The atmosphere is changing. Information and facts about the atmosphere. Earth's atmosphere. History of atmospheric formation

Environmental safety aspects

Environmental Safety – the sum of conditions under which a scientifically based limitation or elimination of the harmful effects of economic activities on the life of the population and the quality of the environment is achieved.

Environmental safety is achieved by a system of measures (forecasting, planning, preparation for the implementation of a set of preventive measures) that ensure a minimum level of adverse impacts of nature and the technological processes of its development on the life and health of people (humans) while maintaining the pace of economic development.

The quality of the environment is made up of the quality of individual components of nature(atmospheric air, climate, natural waters, soil cover, etc.), household items(production, housing, public amenities) and socio-economic conditions(income level, education).

At the present stage of historical development, it is customary to distinguish two forms of interaction between society and nature:

economic– consumption of natural resources;

environmental– protection of the natural environment in order to preserve humans and their natural habitat.

A person, consuming environmental resources to satisfy his material and spiritual needs, changes the natural environment, which begins to affect the person himself. Negative anthropogenic activities manifest themselves in three main directions:

· environmental pollution -the process of introducing into the environment or the emergence in it of new, usually uncharacteristic agents that have a negative impact on its components.

There are three types of pollution: physical (solar radiation, electromagnetic radiation, etc.), chemical (aerosols, heavy metals, etc.), biological (bacteriological, microbiological). Each type of pollution has a characteristic and specific source of pollution. Source of pollution – a natural or economic object that is the beginning of the entry of a pollutant into the environment. Distinguish natural And anthropogenic sources of pollution. The anthropogenic flow of ecotoxicants into the environment prevails over the natural one (50-80%) and is only in some cases comparable to it;

· depletion of natural resources;

· destruction of the natural environment.

The scale of human impact on nature has become planetary in modern conditions, and in terms of quantitative effect, human activity exceeds many natural processes, which leads to severe environmental consequences. Anthropogenic influence extends to all the most important components of the biosphere: atmosphere, hydrosphere, lithosphere. Let's move on to their detailed characteristics.

I. Changes in the state of the atmosphere.

Atmosphere – gaseous envelope of the planet reaching an altitude of 1000 km. Beyond this distance, the atmosphere becomes rarefied and gradually passes into outer space. The atmosphere provides the respiratory function of all living organisms; determines the general thermal regime of the planet’s surface; protects against harmful cosmic and ultraviolet radiation from the Sun. Atmospheric circulation affects local climatic conditions, and through them the regime of rivers, indirectly the vegetation cover and the processes of relief formation.

Specialists who study the atmosphere identify several zones in it, located at different heights from the Earth, depending on their temperature (Fig.).

Troposphere the closest layer to the Earth's surface, its height is 9-16 km. In this layer, phenomena occur that we call weather.

Stratosphere– a layer reaching a height of 45-50 km. It is here that the bulk of atmospheric ozone (20-25 km) is concentrated, which has extremely important biological significance - protecting living organisms from short-wave ultraviolet radiation.

Mesosphere– layer located at altitudes of 50-80 km from the earth’s surface. This layer is characterized by a rapid decrease in temperature, so at its upper boundary the temperature can reach – 100 o C.

Thermosphere begins at an altitude of more than 80 km, its upper limit reaches 600-800 km. This is the area of ​​flights of artificial Earth satellites and intercontinental ballistic missiles. The lower boundary of the thermosphere is characterized by a continuous increase in temperature, reaching +250 o C. The most important physical feature of this layer is increased ionization, i.e. the presence of a huge number of electrically infected particles, which makes it possible to observe auroras.

Exosphere– outer layer of the atmosphere. From here, atmospheric gases are dispersed into outer space. The exosphere differs from outer space in the presence of a large number of free electrons that form the Earth's upper radiation belts.

Although the processes occurring in the earth's atmosphere are extremely complex, it chemical composition relatively homogeneous:

nitrogen (N 2) – 78.1%

· oxygen (O 2) – 20.95%

Argon (Ar) – 0.9%

· carbon dioxide (CO 2) – 0.03%

· hydrogen (H 2), helium (He), neon (Ne) and other gases – 1.8*10 -4%.

The atmosphere has a powerful ability to self-purify. However, exceeding the limits of this ability, human activity changes the existing balance in nature. Most of the environmentally negative consequences of human activity are manifested in the pollution of natural substances.

1. Air pollution– is a change in the physical and chemical composition of air that threatens human health and life, as well as the natural habitat.

In environmental literature, pollutants are called Polutants(ecotoxicants). The degree of air pollution is assessed by two main groups of ecotoxicants:

a) carcinogens– benz(a)pyrene, benzene, formaldehyde (the source of which is vehicle exhaust gases), as well as lead, cadmium, nickel, chromium, arsenic, carbon disulfide, asbestos, chlorine-containing substances (the result of production activities). Carcinogenesis is the ability of a metal to penetrate a cell and react with a DNA molecule, leading to chromosomal abnormalities of the cell.

b) non-carcinogenic substances– oxides of nitrogen, carbon, sulfur, ozone, dust and soot particles. The most common and widely controlled pollutants, of which, according to UNEP, up to 25 billion tons are released annually, include:

· sulfur dioxide and dust particles – 200 million tons/year;

·nitrogen oxides (N x O y) – 60 million tons/year;

· carbon oxides (CO and CO 2) – 8000 million tons/year;

· hydrocarbons (C x H y) – 80 million tons/year.

In recent decades, an accumulation of smoke and fog has formed over industrial centers and large cities called smog(from the English smoke - smoke and fog - fog). Its structure can be divided into three tiers:

· the lower one, lying between houses, is formed by the release of vehicle exhaust gases and raised dust;

· the middle one, fed by the smoke of heating systems, is located above the houses at a height of 20-30 meters;

· high, at a distance of 50-100 meters from the surface of the earth, consists of discharges from industrial enterprises.

Smog makes breathing difficult and contributes to the development of stress reactions. It is especially dangerous for the sick, the elderly and young children. (The London smog of 1951 caused the death of 3.5 thousand people from exacerbation of pulmonary, heart diseases and direct poisoning in two weeks. Ruhr region in 1962. 156 people died in three days).

Main components photochemical smog are nitrogen oxides (NO 2, N 2 O) and hydrocarbons. The interaction of sunlight with these pollutants, concentrated near the earth's surface, leads to the formation of ozone, peroxyacetyl nitrates (PAN) and other substances similar in properties to tear gas. PAN – chemically active organic substances that irritate the mucous membranes, tissues of the respiratory tract and human lungs; discolor the greenery of plants. High ozone concentrations reduce grain yields, slow plant growth and cause tree death.

The accumulation of impurities in sufficient concentration to form photosmog is facilitated by temperature inversion – a special state of the atmosphere in which at a certain altitude the air temperature is higher than the temperature of the air masses in the ground layer. This layer of warm air prevents vertical mixing and makes it impossible for toxic emissions to dissipate. With modern urban planning, similar conditions are created in cities with blocks of multi-story buildings. The inversion layer of warm air can be located at different heights, and the lower it is located above most sources of pollution, the more complicated the situation.

Levels of photochemical air pollution are closely related to vehicle traffic patterns. During periods of high traffic intensity in the morning and evening, there is a peak in emissions of nitrogen oxides and hydrocarbons into the atmosphere, the reaction of which with each other causes photochemical air pollution.

High concentrations and migration of impurities in the atmospheric air stimulate their interaction with the formation of more toxic compounds, which leads to the greenhouse effect, the appearance of ozone holes, acid rain and other environmental problems.

2. Greenhouse effect – heating of the atmosphere as a result of an increase in the amount of carbon monoxide (IV) and a number of other gases that prevent the dissipation of the Earth's thermal energy into outer space. Carbon dioxide of the atmosphere, together with water vapor and other polyatomic minigases (CO 2, H 2 O, CH 4, NO 2, O 3), forms a layer above the surface of the planet that allows solar rays (optical range of electromagnetic waves) to reach the earth's surface, but delays reverse thermal (long-wave infrared) radiation. The higher the concentration of greenhouse gases, the more intense the thermal energy accumulates in the surface layers of the atmosphere. Thus, the share of water vapor molecules in the formation of the greenhouse effect is 62%; carbon dioxide – 22%; methane – 2.5%; nitrogen oxides – 4%; ozone - 7% and other gases 2.5%.

The increase in carbon dioxide content in the atmosphere is due to a long period of systematic increase in the burning of fossil fuels. The extraction of gas, oil and coal, the decay of organic residues and the increase in the number of cattle are sources of methane entering the atmosphere. The scale of use of nitrogen fertilizers and carbon-containing fuels in thermal power plants in agriculture is characterized by the amount of nitrogen oxides emitted into the atmosphere. The presence of water vapor in the atmosphere is due to the intensity of water evaporation from the surface of the oceans due to climate warming.

The greenhouse effect is also enhanced by chlorofluorocarbons (freons) used as solvents, coolants in refrigeration units and various household containers. Their influence on the greenhouse effect is 1000 times stronger than the influence of an equal amount of carbon dioxide.

The consequence of the greenhouse effect is an increase in temperature on the Earth's surface and climate warming. As a result, there is a danger of polar ice melting, which could cause flooding of low-lying coastal land areas. In addition, an increase in air temperature can lead to a decrease in the productivity of agricultural land - desertification(from the English desert - desert). In this regard, the population of the relevant regions will experience food shortages.

3. "Ozone Holes" – areas with a 40-50% reduction in ozone in the atmosphere.

Ozone is a compound of three oxygen atoms (O3), formed in the upper layers of the stratosphere and lower layers of the mesosphere from oxygen under the influence of ultraviolet (UV) rays from sunlight. The result of this interaction is the absorption by the ozone screen of about 99% of the UV radiation of the solar spectrum, which has high energy and is destructive to all living things. A quantitative assessment of the state of ozone in the atmosphere is the thickness of the ozone layer, which, depending on the season, latitude and longitude, ranges from 2.5 to 5 relative millimeters.

Numerous data indicate that the ozone layer is beginning to decline. The main process of ozone destruction is caused by the influence and increase in emissions of nitrogen oxides, the source of which is the exhaust gases of superliners with a high flight ceiling, various rocket systems, volcanic eruptions and other natural phenomena. A serious danger to the ozone layer is the release of chlorofluorocarbons (CFCs) into the atmosphere. The most severe ozone destruction is associated with the production of freons (CH 3 CL, CCL 2 F 2 and CCL 3 F), which are widely used as fillers in aerosol packaging, fire extinguishers, refrigerants in refrigerators and air conditioners, and in the production of polystyrene foam. Freons released into the atmosphere are characterized by great stability and remain in it for 60-100 years.

Being chemically inert, freons are harmless to humans. However, in the stratosphere, under the influence of short-wave ultraviolet radiation from the Sun, their molecules decompose, releasing chlorine.

The chlorine molecule acts as a catalyst, remaining unchanged in tens of thousands of acts of destruction of ozone molecules. One chlorine atom can destroy 100,000 ozone molecules.

A 1% decrease in ozone content in the atmosphere leads to a 1.5% increase in the intensity of hard UV radiation incident on the surface of our planet. Even a slight decrease in the ozone layer can increase the incidence of skin cancer, have an adverse effect on plants and animals, and cause unpredictable changes in the global climate.

The problem of the influence of freons on stratospheric ozone has acquired international significance, especially in connection with the formation of “ozone holes”. An international program has been adopted to reduce production using freons. The industrial production of so-called alternative refrigerants with a low relative ozone activity coefficient has been developed and launched.

4. Acid rain – precipitation (rain, snow, fog), the chemical composition of which is characterized by a low pH factor a. In order to understand this issue, let us remember that water molecules usually dissociate into hydrogen ions (H +) and hydroxyl ions (OH -). A solution with equal concentrations of hydrogen and hydroxyl ions is called neutral. The acidity of a solution is quantitatively determined as the logarithm of the concentration of hydrogen ions, taken with the opposite sign. This quantity is called pH-factor. The pH value = 7 characterizes neutral water – neither acidic nor alkaline. A decrease in pH by 1 means an increase in the acidic properties of the solution by 10 times. The lower the pH value, the more acidic the solution is.

Acid rain is the result of the presence of sulfur oxides and nitrogen oxides in the atmosphere. The main sources of these compounds entering the air are the combustion processes of fossil fuels containing sulfur; metal smelting; vehicle operation. Under the influence of UV radiation, sulfur oxide (IV) is converted into sulfur oxide (VI), which reacts with atmospheric water vapor to form sulfuric acid, which is very hygroscopic and can form toxic fog. Along with sulfur oxides, nitrogen oxides mix with the pores of water to form nitric acid. These two acids, as well as the salts of these acids, cause acid rain. The higher the content of these acids in the air, the more often acid rain falls.

Acid precipitation is present within a radius of 10-20 km around industrial giants. The most unfavorable regions of Russia for acid precipitation include: the Kola Peninsula, the eastern slope of the Ural Range and the Taimyr region. Acid aerosol particles have a low deposition rate and can be transported to remote areas 100-1000 km from pollution sources.

Acid rain leads to the destruction of buildings and structures, especially those made of sandstone and limestone. The corrosive aggressiveness of the atmosphere increases significantly, which causes corrosion of metal objects and structures.

It is not the precipitation itself that poses a particular danger, but the secondary processes it causes. Under the influence of acid rain, the biochemical properties of the soil, the state of fresh water and forests change. As a result of changes in the pH of soil and water, the solubility of heavy metals in them increases. The components of acid rain, after interacting with heavy metals, convert them into a form that is easily digestible by plants.

Further along the food chain, heavy metals enter the bodies of fish, animals and humans. To certain limits, organisms are protected from the direct harmful effects of acidity, but the accumulation (accumulation) of heavy metals poses a serious danger. Acid rain, reducing the pH of lake water, leads to the death of their inhabitants. Once in the human body, heavy metal ions easily bind to proteins, suppressing the synthesis of macromolecules and, in general, metabolism in cells.

5. Reducing the amount of oxygen (O 2). More than three billion years ago, simple cells feeding on chemicals dissolved in water evolved into organisms capable of photosynthesis and began producing oxygen. About two billion years ago, the content of free oxygen in the earth's atmosphere began to increase. A protective ozone layer was formed from part of the atmospheric oxygen under the influence of sunlight, after which land plants and animals began to develop. The oxygen content of the atmosphere has undergone significant changes over time as levels of its production and use have changed. (Rice.)

In modern conditions, the main producers of oxygen on earth are green algae of the ocean surface (60%), tropical forests of land (30%) and terrestrial plants (10%). The possible decrease in the amount of oxygen on the planet is due to several reasons.

Firstly, an increase in the volume of burned fossil fuels (industry, thermal power plants, transport). According to expert calculations, the use of all deposits of coal, oil and natural gas accessible to humans will reduce the oxygen content in the air by no more than 0.15%.

The lack of oxygen in the air of cities contributes to the spread of pulmonary and cardiovascular diseases among the population.

6. Acoustic pollution – an increase in the level of noise in the air that has an irritating effect on a living organism.

At the present stage of development of scientific and technological progress, this increase is due to the introduction of new technological processes, an increase in equipment capacity, mechanization of production processes, the emergence of powerful means of land, air and water transport, which has led to almost constant human exposure to high (60-90 dB) noise levels. This contributes to the emergence and development of neurological, cardiovascular, auditory and other pathologies.

In the overall noise background of the city, the share of transport is 60-80%. Internal noise sources: sports games, games on playgrounds, unloading and loading operations at stores account for 10-20%. The noise regime in apartments consists of noise penetrating from the outside and resulting from the operation of engineering and sanitary equipment: elevators, pumps, water pumping, garbage chutes, ventilation, shut-off valves.

7. Reduced atmospheric transparency due to an increase in the content of suspended impurities (dust). Dust is a complex mixture of particles. Solid or liquid particles suspended in the air are called aerosols. They are perceived as smoke (aerosol with solid particles), fog (aerosol with liquid particles), haze or haze.

The causes of the main natural emissions of dust into the atmosphere are dust storms, soil erosion, volcanic activity, and sea spray. Sources of artificial aerosol air pollution are thermal power plants, enrichment plants, metallurgical and cement plants, industrial dumps, blasting operations, and construction. High concentrations of aerosols have been recorded in the atmospheric air of 50 Russian cities for many years. The average concentration of suspended matter in the most polluted cities reaches 250-300 μg/m3, which is two times higher than the average daily maximum permissible concentration (MPC) of 150 μg/m3. In 2000, in the city of Tambov, the maximum single ground concentration of dust was twice as high, i.e. it amounted to 2 MPC.

Industrial dust from industrial cities contains metal oxides, many of which are toxic: oxides of manganese, lead, molybdenum, vanadium, antimony, tellurium. Their effect on a living organism depends on the size of dust particles, their nature and chemical composition (Fig.).

Suspended particles not only make breathing difficult, cause allergies and poisoning, but also lead to climate change because they reflect solar radiation and make it difficult to remove heat from the Earth. Dust accelerates the destruction of metal structures, buildings and structures. A decrease in atmospheric transparency contributes to interference with aviation and shipping, which often causes major transport accidents.

Related information.

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

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

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

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

If there were no atmosphere, the Earth would be as quiet as the Moon. After all, sound is the vibration of air particles. The blue color of the sky is explained by the fact that the sun's rays, passing through the atmosphere, like through a lens, are decomposed into their component colors. In this case, the rays of blue and blue colors are scattered the most.

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

The structure of the atmosphere

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

Troposphere

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

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

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

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

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

Stratosphere

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

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

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

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

Mesosphere

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

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

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

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

Exosphere

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

Atmospheric composition

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

The gases that make up the atmosphere perform various functional roles. However, the main significance of these gases is determined primarily by the fact that they very strongly absorb radiant energy and thereby have a significant impact on the temperature regime of the Earth's surface and atmosphere.

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

	Volume concentration. %	Molecular weight, units
Oxygen
Carbon dioxide
Nitrous oxide
	from 0 to 0.00001
Sulfur dioxide	from 0 to 0.000007 in summer; from 0 to 0.000002 in winter
	From 0 to 0.000002	46,0055/17,03061
Azog dioxide
Carbon monoxide

Nitrogen, The most common gas in the atmosphere, it is chemically inactive.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Absolute humidity is the amount of water vapor contained in 1 m3 of air. It is expressed in grams. For example, if they say “absolute humidity is 15,” this means that 1 m L contains 15 g of water vapor.

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

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

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

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

To measure relative humidity, a hygrometer is used (from the Greek hygros - wet and metreco - I measure).

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

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

Cloud formation also involves particulate matter suspended in the troposphere.

Clouds can have different shapes, which depend on the conditions of their formation (Table 14).

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

Families	Kinds of clouds	Appearance
A. Upper clouds - above 6 km	I. Cirrus	Thread-like, fibrous, white
	II. Cirrocumulus	Layers and ridges of small flakes and curls, white
	III. Cirrostratus	Transparent whitish veil
B. Mid-level clouds - above 2 km	IV. Altocumulus	Layers and ridges of white and gray color
	V. Altostratified	Smooth veil of milky gray color
B. Low clouds - up to 2 km	VI. Nimbostratus	Solid shapeless gray layer
	VII. Stratocumulus	Non-transparent layers and ridges of gray color
	VIII. Layered	Non-translucent gray veil
D. Clouds of vertical development - from the lower to the upper tier	IX. Cumulus	Clubs and domes are bright white, with torn edges in the wind
	X. Cumulonimbus	Powerful cumulus-shaped masses of dark lead color

Atmospheric protection

The main sources are industrial enterprises and cars. In large cities, the problem of gas pollution on main transport routes is very acute. That is why many large cities around the world, including our country, have introduced environmental control of the toxicity of vehicle exhaust gases. According to experts, smoke and dust in the air can reduce the supply of solar energy to the earth's surface by half, which will lead to a change in natural conditions.

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 the total water vapor present in the atmosphere. Turbulence and convection are highly developed in the troposphere, clouds arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m

Tropopause

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

Stratosphere

A layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and an increase in temperature in the 25-40 km layer from −56.5 to 0.8 ° C (upper layer of the stratosphere or inversion region). 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 mesosphere.

Stratopause

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

Mesosphere

The mesosphere begins at an altitude of 50 km and extends to 80-90 km. Temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc. cause atmospheric luminescence.

Mesopause

Transitional layer between the mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).

Karman Line

The height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. The Karman line is located at an altitude of 100 km above sea level.

Boundary of the Earth's atmosphere

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 to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, ionization of the air (“auroras”) occurs - 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, a noticeable decrease in the size of this layer occurs.

Thermopause

The region of the atmosphere adjacent to the thermosphere. In this region, the absorption of solar radiation is negligible and the temperature does not actually change with altitude.

Exosphere (scattering sphere)

Atmospheric layers up to a height of 120 km

The exosphere is the dispersion zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space (dissipation).

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

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

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutronosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. This implies a 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 the turbopause; it lies at an altitude of about 120 km.

The atmosphere is what makes life possible on Earth. We receive the very first information and facts about the atmosphere in elementary school. In high school, we become more familiar with this concept in geography lessons.

Concept of earth's atmosphere

Not only the Earth, but also other celestial bodies have an atmosphere. This is the name given to the gaseous shell surrounding the planets. The composition of this gas layer varies significantly between planets. Let's look at the basic information and facts about otherwise called air.

Its most important component is oxygen. Some people mistakenly think that the earth's atmosphere consists entirely of oxygen, but in fact, air is a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, and water vapor. Even though the percentage of these gases is small, they perform an important function - they absorb a significant part of the solar radiant energy, thereby preventing the luminary from turning all life on our planet into ashes. The properties of the atmosphere change depending on altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.

Composition of the Earth's atmosphere

• Carbon dioxide necessary for plant nutrition. It appears in the atmosphere as a result of the process of respiration of living organisms, decay, and combustion. Its absence in the atmosphere would make the existence of any plants impossible.
• Oxygen- a vital component of the atmosphere for humans. Its presence is a condition for the existence of all living organisms. It makes up about 20% of the total volume of atmospheric gases.
• Ozone is a natural absorber of solar ultraviolet radiation, which has a detrimental effect on living organisms. Most of it forms a separate layer of the atmosphere - the ozone screen. Recently, human activity has led to the fact that it is gradually beginning to collapse, but since it is of great importance, active work is being carried out to preserve and restore it.
• water vapor determines air humidity. Its content may vary depending on various factors: air temperature, territorial location, season. At low temperatures there is very little water vapor in the air, maybe less than one percent, and at high temperatures its amount reaches 4%.
• In addition to all of the above, the composition of the earth’s atmosphere always contains a certain percentage solid and liquid impurities. These are soot, ash, sea salt, dust, water drops, microorganisms. They can get into the air both naturally and anthropogenically.

Layers of the atmosphere

The temperature, density, and quality composition of the air are not the same at different altitudes. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristics. Let's find out what layers of the atmosphere are distinguished:

• Troposphere - this layer of the atmosphere is closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. 90% of all water vapor in the atmosphere is located here, so active cloud formation occurs. Also in this layer processes such as air (wind) movement, turbulence, and convection are observed. Temperatures range from +45 degrees at midday in the warm season in the tropics to -65 degrees at the poles.
• The stratosphere is the second most distant layer of the atmosphere. Located at an altitude of 11 to 50 km. In the lower layer of the stratosphere the temperature is approximately -55; moving away from the Earth it rises to +1˚С. This region is called an inversion and is the boundary of the stratosphere and mesosphere.
• The mesosphere is located at an altitude of 50 to 90 km. The temperature at its lower boundary is about 0, at the upper it reaches -80...-90 ˚С. Meteorites entering the Earth's atmosphere completely burn up in the mesosphere, causing airglows to occur here.
• The thermosphere is approximately 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the influence of cosmic radiation and radiation emanating from the Sun.
• The exosphere is the zone of air dispersion. Here the concentration of gases is small and they gradually escape into interplanetary space.

The boundary between the earth's atmosphere and outer space is considered to be 100 km. This line is called the Karman line.

Atmospheric pressure

When listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how can it affect us?

We figured out that air consists of gases and impurities. Each of these components has its own weight, which means that the atmosphere is not weightless, as was believed until the 17th century. Atmospheric pressure is the force with which all layers of the atmosphere press on the surface of the Earth and on all objects.

Scientists carried out complex calculations and proved that the atmosphere presses with a force of 10,333 kg per square meter of area. This means that the human body is subject to air pressure, the weight of which is 12-15 tons. Why don't we feel this? It is our internal pressure that saves us, which balances the external. You can feel the pressure of the atmosphere while on an airplane or high in the mountains, since the atmospheric pressure at altitude is much less. In this case, physical discomfort, blocked ears, and dizziness are possible.

A lot can be said about the surrounding atmosphere. We know many interesting facts about her, and some of them may seem surprising:

• The weight of the earth's atmosphere is 5,300,000,000,000,000 tons.
• It promotes sound transmission. At an altitude of more than 100 km, this property disappears due to changes in the composition of the atmosphere.
• The movement of the atmosphere is provoked by uneven heating of the Earth's surface.
• A thermometer is used to determine the air temperature, and a barometer is used to determine the pressure of the atmosphere.
• The presence of an atmosphere saves our planet from 100 tons of meteorites every day.
• The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
• The atmosphere is believed to extend upward to a height of 3000 km.

The importance of the atmosphere for humans

The physiological zone of the atmosphere is 5 km. At an altitude of 5000 m above sea level, a person begins to experience oxygen starvation, which is expressed in a decrease in his performance and deterioration in well-being. This shows that a person cannot survive in a space where there is no this amazing mixture of gases.

All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, it became possible to develop life on Earth. Already today, having assessed the scale of harm that humanity is capable of causing through its actions to the life-giving air, we should think about further measures to preserve and restore the atmosphere.

Composition and structure of the atmosphere.

The atmosphere is the gaseous shell of the Earth. The vertical extent of the atmosphere is more than three Earth radii (the average radius is 6371 km) and the mass is 5.157x10 15 tons, which is approximately a millionth of the Earth's mass.

The division of the atmosphere into layers in the vertical direction is based on the following:

Composition of atmospheric air,

Physico-chemical processes;

Temperature distribution by height;

Interaction of the atmosphere with the underlying surface.

The atmosphere of our planet is a mechanical mixture of various gases, including water vapor, as well as a certain amount of aerosols. The composition of dry air in the lower 100 km remains almost constant. Clean and dry air, free of water vapor, dust and other impurities, is a mixture of gases, mainly nitrogen (78% of air volume) and oxygen (21%). A little less than one percent is argon and there are many other gases in very small quantities - xenon, krypton, carbon dioxide, hydrogen, helium, etc. (Table 1.1).

Nitrogen, oxygen and other components of atmospheric air are always in a gaseous state in the atmosphere, since the critical temperatures, that is, the temperatures at which they can be in a liquid state, are much lower than the temperatures observed at the surface of the Earth. The exception is carbon dioxide. However, in order to transition to a liquid state, in addition to temperature, it is also necessary to achieve a state of saturation. There is little carbon dioxide in the atmosphere (0.03%) and it is found in the form of individual molecules, evenly distributed among the molecules of other atmospheric gases. Over the past 60-70 years, its content has increased by 10-12%, under the influence of human activity.

The most susceptible to change is the content of water vapor, the concentration of which at the Earth's surface at high temperatures can reach 4%. With increasing altitude and decreasing temperature, the content of water vapor decreases sharply (at an altitude of 1.5-2.0 km - by half and 10-15 times from the equator to the pole).

The mass of solid impurities over the past 70 years in the atmosphere of the northern hemisphere has increased approximately 1.5 times.

The constancy of the gas composition of the air is ensured by intensive mixing of the lower layer of air.

Gas composition of the lower layers of dry air (without water vapor)

The role and significance of the main gases of atmospheric air

OXYGEN (ABOUT) vital for almost all inhabitants of the planet. This is an active gas. It participates in chemical reactions with other atmospheric gases. Oxygen actively absorbs radiant energy, especially very short wavelengths less than 2.4 microns. Under the influence of solar ultraviolet radiation (X< 03 µm), the oxygen molecule breaks down into atoms. Atomic oxygen, combining with an oxygen molecule, forms a new substance - triatomic oxygen or ozone(Oz). Ozone is mainly found at high altitudes. There his role for the planet is extremely beneficial. At the Earth's surface, ozone is formed during lightning discharges.

Unlike all other gases in the atmosphere, which are tasteless and odorless, ozone has a characteristic odor. Translated from Greek, the word “ozone” means “pungent-smelling.” After a thunderstorm, this smell is pleasant; it is perceived as the smell of freshness. In large quantities, ozone is a toxic substance. In cities with a large number of cars, and therefore large emissions of automobile gases, ozone is formed under the influence of sunlight in clear or partly cloudy weather. The city is shrouded in a yellow-blue cloud, visibility deteriorates. This is photochemical smog.

NITROGEN (N2) is a neutral gas; it does not react with other atmospheric gases and does not participate in the absorption of radiant energy.

Up to altitudes of 500 km, the atmosphere mainly consists of oxygen and nitrogen. Moreover, if nitrogen predominates in the lower layer of the atmosphere, then at high altitudes there is more oxygen than nitrogen.

ARGON (Ar) is a neutral gas, does not react, and does not participate in the absorption or emission of radiant energy. Similarly - xenon, krypton and many other gases. Argon is a heavy substance; there is very little of it in the high layers of the atmosphere.

CARBON DIOXIDE (CO2) in the atmosphere is on average 0.03%. This gas is very necessary for plants and is actively absorbed by them. The actual amount of it in the air may vary slightly. In industrial areas, its amount can increase to 0.05%. In rural areas, above forests and fields there is less of it. Over Antarctica there is approximately 0.02% carbon dioxide, i.e. almost Uz less than the average amount in the atmosphere. The same amount and even less over the sea - 0.01 - 0.02%, since carbon dioxide is intensively absorbed by water.

In the layer of air that is directly adjacent to the earth's surface, the amount of carbon dioxide also experiences daily fluctuations.

There is more of it at night, less during the day. This is explained by the fact that during daylight hours carbon dioxide is absorbed by plants, but not at night. Plants on the planet take about 550 billion tons of oxygen from the atmosphere throughout the year and return about 400 billion tons of oxygen to it.

Carbon dioxide is completely transparent to the sun's short-wave rays, but intensely absorbs the Earth's thermal infrared radiation. Related to this is the problem of the greenhouse effect, about which discussions periodically flare up in the pages of the scientific press, and mainly in the mass media.

HELIUM (He) is a very light gas. It enters the atmosphere from the earth's crust as a result of the radioactive decay of thorium and uranium. Helium escapes into outer space. The rate of decrease of helium corresponds to the rate of its entry from the bowels of the Earth. From an altitude of 600 km to 16,000 km, our atmosphere consists mainly of helium. This is the “helium crown of the Earth”, according to Vernadsky. Helium does not react with other atmospheric gases and does not participate in radiant heat exchange.

HYDROGEN (Hg) is an even lighter gas. There is very little of it near the Earth's surface. It rises to the upper layers of the atmosphere. In the thermosphere and exosphere, atomic hydrogen becomes the dominant component. Hydrogen is the uppermost, outermost shell of our planet. Above 16,000 km to the upper boundary of the atmosphere, that is, up to altitudes of 30 - 40 thousand km, hydrogen predominates. Thus, the chemical composition of our atmosphere with altitude approaches the chemical composition of the Universe, in which hydrogen and helium are the most common elements. In the outermost, extremely rarefied part of the upper atmosphere, hydrogen and helium escape from the atmosphere. Their individual atoms have sufficiently high speeds for this.