Layers of the atmosphere in order from the surface of the earth. The composition and structure of the atmosphere The history of the formation of the atmosphere

The atmosphere is a mixture of various gases. It extends from the surface of the Earth to a height of up to 900 km, protecting the planet from the harmful spectrum of solar radiation, and contains gases necessary for all life on the planet. The atmosphere traps the heat of the sun, warming near the earth's surface and creating a favorable climate.

Composition of the atmosphere

The Earth's atmosphere consists mainly of two gases - nitrogen (78%) and oxygen (21%). In addition, it contains impurities of carbon dioxide and other gases. in the atmosphere exists in the form of vapor, drops of moisture in clouds and ice crystals.

Layers of the atmosphere

The atmosphere consists of many layers, between which there are no clear boundaries. The temperatures of different layers differ markedly from each other.

• airless magnetosphere. Most of the Earth's satellites fly here outside the Earth's atmosphere.
• Exosphere (450-500 km from the surface). Almost does not contain gases. Some weather satellites fly in the exosphere. The thermosphere (80-450 km) is characterized by high temperatures reaching 1700°C in the upper layer.
• Mesosphere (50-80 km). In this sphere, the temperature drops as the altitude increases. It is here that most of the meteorites (fragments of space rocks) that enter the atmosphere burn down.
• Stratosphere (15-50 km). Contains an ozone layer, i.e. a layer of ozone that absorbs ultraviolet radiation from the sun. This leads to an increase in temperature near the Earth's surface. Jet planes usually fly here, as visibility in this layer is very good and there is almost no interference caused by weather conditions.
• Troposphere. The height varies from 8 to 15 km from the earth's surface. It is here that the weather of the planet is formed, since in this layer contains the most water vapor, dust and winds. The temperature decreases with distance from the earth's surface.

Atmosphere pressure

Although we do not feel it, the layers of the atmosphere exert pressure on the surface of the Earth. The highest is near the surface, and as you move away from it, it gradually decreases. It depends on the temperature difference between land and ocean, and therefore in areas located at the same height above sea level, there is often a different pressure. Low pressure brings wet weather, while high pressure usually sets clear weather.

The movement of air masses in the atmosphere

And the pressures cause the lower atmosphere to mix. This creates winds that blow from areas of high pressure to areas of low pressure. In many regions, local winds also occur, caused by differences in land and sea temperatures. Mountains also have a significant influence on the direction of the winds.

Greenhouse effect

Carbon dioxide and other gases in the earth's atmosphere trap the sun's heat. This process is commonly called the greenhouse effect, as it is in many ways similar to the circulation of heat in greenhouses. The greenhouse effect causes global warming on the planet. In areas of high pressure - anticyclones - a clear solar one is established. In areas of low pressure - cyclones - the weather is usually unstable. Heat and light entering the atmosphere. The gases trap the heat reflected from the earth's surface, thereby causing the temperature on the earth to rise.

There is a special ozone layer in the stratosphere. Ozone blocks most of the ultraviolet radiation from the Sun, protecting the Earth and all life on it from it. Scientists have found that the cause of the destruction of the ozone layer are special chlorofluorocarbon dioxide gases contained in some aerosols and refrigeration equipment. Over the Arctic and Antarctica, huge holes have been found in the ozone layer, contributing to an increase in the amount of ultraviolet radiation affecting the Earth's surface.

Ozone is formed in the lower atmosphere as a result between solar radiation and various exhaust fumes and gases. Usually it disperses through the atmosphere, but if a closed layer of cold air forms under a layer of warm air, ozone concentrates and smog occurs. Unfortunately, this cannot make up for the loss of ozone in the ozone holes.

The satellite image clearly shows a hole in the ozone layer over Antarctica. The size of the hole varies, but scientists believe that it is constantly increasing. Attempts are being made to reduce the level of exhaust gases in the atmosphere. Reduce air pollution and use smokeless fuels in cities. Smog causes eye irritation and choking in many people.

The emergence and evolution of the Earth's atmosphere

The modern atmosphere of the Earth is the result of a long evolutionary development. It arose as a result of the joint action of geological factors and the vital activity of organisms. Throughout geological history, the earth's atmosphere has gone through several profound rearrangements. On the basis of geological data and theoretical (prerequisites), the primordial atmosphere of the young Earth, which existed about 4 billion years ago, could consist of a mixture of inert and noble gases with a small addition of passive nitrogen (N. A. Yasamanov, 1985; A. S. Monin, 1987; O. G. Sorokhtin, S. A. Ushakov, 1991, 1993. At present, the view on the composition and structure of the early atmosphere has somewhat changed. The primary atmosphere (protoatmosphere) is at the earliest protoplanetary stage. 4.2 billion years, could consist of a mixture of methane, ammonia and carbon dioxide.As a result of the degassing of the mantle and active weathering processes occurring on the earth's surface, water vapor, carbon compounds in the form of CO 2 and CO, sulfur and its compounds began to enter the atmosphere , as well as strong halogen acids - HCI, HF, HI and boric acid, which were supplemented with methane, ammonia, hydrogen, argon and some other noble gases in the atmosphere.This primary atmosphere was extremely thin. Therefore, the temperature near the earth's surface was close to the temperature of radiative equilibrium (AS Monin, 1977).

Over time, the gas composition of the primary atmosphere began to transform under the influence of the processes of weathering of rocks protruding on the earth's surface, the vital activity of cyanobacteria and blue-green algae, volcanic processes and the action of sunlight. This led to the decomposition of methane into and carbon dioxide, ammonia - into nitrogen and hydrogen; carbon dioxide began to accumulate in the secondary atmosphere, which slowly descended to the earth's surface, and nitrogen. Thanks to the vital activity of blue-green algae, oxygen began to be produced in the process of photosynthesis, which, however, at the beginning was mainly spent on “oxidizing atmospheric gases, and then rocks. At the same time, ammonia, oxidized to molecular nitrogen, began to intensively accumulate in the atmosphere. It is assumed that a significant part of the nitrogen in the modern atmosphere is relict. Methane and carbon monoxide were oxidized to carbon dioxide. Sulfur and hydrogen sulfide were oxidized to SO 2 and SO 3, which, due to their high mobility and lightness, were quickly removed from the atmosphere. Thus, the atmosphere from a reducing one, as it was in the Archean and early Proterozoic, gradually turned into an oxidizing one.

Carbon dioxide entered the atmosphere both as a result of methane oxidation and as a result of degassing of the mantle and weathering of rocks. In the event that all the carbon dioxide released over the entire history of the Earth remained in the atmosphere, its partial pressure could now become the same as on Venus (O. Sorokhtin, S. A. Ushakov, 1991). But on Earth, the process was reversed. A significant part of carbon dioxide from the atmosphere was dissolved in the hydrosphere, in which it was used by aquatic organisms to build their shells and biogenically converted into carbonates. Subsequently, the most powerful strata of chemogenic and organogenic carbonates were formed from them.

Oxygen was supplied to the atmosphere from three sources. For a long time, starting from the moment of the formation of the Earth, it was released during the degassing of the mantle and was mainly spent on oxidative processes. Another source of oxygen was the photodissociation of water vapor by hard ultraviolet solar radiation. appearances; free oxygen in the atmosphere led to the death of most of the prokaryotes that lived in reducing conditions. Prokaryotic organisms have changed their habitats. They left the surface of the Earth to its depths and regions where reducing conditions were still preserved. They were replaced by eukaryotes, which began to vigorously process carbon dioxide into oxygen.

During the Archean and a significant part of the Proterozoic, almost all oxygen, arising both abiogenically and biogenically, was mainly spent on the oxidation of iron and sulfur. By the end of the Proterozoic, all the metallic divalent iron that was on the earth's surface either oxidized or moved into the earth's core. This led to the fact that the partial pressure of oxygen in the early Proterozoic atmosphere changed.

In the middle of the Proterozoic, the concentration of oxygen in the atmosphere reached the Urey point and amounted to 0.01% of the current level. Starting from that time, oxygen began to accumulate in the atmosphere and, probably, already at the end of the Riphean, its content reached the Pasteur point (0.1% of the current level). It is possible that the ozone layer arose in the Vendian period and that time it never disappeared.

The appearance of free oxygen in the earth's atmosphere stimulated the evolution of life and led to the emergence of new forms with a more perfect metabolism. If earlier eukaryotic unicellular algae and cyanides, which appeared at the beginning of the Proterozoic, required an oxygen content in water of only 10 -3 of its modern concentration, then with the emergence of non-skeletal Metazoa at the end of the Early Vendian, i.e., about 650 million years ago, the oxygen concentration in the atmosphere should have been much higher. After all, Metazoa used oxygen respiration and this required that the partial pressure of oxygen reach a critical level - the Pasteur point. In this case, the anaerobic fermentation process was replaced by an energetically more promising and progressive oxygen metabolism.

After that, the further accumulation of oxygen in the earth's atmosphere occurred rather rapidly. The progressive increase in the volume of blue-green algae contributed to the achievement in the atmosphere of the oxygen level necessary for the life support of the animal world. A certain stabilization of the oxygen content in the atmosphere has occurred since the moment when the plants came to land - about 450 million years ago. The emergence of plants on land, which occurred in the Silurian period, led to the final stabilization of the level of oxygen in the atmosphere. Since that time, its concentration began to fluctuate within rather narrow limits, never going beyond the existence of life. The concentration of oxygen in the atmosphere has completely stabilized since the appearance of flowering plants. This event took place in the middle of the Cretaceous period, i.e. about 100 million years ago.

The bulk of nitrogen was formed in the early stages of the Earth's development, mainly due to the decomposition of ammonia. With the advent of organisms, the process of binding atmospheric nitrogen into organic matter and burying it in marine sediments began. After the release of organisms on land, nitrogen began to be buried in continental sediments. The processes of processing free nitrogen were especially intensified with the advent of terrestrial plants.

At the turn of the Cryptozoic and Phanerozoic, i.e., about 650 million years ago, the carbon dioxide content in the atmosphere decreased to tenths of a percent, and it reached a content close to the current level only quite recently, about 10-20 million years ago.

Thus, the gas composition of the atmosphere not only provided living space for organisms, but also determined the characteristics of their vital activity, promoted settlement and evolution. The resulting failures in the distribution of the atmospheric gas composition favorable for organisms, both due to cosmic and planetary causes, led to mass extinctions of the organic world, which repeatedly occurred during the Cryptozoic and at certain boundaries of the Phanerozoic history.

Ethnospheric functions of the atmosphere

The Earth's atmosphere provides the necessary substance, energy and determines the direction and speed of metabolic processes. The gas composition of the modern atmosphere is optimal for the existence and development of life. As an area of ​​weather and climate formation, the atmosphere must create comfortable conditions for the life of people, animals and vegetation. Deviations in one direction or another in the quality of atmospheric air and weather conditions create extreme conditions for the life of the animal and plant world, including humans.

The atmosphere of the Earth not only provides the conditions for the existence of mankind, being the main factor in the evolution of the ethnosphere. At the same time, it turns out to be an energy and raw material resource for production. In general, the atmosphere is a factor that preserves human health, and some areas, due to physical and geographical conditions and atmospheric air quality, serve as recreational areas and are areas intended for sanatorium treatment and recreation for people. Thus, the atmosphere is a factor of aesthetic and emotional impact.

The ethnospheric and technospheric functions of the atmosphere, determined quite recently (E. D. Nikitin, N. A. Yasamanov, 2001), need an independent and in-depth study. Thus, the study of atmospheric energy functions is very relevant both from the point of view of the occurrence and operation of processes that damage the environment, and from the point of view of the impact on the health and well-being of people. In this case, we are talking about the energy of cyclones and anticyclones, atmospheric vortices, atmospheric pressure and other extreme atmospheric phenomena, the effective use of which will contribute to the successful solution of the problem of obtaining alternative energy sources that do not pollute the environment. After all, the air environment, especially that part of it that is located above the World Ocean, is an area for the release of a colossal amount of free energy.

For example, it has been established that tropical cyclones of average strength release energy equivalent to the energy of 500,000 atomic bombs dropped on Hiroshima and Nagasaki in just a day. For 10 days of the existence of such a cyclone, enough energy is released to meet all the energy needs of a country like the United States for 600 years.

In recent years, a large number of works by scientists of the natural sciences have been published, in one way or another concerning various aspects of activity and the influence of the atmosphere on earth processes, which indicates the intensification of interdisciplinary interactions in modern natural science. At the same time, the integrating role of certain of its directions is manifested, among which it is necessary to note the functional-ecological direction in geoecology.

This direction stimulates the analysis and theoretical generalization of the ecological functions and the planetary role of various geospheres, and this, in turn, is an important prerequisite for the development of methodology and scientific foundations for a holistic study of our planet, the rational use and protection of its natural resources.

The Earth's atmosphere consists of several layers: troposphere, stratosphere, mesosphere, thermosphere, ionosphere and exosphere. In the upper part of the troposphere and the lower part of the stratosphere there is a layer enriched with ozone, called the ozone layer. Certain (daily, seasonal, annual, etc.) regularities in the distribution of ozone have been established. Since its inception, the atmosphere has influenced the course of planetary processes. The primary composition of the atmosphere was completely different than at present, but over time the proportion and role of molecular nitrogen steadily increased, about 650 million years ago free oxygen appeared, the amount of which continuously increased, but the concentration of carbon dioxide decreased accordingly. The high mobility of the atmosphere, its gas composition and the presence of aerosols determine its outstanding role and active participation in various geological and biospheric processes. The role of the atmosphere in the redistribution of solar energy and the development of catastrophic natural phenomena and disasters is great. Atmospheric whirlwinds - tornadoes (tornadoes), hurricanes, typhoons, cyclones and other phenomena have a negative impact on the organic world and natural systems. The main sources of pollution, along with natural factors, are various forms of human economic activity. Anthropogenic impacts on the atmosphere are expressed not only in the appearance of various aerosols and greenhouse gases, but also in an increase in the amount of water vapor, and manifest themselves in the form of smog and acid rain. Greenhouse gases change the temperature regime of the earth's surface, emissions of certain gases reduce the volume of the ozone screen and contribute to the formation of ozone holes. The ethnospheric role of the Earth's atmosphere is great.

The role of the atmosphere in natural processes

The surface atmosphere in its intermediate state between the lithosphere and outer space and its gas composition creates conditions for the life of organisms. At the same time, the weathering and intensity of destruction of rocks, the transfer and accumulation of detrital material depend on the amount, nature and frequency of precipitation, on the frequency and strength of winds, and especially on air temperature. The atmosphere is the central component of the climate system. Air temperature and humidity, cloudiness and precipitation, wind - all this characterizes the weather, that is, the continuously changing state of the atmosphere. At the same time, these same components also characterize the climate, i.e., the average long-term weather regime.

The composition of gases, the presence of clouds and various impurities, which are called aerosol particles (ash, dust, particles of water vapor), determine the characteristics of the passage of solar radiation through the atmosphere and prevent the escape of the Earth's thermal radiation into outer space.

The Earth's atmosphere is very mobile. The processes arising in it and changes in its gas composition, thickness, cloudiness, transparency and the presence of various aerosol particles in it affect both the weather and the climate.

The action and direction of natural processes, as well as life and activity on Earth, are determined by solar radiation. It gives 99.98% of the heat coming to the earth's surface. Annually it makes 134*10 19 kcal. This amount of heat can be obtained by burning 200 billion tons of coal. The reserves of hydrogen, which creates this flow of thermonuclear energy in the mass of the Sun, will be enough for at least another 10 billion years, i.e., for a period twice as long as our planet itself exists.

About 1/3 of the total amount of solar energy entering the upper boundary of the atmosphere is reflected back into the world space, 13% is absorbed by the ozone layer (including almost all ultraviolet radiation). 7% - the rest of the atmosphere and only 44% reaches the earth's surface. The total solar radiation reaching the Earth in a day is equal to the energy that humanity has received as a result of burning all types of fuel over the past millennium.

The amount and nature of the distribution of solar radiation on the earth's surface are closely dependent on the cloudiness and transparency of the atmosphere. The amount of scattered radiation is affected by the height of the Sun above the horizon, the transparency of the atmosphere, the content of water vapor, dust, the total amount of carbon dioxide, etc.

The maximum amount of scattered radiation falls into the polar regions. The lower the Sun is above the horizon, the less heat enters a given area.

Atmospheric transparency and cloudiness are of great importance. On a cloudy summer day, it is usually colder than on a clear one, since daytime clouds prevent the earth's surface from heating.

The dust content of the atmosphere plays an important role in the distribution of heat. The finely dispersed solid particles of dust and ash in it, which affect its transparency, adversely affect the distribution of solar radiation, most of which is reflected. Fine particles enter the atmosphere in two ways: either ashes emitted during volcanic eruptions, or desert dust carried by winds from arid tropical and subtropical regions. Especially a lot of such dust is formed during the period of droughts, when it is carried into the upper layers of the atmosphere by streams of warm air and is able to stay there for a long time. After the eruption of the Krakatoa volcano in 1883, dust thrown tens of kilometers into the atmosphere remained in the stratosphere for about 3 years. As a result of the 1985 eruption of the El Chichon volcano (Mexico), dust reached Europe, and therefore there was a slight decrease in surface temperatures.

The Earth's atmosphere contains a variable amount of water vapor. In absolute terms, by weight or volume, its amount ranges from 2 to 5%.

Water vapor, like carbon dioxide, enhances the greenhouse effect. In the clouds and fogs that arise in the atmosphere, peculiar physicochemical processes take place.

The primary source of water vapor in the atmosphere is the surface of the oceans. A layer of water from 95 to 110 cm thick annually evaporates from it. Part of the moisture returns to the ocean after condensation, and the other is directed towards the continents by air currents. In regions with a variable-humid climate, precipitation moistens the soil, and in humid regions it creates groundwater reserves. Thus, the atmosphere is an accumulator of humidity and a reservoir of precipitation. and fogs that form in the atmosphere provide moisture to the soil cover and thus play a decisive role in the development of the animal and plant world.

Atmospheric moisture is distributed over the earth's surface due to the mobility of the atmosphere. It has a very complex system of winds and pressure distribution. Due to the fact that the atmosphere is in continuous motion, the nature and extent of the distribution of wind flows and pressure are constantly changing. The scales of circulation vary from micrometeorological, with a size of only a few hundred meters, to a global one, with a size of several tens of thousands of kilometers. Huge atmospheric vortices are involved in the creation of systems of large-scale air currents and determine the general circulation of the atmosphere. In addition, they are sources of catastrophic atmospheric phenomena.

The distribution of weather and climatic conditions and the functioning of living matter depend on atmospheric pressure. In the event that atmospheric pressure fluctuates within small limits, it does not play a decisive role in the well-being of people and the behavior of animals and does not affect the physiological functions of plants. As a rule, frontal phenomena and weather changes are associated with pressure changes.

Atmospheric pressure is of fundamental importance for the formation of wind, which, being a relief-forming factor, has the strongest effect on flora and fauna.

The wind is able to suppress the growth of plants and at the same time promotes the transfer of seeds. The role of the wind in the formation of weather and climatic conditions is great. He also acts as a regulator of sea currents. Wind as one of the exogenous factors contributes to the erosion and deflation of weathered material over long distances.

Ecological and geological role of atmospheric processes

The decrease in the transparency of the atmosphere due to the appearance of aerosol particles and solid dust in it affects the distribution of solar radiation, increasing the albedo or reflectivity. Various chemical reactions lead to the same result, causing the decomposition of ozone and the generation of "pearl" clouds, consisting of water vapor. Global change in reflectivity, as well as changes in the gas composition of the atmosphere, mainly greenhouse gases, are the cause of climate change.

Uneven heating, which causes differences in atmospheric pressure over different parts of the earth's surface, leads to atmospheric circulation, which is the hallmark of the troposphere. When there is a difference in pressure, air rushes from areas of high pressure to areas of low pressure. These movements of air masses, together with humidity and temperature, determine the main ecological and geological features of atmospheric processes.

Depending on the speed, the wind produces various geological work on the earth's surface. At a speed of 10 m/s, it shakes thick branches of trees, picks up and carries dust and fine sand; breaks tree branches at a speed of 20 m/s, carries sand and gravel; at a speed of 30 m/s (storm) tears off the roofs of houses, uproots trees, breaks poles, moves pebbles and carries small gravel, and a hurricane at a speed of 40 m/s destroys houses, breaks and demolishes power line poles, uproots large trees.

Squall storms and tornadoes (tornadoes) have a great negative environmental impact with catastrophic consequences - atmospheric vortices that occur in the warm season on powerful atmospheric fronts with a speed of up to 100 m/s. Squalls are horizontal whirlwinds with hurricane wind speeds (up to 60-80 m/s). They are often accompanied by heavy showers and thunderstorms lasting from a few minutes to half an hour. The squalls cover areas up to 50 km wide and travel a distance of 200-250 km. A heavy storm in Moscow and the Moscow region in 1998 damaged the roofs of many houses and knocked down trees.

Tornadoes, called tornadoes in North America, are powerful funnel-shaped atmospheric eddies often associated with thunderclouds. These are columns of air narrowing in the middle with a diameter of several tens to hundreds of meters. The tornado has the appearance of a funnel, very similar to an elephant's trunk, descending from the clouds or rising from the surface of the earth. Possessing a strong rarefaction and high rotation speed, the tornado travels up to several hundred kilometers, drawing in dust, water from reservoirs and various objects. Powerful tornadoes are accompanied by thunderstorms, rain and have great destructive power.

Tornadoes rarely occur in subpolar or equatorial regions, where it is constantly cold or hot. Few tornadoes in the open ocean. Tornadoes occur in Europe, Japan, Australia, the USA, and in Russia they are especially frequent in the Central Black Earth region, in the Moscow, Yaroslavl, Nizhny Novgorod and Ivanovo regions.

Tornadoes lift and move cars, houses, wagons, bridges. Particularly destructive tornadoes (tornadoes) are observed in the United States. From 450 to 1500 tornadoes are recorded annually, with an average of about 100 victims. Tornadoes are fast-acting catastrophic atmospheric processes. They are formed in just 20-30 minutes, and their existence time is 30 minutes. Therefore, it is almost impossible to predict the time and place of occurrence of tornadoes.

Other destructive, but long-term atmospheric vortices are cyclones. They are formed due to a pressure drop, which, under certain conditions, contributes to the occurrence of a circular movement of air currents. Atmospheric vortices originate around powerful ascending currents of humid warm air and rotate at high speed clockwise in the southern hemisphere and counterclockwise in the northern hemisphere. Cyclones, unlike tornadoes, originate over the oceans and produce their destructive actions over the continents. The main destructive factors are strong winds, intense precipitation in the form of snowfall, downpours, hail and surge floods. Winds with speeds of 19 - 30 m / s form a storm, 30 - 35 m / s - a storm, and more than 35 m / s - a hurricane.

Tropical cyclones - hurricanes and typhoons - have an average width of several hundred kilometers. The wind speed inside the cyclone reaches hurricane force. Tropical cyclones last from several days to several weeks, moving at a speed of 50 to 200 km/h. Mid-latitude cyclones have a larger diameter. Their transverse dimensions range from a thousand to several thousand kilometers, the wind speed is stormy. They move in the northern hemisphere from the west and are accompanied by hail and snowfall, which are catastrophic. Cyclones and their associated hurricanes and typhoons are the largest natural disasters after floods in terms of the number of victims and damage caused. In densely populated areas of Asia, the number of victims during hurricanes is measured in the thousands. In 1991, in Bangladesh, during a hurricane that caused the formation of sea waves 6 m high, 125 thousand people died. Typhoons cause great damage to the United States. As a result, dozens and hundreds of people die. In Western Europe, hurricanes cause less damage.

Thunderstorms are considered a catastrophic atmospheric phenomenon. They occur when warm, moist air rises very quickly. On the border of the tropical and subtropical zones, thunderstorms occur for 90-100 days a year, in the temperate zone for 10-30 days. In our country, the largest number of thunderstorms occurs in the North Caucasus.

Thunderstorms usually last less than an hour. Intense downpours, hailstorms, lightning strikes, gusts of wind, and vertical air currents pose a particular danger. The hail hazard is determined by the size of the hailstones. In the North Caucasus, the mass of hailstones once reached 0.5 kg, and in India, hailstones weighing 7 kg were noted. The most hazardous areas in our country are located in the North Caucasus. In July 1992, hail damaged 18 aircraft at the Mineralnye Vody airport.

Lightning is a hazardous weather phenomenon. They kill people, livestock, cause fires, damage the power grid. About 10,000 people die every year from thunderstorms and their consequences worldwide. Moreover, in some parts of Africa, in France and the United States, the number of victims from lightning is greater than from other natural phenomena. The annual economic damage from thunderstorms in the United States is at least $700 million.

Droughts are typical for desert, steppe and forest-steppe regions. The lack of precipitation causes drying up of the soil, lowering the level of groundwater and in reservoirs until they dry up completely. Moisture deficiency leads to the death of vegetation and crops. Droughts are especially severe in Africa, the Near and Middle East, Central Asia and southern North America.

Droughts change the conditions of human life, have an adverse impact on the natural environment through processes such as salinization of the soil, dry winds, dust storms, soil erosion and forest fires. Fires are especially strong during drought in taiga regions, tropical and subtropical forests and savannahs.

Droughts are short-term processes that last for one season. When droughts last more than two seasons, there is a threat of starvation and mass mortality. Typically, the effect of drought extends to the territory of one or more countries. Especially often prolonged droughts with tragic consequences occur in the Sahel region of Africa.

Atmospheric phenomena such as snowfalls, intermittent heavy rains and prolonged prolonged rains cause great damage. Snowfalls cause massive avalanches in the mountains, and the rapid melting of the fallen snow and prolonged heavy rains lead to floods. A huge mass of water falling on the earth's surface, especially in treeless areas, causes severe erosion of the soil cover. There is an intensive growth of ravine-beam systems. Floods occur as a result of large floods during a period of heavy precipitation or floods after a sudden warming or spring snowmelt and, therefore, are atmospheric phenomena in origin (they are discussed in the chapter on the ecological role of the hydrosphere).

Anthropogenic changes in the atmosphere

Currently, there are many different sources of anthropogenic nature that cause atmospheric pollution and lead to serious violations of the ecological balance. In terms of scale, two sources have the greatest impact on the atmosphere: transport and industry. On average, transport accounts for about 60% of the total amount of atmospheric pollution, industry - 15%, thermal energy - 15%, technologies for the destruction of household and industrial waste - 10%.

Transport, depending on the fuel used and the types of oxidizing agents, emits into the atmosphere nitrogen oxides, sulfur, oxides and dioxides of carbon, lead and its compounds, soot, benzopyrene (a substance from the group of polycyclic aromatic hydrocarbons, which is a strong carcinogen that causes skin cancer).

Industry emits sulfur dioxide, carbon oxides and dioxides, hydrocarbons, ammonia, hydrogen sulfide, sulfuric acid, phenol, chlorine, fluorine and other compounds and chemicals into the atmosphere. But the dominant position among emissions (up to 85%) is occupied by dust.

As a result of pollution, the transparency of the atmosphere changes, aerosols, smog and acid rains appear in it.

Aerosols are dispersed systems consisting of solid particles or liquid droplets suspended in a gaseous medium. The particle size of the dispersed phase is usually 10 -3 -10 -7 cm Depending on the composition of the dispersed phase, aerosols are divided into two groups. One includes aerosols consisting of solid particles dispersed in a gaseous medium, the second - aerosols, which are a mixture of gaseous and liquid phases. The first are called smokes, and the second - fogs. Condensation centers play an important role in the process of their formation. Volcanic ash, cosmic dust, products of industrial emissions, various bacteria, etc. act as condensation nuclei. The number of possible sources of concentration nuclei is constantly growing. So, for example, when dry grass is destroyed by fire on an area of ​​4000 m 2, an average of 11 * 10 22 aerosol nuclei is formed.

Aerosols began to form from the moment of the emergence of our planet and influenced natural conditions. However, their number and actions, balanced with the general circulation of substances in nature, did not cause deep ecological changes. Anthropogenic factors of their formation shifted this balance towards significant biospheric overloads. This feature has been especially pronounced since mankind began to use specially created aerosols both in the form of toxic substances and for plant protection.

The most dangerous for vegetation cover are aerosols of sulfur dioxide, hydrogen fluoride and nitrogen. When in contact with a wet leaf surface, they form acids that have a detrimental effect on living things. Acid mists, together with the inhaled air, enter the respiratory organs of animals and humans, and aggressively affect the mucous membranes. Some of them decompose living tissue, and radioactive aerosols cause cancer. Among radioactive isotopes, SG 90 is of particular danger not only because of its carcinogenicity, but also as an analogue of calcium, replacing it in the bones of organisms, causing their decomposition.

During nuclear explosions, radioactive aerosol clouds form in the atmosphere. Small particles with a radius of 1 - 10 microns fall not only into the upper layers of the troposphere, but also into the stratosphere, in which they are able to stay for a long time. Aerosol clouds are also formed during the operation of reactors of industrial plants that produce nuclear fuel, as well as as a result of accidents at nuclear power plants.

Smog is a mixture of aerosols with liquid and solid dispersed phases that form a foggy curtain over industrial areas and large cities.

There are three types of smog: ice, wet and dry. Ice smog is called Alaskan. This is a combination of gaseous pollutants with the addition of dusty particles and ice crystals that occur when fog droplets and steam from heating systems freeze.

Wet smog, or London-type smog, is sometimes called winter smog. It is a mixture of gaseous pollutants (mainly sulfur dioxide), dust particles and fog droplets. The meteorological prerequisite for the appearance of winter smog is calm weather, in which a layer of warm air is located above the surface layer of cold air (below 700 m). At the same time, not only horizontal, but also vertical exchange is absent. Pollutants, usually dispersed in high layers, in this case accumulate in the surface layer.

Dry smog occurs during the summer and is often referred to as LA-type smog. It is a mixture of ozone, carbon monoxide, nitrogen oxides and acid vapors. Such smog is formed as a result of the decomposition of pollutants by solar radiation, especially its ultraviolet part. The meteorological prerequisite is atmospheric inversion, which is expressed in the appearance of a layer of cold air above the warm one. Gases and solid particles usually lifted by warm air currents are then dispersed in the upper cold layers, but in this case they accumulate in the inversion layer. In the process of photolysis, nitrogen dioxides formed during the combustion of fuel in car engines decompose:

NO 2 → NO + O

Then ozone synthesis occurs:

O + O 2 + M → O 3 + M

NO + O → NO 2

Photodissociation processes are accompanied by a yellow-green glow.

In addition, reactions occur according to the type: SO 3 + H 2 0 -> H 2 SO 4, i.e. strong sulfuric acid is formed.

With a change in meteorological conditions (the appearance of wind or a change in humidity), the cold air dissipates and the smog disappears.

The presence of carcinogens in smog leads to respiratory failure, irritation of the mucous membranes, circulatory disorders, asthmatic suffocation, and often death. Smog is especially dangerous for young children.

Acid rain is atmospheric precipitation acidified by industrial emissions of sulfur oxides, nitrogen oxides, and vapors of perchloric acid and chlorine dissolved in them. In the process of burning coal and gas, most of the sulfur in it, both in the form of oxide, and in compounds with iron, in particular in pyrite, pyrrhotite, chalcopyrite, etc., turns into sulfur oxide, which, together with carbon dioxide, is released into atmosphere. When atmospheric nitrogen and technical emissions are combined with oxygen, various nitrogen oxides are formed, and the volume of nitrogen oxides formed depends on the combustion temperature. The bulk of nitrogen oxides occurs during the operation of vehicles and diesel locomotives, and a smaller part occurs in the energy sector and industrial enterprises. Sulfur and nitrogen oxides are the main acid formers. When reacting with atmospheric oxygen and the water vapor in it, sulfuric and nitric acids are formed.

It is known that the alkaline-acid balance of the medium is determined by the pH value. A neutral environment has a pH value of 7, an acidic environment has a pH value of 0, and an alkaline environment has a pH value of 14. In the modern era, the pH value of rainwater is 5.6, although in the recent past it was neutral. A decrease in pH value by one corresponds to a tenfold increase in acidity and, therefore, at present, rains with increased acidity fall almost everywhere. The maximum acidity of rains recorded in Western Europe was 4-3.5 pH. It should be taken into account that the pH value equal to 4-4.5 is fatal for most fish.

Acid rains have an aggressive effect on the Earth's vegetation cover, on industrial and residential buildings and contribute to a significant acceleration of the weathering of exposed rocks. An increase in acidity prevents the self-regulation of neutralization of soils in which nutrients are dissolved. In turn, this leads to a sharp decrease in yields and causes degradation of the vegetation cover. The acidity of the soil contributes to the release of heavy, which are in a bound state, which are gradually absorbed by plants, causing serious tissue damage in them and penetrating into human food chains.

A change in the alkaline-acid potential of sea waters, especially in shallow waters, leads to the cessation of the reproduction of many invertebrates, causes the death of fish and disrupts the ecological balance in the oceans.

As a result of acid rain, the forests of Western Europe, the Baltic States, Karelia, the Urals, Siberia and Canada are under the threat of death.

He is invisible, and yet we cannot live without him.

Each of us understands how much air is necessary for life. The expression "It is necessary as air" can be heard when talking about something very important for a person's life. Since childhood, we know that living and breathing are practically the same thing.

Do you know how long a person can live without air?

Not all people know how much air they inhale. It turns out that during the day, making about 20,000 breaths, a person passes 15 kg of air through the lungs, while he absorbs only about 1.5 kg of food, and 2-3 kg of water. At the same time, air is a matter of course for us, like the sunrise every morning. Unfortunately, we only feel it when there is not enough of it, or when it is polluted. We forget that all life on Earth, developing over millions of years, has adapted to life in an atmosphere of a certain natural composition.

Let's see what air is made of.

And let's conclude: Air is a mixture of gases. Oxygen in it is about 21% (approximately 1/5 by volume), nitrogen accounts for about 78%. The remaining mandatory components are inert gases (primarily argon), carbon dioxide, and other chemical compounds.

The study of the composition of air began in the 18th century, when chemists learned to collect gases and conduct experiments with them. If you are interested in the history of science, watch a short film about the history of the discovery of air.

The oxygen contained in the air is required for the respiration of living organisms. What is the essence of the breathing process? As you know, in the process of breathing, the body consumes oxygen from the air. Air oxygen is required for numerous chemical reactions that continuously occur in all cells, tissues and organs of living organisms. In the process of these reactions, with the participation of oxygen, those substances that come with food slowly “burn out” with the formation of carbon dioxide. At the same time, the energy contained in them is released. Due to this energy, the body exists, using it for all functions - the synthesis of substances, muscle contraction, the work of all organs, etc.

In nature, there are also some microorganisms that can use nitrogen in the process of life. Due to the carbon dioxide contained in the air, the process of photosynthesis takes place, the biosphere of the Earth as a whole lives.

As you know, the air shell of the Earth is called the atmosphere. The atmosphere extends for about 1000 km from the Earth - it is a kind of barrier between the Earth and space. According to the nature of temperature changes in the atmosphere, there are several layers:

Atmosphere is a kind of barrier between the Earth and space. It softens the effect of cosmic radiation and provides conditions on Earth for the development and existence of life. It is the atmosphere of the first of the earth's shells that meets the sun's rays and absorbs the hard ultraviolet radiation of the Sun, which has a detrimental effect on all living organisms.

Another "merit" of the atmosphere is related to the fact that it almost completely absorbs the Earth's own invisible thermal (infrared) radiation and returns most of it back. That is, the atmosphere, transparent in relation to the sun's rays, at the same time is an air "blanket" that does not allow the Earth to cool down. Thus, on our planet, the temperature that is optimal for the life of various living beings is maintained.

The composition of the modern atmosphere is unique, the only one in our planetary system.

The Earth's primary atmosphere consisted of methane, ammonia, and other gases. Along with the development of the planet, the atmosphere changed significantly. Living organisms played a leading role in the formation of the composition of atmospheric air, which arose and is maintained with their participation at the present time. You can see in more detail the history of the formation of the atmosphere on Earth.

Natural processes, both consumption and formation of atmospheric components, approximately balance each other, that is, provide a constant composition of the gases that make up the atmosphere.

Without human economic activity, nature copes with such phenomena as the entry into the atmosphere of volcanic gases, smoke from natural fires, dust from natural dust storms. These emissions dissipate in the atmosphere, settle or fall on the Earth's surface with precipitation. Soil microorganisms are taken for them, and in the end they are processed into carbon dioxide, sulfur and nitrogen compounds of the soil, that is, into the “ordinary” components of air and soil. This is the reason why atmospheric air has a constant composition on average. With the advent of man on Earth, at first gradually, then rapidly and now threateningly, the process of changing the gas composition of the air and destroying the natural stability of the atmosphere began.About 10,000 years ago people learned to use fire. Combustion products of various types of fuel have been added to natural sources of pollution. Initially, it was wood and other types of plant material.

At present, the most harmful to the atmosphere is caused by artificially produced fuel - petroleum products (gasoline, kerosene, solar oil, fuel oil) and synthetic fuel. When burned, they form nitrogen and sulfur oxides, carbon monoxide, heavy metals and other toxic substances of non-natural origin (pollutants).

Considering the huge scale of the use of technology today, one can imagine how many engines of cars, aircraft, ships and other equipment every second the atmosphere was killed Aleksashina I.Yu., Kosmodamiansky A.V., Oreshchenko N.I. Natural science: A textbook for the 6th grade of educational institutions. - St. Petersburg: SpecLit, 2001. - 239 p. .

Why are trolleybuses and trams considered environmentally friendly modes of transport compared to buses?

Especially dangerous for all living things are those stable aerosol systems that form in the atmosphere along with acidic and many other gaseous waste products. Europe is one of the most densely populated and industrialized parts of the world. A powerful transport system, large-scale industry, high consumption of fossil fuels and minerals lead to a noticeable increase in the concentrations of pollutants in the air. In almost all major European cities, there is smog Smog is an aerosol consisting of smoke, fog and dust, one of the types of air pollution in large cities and industrial centers. For more information see: http://en.wikipedia.org/wiki/Smog and an increased content in the air of such hazardous pollutants as nitrogen and sulfur oxides, carbon monoxide, benzene, phenols, fine dust, etc. is regularly recorded.

There is no doubt that the increase in the content of harmful substances in the atmosphere is directly related to the growth of allergic and respiratory diseases, as well as a number of other diseases.

Serious measures are needed in connection with the increase in the number of cars in cities, the development of industry planned in a number of Russian cities, which will inevitably increase the amount of pollutant emissions into the atmosphere.

See how the problems of cleanliness of atmospheric air are being solved in the "green capital of Europe" - Stockholm.

A set of measures to improve air quality must necessarily include improving the environmental performance of cars; construction of a gas cleaning system at industrial enterprises; the use of natural gas, not coal, as a fuel in energy enterprises. Now in every developed country there is a service for monitoring the state of air purity in cities and industrial centers, which somewhat improved the current bad situation. Thus, in St. Petersburg there is an automated system for monitoring the atmospheric air of St. Petersburg (ASM). Thanks to it, not only state authorities and local self-government, but also city residents can learn about the state of atmospheric air.

The health of residents of St. Petersburg, a metropolis with a developed network of transport routes, is affected, first of all, by the main pollutants: carbon monoxide, nitrogen oxide, nitrogen dioxide, suspended solids (dust), sulfur dioxide, which enter the atmospheric air of the city from emissions from thermal power plants, industry, and from transport. Currently, the share of emissions from vehicles is 80% of the total emissions of major pollutants. (According to expert estimates, in more than 150 cities of Russia, the predominant influence on air pollution is exerted by motor vehicles).

How are things in your city? What do you think can and should be done to make the air in our cities cleaner?

The information about the level of atmospheric air pollution in the areas where AFM stations are located in St. Petersburg has been posted.

It must be said that in St. Petersburg there is a tendency to reduce emissions of pollutants into the atmosphere, but the reasons for this phenomenon are mainly associated with a decrease in the number of operating enterprises. It is clear that from an economic point of view this is not the best way to reduce pollution.

Let's draw conclusions.

The air shell of the Earth - the atmosphere - is necessary for the existence of life. The gases that make up the air are involved in such important processes as respiration, photosynthesis. The atmosphere reflects and absorbs solar radiation and thus protects living organisms from harmful X-rays and ultraviolet rays. Carbon dioxide keeps the thermal radiation of the earth's surface. Earth's atmosphere is unique! Our health and life depend on it.

Man thoughtlessly accumulates waste products of his activities in the atmosphere, which causes serious environmental problems. We all need to not only be aware of our responsibility for the state of the atmosphere, but also, to the best of our ability, do what we can to preserve the purity of the air, the basis of our life.

The gaseous envelope that surrounds our planet Earth, known as the atmosphere, consists of five main layers. These layers originate on the surface of the planet, from sea level (sometimes below) and rise to outer space in the following sequence:

• Troposphere;
• Stratosphere;
• Mesosphere;
• Thermosphere;
• Exosphere.

In between each of these main five layers are transitional zones called "pauses" where changes in air temperature, composition and density occur. Together with pauses, the Earth's atmosphere includes a total of 9 layers.

Troposphere: where the weather happens

Of all the layers of the atmosphere, the troposphere is the one with which we are most familiar (whether you realize it or not), since we live at its bottom - the surface of the planet. It envelops the surface of the Earth and extends upwards for several kilometers. The word troposphere means "change of the ball". A very fitting name, as this layer is where our day to day weather happens.

Starting from the surface of the planet, the troposphere rises to a height of 6 to 20 km. The lower third of the layer closest to us contains 50% of all atmospheric gases. It is the only part of the entire composition of the atmosphere that breathes. Due to the fact that the air is heated from below by the earth's surface, which absorbs the thermal energy of the Sun, the temperature and pressure of the troposphere decrease with increasing altitude.

At the top is a thin layer called the tropopause, which is just a buffer between the troposphere and stratosphere.

Stratosphere: home of ozone

The stratosphere is the next layer of the atmosphere. It extends from 6-20 km to 50 km above the earth's surface. This is the layer in which most commercial airliners fly and balloons travel.

Here, the air does not flow up and down, but moves parallel to the surface in very fast air currents. Temperatures increase as you ascend, thanks to an abundance of naturally occurring ozone (O3), a by-product of solar radiation, and oxygen, which has the ability to absorb the sun's harmful ultraviolet rays (any rise in temperature with altitude is known in meteorology as an "inversion") .

Because the stratosphere has warmer temperatures at the bottom and cooler temperatures at the top, convection (vertical movements of air masses) is rare in this part of the atmosphere. In fact, you can view a storm raging in the troposphere from the stratosphere, because the layer acts as a "cap" for convection, through which storm clouds do not penetrate.

The stratosphere is again followed by a buffer layer, this time called the stratopause.

Mesosphere: middle atmosphere

The mesosphere is located approximately 50-80 km from the Earth's surface. The upper mesosphere is the coldest natural place on Earth, where temperatures can drop below -143°C.

Thermosphere: upper atmosphere

The mesosphere and mesopause are followed by the thermosphere, located between 80 and 700 km above the surface of the planet, and containing less than 0.01% of the total air in the atmospheric envelope. Temperatures here reach up to +2000° C, but due to the strong rarefaction of the air and the lack of gas molecules to transfer heat, these high temperatures are perceived as very cold.

Exosphere: the boundary of the atmosphere and space

At an altitude of about 700-10,000 km above the earth's surface is the exosphere - the outer edge of the atmosphere, bordering space. Here meteorological satellites revolve around the Earth.

ATMOSPHERE OF THE EARTH(Greek atmos steam + sphaira ball) - 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, there is a mass-energy exchange between animate and inanimate nature, between flora and fauna. Atmospheric nitrogen is assimilated by microorganisms; plants synthesize organic substances from carbon dioxide and water due to the energy of the sun and release oxygen. The presence of the atmosphere ensures the preservation of water on Earth, which is also an important condition for the existence of living organisms.

Studies carried out with the help of 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 sunlight. Above the equator in the region of the earth's shadow, the atmosphere reaches heights of about 10,000 km, and above the poles, its boundaries are 3,000 km from the earth's surface. The bulk of the atmosphere (80-90%) is within altitudes up to 12-16 km, which is explained by the exponential (non-linear) nature of the decrease in the density (rarefaction) of its gaseous medium as the height above sea level increases.

The existence of most living organisms in natural conditions is possible in even narrower boundaries of the atmosphere, up to 7-8 km, where a combination of such atmospheric factors as gas composition, temperature, pressure, and humidity, necessary for the active course of biological processes, takes place. The movement and ionization of air, atmospheric 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 due to the relative balancing of the processes of gas exchange between animate 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 NEAR THE EARTH'S SURFACE

At altitudes above 100 km, the percentage of individual gases changes due to their diffuse stratification under the influence of gravity and temperature. In addition, under the action of the short-wavelength part of ultraviolet and X-rays at an altitude of 100 km or more, oxygen, nitrogen and carbon dioxide molecules dissociate into atoms. At 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 that pollute the air, as well as the uneven distribution of vegetation and water basins that absorb carbon dioxide on the Earth. 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, pollution by industrial enterprises. The concentration of aerosols decreases rapidly with height.

The most unstable and important of the variable components of the atmosphere is water vapor, the concentration of which at the earth's surface can vary from 3% (in the tropics) to 2 × 10 -10% (in Antarctica). The higher the air temperature, the more moisture, ceteris paribus, can be in the atmosphere and vice versa. The bulk of water vapor is concentrated in the atmosphere up to altitudes of 8-10 km. The content of water vapor in the atmosphere depends on the combined influence of the processes of evaporation, condensation and horizontal transport. At high altitudes, due to a decrease in temperature and condensation of vapors, the air is practically dry.

The Earth's atmosphere, in addition to molecular and atomic oxygen, contains a small amount of ozone (see), the concentration of which is very variable and varies depending on the height and season. Most of the ozone is contained in the region of the poles by 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 action of ultraviolet solar radiation on oxygen, mainly at altitudes of 20-50 km. In this case, diatomic oxygen molecules partially decompose into atoms and, joining undecomposed molecules, form triatomic ozone molecules (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 flow of natural radioactive decay processes.

The biological significance of gases the atmosphere is very large. For most multicellular organisms, a certain content of molecular oxygen in a gaseous or aqueous medium is an indispensable factor in their existence, which during respiration determines the release of energy from organic substances created initially during photosynthesis. It is no coincidence that the upper boundaries of the biosphere (the part of the surface of the globe and the lower part of the atmosphere where life exists) are determined by the presence of a sufficient amount of oxygen. In the process of evolution, organisms have adapted to a certain level of oxygen in the atmosphere; changing the oxygen content in the direction of 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 a healing effect - it stimulates respiration and cardiovascular activity, improves sleep. With an increase in the concentration of ozone, its toxic effect is manifested: eye irritation, necrotic inflammation of the mucous membranes of the respiratory tract, exacerbation of pulmonary diseases, autonomic neuroses. Entering into combination with hemoglobin, ozone forms methemoglobin, which leads to a violation of the respiratory function of the blood; the transfer of oxygen from the lungs to the tissues becomes difficult, the phenomena of suffocation develop. 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 intensively. Solar rays with a wavelength of 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 of ultraviolet radiation from the sun. Nitrogen in atmospheric air is of great biological importance, primarily as a source of 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 of atmospheric pressure necessary for life processes. Under certain conditions of pressure changes, 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 due to the photosynthesis of complex carbon compounds, which continuously arise, change and decompose in the course of life. This dynamic system is maintained as a result of the activity of algae and land plants that 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 of more than 6-7 km, chlorophyll-containing plants cannot live due to the low partial pressure of carbon dioxide. Carbon dioxide is also very active in physiological terms, as it plays an important role in the regulation of metabolic processes, the activity of the central nervous system, respiration, blood circulation, and the oxygen regime of the body. However, this regulation is mediated by the influence of carbon dioxide produced by the body itself, and not 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 content of carbon dioxide in the atmosphere (more than 0.6-1%), there are violations in the body, denoted by the term hypercapnia (see). The complete elimination of carbon dioxide from the inhaled air cannot directly have an adverse effect on the human and animal organisms.

Carbon dioxide plays a role in absorbing long-wavelength radiation and maintaining the "greenhouse effect" that raises the temperature near the Earth's surface. The problem of the influence on thermal and other regimes of the atmosphere of carbon dioxide, which enters the air in huge quantities as a waste product of industry, 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 the condensation of water vapor in the atmosphere, clouds form and precipitation (rain, hail, snow) falls. Water vapor, scattering solar radiation, participate in the creation of the thermal regime of the Earth and the lower layers of the atmosphere, in the formation of meteorological conditions.

Atmosphere pressure

Atmospheric pressure (barometric) is the pressure exerted by the atmosphere under the influence of gravity on the surface of the Earth. The value of this pressure at each point in the atmosphere is equal to the weight of the overlying column of air with a unit base, extending above the place of measurement to the boundaries of the atmosphere. Atmospheric pressure is measured with a barometer (see) 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. 2 shows the most commonly used units of atmospheric pressure.

The change in pressure occurs due to uneven heating of air masses located above land and water at different geographical latitudes. As the temperature rises, the density of air and the pressure it creates decrease. A huge accumulation of fast-moving air with reduced pressure (with a decrease in pressure from the periphery to the center of the vortex) is called a cyclone, with increased pressure (with an increase in pressure towards the center of the vortex) - an anticyclone. For weather forecasting, non-periodic changes in atmospheric pressure are important, which occur in moving vast masses and are associated with the emergence, development and destruction of anticyclones and cyclones. Especially large changes in atmospheric pressure are associated with the rapid movement of tropical cyclones. At the same time, atmospheric pressure can vary 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 rises to tens of millibars per 100 km.

As the altitude rises, atmospheric pressure decreases in a logarithmic relationship: at first very sharply, and then less and less noticeably (Fig. 1). Therefore, the barometric pressure curve is exponential.

The decrease in pressure per unit vertical distance is called the vertical barometric gradient. Often they use the reciprocal of it - the barometric step.

Since the barometric pressure is the sum of the partial pressures of the gases that form the air, it is obvious that with the rise to a height, 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 value of 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 altitude Z, X% is the percentage of gas whose partial pressure is to be determined.

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

Rice. 2. Change in the partial pressure of oxygen in the alveolar air and saturation of arterial blood with oxygen depending on the change in altitude when breathing air and oxygen. Oxygen breathing starts from a height of 8.5 km (experiment in a pressure chamber).

Rice. 3. Comparative curves of the average values ​​of active consciousness in a person in minutes at different heights after a quick rise while breathing air (I) and oxygen (II). At altitudes above 15 km, active consciousness is equally disturbed 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, then to determine the partial pressure of any gas, it is only necessary 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 by the column "Partial pressure of oxygen".

When determining the partial pressure of a gas in moist air, the pressure (elasticity) of saturated vapors must be subtracted from the barometric pressure.

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

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

Effects of high and low blood pressure on the body. Changes in barometric pressure upwards or downwards have a variety of effects on the organism of animals and humans. The influence of increased pressure is associated with the mechanical and penetrating physical and chemical action of the gaseous medium (the so-called compression and penetrating effects).

The compression effect is manifested by: general volumetric compression, due to a uniform increase in the forces of mechanical pressure on organs and tissues; mechanonarcosis due to uniform volumetric compression at very high barometric pressure; local uneven pressure on tissues that limit gas-containing cavities in case of impaired communication between the outside air and the air in the cavity, for example, the middle ear, the accessory cavities of the nose (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 (exercise, 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 shutdown of the regulatory influence of physiological hypoxemia. With an increase in the partial pressure of oxygen in the lungs more than 0.8-1 ata, its toxic effect is manifested (damage to the lung tissue, convulsions, collapse).

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

Lowering the pressure has an even more pronounced effect on the body. In 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 system and hemodynamics, 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 a breakdown in the functions of vital organs, and then to irreversible structural damage and death of the body. The development of adaptive and pathological reactions, a change in the functional state of the body and human performance with a decrease in atmospheric pressure is determined by the degree and rate of decrease in the partial pressure of oxygen in the inhaled air, the duration of stay at a height, the intensity of the work performed, the initial state of the body (see Altitude sickness).

A decrease in pressure at altitudes (even with the exclusion of lack of oxygen) 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 ascending to altitudes of 7-12 km or more. Of certain importance is the release of gases dissolved in the intestinal contents.

The expansion of gases leads to stretching of the stomach and intestines, raising the diaphragm, changing the position of the heart, irritating the receptor apparatus of these organs and causing pathological reflexes that disrupt breathing and blood circulation. Often there are sharp pains in the abdomen. Similar phenomena sometimes occur in divers when ascending 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 accessory cavities of the nose, is similar to the development of high-altitude flatulence.

The 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 at sea level or at depth, and the formation of gas bubbles in the body.

This process of an exit of the dissolved gases (first of all nitrogen) causes development of a decompression sickness (see).

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

With a decrease in atmospheric pressure, the boiling point of liquids decreases (Fig. 4). At an altitude of more than 19 km, where the barometric pressure is equal to (or less than) the elasticity of saturated vapors 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 adipose tissue, that is, in areas with low hydrostatic and interstitial pressure, water vapor bubbles form, high-altitude tissue emphysema develops. Altitude "boiling" does not affect cellular structures, being localized only in the intercellular fluid and blood.

Massive steam bubbles can block the work of 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 counterpressure on the body with high-altitude equipment.

The very 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 proceeds in less than 1 second and is accompanied by a strong bang (as in a shot), the formation of fog (condensation of water vapor due to cooling of expanding air). Usually, explosive decompression occurs at altitudes when the glazing of a pressurized cabin or a pressure suit breaks.

In explosive decompression, the lungs are the first to suffer. A rapid increase in intrapulmonary excess pressure (more than 80 mm Hg) leads to a significant stretching of the lung tissue, which can cause rupture of the lungs (with their expansion by 2.3 times). Explosive decompression can also cause damage to the gastrointestinal tract. The amount of overpressure that occurs in the lungs will largely depend on the rate of air outflow from them during decompression and the volume of air in the lungs. It is especially dangerous if the upper airways at the time of decompression turn out to be closed (during swallowing, holding the breath) or decompression coincides with the phase of deep inspiration, when the lungs are filled with a large amount of air.

Atmospheric temperature

The temperature of the atmosphere initially decreases with increasing altitude (on average, from 15° near 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 during the day and year (Table 4).

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

Rice. 5. Change in the temperature of the atmosphere at different heights. The boundaries of the spheres are indicated by a dotted line.

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 a height of 60-80 km, the air temperature again decreases slightly (up to 60°C), and then progressively increases and reaches 270°C at an altitude of 120 km, 800°C at an altitude of 220 km, 1500°C at an altitude of 300 km, and

on 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 heights, their heat capacity and ability to heat colder bodies is very small. Under these conditions, the transfer of heat from one body to another occurs only through radiation. All considered changes in temperature in the atmosphere are associated with the absorption by air masses of the thermal energy of the Sun - 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 latitudes. Since the atmosphere in the lower layers is heated from 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. Usually, 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 regions 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 as a distance of 100 km along the 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 able to maintain thermal homeostasis (see) within a fairly narrow range of outdoor temperature fluctuations - from 15 to 45 °. Significant differences in the temperature of the atmosphere near the Earth and at heights require the use of special protective technical means to ensure the thermal balance between the human body and the environment in high-altitude and space flights.

Characteristic changes in the parameters of the atmosphere (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 at the equator up to 17-18 km, at the poles - up to 7-8 km, in middle latitudes - up to 12-16 km. The troposphere is characterized by an exponential pressure drop, 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; here all the main types of clouds arise, air masses and fronts are formed, 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 the surface layers of air, the so-called inversion takes place, that is, an increase in temperature in the atmosphere from the bottom up instead of the usual decrease.

In the warm season in the troposphere there is a constant turbulent (random, chaotic) mixing of air masses and heat transfer by air flows (convection). Convection destroys fogs and reduces the dust content of the lower atmosphere.

The second layer of the atmosphere is stratosphere.

It starts from the troposphere as a narrow zone (1-3 km) with a constant temperature (tropopause) and extends to heights of about 80 km. A feature of the stratosphere is the progressive rarefaction of the air, the exceptionally high intensity of ultraviolet radiation, the absence of water vapor, the presence of a large amount of ozone and the gradual increase in temperature. The high content of ozone causes a number of optical phenomena (mirages), causes the reflection of sounds and has a significant effect on the intensity and spectral composition of electromagnetic radiation. In the stratosphere there is a constant mixing of air, so its composition is similar to the air of the troposphere, although its density at the upper boundaries of the stratosphere is extremely low. The prevailing winds in the stratosphere are westerly, and in the upper zone there is a transition to easterly 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 the extreme rarefaction of the gaseous medium, a high concentration of molecular and atomic ions and free electrons, as well as high temperature. The ionosphere affects the propagation of radio waves, causing their refraction, reflection and absorption.

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

The electrical conductivity in the ionosphere, associated with a 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 area of ​​flights of artificial earth satellites and intercontinental ballistic missiles. Currently, space medicine is studying the possible effects on the human body of flight conditions in this part of the atmosphere.

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

The division of the atmosphere into 4 layers is very arbitrary. So, 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. The temperature distinguishes the troposphere, stratosphere, mesosphere and thermosphere, separated respectively by tropo-, strato- and mesopauses. 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: the pressure at sea level at t ° 15 ° is 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 the atmospheric water vapor is concentrated in the troposphere, the processes of phase transitions of water, which cause precipitation, proceed mainly 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 mother-of-pearl and noctilucent clouds, respectively, are observed relatively rarely. As a result of the condensation of water vapor in the troposphere, clouds form and precipitation occurs.

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

The distribution of precipitation in certain seasons and days, as well as over the territory, is extremely uneven, due to the circulation of the atmosphere and the influence of the Earth's surface. Thus, on the Hawaiian Islands, on average, 12,000 mm falls per year, and in the driest regions 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 a maximum of precipitation after the spring and autumn equinoxes; tropical - with a maximum of 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 a maximum of precipitation in summer; marine temperate latitudes - with a maximum of precipitation in winter.

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

Meteotropic reactions are observed more often in people suffering from diseases of the 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. Moscow, 1971. Danilov A. D. Chemistry of the ionosphere, L., 1967; Kolobkov N. V. Atmosphere and its life, M., 1968; Kalitin H.H. Fundamentals of atmospheric physics as applied to medicine, L., 1935; Matveev L. T. Fundamentals of general meteorology, Physics of the atmosphere, L., 1965, bibliogr.; Minkh A. A. Air ionization and its hygienic value, M., 1963, bibliogr.; it, Methods of hygienic researches, 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, L., 1964; X r g and a N A. X. Physics of the atmosphere, L., 1969, bibliogr.; Khromov S.P. Meteorology and climatology for geographical faculties, L., 1968.

Effects of high and low blood pressure on the body- Armstrong G. Aviation medicine, trans. from English, M., 1954, bibliogr.; Saltsman G.L. Physiological bases of a person's stay in conditions of high pressure of the gases of the environment, 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., etc. Theory and practice of aviation medicine, M., 1971, bibliogr.; Kovalenko E. A. and Chernyakov I. N. Oxygen of fabrics at extreme factors of flight, M., 1972, bibliogr.; Miles S. Underwater medicine, trans. from English, M., 1971, bibliography; Busby D. E. Space clinical medicine, Dordrecht, 1968.

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

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✪ Earth spaceship (Episode 14) - Atmosphere

✪ Why wasn't the atmosphere pulled into the vacuum of space?

✪ Entry into the Earth's atmosphere of the spacecraft "Soyuz TMA-8"

✪ Atmosphere structure, meaning, study

✪ O. S. Ugolnikov "Upper atmosphere. Meeting of the Earth and space"

Subtitles

Atmosphere boundary

The atmosphere is considered to be that area around the Earth in which the gaseous medium rotates together with the Earth as a whole. The atmosphere passes into interplanetary space gradually, in the exosphere, starting at an altitude of 500-1000 km from the Earth's surface.

According to the definition proposed by the International Aviation Federation, the boundary between the atmosphere and space is drawn along the Karmana line located at an altitude of 100 km, above which air flights become completely impossible. NASA uses the 122-kilometer (400,000 ft) mark as the boundary of the atmosphere, where the "shuttles" switched from propulsion maneuvering to aerodynamic maneuvering.

Physical properties

In addition to the gases listed in the table, the atmosphere contains N 2 O (\displaystyle ((\ce (N2O)))) and other nitrogen oxides ( NO 2 (\displaystyle (\ce (NO2))), ), propane and other hydrocarbons, O 3 (\displaystyle ((\ce (O3)))) , Cl 2 (\displaystyle (\ce (Cl2))) , SO 2 (\displaystyle (\ce (SO2))) , NH 3 (\displaystyle (\ce (NH3))) , CO (\displaystyle ((\ce (CO)))) , HCl (\displaystyle (\ce (HCl))) , HF (\displaystyle (\ce (HF))) , HBr (\displaystyle (\ce (HBr))) , HI (\displaystyle ((\ce (HI)))), couples Hg (\displaystyle (\ce (Hg))) , I 2 (\displaystyle (\ce (I2))) , Br 2 (\displaystyle (\ce (Br2))), as well as many other gases in small quantities. In the troposphere there is constantly a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is Rn (\displaystyle (\ce (Rn))) .

The structure of the atmosphere

boundary layer of the atmosphere

The lower layer of the troposphere (1-2 km thick), in which the state and properties of the Earth's surface directly affect the dynamics of the atmosphere.

Troposphere

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

tropopause

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

Stratosphere

The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from minus 56.5 to +0.8 °C (the upper layer of the stratosphere or the inversion region) are typical. Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere. In the middle of the 19th century, it was believed that at an altitude of 12 km (6 thousand toises) the Earth's atmosphere ends (Five weeks in a balloon, ch. 13). The stratosphere contains the ozone layer, which protects the Earth from ultraviolet radiation.

Stratopause

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

Mesosphere

Thermosphere

The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values ​​of the order of 1500 K, after which it remains almost constant up to high altitudes. Under the action of solar radiation and cosmic radiation, air is ionized (“polar lights”) - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity - for example, in 2008-2009 - there is a noticeable decrease in the size of this layer.

Thermopause

The region of the atmosphere above the thermosphere. In this region, the absorption of solar radiation is insignificant and the temperature practically does not change with height.

Exosphere (sphere of scattering)

Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular masses, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to minus 110 °C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200-250 km corresponds to a temperature of ~ 150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

At an altitude of about 2000-3500 km, the exosphere gradually passes into the so-called near space vacuum, which is filled with rare particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is composed of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

Analysis of data from the SWAN instrument on the SOHO spacecraft showed that the outermost part of the Earth's exosphere (the geocorona) extends for about 100 Earth radii or about 640 thousand km, that is, much further than the Moon's orbit.

Review

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere.

Based on the electrical properties in the atmosphere, they emit the neutrosphere And ionosphere.

Depending on the composition of the gas in the atmosphere, they emit homosphere And heterosphere. heterosphere- this is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. Hence follows the variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere, called the homosphere. The boundary between these layers is called turbopause, it lies at an altitude of about 120 km.

Other properties of the atmosphere and effects on the human body

Already at an altitude of 5 km above sea level, an untrained person develops oxygen starvation, and without adaptation, a person's performance is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 9 km, although up to about 115 km the atmosphere contains oxygen.

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

History of the formation of the atmosphere

According to the most common theory, the Earth's atmosphere has been in three different compositions throughout its history. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This so-called primary atmosphere. At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). This is how secondary atmosphere. This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors:

• leakage of light gases (hydrogen and helium) into interplanetary space;
• chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.

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

Nitrogen

The formation of a large amount of nitrogen is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O 2 (\displaystyle (\ce (O2))), which began to come from the surface of the planet as a result of photosynthesis, starting from 3 billion years ago. Also nitrogen N 2 (\displaystyle (\ce (N2))) is released into the atmosphere as a result of the denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO (\displaystyle ((\ce (NO)))) in the upper layers of the atmosphere.

Nitrogen N 2 (\displaystyle (\ce (N2))) enters into reactions only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen by ozone during electrical discharges is used in small quantities in the industrial production of nitrogen fertilizers. It can be oxidized with low energy consumption and converted into a biologically active form by cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with legumes, which can be effective green manure plants that do not deplete, but enrich the soil with natural fertilizers.

Oxygen

The composition of the atmosphere began to change radically with the advent of living organisms on Earth, as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, hydrocarbons, the ferrous form of iron contained in the oceans and others. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties formed. Since this caused serious and abrupt changes in many processes occurring in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe.

inert gases

The sources of inert gases are volcanic eruptions and the decay of radioactive elements. The earth as a whole, and the atmosphere in particular, are depleted in inert gases compared to space and some other planets. This applies to helium, neon, krypton, xenon and radon. The concentration of argon, on the contrary, is anomalously high and amounts to almost 1% of the gas composition of the atmosphere. A large amount of this gas is due to the intense decay of the radioactive isotope potassium-40 in the bowels of the Earth.

Air pollution

Recently, man has begun to influence the evolution of the atmosphere. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological epochs. Enormous quantities are consumed in photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic substances of plant and animal origin, as well as due to volcanism and human production activities. Over the past 100 years content CO 2 (\displaystyle (\ce (CO2))) in the atmosphere increased by 10%, with the main part (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the next 200-300 years the amount CO 2 (\displaystyle (\ce (CO2))) doubles in the atmosphere and can lead to