Greek atmos steam + sphaira sphere) - a gaseous shell surrounding the Earth. The mass of the atmosphere is about 5.15 10 15 The biological significance of the atmosphere is enormous. In the atmosphere, mass and energy exchange takes place between living and inanimate nature, between flora and fauna. Atmospheric nitrogen is absorbed by microorganisms; From carbon dioxide and water, using the energy of the sun, plants synthesize organic substances and release oxygen. The presence of an atmosphere ensures the preservation of water on Earth, which is also an important condition for the existence of living organisms.

Studies carried out using high-altitude geophysical rockets, artificial Earth satellites and interplanetary automatic stations have established that the earth's atmosphere extends for thousands of kilometers. The boundaries of the atmosphere are unstable, they are influenced by the gravitational field of the Moon and the pressure of the flow of solar rays. Above the equator in the region of the earth's shadow, the atmosphere reaches altitudes of about 10,000 km, and above the poles its boundaries are 3,000 km away from the earth's surface. The bulk of the atmosphere (80-90%) is located within altitudes of up to 12-16 km, which is explained by the exponential (nonlinear) nature of the decrease in the density (rarefaction) of its gaseous environment as the altitude increases above sea level.

The existence of most living organisms in natural conditions is possible within even narrower boundaries of the atmosphere, up to 7-8 km, where the necessary combination of atmospheric factors such as gas composition, temperature, pressure, and humidity takes place. The movement and ionization of air, precipitation, and the electrical state of the atmosphere are also of hygienic importance.

Gas composition

The atmosphere is a physical mixture of gases (Table 1), mainly nitrogen and oxygen (78.08 and 20.95 vol.%). The ratio of atmospheric gases is almost the same up to altitudes of 80-100 km. The constancy of the main part of the gas composition of the atmosphere is determined by the relative balancing of gas exchange processes between living and inanimate nature and the continuous mixing of air masses in the horizontal and vertical directions.

Table 1. CHARACTERISTICS OF THE CHEMICAL COMPOSITION OF DRY ATMOSPHERIC AIR AT THE EARTH'S SURFACE

At altitudes above 100 km, there is a change in the percentage of individual gases associated with their diffuse stratification under the influence of gravity and temperature. In addition, under the influence of short-wavelength ultraviolet and x-rays at an altitude of 100 km or more, dissociation of oxygen, nitrogen and carbon dioxide molecules into atoms occurs. On high altitudes these gases are in the form of highly ionized atoms.

The content of carbon dioxide in the atmosphere of different regions of the Earth is less constant, which is partly due to the uneven distribution of large industrial enterprises polluting the air, as well as the uneven distribution of vegetation and water basins on Earth that absorb carbon dioxide. Also variable in the atmosphere is the content of aerosols (see) - particles suspended in the air ranging in size from several millimicrons to several tens of microns - formed as a result of volcanic eruptions, powerful artificial explosions, and pollution from industrial enterprises. The concentration of aerosols decreases rapidly with altitude.

The most variable and important of the variable components of the atmosphere is water vapor, the concentration of which is earth's surface can vary from 3% (in the tropics) to 2×10 -10% (in Antarctica). The higher the air temperature, the more moisture, other things being equal, can be in the atmosphere and vice versa. The bulk of water vapor is concentrated in the atmosphere to altitudes of 8-10 km. The content of water vapor in the atmosphere depends on the combined influence of evaporation, condensation and horizontal transport. At high altitudes, due to lower temperatures and condensation of vapors, the air is almost dry.

The Earth's atmosphere, in addition to molecular and atomic oxygen, also contains small amounts of ozone (see), the concentration of which is very variable and varies depending on the altitude and time of year. Most ozone is contained in the pole region towards the end of the polar night at an altitude of 15-30 km with a sharp decrease up and down. Ozone arises as a result of the photochemical effect of ultraviolet solar radiation on oxygen, mainly at altitudes of 20-50 km. Diatomic oxygen molecules partially disintegrate into atoms and, joining undecomposed molecules, form triatomic ozone molecules (a polymeric, allotropic form of oxygen).

The presence in the atmosphere of a group of so-called inert gases (helium, neon, argon, krypton, xenon) is associated with the continuous occurrence of natural radioactive decay processes.

Biological significance of gases the atmosphere is very great. For most multicellular organisms a certain content of molecular oxygen in a gas or aquatic environment is an indispensable factor in their existence, which during respiration determines the release of energy from organic substances initially created during photosynthesis. It is no coincidence that the upper boundaries of the biosphere (part of the surface globe and the lower part of the atmosphere where life exists) are determined by the presence sufficient quantity oxygen. In the process of evolution, organisms have adapted to a certain level of oxygen in the atmosphere; a change in oxygen content, either decreasing or increasing, has an adverse effect (see Altitude sickness, Hyperoxia, Hypoxia).

The ozone allotropic form of oxygen also has a pronounced biological effect. At concentrations not exceeding 0.0001 mg/l, which is typical for resort areas and sea coasts, ozone has healing effect- stimulates breathing and cardiovascular activity, improves sleep. With an increase in ozone concentration, its toxic effect appears: eye irritation, necrotic inflammation of the mucous membranes of the respiratory tract, exacerbation of pulmonary diseases, autonomic neuroses. Combining with hemoglobin, ozone forms methemoglobin, which leads to disruption of the respiratory function of the blood; the transfer of oxygen from the lungs to the tissues becomes difficult, and suffocation develops. Atomic oxygen has a similar adverse effect on the body. Ozone plays a significant role in creating the thermal regimes of various layers of the atmosphere due to the extremely strong absorption of solar radiation and terrestrial radiation. Ozone absorbs ultraviolet and infrared rays most intensely. Solar rays with wavelengths less than 300 nm are almost completely absorbed by atmospheric ozone. Thus, the Earth is surrounded by a kind of “ozone screen” that protects many organisms from the harmful effects ultraviolet radiation Sun, Nitrogen in atmospheric air is important biological significance primarily as a source of the so-called. fixed nitrogen - a resource of plant (and ultimately animal) food. The physiological significance of nitrogen is determined by its participation in creating the level necessary for life processes atmospheric pressure. Under certain conditions of pressure change, nitrogen plays a major role in the development of a number of disorders in the body (see Decompression sickness). Assumptions that nitrogen weakens the toxic effect of oxygen on the body and is absorbed from the atmosphere not only by microorganisms, but also by higher animals, are controversial.

The inert gases of the atmosphere (xenon, krypton, argon, neon, helium) at the partial pressure they create under normal conditions can be classified as biologically indifferent gases. With a significant increase in partial pressure, these gases have a narcotic effect.

The presence of carbon dioxide in the atmosphere ensures the accumulation of solar energy in the biosphere through photosynthesis complex compounds carbon, which continuously arise, change and decompose during life. This dynamic system is maintained by the activity of algae and land plants, which capture the energy of sunlight and use it to convert carbon dioxide (see) and water into a variety of organic compounds with the release of oxygen. The upward extension of the biosphere is partially limited by the fact that at altitudes above 6-7 km, chlorophyll-containing plants cannot live due to the low partial pressure of carbon dioxide. Carbon dioxide is also very active physiologically, as it plays an important role in the regulation metabolic processes, activities of the central nervous system, breathing, blood circulation, oxygen regime of the body. However, this regulation is mediated by the influence of carbon dioxide produced by the body itself, and not coming from the atmosphere. In the tissues and blood of animals and humans, the partial pressure of carbon dioxide is approximately 200 times higher than its pressure in the atmosphere. And only with a significant increase in the carbon dioxide content in the atmosphere (more than 0.6-1%) are disturbances observed in the body, designated by the term hypercapnia (see). Complete elimination of carbon dioxide from inhaled air cannot directly have an adverse effect on the human body and animals.

Carbon dioxide plays a role in absorbing long-wave radiation and maintaining the "greenhouse effect" that increases temperatures at the Earth's surface. The problem of the influence on thermal and other atmospheric conditions of carbon dioxide, which enters the air in huge quantities as industrial waste, is also being studied.

Atmospheric water vapor (air humidity) also affects the human body, in particular heat exchange with the environment.

As a result of condensation of water vapor in the atmosphere, clouds form and precipitation (rain, hail, snow) falls. Water vapor, scattering solar radiation, participates in the creation of the thermal regime of the Earth and the lower layers of the atmosphere, and in the formation of meteorological conditions.

Atmospheric pressure

Atmospheric pressure (barometric) is the pressure exerted by the atmosphere under the influence of gravity on the surface of the Earth. The magnitude of this pressure at each point in the atmosphere is equal to the weight of the overlying column of air with a single base, extending above the measurement location to the boundaries of the atmosphere. Atmospheric pressure is measured with a barometer (cm) and expressed in millibars, in newtons per square meter or the height of the mercury column in the barometer in millimeters, reduced to 0° and the normal value of the acceleration of gravity. In table Table 2 shows the most commonly used units of measurement of atmospheric pressure.

Pressure changes occur due to uneven heating of air masses located over land and water at different geographic latitudes. As the temperature rises, the density of the air and the pressure it creates decreases. A huge accumulation of fast-moving air with low pressure (with a decrease in pressure from the periphery to the center of the vortex) is called a cyclone, with high pressure (with an increase in pressure towards the center of the vortex) - an anticyclone. For weather forecasting, non-periodic changes in atmospheric pressure that occur in moving vast masses and are associated with the emergence, development and destruction of anticyclones and cyclones are important. Particularly large changes in atmospheric pressure are associated with the rapid movement of tropical cyclones. In this case, atmospheric pressure can change by 30-40 mbar per day.

The drop in atmospheric pressure in millibars over a distance of 100 km is called the horizontal barometric gradient. Typically, the horizontal barometric gradient is 1-3 mbar, but in tropical cyclones it sometimes increases to tens of millibars per 100 km.

With increasing altitude, atmospheric pressure decreases logarithmically: at first very sharply, and then less and less noticeably (Fig. 1). Therefore, the barometric pressure change curve is exponential.

The decrease in pressure per unit vertical distance is called the vertical barometric gradient. Often they use its inverse value - the barometric stage.

Since barometric pressure is the sum of the partial pressures of the gases that form air, it is obvious that with an increase in altitude, along with a decrease in the total pressure of the atmosphere, the partial pressure of the gases that make up the air also decreases. The partial pressure of any gas in the atmosphere is calculated by the formula

where P x ​​is the partial pressure of the gas, P z is the atmospheric pressure at height Z, X% is the percentage of gas whose partial pressure should be determined.

Rice. 1. Change in barometric pressure depending on altitude above sea level.

Rice. 2. Changes in the partial pressure of oxygen in the alveolar air and the saturation of arterial blood with oxygen depending on changes in altitude when breathing air and oxygen. Breathing oxygen begins at an altitude of 8.5 km (experiment in a pressure chamber).

Rice. 3. Comparative curves of average values ​​of active consciousness in a person in minutes at different altitudes after a rapid ascent while breathing air (I) and oxygen (II). At altitudes above 15 km, active consciousness is equally impaired when breathing oxygen and air. At altitudes up to 15 km, oxygen breathing significantly prolongs the period of active consciousness (experiment in a pressure chamber).

Since the percentage composition of atmospheric gases is relatively constant, to determine the partial pressure of any gas, you only need to know the total barometric pressure at a given altitude (Fig. 1 and Table 3).

Table 3. TABLE OF STANDARD ATMOSPHERE (GOST 4401-64) 1

1 Given in abbreviated form and supplemented with the column “Partial pressure of oxygen”.

When determining the partial pressure of a gas in moist air, it is necessary to subtract the pressure (elasticity) of saturated vapors from the value of barometric pressure.

The formula for determining the partial pressure of gas in humid air will be slightly different than for dry air:

where pH 2 O is the water vapor pressure. At t° 37°, the pressure of saturated water vapor is 47 mm Hg. Art. This value is used in calculating the partial pressures of alveolar air gases in ground and high-altitude conditions.

The effect on the body of increased and low blood pressure. Changes in barometric pressure upward or downward have a variety of effects on the body of animals and humans. Influence high blood pressure associated with the mechanical and penetrating physical and chemical action of the gas environment (the so-called compression and penetrating effects).

The compression effect is manifested by: general volumetric compression caused by a uniform increase in mechanical pressure forces on organs and tissues; mechanonarcosis caused by uniform volumetric compression at very high barometric pressure; local uneven pressure on tissues that limit gas-containing cavities when there is a broken connection between the outside air and the air in the cavity, for example, the middle ear, paranasal cavities (see Barotrauma); an increase in gas density in the external respiration system, which causes an increase in resistance to respiratory movements, especially during forced breathing ( physical activity, hypercapnia).

The penetrating effect can lead to the toxic effect of oxygen and indifferent gases, an increase in the content of which in the blood and tissues causes a narcotic reaction; the first signs of a cut when using a nitrogen-oxygen mixture in humans occur at a pressure of 4-8 atm. An increase in the partial pressure of oxygen initially reduces the level of functioning of the cardiovascular and respiratory systems due to the switching off of the regulatory influence of physiological hypoxemia. When the partial pressure of oxygen in the lungs increases by more than 0.8-1 ata, its toxic effect appears (damage to lung tissue, convulsions, collapse).

The penetrating and compression effects of increased gas pressure are used in clinical medicine in the treatment of various diseases with general and local impairment of oxygen supply (see Barotherapy, Oxygen therapy).

A decrease in pressure has an even more pronounced effect on the body. In conditions of an extremely rarefied atmosphere, the main pathogenetic factor leading to loss of consciousness in a few seconds, and to death in 4-5 minutes, is a decrease in the partial pressure of oxygen in the inhaled air, and then in the alveolar air, blood and tissues (Fig. 2 and 3). Moderate hypoxia causes the development of adaptive reactions of the respiratory and hemodynamic systems, aimed at maintaining oxygen supply primarily to vital organs (brain, heart). With a pronounced lack of oxygen, oxidative processes are inhibited (due to respiratory enzymes), and aerobic processes of energy production in mitochondria are disrupted. This leads first to disruption of the functions of vital organs, and then to irreversible structural damage and death of the body. The development of adaptive and pathological reactions, changes in the functional state of the body and a person’s performance when atmospheric pressure decreases are determined by the degree and rate of decrease in the partial pressure of oxygen in the inhaled air, the duration of stay at altitude, the intensity of the work performed, and the initial state of the body (see Altitude sickness).

A decrease in pressure at altitudes (even if oxygen deficiency is excluded) causes serious disorders in the body, united by the concept of “decompression disorders,” which include: high-altitude flatulence, barotitis and barosinusitis, high-altitude decompression sickness and high-altitude tissue emphysema.

High-altitude flatulence develops due to the expansion of gases in the gastrointestinal tract with a decrease in barometric pressure on the abdominal wall when rising to altitudes of 7-12 km or more. The release of gases dissolved in the intestinal contents is also of certain importance.

The expansion of gases leads to stretching of the stomach and intestines, elevation of the diaphragm, changes in the position of the heart, irritation of the receptor apparatus of these organs and the occurrence of pathological reflexes that impair breathing and blood circulation. Often arise sharp pains in the abdominal area. Similar phenomena sometimes occur among divers when rising from depth to the surface.

The mechanism of development of barotitis and barosinusitis, manifested by a feeling of congestion and pain, respectively, in the middle ear or paranasal cavities, is similar to the development of high-altitude flatulence.

A decrease in pressure, in addition to the expansion of gases contained in the body cavities, also causes the release of gases from liquids and tissues in which they were dissolved under pressure conditions at sea level or at depth, and the formation of gas bubbles in the body.

This process of release of dissolved gases (primarily nitrogen) causes the development of decompression sickness (see).

Rice. 4. Dependence of the boiling point of water on altitude above sea level and barometric pressure. The pressure numbers are located below the corresponding altitude numbers.

As atmospheric pressure decreases, the boiling point of liquids decreases (Fig. 4). At an altitude of more than 19 km, where barometric pressure is equal to (or less than) the elasticity of saturated vapor at body temperature (37°), “boiling” of the interstitial and intercellular fluid of the body can occur, resulting in large veins, in the cavity of the pleura, stomach, pericardium , in loose fatty tissue, that is, in areas with low hydrostatic and interstitial pressure, bubbles of water vapor form, and high-altitude tissue emphysema develops. High-altitude “boiling” does not affect cellular structures, being localized only in the intercellular fluid and blood.

Massive steam bubbles can block the heart and blood circulation and disrupt the functioning of vital systems and organs. This is a serious complication of acute oxygen starvation that develops at high altitudes. Prevention of high-altitude tissue emphysema can be achieved by creating external back pressure on the body using high-altitude equipment.

The process of lowering barometric pressure (decompression) under certain parameters can become a damaging factor. Depending on the speed, decompression is divided into smooth (slow) and explosive. The latter occurs in less than 1 second and is accompanied by a strong bang (as when fired) and the formation of fog (condensation of water vapor due to cooling of the expanding air). Typically, explosive decompression occurs at altitudes when the glazing of a pressurized cabin or pressure suit is destroyed.

During explosive decompression, the lungs are the first to be affected. A rapid increase in intrapulmonary excess pressure (by more than 80 mm Hg) leads to significant stretching of the lung tissue, which can cause rupture of the lungs (if they expand 2.3 times). Explosive decompression can cause damage and gastrointestinal tract. The amount of excess pressure that occurs in the lungs will largely depend on the rate of air expiration from them during decompression and the volume of air in the lungs. It is especially dangerous if the upper respiratory tract at the moment of decompression they will be closed (when swallowing, holding your breath) or decompression will coincide with the phase of deep inspiration when the lungs are filled a large number air.

Atmospheric temperature

The temperature of the atmosphere initially decreases with increasing altitude (on average from 15° at the ground to -56.5° at an altitude of 11-18 km). The vertical temperature gradient in this zone of the atmosphere is about 0.6° for every 100 m; it changes throughout the day and year (Table 4).

Table 4. CHANGES IN THE VERTICAL TEMPERATURE GRADIENT OVER THE MIDDLE BAND OF THE USSR TERRITORY

Rice. 5. Changes in atmospheric temperature at different altitudes. The boundaries of the spheres are indicated by dotted lines.

At altitudes of 11 - 25 km, the temperature becomes constant and amounts to -56.5°; then the temperature begins to rise, reaching 30-40° at an altitude of 40 km, and 70° at an altitude of 50-60 km (Fig. 5), which is associated with intense absorption of solar radiation by ozone. From an altitude of 60-80 km, the air temperature again decreases slightly (to 60°), and then progressively increases and is 270° at an altitude of 120 km, 800° at 220 km, 1500° at an altitude of 300 km, and

at the border with outer space - more than 3000°. It should be noted that due to the high rarefaction and low density of gases at these altitudes, their heat capacity and ability to heat colder bodies is very insignificant. Under these conditions, heat transfer from one body to another occurs only through radiation. All considered changes in temperature in the atmosphere are associated with the absorption of thermal energy from the Sun by air masses - direct and reflected.

In the lower part of the atmosphere near the Earth's surface, the temperature distribution depends on the influx of solar radiation and therefore has a mainly latitudinal character, that is, lines of equal temperature - isotherms - are parallel to the latitudes. Since the atmosphere in the lower layers is heated by the earth's surface, the horizontal temperature change is strongly influenced by the distribution of continents and oceans, the thermal properties of which are different. Typically, reference books indicate the temperature measured during network meteorological observations with a thermometer installed at a height of 2 m above the soil surface. The highest temperatures (up to 58°C) are observed in the deserts of Iran, and in the USSR - in the south of Turkmenistan (up to 50°), the lowest (up to -87°) in Antarctica, and in the USSR - in the areas of Verkhoyansk and Oymyakon (up to -68° ). In winter, the vertical temperature gradient in some cases, instead of 0.6°, can exceed 1° per 100 m or even take a negative value. During the day in the warm season, it can be equal to many tens of degrees per 100 m. There is also a horizontal temperature gradient, which is usually referred to a distance of 100 km normal to the isotherm. The magnitude of the horizontal temperature gradient is tenths of a degree per 100 km, and in frontal zones it can exceed 10° per 100 m.

The human body is capable of maintaining thermal homeostasis (see) within a fairly narrow range of fluctuations in outside air temperature - from 15 to 45°. Significant differences in atmospheric temperature near the Earth and at altitudes require the use of special protective technical means to ensure thermal balance between the human body and external environment in high altitude and space flights.

Characteristic changes in atmospheric parameters (temperature, pressure, chemical composition, electrical state) make it possible to conditionally divide the atmosphere into zones or layers. Troposphere- the closest layer to the Earth, the upper boundary of which extends up to 17-18 km at the equator, up to 7-8 km at the poles, and up to 12-16 km at the middle latitudes. The troposphere is characterized by an exponential drop in pressure, the presence of a constant vertical temperature gradient, horizontal and vertical movements of air masses, and significant changes in air humidity. The troposphere contains the bulk of the atmosphere, as well as a significant part of the biosphere; All main types of clouds arise here, air masses and fronts form, cyclones and anticyclones develop. In the troposphere, due to the reflection of the sun's rays by the snow cover of the Earth and the cooling of surface air layers, a so-called inversion occurs, that is, an increase in temperature in the atmosphere from bottom to top instead of the usual decrease.

During the warm season, constant turbulent (disorderly, chaotic) mixing of air masses and heat transfer by air currents (convection) occur in the troposphere. Convection destroys fogs and reduces dust in the lower layer of the atmosphere.

The second layer of the atmosphere is stratosphere.

It starts from the troposphere in a narrow zone (1-3 km) with a constant temperature (tropopause) and extends to altitudes of about 80 km. A feature of the stratosphere is the progressive thinness of air, extremely high intensity of ultraviolet radiation, the absence of water vapor, the presence of large amounts of ozone and a gradual increase in temperature. High ozone content causes a number of optical phenomena(mirages), causes reflection of sounds and has a significant impact on the intensity and spectral composition of electromagnetic radiation. In the stratosphere there is constant mixing of air, so its composition is similar to that of the troposphere, although its density at the upper boundaries of the stratosphere is extremely low. The predominant winds in the stratosphere are westerly, and in the upper zone there is a transition to eastern winds.

The third layer of the atmosphere is ionosphere, which starts from the stratosphere and extends to altitudes of 600-800 km.

Distinctive features of the ionosphere are extreme rarefaction of the gaseous environment, high concentration of molecular and atomic ions and free electrons, as well as high temperature. The ionosphere influences the propagation of radio waves, causing their refraction, reflection and absorption.

The main source of ionization in the high layers of the atmosphere is ultraviolet radiation from the Sun. In this case, electrons are knocked out from gas atoms, the atoms turn into positive ions, and the knocked out electrons remain free or are captured by neutral molecules to form negative ions. The ionization of the ionosphere is influenced by meteors, corpuscular, X-ray and gamma radiation from the Sun, as well as seismic processes of the Earth (earthquakes, volcanic eruptions, powerful explosions), which generate acoustic waves in the ionosphere, increasing the amplitude and speed of oscillations of atmospheric particles and promoting the ionization of gas molecules and atoms (see Aeroionization).

Electrical conductivity in the ionosphere, associated with the high concentration of ions and electrons, is very high. The increased electrical conductivity of the ionosphere plays an important role in the reflection of radio waves and the occurrence of auroras.

The ionosphere is the flight area of ​​artificial Earth satellites and intercontinental ballistic missiles. Currently, space medicine is studying the possible effects of flight conditions in this part of the atmosphere on the human body.

The fourth, outer layer of the atmosphere - exosphere. From here, atmospheric gases are dispersed into space due to dissipation (overcoming the forces of gravity by molecules). Then there is a gradual transition from the atmosphere to interplanetary space. The exosphere differs from the latter in the presence of a large number of free electrons, forming the 2nd and 3rd radiation belts of the Earth.

The division of the atmosphere into 4 layers is very arbitrary. Thus, according to electrical parameters, the entire thickness of the atmosphere is divided into 2 layers: the neutrosphere, in which neutral particles predominate, and the ionosphere. Based on temperature, the troposphere, stratosphere, mesosphere and thermosphere are distinguished, separated by tropopause, stratosphere and mesopause, respectively. The layer of the atmosphere located between 15 and 70 km and characterized by a high content of ozone is called the ozonosphere.

For practical purposes, it is convenient to use the International Standard Atmosphere (MCA), for which the following conditions are accepted: pressure at sea level at t° 15° is equal to 1013 mbar (1.013 X 10 5 nm 2, or 760 mm Hg); the temperature decreases by 6.5° per 1 km to a level of 11 km (conditional stratosphere), and then remains constant. In the USSR, the standard atmosphere GOST 4401 - 64 was adopted (Table 3).

Precipitation. Since the bulk of atmospheric water vapor is concentrated in the troposphere, the processes of phase transitions of water that cause precipitation occur predominantly in the troposphere. Tropospheric clouds usually cover about 50% of the entire earth's surface, while clouds in the stratosphere (at altitudes of 20-30 km) and near the mesopause, called pearlescent and noctilucent, respectively, are observed relatively rarely. As a result of condensation of water vapor in the troposphere, clouds form and precipitation occurs.

Based on the nature of precipitation, precipitation is divided into 3 types: heavy, torrential, and drizzling. The amount of precipitation is determined by the thickness of the layer of fallen water in millimeters; Precipitation is measured using rain gauges and precipitation gauges. Precipitation intensity is expressed in millimeters per minute.

The distribution of precipitation in individual seasons and days, as well as over the territory, is extremely uneven, which is due to atmospheric circulation and the influence of the Earth's surface. Thus, on the Hawaiian Islands, an average of 12,000 mm falls per year, and in the driest areas of Peru and the Sahara, precipitation does not exceed 250 mm, and sometimes does not fall for several years. In the annual dynamics of precipitation, the following types are distinguished: equatorial - with maximum precipitation after the spring and autumn equinox; tropical - with maximum precipitation in summer; monsoon - with a very pronounced peak in summer and dry winter; subtropical - with maximum precipitation in winter and dry summer; continental temperate latitudes - with maximum precipitation in summer; maritime temperate latitudes - with maximum precipitation in winter.

The entire atmospheric-physical complex of climatic and meteorological factors that makes up the weather is widely used to improve health, harden and medicinal purposes(see Climatotherapy). Along with this, it has been established that sharp fluctuations in these atmospheric factors can negatively affect physiological processes in the body, causing the development of various pathological conditions and exacerbation of diseases called meteotropic reactions (see Climatopathology). Of particular importance in this regard are frequent long-term atmospheric disturbances and sharp abrupt fluctuations in meteorological factors.

Meteotropic reactions are observed more often in people suffering from diseases cardiovascular system, polyarthritis, bronchial asthma, peptic ulcer, skin diseases.

Bibliography: Belinsky V. A. and Pobiyaho V. A. Aerology, L., 1962, bibliogr.; Biosphere and its resources, ed. V. A. Kovdy, M., 1971; Danilov A.D. Chemistry of the ionosphere, Leningrad, 1967; Kolobkov N.V. Atmosphere and its life, M., 1968; Kalitin N.H. Fundamentals of atmospheric physics as applied to medicine, Leningrad, 1935; Matveev L. T. Fundamentals of general meteorology, Atmospheric Physics, Leningrad, 1965, bibliogr.; Minkh A. A. Air ionization and its hygienic significance, M., 1963, bibliogr.; aka, Methods of hygienic research, M., 1971, bibliogr.; Tverskoy P.N. Course of meteorology, L., 1962; Umansky S.P. Man in Space, M., 1970; Khvostikov I. A. High layers of the atmosphere, Leningrad, 1964; X r g i a n A. X. Physics of the atmosphere, L., 1969, bibliogr.; Khromov S.P. Meteorology and climatology for geographical faculties, Leningrad, 1968.

The effect of high and low blood pressure on the body- Armstrong G. Aviation Medicine, trans. from English, M., 1954, bibliogr.; Zaltsman G.L. Physiological foundations of a person’s stay in conditions of high pressure of environmental gases, L., 1961, bibliogr.; Ivanov D.I. and Khromushkin A.I. Human life support systems during high-altitude and space flights, M., 1968, bibliogr.; Isakov P.K. et al. Theory and practice of aviation medicine, M., 1971, bibliogr.; Kovalenko E. A. and Chernyakov I. N. Tissue oxygen under extreme flight factors, M., 1972, bibliogr.; Miles S. Underwater medicine, trans. from English, M., 1971, bibliogr.; Busby D. E. Space clinical medicine, Dordrecht, 1968.

I. N. Chernyakov, M. T. Dmitriev, S. I. Nepomnyashchy.

The Earth's atmosphere is a shell of air.

The presence of a special ball above the earth's surface was proven by the ancient Greeks, who called the atmosphere a steam or gas ball.

This is one of the geospheres of the planet, without which the existence of all living things would not be possible.

Where is the atmosphere

The atmosphere surrounds the planets with a dense layer of air, starting from the earth's surface. It comes into contact with the hydrosphere, covers the lithosphere, extending far into outer space.

What does the atmosphere consist of?

The air layer of the Earth consists mainly of air, the total mass of which reaches 5.3 * 1018 kilograms. Of these, the diseased part is dry air, and much less is water vapor.

Over the sea, the density of the atmosphere is 1.2 kilograms per cubic meter. The temperature in the atmosphere can reach –140.7 degrees, air dissolves in water at zero temperature.

The atmosphere consists of several layers:

• Troposphere;
• Tropopause;
• Stratosphere and stratopause;
• Mesosphere and mesopause;
• A special line above sea level called the Karman line;
• Thermosphere and thermopause;
• Scattering zone or exosphere.

Each layer has its own characteristics; they are interconnected and ensure the functioning of the planet’s air envelope.

Limits of the atmosphere

The lowest edge of the atmosphere passes through the hydrosphere and the upper layers of the lithosphere. The upper boundary begins in the exosphere, which is located 700 kilometers from the surface of the planet and will reach 1.3 thousand kilometers.

According to some reports, the atmosphere reaches 10 thousand kilometers. Scientists agreed that the upper boundary of the air layer should be the Karman line, since aeronautics is no longer possible here.

Thanks to constant study In this area, scientists have found that the atmosphere comes into contact with the ionosphere at an altitude of 118 kilometers.

Chemical composition

This layer of the Earth consists of gases and gaseous impurities, which include combustion residues, sea salt, ice, water, and dust. The composition and mass of gases that can be found in the atmosphere almost never changes, only the concentration of water and carbon dioxide changes.

The composition of the water can vary from 0.2 percent to 2.5 percent, depending on latitude. Additional elements are chlorine, nitrogen, sulfur, ammonia, carbon, ozone, hydrocarbons, hydrochloric acid, hydrogen fluoride, hydrogen bromide, hydrogen iodide.

A separate part is occupied by mercury, iodine, bromine, and nitric oxide. In addition, liquid and solid particles called aerosol are found in the troposphere. One of the rarest gases on the planet, radon, is found in the atmosphere.

In terms of chemical composition, nitrogen occupies more than 78% of the atmosphere, oxygen - almost 21%, carbon dioxide - 0.03%, argon - almost 1%, the total amount of the substance is less than 0.01%. This air composition was formed when the planet first emerged and began to develop.

With the advent of man, who gradually moved to production, chemical composition changed. In particular, the amount of carbon dioxide is constantly increasing.

Functions of the atmosphere

Gases in the air layer perform a variety of functions. Firstly, they absorb rays and radiant energy. Secondly, they influence the formation of temperature in the atmosphere and on Earth. Thirdly, it ensures life and its course on Earth.

In addition, this layer provides thermoregulation, which determines the weather and climate, the mode of heat distribution and atmospheric pressure. The troposphere helps regulate the flow of air masses, determine the movement of water, and heat exchange processes.

The atmosphere constantly interacts with the lithosphere and hydrosphere, providing geological processes. Most main function is that there is protection from dust of meteorite origin, from the influence of space and the sun.

Facts

• Oxygen is provided on Earth by the decomposition of organic matter in solid rock, which is very important during emissions, decomposition of rocks, and oxidation of organisms.
• Carbon dioxide helps photosynthesis occur, and also contributes to the transmission of short waves of solar radiation and the absorption of long thermal waves. If this does not happen, then the so-called greenhouse effect is observed.
• One of the main problems associated with the atmosphere is pollution, which occurs due to the operation of factories and automobile emissions. Therefore, many countries have introduced special environmental control, and at the international level special mechanisms are being undertaken to regulate emissions and the greenhouse effect.

The atmosphere is the air envelope of the Earth. Extending up to 3000 km from the earth's surface. Its traces can be traced to altitudes of up to 10,000 km. A. has an uneven density 50 5 its masses are concentrated up to 5 km, 75% - up to 10 km, 90% - up to 16 km.

The atmosphere consists of air - a mechanical mixture of several gases.

Nitrogen(78%) in the atmosphere plays the role of an oxygen diluent, regulating the rate of oxidation, and, consequently, the speed and intensity of biological processes. Nitrogen – main element earth's atmosphere, which continuously exchanges with living matter of the biosphere, and components the latter are nitrogen compounds (amino acids, purines, etc.). Nitrogen is extracted from the atmosphere by inorganic and biochemical routes, although they are closely interrelated. Inorganic extraction is associated with the formation of its compounds N 2 O, N 2 O 5, NO 2, NH 3. They are found in precipitation and are formed in the atmosphere under the influence of electrical discharges during thunderstorms or photochemical reactions under the influence of solar radiation.

Biological fixation of nitrogen is carried out by some bacteria in symbiosis with higher plants in soils. Nitrogen is also fixed by some plankton microorganisms and algae in the marine environment. In quantitative terms, the biological fixation of nitrogen exceeds its inorganic fixation. The exchange of all nitrogen in the atmosphere occurs within approximately 10 million years. Nitrogen is found in gases of volcanic origin and in eruptive rocks Oh. When various samples of crystalline rocks and meteorites are heated, nitrogen is released in the form of N 2 and NH 3 molecules. However, the main form of the presence of nitrogen, both on Earth and on the terrestrial planets, is molecular. Ammonia, entering the upper atmosphere, quickly oxidizes, releasing nitrogen. In sedimentary rocks it is buried together with organic matter and is found in increased quantities in bituminous deposits. During regional metamorphism of these rocks, nitrogen is released in various forms into the Earth's atmosphere.

Geochemical nitrogen cycle (

Oxygen(21%) is used by living organisms for respiration, is part of organic matter(proteins, fats, carbohydrates). Ozone O 3. delays life-destructive ultraviolet radiation from the Sun.

Oxygen is the second most widespread gas in the atmosphere, playing an extremely important role in many processes in the biosphere. The dominant form of its existence is O 2. In the upper layers of the atmosphere, under the influence of ultraviolet radiation, dissociation of oxygen molecules occurs, and at an altitude of approximately 200 km, the ratio of atomic oxygen to molecular (O: O 2) becomes equal to 10. When these forms of oxygen interact in the atmosphere (at an altitude of 20-30 km), a ozone belt (ozone screen). Ozone (O 3) is necessary for living organisms, blocking most of the ultraviolet radiation from the Sun, which is harmful to them.

In the early stages of the Earth's development, free oxygen appeared in very small quantities as a result of photodissociation of carbon dioxide and water molecules in the upper layers of the atmosphere. However, these small amounts were quickly consumed by the oxidation of other gases. With the appearance of autotrophic photosynthetic organisms in the ocean, the situation changed significantly. The amount of free oxygen in the atmosphere began to increase progressively, actively oxidizing many components of the biosphere. Thus, the first portions of free oxygen contributed primarily to the transition of ferrous forms of iron into oxide forms, and sulfides into sulfates.

Eventually, the amount of free oxygen in the Earth's atmosphere reached a certain mass and was balanced in such a way that the amount produced became equal to the amount absorbed. A relative constant content of free oxygen has been established in the atmosphere.

Geochemical oxygen cycle (V.A. Vronsky, G.V. Voitkevich)

Carbon dioxide, goes into the formation of living matter, and together with water vapor creates the so-called “greenhouse (greenhouse) effect.”

Carbon (carbon dioxide) - most of it in the atmosphere is in the form of CO 2 and much less in the form of CH 4. The significance of the geochemical history of carbon in the biosphere is extremely great, since it is part of all living organisms. Within living organisms, reduced forms of carbon predominate, and in environment biospheres are oxidized. Thus, a chemical exchange is established life cycle: CO 2 ↔ living matter.

The source of primary carbon dioxide in the biosphere is volcanic activity associated with secular degassing of the mantle and lower horizons of the earth's crust. Part of this carbon dioxide arises during the thermal decomposition of ancient limestones in various metamorphic zones. Migration of CO 2 in the biosphere occurs in two ways.

The first method is expressed in the absorption of CO 2 during photosynthesis with the formation of organic substances and subsequent burial in favorable reducing conditions in the lithosphere in the form of peat, coal, oil, and oil shale. According to the second method, carbon migration leads to the creation of a carbonate system in the hydrosphere, where CO 2 turns into H 2 CO 3, HCO 3 -1, CO 3 -2. Then, with the participation of calcium (less commonly magnesium and iron), carbonates are deposited via biogenic and abiogenic pathways. Thick layers of limestone and dolomite appear. According to A.B. Ronov, the ratio of organic carbon (Corg) to carbonate carbon (Ccarb) in the history of the biosphere was 1:4.

Along with the global carbon cycle, there are also a number of small carbon cycles. So, on land, green plants absorb CO 2 for the process of photosynthesis during the daytime, and at night they release it into the atmosphere. With the death of living organisms on the earth's surface, oxidation of organic substances occurs (with the participation of microorganisms) with the release of CO 2 into the atmosphere. IN last decades A special place in the carbon cycle is occupied by the massive combustion of fossil fuels and the increase in its content in the modern atmosphere.

Carbon cycle in the geographic envelope (according to F. Ramad, 1981)

Argon- the third most widespread atmospheric gas, which sharply distinguishes it from the extremely sparsely distributed other inert gases. However, argon in its geological history shares the fate of these gases, which are characterized by two features:

1. the irreversibility of their accumulation in the atmosphere;
2. close connection with radioactive decay certain unstable isotopes.

Inert gases are outside the cycle of most cyclic elements in the Earth's biosphere.

All inert gases can be divided into primary and radiogenic. The primary ones include those that were captured by the Earth during the period of its formation. They are extremely rare. The primary part of argon is represented mainly by the isotopes 36 Ar and 38 Ar, while atmospheric argon consists entirely of the isotope 40 Ar (99.6%), which is undoubtedly radiogenic. In potassium-containing rocks, the accumulation of radiogenic argon occurred and continues to occur due to the decay of potassium-40 through electron capture: 40 K + e → 40 Ar.

Therefore, the argon content in rocks is determined by their age and the amount of potassium. To this extent, the helium concentration in rocks is a function of their age and thorium and uranium content. Argon and helium are released into the atmosphere from the bowels of the earth during volcanic eruptions, through cracks in the earth's crust in the form of gas jets, and also during weathering of rocks. According to calculations performed by P. Dimon and J. Culp, helium and argon in the modern era accumulate in the earth's crust and enter the atmosphere in relatively small quantities. The rate of entry of these radiogenic gases is so low that during the geological history of the Earth it could not ensure their observed content in the modern atmosphere. Therefore, it remains to be assumed that most of the argon in the atmosphere came from the interior of the Earth at the earliest stages of its development, and much less was added subsequently during the process of volcanism and during the weathering of potassium-containing rocks.

Thus, over geological time, helium and argon have had different migration processes. There is very little helium in the atmosphere (about 5 * 10 -4%), and the “helium breathing” of the Earth was lighter, since it, as the lightest gas, evaporated into outer space. And “argon breathing” was heavy and argon remained within our planet. Most of the primordial noble gases, such as neon and xenon, were associated with primordial neon captured by the Earth during its formation, as well as with release during degassing of the mantle into the atmosphere. The entire body of data on the geochemistry of noble gases indicates that the primary atmosphere of the Earth arose at the earliest stages of its development.

The atmosphere contains water vapor And water in liquid and solid state. Water in the atmosphere is an important heat accumulator.

The lower layers of the atmosphere contain a large amount of mineral and technogenic dust and aerosols, combustion products, salts, spores and pollen, etc.

Up to an altitude of 100-120 km, due to complete mixing of the air, the composition of the atmosphere is homogeneous. The ratio between nitrogen and oxygen is constant. Above, inert gases, hydrogen, etc. predominate. In the lower layers of the atmosphere there is water vapor. With distance from the earth its content decreases. Higher the ratio of gases changes, for example, at an altitude of 200-800 km, oxygen predominates over nitrogen by 10-100 times.

The world around us is formed from three very different parts: earth, water and air. Each of them is unique and interesting in its own way. Now we will talk only about the last of them. What is atmosphere? How did it come about? What does it consist of and into what parts is it divided? All these questions are extremely interesting.

The name “atmosphere” itself is formed from two words Greek origin, translated into Russian they mean “steam” and “ball”. And if you look at the exact definition, you can read the following: “The atmosphere is the air shell of the planet Earth, which rushes along with it in outer space.” It developed in parallel with the geological and geochemical processes that took place on the planet. And today all processes occurring in living organisms depend on it. Without an atmosphere, the planet would become a lifeless desert, like the Moon.

What does it consist of?

The question of what the atmosphere is and what elements are included in it has interested people for a long time. The main components of this shell were already known in 1774. They were installed by Antoine Lavoisier. He discovered that the composition of the atmosphere was largely composed of nitrogen and oxygen. Over time, its components were refined. And now it is known that it contains many other gases, as well as water and dust.

Let's take a closer look at what makes up the Earth's atmosphere near its surface. The most common gas is nitrogen. It contains slightly more than 78 percent. But, despite such a large amount, nitrogen is practically inactive in the air.

The next element in quantity and very important in importance is oxygen. This gas contains almost 21%, and it exhibits very high activity. Its specific function is to oxidize dead organic matter, which decomposes as a result of this reaction.

Low but important gases

The third gas that is part of the atmosphere is argon. It's a little less than one percent. After it come carbon dioxide with neon, helium with methane, krypton with hydrogen, xenon, ozone and even ammonia. But there are so few of them that the percentage of such components is equal to hundredths, thousandths and millionths. Of these, only carbon dioxide plays a significant role, since it is building material, which plants need for photosynthesis. His other important function is to block radiation and absorb some of the solar heat.

Another small but important gas, ozone exists to trap ultraviolet radiation coming from the Sun. Thanks to this property, all life on the planet is reliably protected. On the other hand, ozone affects the temperature of the stratosphere. Due to the fact that it absorbs this radiation, the air heats up.

The constancy of the quantitative composition of the atmosphere is maintained by non-stop mixing. Its layers move both horizontally and vertically. Therefore, anywhere on the globe there is enough oxygen and no excess carbon dioxide.

What else is in the air?

It should be noted that steam and dust can be found in the airspace. The latter consists of pollen and soil particles; in the city they are joined by impurities of solid emissions from exhaust gases.

But there is a lot of water in the atmosphere. Under certain conditions, it condenses and clouds and fog appear. In essence, these are the same thing, only the first ones appear high above the surface of the Earth, and the last one spreads along it. Clouds take different shapes. This process depends on the height above the Earth.

If they formed 2 km above land, then they are called layered. It is from them that rain pours on the ground or snow falls. Above them, cumulus clouds form up to a height of 8 km. They are always the most beautiful and picturesque. They are the ones who look at them and wonder what they look like. If such formations appear in the next 10 km, they will be very light and airy. Their name is feathery.

What layers is the atmosphere divided into?

Although they have very different temperatures from each other, it is very difficult to tell at what specific height one layer begins and the other ends. This division is very conditional and is approximate. However, the layers of the atmosphere still exist and perform their functions.

The lowest part of the air shell is called the troposphere. Its thickness increases as it moves from the poles to the equator from 8 to 18 km. This is the warmest part of the atmosphere because the air in it is heated by the earth's surface. Most of the water vapor is concentrated in the troposphere, which is why clouds form, precipitation falls, thunderstorms rumble and winds blow.

The next layer is about 40 km thick and is called the stratosphere. If an observer moves into this part of the air, he will find that the sky has turned purple. This is explained by the low density of the substance, which practically does not scatter sun rays. It is in this layer that jet planes fly. All open spaces are open for them, since there are practically no clouds. Inside the stratosphere there is a layer consisting of large amounts of ozone.

After it come the stratopause and mesosphere. The latter is about 30 km thick. It is characterized by a sharp decrease in air density and temperature. The sky appears black to the observer. Here you can even watch the stars during the day.

Layers in which there is practically no air

The structure of the atmosphere continues with a layer called the thermosphere - the longest of all the others, its thickness reaches 400 km. This layer is distinguished by its enormous temperature, which can reach 1700 °C.

The last two spheres are often combined into one and called the ionosphere. This is due to the fact that reactions occur in them with the release of ions. It is these layers that make it possible to observe such a natural phenomenon as the northern lights.

The next 50 km from the Earth are allocated to the exosphere. This is the outer shell of the atmosphere. It disperses air particles into space. Weather satellites usually move in this layer.

The Earth's atmosphere ends with the magnetosphere. It is she who sheltered most of the planet’s artificial satellites.

After all that has been said, there should be no questions left about what the atmosphere is. If you have any doubts about its necessity, they can be easily dispelled.

The meaning of atmosphere

The main function of the atmosphere is to protect the planet's surface from overheating during the day and excessive cooling at night. The next important purpose of this shell, which no one will dispute, is to supply oxygen to all living beings. Without this they would suffocate.

Most meteorites burn up in the upper layers, never reaching the Earth's surface. And people can admire the flying lights, mistaking them for shooting stars. Without an atmosphere, the entire Earth would be littered with craters. And protection from solar radiation has already been discussed above.

How does a person influence the atmosphere?

Very negative. This is due to the growing activity of people. The main share of all negative aspects falls on industry and transport. By the way, it is cars that emit almost 60% of all pollutants that penetrate into the atmosphere. The remaining forty are divided between energy and industry, as well as waste disposal industries.

List harmful substances, which daily replenish the composition of the air, is very long. Due to transport in the atmosphere there are: nitrogen and sulfur, carbon, blue and soot, as well as a strong carcinogen that causes skin cancer - benzopyrene.

The industry accounts for such chemical elements: sulfur dioxide, hydrocarbon and hydrogen sulfide, ammonia and phenol, chlorine and fluorine. If the process continues, then soon the answers to the questions: “What is the atmosphere? What does it consist of? will be completely different.

The atmosphere is the outer shell celestial bodies. On different planets it differs in composition, chemical and physical properties. What are the main properties of the Earth's atmosphere? What does it consist of? How and when did it arise? Let's find out about this further.

Atmospheric formation

The atmosphere is a mixture of gases that envelop the planet from the outside and are held in place by its gravitational forces. At the time of its formation, our planet did not yet have a gaseous shell. It was formed a little later and managed to change several times. It is not completely known what the basic properties of the atmosphere were then.

Scientists suggest that the very first atmosphere was picked up from the solar nebula and consisted of helium and hydrogen. High temperatures planets and the influence of the solar wind quickly destroyed this shell.

The next atmosphere was formed thanks to volcanoes that released gases from it. It was thin and consisted of greenhouse gases (methane, carbon dioxide, ammonia), water vapor and acids.

Two billion years ago, the state of the atmosphere began to transform into the present one. External processes (weathering, solar activity) on the planet and the first bacteria and algae took part in this, due to their release of oxygen.

Composition and properties of the atmosphere

The gas shell of our planet does not have a clear edge. Its outer contour is blurred and gradually passes into outer space, merging with it into a homogeneous mass. The inner edge of the shell is in contact with earth's crust and the Earth's hydrosphere.

The basic properties of the atmosphere are largely determined by its composition. Most of it is represented by gases. The main share is accounted for by nitrogen (75.5%) and oxygen (23.1%). Besides them atmospheric air consists of argon, carbon dioxide, hydrogen, methane, helium, xenon, etc.

The concentration of substances remains virtually unchanged. Variable values ​​are typical for water and are determined by the amount of vegetation. Water is contained in the form of water vapor. Its amount varies depending on geographic latitudes and amounts to up to 2.5%. The atmosphere also contains combustion products, sea salt, dust impurities, and ice in the form of small crystals.

Physical properties of the atmosphere

The main properties of the atmosphere are pressure, humidity, temperature and density. In each layer of the atmosphere their values ​​differ. The air of the Earth's shell is a set of molecules various substances. Gravitational forces keep them within the planet, pulling them closer to its surface.

There are more molecules at the bottom, so the density and pressure are greater there. They decrease with height, and in outer space they become almost invisible. In the lower layers of the atmosphere, pressure decreases by 1 mm Hg. Art. every 10 meters.

Unlike the surface of the planet, the atmosphere is not heated by the Sun. Therefore, the closer to Earth, the higher the temperature. For every hundred meters it decreases by about 0.6 degrees. In the upper part of the troposphere it reaches -56 degrees.

Air parameters are greatly influenced by the water content in it, that is, humidity. The total air mass of the planet is (5.1-5.3) 10 18 kg, where the share of water vapor is 1.27 10 16 kg. Since the properties of the atmosphere differ in different areas, standard values ​​were derived and taken as “ normal conditions» on the surface of the Earth:

The structure of the gas shell of the Earth

The nature of the gas shell changes with altitude. Depending on the basic properties of the atmosphere, it is divided into several layers:

• troposphere;
• stratosphere;
• mesosphere;
• thermosphere;
• exosphere.

The main parameter for differentiation is temperature. Between the layers there are boundary areas called pauses, in which a constant temperature is recorded.

The troposphere is the lowest layer. Its border runs at an altitude of 8 to 18 kilometers, depending on latitude. It is highest at the equator line. Approximately 80% of the atmospheric air mass falls in the troposphere.

The outer layer of the atmosphere is represented by the exosphere. Its lower boundary and thickness depend on the activity of the Sun. On Earth, the exosphere begins at an altitude of 500 to 1000 kilometers and reaches one hundred thousand kilometers. At the bottom it is saturated with oxygen and nitrogen, at the top - with hydrogen and other light gases.

The role of the atmosphere

The atmosphere is the air we breathe. Without it, a person cannot live even five minutes. It saturates all cells of plants and animals, promoting the exchange of energies between the body and the external environment.

The atmosphere is the planet's filter. Passing through it solar radiation dissipates. This reduces its intensity and the harm it can cause in concentrated form. The shell plays the role of the Earth's shield, in the upper layers of which many meteorites and comets burn up before reaching the surface of the planet.

Temperature, density, humidity and pressure of the atmosphere form climate and weather conditions. The atmosphere is involved in the distribution of heat on the planet. Without it, the temperature would fluctuate within two hundred degrees.

The Earth's shell participates in the cycle of substances, is the habitat of some living beings, and contributes to the transmission of sounds. Its absence would make it impossible for life to exist on the planet.