Without an atmosphere of air, our earth is. Composition and structure of the atmosphere. The air envelope of the Earth and its composition

Atmosphere- the gaseous shell of the planet. The Earth's atmosphere consists of a mixture of gases, water vapor and small particles of solids. The basis of the atmosphere, air, is a mixture of gases, primarily nitrogen, oxygen, argon, and carbon dioxide. The air shell of our planet is called the Greek word - Atmosphere, which can be translated as a shell of gas.

The total mass of the earth's atmosphere is approximately 5.15·10 15 tons. The upper boundary of the atmosphere lies at an altitude of about 1000 km above sea level; above is the so-called corona of the Earth, extending over a distance of about 20,000 km and consisting mainly of hydrogen and helium. The atmosphere has the smallest mass of all other geospheres on our planet: it is approximately 1/1000 of the mass of the hydrosphere and about 1/10,000 of the mass of the earth's crust.

According to experts, the Earth's air shell consists of several main layers: the troposphere, tropopause, stratosphere, stratopause, mesosphere, mesopause, thermosphere and exosphere.

In total, the atmosphere has a thickness of from two to 3 thousand km. from the surface of our planet. The air shell of the Earth has the following functions:

• - regulation of the Earth's climate;
• - absorption of solar radiation;
• - transmits thermal radiation from the Sun;
• - retains heat;
• - is a medium for sound propagation;
• - source of oxygen breathing;
• - formation of moisture circulation associated with the formation of clouds and precipitation;
• - forming factor of the lithosphere (weathering).

I really love the air in the mountains. I am, of course, not a climber; my maximum altitude was 2300 m. But if you rise 5 km above sea level, your health can deteriorate sharply, since there will be less oxygen. I will now tell you about these and other features of the air shell.

The air envelope of the Earth and its composition

The shell around our planet, consisting of gases, is called the atmosphere. It is thanks to her that you and I can breathe. It contains:

• nitrogen;
• oxygen;
• inert gases;
• carbon dioxide.

78% of the air is nitrogen, but oxygen, without which we could not exist, is 21%. The volume of carbon dioxide in the atmosphere is regularly increasing. The reason for this is human activity. Industrial enterprises and cars emit huge amounts of combustion products into the atmosphere, and the area of ​​forests that could correct the situation is rapidly declining.

There is also ozone in the atmosphere, from which a protective layer has formed around the planet. It is located at an altitude of about 30 km and protects our planet from the dangerous effects of the Sun.

At different heights, the air shell has its own characteristics. In total, there are 5 layers in the atmosphere: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The troposphere is closest to the earth's surface. Rain, snow, fog are formed within this layer.

What functions does the atmosphere perform?

If the Earth did not have a shell, then it is unlikely that there could be living beings on its territory. Firstly, it protects all life on the planet from solar radiation. In addition, the atmosphere allows you to maintain a comfortable temperature for living. We are used to seeing blue skies above our heads, perhaps this is due to various particles in the air.

The air envelope distributes sunlight and also allows sound to travel. It is thanks to the air that we can hear each other, birdsong, falling raindrops and the wind. Of course, without the atmosphere, moisture would not be able to be redistributed. Air creates a favorable habitat for humans, animals and plants.

The earth's surface is surrounded by a shell of air - atmosphere, which, according to modern data, extends above it for 1500–2000 km, that is, the height of the atmosphere is about 1/3 of the radius of the Earth. However, traces of atmospheric air were also found at an altitude of 20,000 km. Almost half of the total air mass is concentrated within the first kilometers from the Earth’s surface (in the lower layers 20 km high - 95%, and in the overlying layers with low density - 5% of its mass).

The air shell of the Earth consists of a mechanical mixture of gases.

The atmosphere always contains water vapor, which accounts for up to 3% of the atmospheric volume, as well as dust and other components. Therefore, air should not be considered simply as a mixture of gases; it is necessary to take into account the presence in the mixture of ions and larger particles (dust, aerosols), which are of great importance.

The percentage of gases, moisture and dust in the earth's atmosphere is subject to changes over time. These changes are caused, on the one hand, by natural processes, and on the other, by human economic activity.

Atmospheric dust is the smallest solid particles suspended in the air with a radius of 10 - 4 -10 -3 cm. It is formed as a result of the destruction and weathering of rocks and soil, volcanic eruptions (there is a known case when, as a result of the eruption of the Krakatoa volcano in 1833, dust formed on altitude of 8–24 km and its 16 km thick layer remained in the air for about 5 years), forest, steppe and peat fires, crushing of cosmic bodies (cosmic dust), etc. Atmospheric dust is of great importance for the processes occurring on Earth: it contributes condensation of water vapor, and consequently the formation of precipitation, dissipates solar radiation and thereby protects the Earth from excessive heating.

A huge amount of various industrial dust and harmful gases joins the natural dust background of the atmosphere in large cities and industrial centers. It was determined experimentally that in a city there are 100 thousand dust particles in 1 cm 3 of air, while above the ocean there are only 200 dust particles; at an altitude of 5 km there is 1000 times less dust than at an altitude of 2 m, that is, in the layer in which humans live. Atmospheric pollution is harmful to human health, since dust and gases can either directly penetrate the human body (into the lungs and alveoli) or enter it with water and food.

The composition and properties of the atmosphere at different altitudes are not the same, therefore it is divided into tropo-, strato-, meso-, thermo- and exosphere. The last three layers are sometimes considered as ionosphere.

Troposphere 1 (Fig. 3.1) extends to a height of up to 7 km at the poles and up to 18 km at the Earth’s equator. All water vapor and 4/5 of the mass of the atmosphere are concentrated in the troposphere. All weather phenomena develop here. Weather and climate on Earth depend on the distribution of heat, pressure and water vapor content in the atmosphere. Water vapor absorbs solar radiation, increases air density, and is the source of all precipitation. The temperature of the troposphere decreases with altitude and at an altitude of 10–12 km reaches minus 55 °C.

Stratosphere 2(up to 40 km) is the layer of the atmosphere next to the troposphere. Here the temperature gradually increases to 0 °C. At an altitude of 22–24 km there is a maximum concentration of ozone (ozone layer), which absorbs most of the hard radiation from the Sun that is harmful to living organisms.

IN mesosphere 3(up to 80 km) the temperature drops to minus 60–80 С. There is a high content of gas ions that cause auroras.

Thermosphere(up to 800 km) is characterized by an increase in temperature. The content of light gases – hydrogen and helium – and charged particles increases.

IN exosphere(up to 1500–2000 km) atmospheric gases are dissipated into outer space.

Air envelope of the Earth

1. From tropical and subtropical areas of high pressure, the main flow of air rushes towards the equator, into an area of ​​​​constantly low pressure. Under the influence of the deflecting force of the Earth's rotation, these flows are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. These constantly blowing winds are called trade winds.

2. Some tropical air moves to temperate latitudes. This movement is especially active in the summer, when lower pressure prevails there. These air flows in the Northern Hemisphere also deviate to the right and take first a southwestern and then a western direction, and in the Southern Hemisphere - a northwestern one, turning into a western one. Thus, in the temperate latitudes of both hemispheres, western air transport.

3. From polar areas of high pressure, air moves to moderate latitudes, taking a northeast direction in the Northern and southeast in the Southern Hemispheres.

Trade winds, westerly winds from temperate latitudes and winds from the polar regions are called planetary and are distributed zonally.

4. This distribution is disrupted on the eastern coasts of the continents of the Northern Hemisphere in temperate latitudes. As a result of seasonal changes in pressure over the land and the adjacent water surface of the ocean, winds blow here from land to sea in winter, and from sea to land in summer. These winds, changing their direction with the seasons, are called monsoons. Under the influence of the deflecting influence of the rotating Earth, the summer monsoons take a southeastern direction, and the winter monsoons take a northwestern direction. Monsoon winds are especially characteristic of the Far East and Eastern China, and to a lesser extent they occur on the east coast of North America.

5. In addition to planetary winds and monsoons, there are local, so-called local winds. They arise due to the characteristics of the relief and uneven heating of the underlying surface.

Breezes- coastal winds observed in clear weather on the shores of bodies of water: oceans, seas, large lakes, reservoirs and even rivers. During the day they blow from the water surface (sea breeze), at night - from land (shore breeze). During the day, the land heats up more than the sea. The air above the land rises, air currents from the sea rush into its place, forming a day breeze. In tropical latitudes, daytime breezes are quite strong winds that bring moisture and coolness from the sea.

At night, the surface of the water is warmer than the land. The air rises, and air from land rushes in its place. A night breeze forms. It is usually inferior in strength to daytime.

observed in the mountains hair dryers- warm and dry winds blowing along the slopes.

If low mountains rise like a dam in the path of moving cold air, it may occur. boron Cold air, having overcome a low barrier, falls down with enormous force, and a sharp drop in temperature occurs. Bora is known under different names: on Baikal it is sarma, in North America - chinook, in France - mistral, etc. In Russia, bora reaches particular strength in Novorossiysk.

Suhovei- these are dry and hot winds. They are characteristic of arid regions of the globe. In Central Asia, dry winds are called samum, in Algeria - sirocco, in Egypt - hatsin, etc. The speed of the dry wind reaches 20 m/s, and the air temperature is 40 °C. Relative humidity during dry winds drops sharply and drops to 10%. Plants, evaporating moisture, dry out on the root. In deserts, dry winds are often accompanied by dust storms.

The direction and strength of the wind must be taken into account when constructing populated areas, industrial enterprises, and housing. Wind is one of the most important sources of alternative energy; it is used to generate electricity, as well as to operate mills, water pumps, etc.

8. Weather and its forecasting

Weather call the state of the lower layer of the atmosphere at a given time and place.

Its most characteristic feature is variability; often the weather changes several times during the day.

Sudden changes in weather are most often associated with changes in air masses.

Air mass -This is a huge moving volume of air with certain physical properties: temperature, density, humidity, transparency.

The lower layers of the atmosphere, in contact with the underlying surface, acquire some of its properties. Warm air masses form above a heated surface, and cold air masses form above a cooled surface. The longer the air mass remains above the surface from which moisture evaporates, the greater its humidity becomes.

Depending on the place of formation, air masses are divided into arctic, temperate, tropical, and equatorial. If the formation of air masses occurs over the ocean, they are called marine. In winter they are very humid and warm, in summer they are cool. Continental air masses have low relative humidity, higher temperatures and are highly dusty.

Russia is located in the temperate zone, so maritime temperate air masses predominate in the west, and continental air masses predominate over most of the rest of the territory. Arctic air masses form beyond the Arctic Circle (Fig. 39).

Rice. 39.

When different air masses come into contact in the troposphere, transition regions arise - atmospheric fronts; their length reaches 1000 km and their height reaches several hundred meters.

Warm front(Fig. 40, 1) is formed by the active movement of warm air towards cold air. Then light warm air flows onto the retreating wedge of cold air and rises along the interface plane. It cools as it rises. This leads to condensation of water vapor and the formation of cirrus and nimbostratus clouds, and then to precipitation.

When a warm front approaches within a day, its harbingers appear - cirrus clouds. They float like feathers at an altitude of 7-10 km. At this time, atmospheric pressure decreases. The arrival of a warm front is usually associated with warming and heavy, drizzling precipitation.

Rice. 40.

Cold front(Fig. 40, 2) is formed when cold air moves towards warm air. Cold air, being heavier, flows under the warm air and pushes it upward. In this case, stratocumulus rain clouds appear, piling up like mountains or towers, and precipitation from them falls in the form of showers with squalls and thunderstorms. The passage of a cold front is associated with colder temperatures and stronger winds.

Powerful turbulences of air sometimes form at fronts, similar to whirlpools when two streams of water meet. The size of these air vortices can reach 2-3 thousand km in diameter. If the pressure in their central parts is lower than at the edges, this is cyclone.

In the central part of the cyclone, the air rises and spreads to its outskirts (Fig. 41, 1). As the air rises, it expands, cools, water vapor condenses, and cloudiness occurs. When cyclones pass, cloudy weather usually occurs with rain in summer and snowfall in winter.

Cyclones usually move from west to east at an average speed of about 30 km/h, or 700 km per day.

Rice. 41.

Tropical cyclones differ from temperate cyclones by being smaller in size and having exceptionally stormy weather. The diameter of tropical cyclones is usually 200-500 km, the pressure in the center drops to 960-970 hPa. They are accompanied by hurricane-force winds of up to 50 m/s, and the width of the storm zone reaches 200-250 km. In tropical cyclones, powerful clouds form and heavy precipitation falls (up to 300-400 mm per day). A characteristic feature of tropical cyclones is the presence in the center of a small, about 20 km across, calm area with clear weather.

If, on the contrary, the pressure is increased in the center, then this vortex is called anticyclone. In anticyclones, the outflow of air at the Earth's surface occurs from the center to the edges, moving clockwise (Fig. 41, 2). Simultaneously with the outflow of air from the anticyclone, air from the upper layers of the atmosphere enters its central part. As it descends, it heats up, absorbing water vapor, and the clouds dissipate. Therefore, in areas where anticyclones appear, clear, cloudless weather with weak winds sets in, hot in summer and cold in winter.

Anticyclones cover larger areas than cyclones. They are more stable, move at a lower speed, break down more slowly, and often stay in one place for a long time. As the anticyclone approaches, the atmospheric pressure increases. This sign should be used when predicting the weather.

A series of cyclones and anticyclones continuously pass through the territory of Russia. This is what causes weather variability.

Synoptic map- a weather map compiled for a specific period. It is compiled several times a day based on data received from the network of meteorological stations of the Hydrometeorological Service of Russia and foreign countries. This map shows weather information in numbers and symbols - air pressure in millibars, air temperature, wind direction and speed, cloudiness, position of warm and cold fronts, cyclones and anticyclones, precipitation patterns.

Rice. 42.

To forecast the weather, maps are compared (for example, for November 3 and 4) and changes in the position of warm and cold fronts, displacements of cyclones and anticyclones, and the nature of the weather in each of them are established (Fig. 42). Currently, space stations are widely used to improve weather forecasts.

Signs of stable and clear weather

1. Air pressure is high, hardly changes or increases slowly.

2. The diurnal variation in temperature is sharply expressed: hot during the day, cool at night.

3. The wind is weak, intensifies in the afternoon, and subsides in the evening.

4. The sky is cloudless all day or covered with cumulus clouds, disappearing in the evening. Relative air humidity decreases during the day and increases at night.

5. During the day the sky is bright blue, twilight is short, the stars twinkle faintly. In the evening the dawn is yellow or orange.

6. Heavy dew or frost at night.

7. Fogs over lowlands, increasing at night and disappearing during the day.

8. At night it is warmer in the forest than in the field.

9. Smoke rises from chimneys and fires.

10. Swallows fly high.

Signs of Unsustainable Severe Weather

1. The pressure fluctuates sharply or continuously decreases.

2. The daily variation of temperature is weakly expressed or with a violation of the general variation (for example, at night the temperature rises).

3. The wind increases, abruptly changes its direction, the movement of the lower layers of clouds does not coincide with the movement of the upper ones.

4. Cloudiness is increasing. Cirrostratus clouds appear on the western or southwestern side of the horizon and spread throughout the sky. They give way to altostratus and nimbostratus clouds.

5. It’s stuffy in the morning. Cumulus clouds grow upward, turning into cumulonimbus - to a thunderstorm.

6. Morning and evening dawns are red.

7. By night the wind does not subside, but intensifies.

8. Light circles (halos) appear around the Sun and Moon in cirrostratus clouds. There are crowns in the middle-tier clouds.

9. There is no morning dew.

10. Swallows fly low. Ants hide in anthills.

9. Concept of climate

Climate -This is a long-term weather regime characteristic of a given area.

Climate influences the regime of rivers, the formation of various types of soils, vegetation and fauna. So, in areas where the earth's surface receives a lot of heat and moisture, moist evergreen forests grow. Areas located near the tropics receive almost as much heat as at the equator, but much less moisture, so they are covered with sparse desert vegetation. Most of our country is occupied by coniferous forests, which have adapted to the harsh climate: cold and long winters, short and moderately warm summers, and average humidity.

The formation of climate depends on many factors, primarily on geographic location. The latitude of the place determines the angle of incidence of the sun's rays and, accordingly, the amount of heat coming from the Sun. The amount of heat also depends on the nature of the underlying surface and on the distribution of land and water. Water, as you know, heats up slowly, but also cools down slowly. Land, on the contrary, heats up quickly and cools down just as quickly. As a result, different weather regimes are formed over the water surface and over land.

Table 3

Temperature fluctuations in cities located between 50 and 53°C. w.

From this table it can be seen that Bantry on the west coast of Ireland, which is directly influenced by the Atlantic Ocean, has an average temperature of 15.2 °C in the warmest month and 7.1 °C in the coldest month, i.e. its annual amplitude is 8. 1 °C. With distance from the ocean, the average temperature of the warmest month increases and the coldest month decreases, i.e., the amplitude of annual temperatures increases. In Nerchinsk it reaches 53.2 °C.

Relief has a great influence on the climate: mountain ranges and basins, plains, river valleys, and ravines create special climate conditions. Mountains are often climate dividers.

They influence climate and sea currents. Warm currents transfer enormous amounts of heat from low latitudes to higher latitudes, while cold currents transfer cold from higher latitudes to lower latitudes. In places washed by warm currents, the annual air temperature is 5-10 °C higher than at the same latitudes washed by cold currents.

Thus, the climate of each territory depends on the latitude of the place, the underlying surface, sea currents, topography and altitude of the place above sea level.

The Russian scientist B.P. Alisov developed a classification of the climates of the globe. It is based on the types of air masses, their formation and changes during movement under the influence of the underlying surface.

Climatic zones. Depending on the prevailing climate, the following climatic zones are distinguished: equatorial, two tropical, two temperate, two polar (Arctic, Antarctic) and transitional - two subequatorial, two subtropical and two subpolar (subarctic and subantarctic).

Equatorial belt covers the basins of the Congo and Amazon rivers, the coast of the Gulf of Guinea, and the Sunda Islands. The high position of the sun throughout the year causes strong surface heating. Average annual temperatures here range from 25 to 28 °C. During the daytime, the air temperature rarely rises to 30 °C, but high relative humidity remains - 70-90%. Heated air, saturated with water vapor, rises upward under conditions of low pressure. Cumulus clouds appear in the sky and cover the entire sky by midday. The air continues to rise, cumulus clouds turning into cumulonimbus clouds, which produce intense rain showers in the afternoon. In this belt, the annual precipitation exceeds 2000 mm. There are places where their number increases to 5000 mm. Precipitation is distributed evenly throughout the year.

High temperatures throughout the year and large amounts of precipitation create conditions for the development of rich vegetation - moist equatorial forests.

Subequatorial belt occupies vast areas - the Brazilian Highlands in South America, Central Africa to the north and east of the Congo Basin, most of the Indian subcontinent and Indochina peninsulas, as well as Northern Australia.

The most characteristic feature of the climate of this zone is the change in air masses over the seasons: in summer this entire area is occupied by equatorial air, in winter by tropical air. As a result, two seasons are distinguished - wet (summer) and dry (winter). In the summer season, the weather is not much different from the equatorial one. Warm, moist air rises, creating conditions for cloud formation and heavy precipitation. It is in this belt that the places with the highest rainfall are located (northeast India and the Hawaiian Islands). In winter, conditions change dramatically, dry tropical air dominates, and dry weather sets in. The grasses burn out and the trees shed their leaves. Most of the territories of the subequatorial belt are occupied by the zone of savannas and woodlands.

Tropical zone located on both sides of the tropics, both on the oceans and on the continents. Tropical air prevails here all year round. In conditions of high pressure and low clouds, it is characterized by high temperatures. The average temperature of the warmest month exceeds 30 °C, and on some days it rises to 50-55 °C.

There is little precipitation in most of the territory (less than 200 mm); the greatest deserts in the world are located here - the Sahara, Western Australia, and the desert of the Arabian Peninsula.

But not everywhere in the tropical zones the climate is arid. On the eastern coasts of the continents, where trade winds blow from the oceans, there is a lot of precipitation (Greater Antilles, eastern coast of Brazil, eastern coast of Africa). The climate of these areas is not much different from the equatorial climate, although annual temperature fluctuations are significant, since there is a large difference in the height of the sun between seasons. Thanks to high rainfall and high temperatures, tropical rainforests grow here.

Subtropical zone occupies large spaces between the 25th and 40th parallels of northern and southern latitude. This belt is characterized by a change in air masses according to the seasons: in summer the entire region is occupied by tropical air, in winter by air of temperate latitudes. There are three climatic regions here: western, central and eastern. The western climatic region covers the western parts of the continents: the Mediterranean coast, California, the central part of the Andes, and southwestern Australia. In summer, tropical air moves here, creating an area of ​​high pressure. As a result, dry and sunny weather sets in. Winter is warm and humid. This climate is sometimes called Mediterranean.

A completely different climate regime is observed in East Asia and the southeastern part of North America. In summer, moist masses of tropical air from the ocean (summer monsoons) arrive here, bringing heavy clouds and precipitation. And the winter monsoons bring streams of dry continental air from temperate latitudes. The temperature of the coldest month is above 0 °C.

In the central region (Eastern Turkey, Iran, Afghanistan, Great Basin in North America), dry air prevails all year round: tropical air in summer, continental air of temperate latitudes in winter. Summer here is hot and dry; winters are short and wet, although the total precipitation does not exceed 400 mm. In winter there are frosts and snow falls, but a stable snow cover does not form. The daily temperature ranges are large (up to 30 °C), and there is a large difference between the warmest and coldest months. Here, in the central regions of the continents, there are deserts.

Temperate zone occupies areas north and south of the subtropics approximately to the polar circles. In the Southern Hemisphere, the oceanic climate predominates, while in the Northern Hemisphere there are three climatic regions: western, central and eastern.

In western Europe and Canada, the southern Andes, humid sea air of temperate latitudes, brought by westerly winds from the oceans (500-1000 mm of precipitation per year), prevails. Precipitation is distributed evenly throughout the year, and there are no dry periods. Under the influence of the oceans, the course of temperatures is smooth, and annual amplitudes are small. Cold snaps are brought by Arctic (Antarctic) air masses, which lower the temperature in winter. Heavy snowfalls are observed at this time. Summer is long, cool, and there are no sudden changes in air temperature.

In the east (northeast China, Far East) the climate is monsoon. In winter, cold continental air masses arrive and form over the continent. The temperature of the coldest month ranges from -5 to -25 °C. In summer, wet monsoons bring large amounts of precipitation to the mainland.

In the center (central Russia, Ukraine, northern Kazakhstan, southern Canada) continental air of temperate latitudes is formed. Arctic air with very low temperatures often enters here in winter. Winter is long and frosty; snow cover lasts for over three months. Summer is rainy and warm. The amount of precipitation decreases as we move deeper into the continent (from 700 to 200 mm). The most characteristic feature of the climate of this area is sharp temperature changes throughout the year and uneven distribution of precipitation, which sometimes causes droughts.

Subarctic And subantarctic belt. These transitional zones are located north of the temperate zone (in the Northern Hemisphere) and south of it (in the Southern Hemisphere) - subarctic and subantarctic. They are characterized by a change in air masses by season: in summer - air of temperate latitudes, in winter - Arctic (Antarctic). Summer here is short, cool, with an average temperature of the warmest month from 0 to 12 °C, with little precipitation (an average of 200 mm), with frequent returns of cold weather. Winter is long, frosty, with blizzards and deep snow. In the Northern Hemisphere, at these latitudes there is a tundra zone.

Arctic And Antarctic belt. In the polar zones, cold air masses form under conditions of high pressure. These zones are characterized by long polar nights and polar days. Their duration at the poles reaches up to six months. Although the sun does not set beyond the horizon in summer, it rises low, its rays glide over the surface and provide little heat. During the short summer, snow and ice do not have time to melt, so ice cover remains in these areas. It covers Greenland and Antarctica with a thick layer, and ice mountains - icebergs - float in the polar regions of the oceans. Cold air accumulating over the polar regions is carried by strong winds to the temperate zone. On the outskirts of Antarctica, winds reach speeds of 100 m/s. The Arctic and Antarctica are the “refrigerators” of the Earth.

In even a small area, climatic conditions are not uniform. Under the influence of local factors: small relief forms, slope exposure, soil and ground characteristics, the nature of vegetation cover, special conditions are created, called microclimate.

The study of microclimate is important for the development of many branches of agriculture, especially field cultivation, horticulture, and vegetable growing.

List of used literature

1. Arutsev A.A., Ermolaev B.V., Kutateladze I.O., Slutsky M. Concepts of modern natural science. With study guide. M. 1999

2. Petrosova R.A., Golov V.P., Sivoglazov V.I., Strout E.K. Natural science and basic ecology. Textbook for secondary pedagogical educational institutions. M.: Bustard, 2007, 303 pp.

3. Savchenko V.N., Smagin V.P.. BEGINNINGS OF MODERN NATURAL SCIENCE CONCEPTS AND PRINCIPLES. Tutorial. Rostov-on-Don. 2006.

The atmosphere is the gaseous shell of our planet, which rotates along with the Earth. The gas in the atmosphere is called air. The atmosphere is in contact with the hydrosphere and partially covers the lithosphere. But the upper limits are difficult to determine. It is conventionally accepted that the atmosphere extends upward for approximately three thousand kilometers. There it smoothly flows into airless space.

Chemical composition of the Earth's atmosphere

The formation of the chemical composition of the atmosphere began about four billion years ago. Initially, the atmosphere consisted only of light gases - helium and hydrogen. According to scientists, the initial prerequisites for the creation of a gas shell around the Earth were volcanic eruptions, which, along with lava, emitted huge amounts of gases. Subsequently, gas exchange began with water spaces, with living organisms, and with the products of their activities. The composition of the air gradually changed and was fixed in its modern form several million years ago.

The main components of the atmosphere are nitrogen (about 79%) and oxygen (20%). The remaining percentage (1%) is made up of the following gases: argon, neon, helium, methane, carbon dioxide, hydrogen, krypton, xenon, ozone, ammonia, sulfur and nitrogen dioxides, nitrous oxide and carbon monoxide, which are included in this one percent.

In addition, the air contains water vapor and particulate matter (pollen, dust, salt crystals, aerosol impurities).

Recently, scientists have noted not a qualitative, but a quantitative change in some air ingredients. And the reason for this is man and his activities. In the last 100 years alone, carbon dioxide levels have increased significantly! This is fraught with many problems, the most global of which is climate change.

Formation of weather and climate

The atmosphere plays a critical role in shaping the climate and weather on Earth. A lot depends on the amount of sunlight, the nature of the underlying surface and atmospheric circulation.

Let's look at the factors in order.

1. The atmosphere transmits the heat of the sun's rays and absorbs harmful radiation. The ancient Greeks knew that the rays of the Sun fall on different parts of the Earth at different angles. The word “climate” itself translated from ancient Greek means “slope”. So, at the equator, the sun's rays fall almost vertically, which is why it is very hot here. The closer to the poles, the greater the angle of inclination. And the temperature drops.

2. Due to the uneven heating of the Earth, air currents are formed in the atmosphere. They are classified according to their sizes. The smallest (tens and hundreds of meters) are local winds. This is followed by monsoons and trade winds, cyclones and anticyclones, and planetary frontal zones.

All these air masses are constantly moving. Some of them are quite static. For example, trade winds that blow from the subtropics towards the equator. The movement of others depends largely on atmospheric pressure.

3. Atmospheric pressure is another factor influencing climate formation. This is the air pressure on the surface of the earth. As is known, air masses move from an area with high atmospheric pressure towards an area where this pressure is lower.

A total of 7 zones are allocated. The equator is a low pressure zone. Further, on both sides of the equator up to the thirties latitudes there is an area of ​​high pressure. From 30° to 60° - low pressure again. And from 60° to the poles is a high pressure zone. Air masses circulate between these zones. Those that come from the sea to land bring rain and bad weather, and those that blow from the continents bring clear and dry weather. In places where air currents collide, atmospheric front zones are formed, which are characterized by precipitation and inclement, windy weather.

Scientists have proven that even a person’s well-being depends on atmospheric pressure. According to international standards, normal atmospheric pressure is 760 mm Hg. column at a temperature of 0°C. This indicator is calculated for those areas of land that are almost level with sea level. With altitude the pressure decreases. Therefore, for example, for St. Petersburg 760 mm Hg. - this is the norm. But for Moscow, which is located higher, normal pressure is 748 mm Hg.

The pressure changes not only vertically, but also horizontally. This is especially felt during the passage of cyclones.

The structure of the atmosphere

The atmosphere is reminiscent of a layer cake. And each layer has its own characteristics.

. Troposphere- the layer closest to the Earth. The "thickness" of this layer changes with distance from the equator. Above the equator, the layer extends upward by 16-18 km, in temperate zones by 10-12 km, at the poles by 8-10 km.

It is here that 80% of the total air mass and 90% of water vapor are contained. Clouds form here, cyclones and anticyclones arise. The air temperature depends on the altitude of the area. On average, it decreases by 0.65° C for every 100 meters.

. Tropopause- transition layer of the atmosphere. Its height ranges from several hundred meters to 1-2 km. The air temperature in summer is higher than in winter. For example, above the poles in winter it is -65° C. And above the equator it is -70° C at any time of the year.

. Stratosphere- this is a layer whose upper boundary lies at an altitude of 50-55 kilometers. Turbulence here is low, the content of water vapor in the air is negligible. But there is a lot of ozone. Its maximum concentration is at an altitude of 20-25 km. In the stratosphere, the air temperature begins to rise and reaches +0.8° C. This is due to the fact that the ozone layer interacts with ultraviolet radiation.

. Stratopause- a low intermediate layer between the stratosphere and the mesosphere that follows it.

. Mesosphere- the upper boundary of this layer is 80-85 kilometers. Complex photochemical processes involving free radicals occur here. They are the ones who provide that gentle blue glow of our planet, which is seen from space.

Most comets and meteorites burn up in the mesosphere.

. Mesopause- the next intermediate layer, the air temperature in which is at least -90°.

. Thermosphere- the lower boundary begins at an altitude of 80 - 90 km, and the upper boundary of the layer runs approximately at 800 km. The air temperature is rising. It can vary from +500° C to +1000° C. During the day, temperature fluctuations amount to hundreds of degrees! But the air here is so rarefied that understanding the term “temperature” as we imagine it is not appropriate here.

. Ionosphere- combines the mesosphere, mesopause and thermosphere. The air here consists mainly of oxygen and nitrogen molecules, as well as quasi-neutral plasma. The sun's rays entering the ionosphere strongly ionize air molecules. In the lower layer (up to 90 km) the degree of ionization is low. The higher, the greater the ionization. So, at an altitude of 100-110 km, electrons are concentrated. This helps to reflect short and medium radio waves.

The most important layer of the ionosphere is the upper one, which is located at an altitude of 150-400 km. Its peculiarity is that it reflects radio waves, and this facilitates the transmission of radio signals over considerable distances.

It is in the ionosphere that such a phenomenon as the aurora occurs.

. Exosphere- consists of oxygen, helium and hydrogen atoms. The gas in this layer is very rarefied and hydrogen atoms often escape into outer space. Therefore, this layer is called the “dispersion zone”.

The first scientist to suggest that our atmosphere has weight was the Italian E. Torricelli. Ostap Bender, for example, in his novel “The Golden Calf” lamented that every person is pressed by a column of air weighing 14 kg! But the great schemer was a little mistaken. An adult experiences pressure of 13-15 tons! But we do not feel this heaviness, because atmospheric pressure is balanced by the internal pressure of a person. The weight of our atmosphere is 5,300,000,000,000,000 tons. The figure is colossal, although it is only a millionth of the weight of our planet.