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

The concept of the earth's atmosphere

The atmosphere is present not only in the Earth, but also in other celestial bodies. This is the name of the gaseous shell surrounding the planets. The composition of this gas layer of different planets is significantly different. Let's look at the basic information and facts about otherwise called air.

Its most important component is oxygen. Some mistakenly think that the earth's atmosphere is made entirely of oxygen, but air is actually a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, water vapor. Let the percentage of these gases be small, but 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 with altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.

The composition of the Earth's atmosphere

• Carbon dioxide essential for plant nutrition. In the atmosphere, it appears as a result of the process of respiration of living organisms, rotting, burning. The absence of it in the composition of the atmosphere would make it impossible for any plants to exist.
• Oxygen is 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 It is a natural absorber of solar ultraviolet radiation, which adversely affects living organisms. Most of it forms a separate layer of the atmosphere - the ozone screen. Recently, human activity leads to the fact that it begins to gradually collapse, but since it is of great importance, active work is underway to preserve and restore it.
• water vapor determines the humidity of the air. Its content may vary depending on various factors: air temperature, geographical 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, in the composition of the earth's atmosphere there is always 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 by anthropogenic means.

Layers of the atmosphere

And the temperature, and density, and the qualitative composition of the air is not the same at different heights. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristic. Let's find out which layers of the atmosphere are distinguished:

• The troposphere is the layer of the atmosphere closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. Here is 90% of all water vapor that is available in the atmosphere, so there is an active formation of clouds. Also in this layer there are such processes as the movement of air (wind), turbulence, convection. The temperature ranges from +45 degrees at noon in the warm season in the tropics to -65 degrees at the poles.
• The stratosphere is the second furthest layer from the atmosphere. It is located at an altitude of 11 to 50 km. In the lower layer of the stratosphere, the temperature is approximately -55, towards the distance from the Earth it rises to +1˚С. This region is called the inversion and is the boundary between the stratosphere and the 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 burn out completely in the mesosphere, which causes airglows to occur here.
• The thermosphere is about 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the action of cosmic radiation and radiation emanating from the Sun.
• The exosphere is a zone of air dispersion. Here, the concentration of gases is small and their gradual escape into interplanetary space takes place.

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

atmospheric pressure

Listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how might 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 conducted complex calculations and proved that the atmosphere presses on one square meter of area with a force of 10,333 kg. This means that the human body is subject to air pressure, the weight of which is 12-15 tons. Why don't we feel it? It saves us its internal pressure, which balances the external one. You can feel the pressure of the atmosphere while in an airplane or high in the mountains, since the atmospheric pressure at altitude is much less. In this case, physical discomfort, stuffy ears, dizziness are possible.

A lot can be said about the atmosphere around. We know a lot of 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 contributes to the transmission of sound. 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 measure air temperature, and a barometer is used to measure atmospheric pressure.
• The presence of an atmosphere saves our planet from 100 tons of meteorites daily.
• The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
• It is believed that the atmosphere extends upwards to an altitude of 3000 km.

The value 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 show oxygen starvation, which is expressed in a decrease in his working capacity and a deterioration in well-being. This shows that a person cannot survive in a space where this amazing mixture of gases does not exist.

All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, the possibility of the development of life on Earth appeared. Even today, having assessed the extent of the harm that mankind is capable of inflicting with its actions on the life-giving air, we should think about further measures to preserve and restore the atmosphere.

Layers of the atmosphere in order from the Earth's surface

The role of the atmosphere in the life of the Earth

The atmosphere is the source of oxygen that people breathe. However, as you ascend to altitude, the total atmospheric pressure drops, resulting in a decrease in partial oxygen pressure.

The human lungs contain approximately three liters of alveolar air. If the atmospheric pressure is normal, then the partial oxygen pressure in the alveolar air will be 11 mm Hg. Art., pressure of carbon dioxide - 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. With an increase in altitude, oxygen pressure decreases, and the pressure of water vapor and carbon dioxide in the lungs in total will remain constant - approximately 87 mm Hg. Art. When the air pressure equals this value, oxygen will stop flowing into the lungs.

Due to the decrease in atmospheric pressure at an altitude of 20 km, water and interstitial body fluid in the human body will boil here. If you do not use a pressurized cabin, at such a height a person will die almost instantly. Therefore, from the point of view of the physiological characteristics of the human body, "space" originates from a height of 20 km above sea level.

The role of the atmosphere in the life of the Earth is very great. So, for example, thanks to dense air layers - the troposphere and stratosphere, people are protected from radiation exposure. In space, in rarefied air, at an altitude of over 36 km, ionizing radiation acts. At an altitude of over 40 km - ultraviolet.

When rising above the Earth's surface to a height of over 90-100 km, there will be a gradual weakening, and then the complete disappearance of phenomena familiar to humans, observed in the lower atmospheric layer:

Sound does not propagate.

There is no aerodynamic force and drag.

Heat is not transferred by convection, etc.

The atmospheric layer protects the Earth and all living organisms from cosmic radiation, from meteorites, is responsible for regulating seasonal temperature fluctuations, balancing and equalizing daily ones. In the absence of an atmosphere on Earth, the daily temperature would fluctuate within +/-200С˚. The atmospheric layer is a life-giving "buffer" between the earth's surface and outer space, a carrier of moisture and heat; processes of photosynthesis and energy exchange take place in the atmosphere - the most important biospheric processes.

Layers of the atmosphere in order from the Earth's surface

The atmosphere is a layered structure, which is the following layers of the atmosphere in order from the surface of the Earth:

Troposphere.

Stratosphere.

Mesosphere.

Thermosphere.

Exosphere

Each layer does not have sharp boundaries between them, and their height is affected by latitude and seasons. This layered structure was formed as a result of temperature changes at different heights. It is thanks to the atmosphere that we see twinkling stars.

The structure of the Earth's atmosphere by layers:

What is the earth's atmosphere made of?

Each atmospheric layer differs in temperature, density and composition. The total thickness of the atmosphere is 1.5-2.0 thousand km. What is the earth's atmosphere made of? At present, it is a mixture of gases with various impurities.

Troposphere

The structure of the Earth's atmosphere begins with the troposphere, which is the lower part of the atmosphere about 10-15 km high. This is where most of the atmospheric air is concentrated. A characteristic feature of the troposphere is a drop in temperature of 0.6 ˚C as you rise up for every 100 meters. The troposphere has concentrated in itself almost all atmospheric water vapor, and clouds are also formed here.

The height of the troposphere changes daily. In addition, its average value varies depending on the latitude and the season of the year. The average height of the troposphere above the poles is 9 km, above the equator - about 17 km. The average annual air temperature over the equator is close to +26 ˚C, and over the North Pole -23 ˚C. The upper line of the boundary of the troposphere above the equator is the average annual temperature of about -70 ˚C, and over the north pole in summer -45 ˚C and in winter -65 ˚C. Thus, the higher the altitude, the lower the temperature. The rays of the sun pass freely through the troposphere, heating the surface of the Earth. The heat radiated by the sun is retained by carbon dioxide, methane and water vapor.

Stratosphere

Above the layer of the troposphere is the stratosphere, which is 50-55 km in height. The peculiarity of this layer is the increase in temperature with height. Between the troposphere and stratosphere lies a transitional layer called the tropopause.

Approximately from a height of 25 kilometers, the temperature of the stratospheric layer begins to increase and, upon reaching a maximum height of 50 km, it acquires values ​​from +10 to +30 ˚C.

There is very little water vapor in the stratosphere. Sometimes at an altitude of about 25 km you can find quite thin clouds, which are called "mother-of-pearl". In the daytime, they are not noticeable, but at night they glow due to the illumination of the sun, which is below the horizon. The composition of mother-of-pearl clouds is supercooled water droplets. The stratosphere is made up mostly of ozone.

Mesosphere

The height of the mesosphere layer is approximately 80 km. Here, as it rises upwards, the temperature decreases and at the uppermost boundary it reaches values ​​several tens of C˚ below zero. In the mesosphere, clouds can also be observed, which are presumably formed from ice crystals. These clouds are called "silvery". The mesosphere is characterized by the coldest temperature in the atmosphere: from -2 to -138 ˚C.

Thermosphere

This atmospheric layer got its name due to high temperatures. The thermosphere is made up of:

Ionosphere.

exospheres.

The ionosphere is characterized by rarefied air, each centimeter of which at an altitude of 300 km consists of 1 billion atoms and molecules, and at an altitude of 600 km - more than 100 million.

The ionosphere is also characterized by high air ionization. These ions are composed of charged oxygen atoms, charged molecules of nitrogen atoms and free electrons.

Exosphere

From a height of 800-1000 km, the exospheric layer begins. Gas particles, especially light ones, move here at great speed, overcoming the force of gravity. Such particles, due to their rapid movement, fly out of the atmosphere into outer space and disperse. Therefore, the exosphere is called the sphere of dispersion. It is predominantly hydrogen atoms that fly into space, which make up the highest layers of the exosphere. Thanks to particles in the upper atmosphere and particles of the solar wind, we can observe the northern lights.

Satellites and geophysical rockets made it possible to establish the presence in the upper atmosphere of the planet's radiation belt, which consists of electrically charged particles - electrons and protons.

The atmosphere is one of the most important components of our planet. It is she who "shelters" people from the harsh conditions of outer space, such as solar radiation and space debris. However, many facts about the atmosphere are unknown to most people.

1. The true color of the sky

Although it's hard to believe, the sky is actually purple. When light enters the atmosphere, air and water particles absorb the light, scattering it. At the same time, violet color is scattered most of all, which is why people see the blue sky.

2. An exclusive element in the Earth's atmosphere

As many remember from school, the Earth's atmosphere consists of approximately 78% nitrogen, 21% oxygen, and small impurities of argon, carbon dioxide and other gases. But few people know that our atmosphere is the only one so far discovered by scientists (besides comet 67P) that has free oxygen. Because oxygen is a highly reactive gas, it often reacts with other chemicals in space. Its pure form on Earth makes the planet habitable.

3. White stripe in the sky

Surely, some sometimes wondered why a white stripe remains in the sky behind a jet plane. These white trails, known as contrails, form when hot, moist exhaust gases from an aircraft engine mix with colder outside air. Water vapor from exhaust gases freezes and becomes visible.

4. The main layers of the atmosphere

The atmosphere of the Earth consists of five main layers, which make life possible on the planet. The first of these, the troposphere, extends from sea level to an altitude of about 17 km to the equator. Most of the weather events occur in it.

5. Ozone layer

The next layer of the atmosphere, the stratosphere, reaches a height of about 50 km at the equator. It contains the ozone layer, which protects people from dangerous ultraviolet rays. Even though this layer is above the troposphere, it may actually be warmer due to the energy it absorbs from the sun's rays. Most jet planes and weather balloons fly in the stratosphere. Planes can fly faster in it because they are less affected by gravity and friction. Weather balloons can get a better idea of ​​storms, most of which occur lower in the troposphere.

6. Mesosphere

The mesosphere is the middle layer, extending to a height of 85 km above the surface of the planet. Its temperature fluctuates around -120°C. Most of the meteors that enter the Earth's atmosphere burn up in the mesosphere. The last two layers that pass into space are the thermosphere and the exosphere.

7. The disappearance of the atmosphere

The Earth has most likely lost its atmosphere several times. When the planet was covered in oceans of magma, massive interstellar objects crashed into it. These impacts, which also formed the Moon, may have formed the planet's atmosphere for the first time.

8. If there were no atmospheric gases ...

Without various gases in the atmosphere, the Earth would be too cold for human existence. Water vapor, carbon dioxide, and other atmospheric gases absorb heat from the sun and "distribute" it over the planet's surface, helping to create a habitable climate.

9. Formation of the ozone layer

The notorious (and importantly necessary) ozone layer was created when oxygen atoms reacted with ultraviolet light from the sun to form ozone. It is ozone that absorbs most of the harmful radiation from the sun. Despite its importance, the ozone layer was formed relatively recently after enough life arose in the oceans to release into the atmosphere the amount of oxygen needed to create a minimum concentration of ozone.

10. Ionosphere

The ionosphere is so named because high-energy particles from space and from the sun help form ions, creating an "electric layer" around the planet. When there were no satellites, this layer helped reflect radio waves.

11. Acid rain

Acid rain, which destroys entire forests and devastates aquatic ecosystems, forms in the atmosphere when sulfur dioxide or nitrogen oxide particles mix with water vapor and fall to the ground as rain. These chemical compounds are also found in nature: sulfur dioxide is produced during volcanic eruptions, and nitric oxide is produced during lightning strikes.

12. Lightning Power

Lightning is so powerful that just a single discharge can heat the surrounding air up to 30,000 °C. The rapid heating causes an explosive expansion of the nearby air, which is heard in the form of a sound wave called thunder.

Aurora Borealis and Aurora Australis (Northern and Southern Aurora) are caused by ion reactions taking place in the fourth level of the atmosphere, the thermosphere. When highly charged solar wind particles collide with air molecules over the planet's magnetic poles, they glow and create magnificent light shows.

14. Sunsets

Sunsets often look like a burning sky as small atmospheric particles scatter light, reflecting it in orange and yellow hues. The same principle underlies the formation of rainbows.

In 2013, scientists discovered that tiny microbes can survive many kilometers above the Earth's surface. At an altitude of 8-15 km above the planet, microbes were found that destroy organic chemicals that float in the atmosphere, "feeding" on them.

Adherents of the theory of the apocalypse and various other horror stories will be interested to learn about.

STRUCTURE OF THE ATMOSPHERE

Atmosphere(from other Greek ἀτμός - steam and σφαῖρα - ball) - a gaseous shell (geosphere) surrounding the planet Earth. Its inner surface covers the hydrosphere and partially the earth's crust, while its outer surface borders on the near-Earth part of outer space.

Physical Properties

The thickness of the atmosphere is about 120 km from the Earth's surface. The total mass of air in the atmosphere is (5.1-5.3) 10 18 kg. Of these, the mass of dry air is (5.1352 ± 0.0003) 10 18 kg, the total mass of water vapor is on average 1.27 10 16 kg.

The molar mass of clean dry air is 28.966 g/mol, the air density at the sea surface is approximately 1.2 kg/m 3 . The pressure at 0 °C at sea level is 101.325 kPa; critical temperature - -140.7 ° C; critical pressure - 3.7 MPa; C p at 0 °C - 1.0048 10 3 J/(kg K), C v - 0.7159 10 3 J/(kg K) (at 0 °C). The solubility of air in water (by mass) at 0 ° C - 0.0036%, at 25 ° C - 0.0023%.

For "normal conditions" at the Earth's surface are taken: density 1.2 kg / m 3, barometric pressure 101.35 kPa, temperature plus 20 ° C and relative humidity 50%. These conditional indicators have a purely engineering value.

The structure of the atmosphere

The atmosphere has a layered structure. The layers of the atmosphere differ from each other in air temperature, its density, the amount of water vapor in the air and other properties.

Troposphere(ancient Greek τρόπος - "turn", "change" and σφαῖρα - "ball") - the lower, most studied layer of the atmosphere, 8-10 km high in the polar regions, up to 10-12 km in temperate latitudes, at the equator - 16-18 km.

When rising in the troposphere, the temperature drops by an average of 0.65 K every 100 m and reaches 180-220 K in the upper part. This upper layer of the troposphere, in which the decrease in temperature with height stops, is called the tropopause. The next layer of the atmosphere above the troposphere is called the stratosphere.

More than 80% of the total mass of atmospheric air is concentrated in the troposphere, turbulence and convection are highly developed, the predominant part of water vapor is concentrated, clouds arise, atmospheric fronts also form, cyclones and anticyclones develop, as well as other processes that determine weather and climate. The processes occurring in the troposphere are primarily due to convection.

The part of the troposphere within which glaciers can form on the earth's surface is called the chionosphere.

tropopause(from the Greek τροπος - turn, change and παῦσις - stop, cessation) - the layer of the atmosphere in which the decrease in temperature with height stops; transition layer from troposphere to stratosphere. In the earth's atmosphere, the tropopause is located at altitudes from 8-12 km (above sea level) in the polar regions and up to 16-18 km above the equator. The height of the tropopause also depends on the time of year (the tropopause is higher in summer than in winter) and cyclonic activity (it is lower in cyclones and higher in anticyclones)

The thickness of the tropopause ranges from several hundred meters to 2-3 kilometers. In the subtropics, tropopause ruptures are observed due to powerful jet streams. The tropopause over certain areas is often destroyed and re-formed.

Stratosphere(from Latin stratum - flooring, layer) - a layer of the atmosphere, located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from -56.5 to 0.8 °C (the upper stratosphere layer or inversion region) are typical. Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere. The density of air in the stratosphere is tens and hundreds of times less than at sea level.

It is in the stratosphere that the ozonosphere layer ("ozone layer") is located (at an altitude of 15-20 to 55-60 km), which determines the upper limit of life in the biosphere. Ozone (O 3 ) is formed as a result of photochemical reactions most intensively at an altitude of ~30 km. The total mass of O 3 at normal pressure would be a layer 1.7-4.0 mm thick, but even this is enough to absorb the solar ultraviolet radiation that is harmful to life. The destruction of O 3 occurs when it interacts with free radicals, NO, halogen-containing compounds (including "freons").

Most of the short-wavelength part of ultraviolet radiation (180-200 nm) is retained in the stratosphere and the energy of short waves is transformed. Under the influence of these rays, magnetic fields change, molecules break up, ionization, new formation of gases and other chemical compounds occur. These processes can be observed in the form of northern lights, lightning and other glows.

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate - into atoms (above 80 km, CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - N 2). At an altitude of 200-500 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O - 2, N + 2) is ~ 1/300 of the concentration of neutral particles. In the upper layers of the atmosphere there are free radicals - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

Flights into the stratosphere began in the 1930s. The flight on the first stratospheric balloon (FNRS-1), which Auguste Picard and Paul Kipfer made on May 27, 1931 to a height of 16.2 km, is widely known. Modern combat and supersonic commercial aircraft fly in the stratosphere at altitudes generally up to 20 km (although the dynamic ceiling can be much higher). High-altitude weather balloons rise up to 40 km; the record for an unmanned balloon is 51.8 km.

Recently, in the military circles of the United States, much attention has been paid to the development of layers of the stratosphere above 20 km, often called the "prespace" (Eng. « near space» ). It is assumed that unmanned airships and solar-powered aircraft (like NASA Pathfinder) will be able to stay at an altitude of about 30 km for a long time and provide observation and communication for very large areas, while remaining low-vulnerability to air defense systems; such devices will be many times cheaper than satellites.

Stratopause- the layer of the atmosphere, which is the boundary between two layers, the stratosphere and the mesosphere. In the stratosphere, temperature rises with altitude, and the stratopause is the layer where the temperature reaches its maximum. The temperature of the stratopause is about 0 °C.

This phenomenon is observed not only on Earth, but also on other planets with an atmosphere.

On Earth, the stratopause is located at an altitude of 50 - 55 km above sea level. Atmospheric pressure is about 1/1000 of the pressure at sea level.

Mesosphere(from the Greek μεσο- - “middle” and σφαῖρα - “ball”, “sphere”) - the layer of the atmosphere at altitudes from 40-50 to 80-90 km. It is characterized by an increase in temperature with height; the maximum (about +50°C) temperature is located at an altitude of about 60 km, after which the temperature begins to decrease to −70° or −80°C. Such a decrease in temperature is associated with the energetic absorption of solar radiation (radiation) by ozone. The term was adopted by the Geographical and Geophysical Union in 1951.

The gas composition of the mesosphere, as well as those of the lower atmospheric layers, is constant and contains about 80% nitrogen and 20% oxygen.

The mesosphere is separated from the underlying stratosphere by the stratopause, and from the overlying thermosphere by the mesopause. The mesopause basically coincides with the turbopause.

Meteors begin to glow and, as a rule, burn up completely in the mesosphere.

Noctilucent clouds may appear in the mesosphere.

For flights, the mesosphere is a kind of "dead zone" - the air here is too rarefied to support airplanes or balloons (at an altitude of 50 km, the air density is 1000 times less than at sea level), and at the same time too dense for artificial flights. satellites in such a low orbit. Direct studies of the mesosphere are carried out mainly with the help of suborbital meteorological rockets; in general, the mesosphere has been studied worse than other layers of the atmosphere, in connection with which scientists called it the “ignorosphere”.

mesopause

mesopause The layer of the atmosphere that separates the mesosphere and thermosphere. On Earth, it is located at an altitude of 80-90 km above sea level. In the mesopause, there is a temperature minimum, which is about -100 ° C. Below (starting from a height of about 50 km) the temperature drops with height, above (up to a height of about 400 km) it rises again. The mesopause coincides with the lower boundary of the region of active absorption of the X-ray and the shortest wavelength ultraviolet radiation of the Sun. Silvery clouds are observed at this altitude.

The mesopause exists not only on Earth, but also on other planets with an atmosphere.

Karman Line- height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space.

As defined by the Fédération Aéronautique Internationale (FAI), the Karman Line is at an altitude of 100 km above sea level.

The height was named after Theodor von Karman, an American scientist of Hungarian origin. He was the first to determine that at about this altitude the atmosphere becomes so rarefied that aeronautics becomes impossible, since the speed of the aircraft, necessary to create sufficient lift, becomes greater than the first cosmic speed, and therefore, in order to achieve higher altitudes, it is necessary to use the means of astronautics.

The Earth's atmosphere continues beyond the Karman line. The outer part of the earth's atmosphere, the exosphere, extends to an altitude of 10,000 km or more, at such an altitude the atmosphere consists mainly of hydrogen atoms that can leave the atmosphere.

Reaching the Karman Line was the first condition for the Ansari X Prize, as this is the basis for recognizing the flight as a space flight.

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 connected with the geological and geochemical processes taking place on our planet, as well as with the activities of living organisms.

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

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

Oxygen-rich atmosphere makes life possible on Earth. Atmospheric oxygen is used in the process of breathing by 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, as if through a lens, are decomposed into their component colors. In this case, the rays of blue and blue colors are scattered most of all.

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

The structure of the atmosphere

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

Troposphere

Troposphere- the lowest layer of the atmosphere, whose thickness 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 from the earth's surface, i.e. from land and water. Therefore, the air temperature in this layer decreases with height by an average of 0.6 °C for every 100 m. At the upper 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 °С, and in the region of the North Pole -65 °С.

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

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

Stratosphere

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

The stratosphere contains 20% of the mass of the atmosphere. The air in this layer is rarefied, there is practically no water vapor, and therefore clouds and precipitation are almost not formed. However, stable air currents are observed in the stratosphere, the speed of which reaches 300 km / h.

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

Between the mesosphere and the stratosphere there is a transitional 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 surface of the Earth. The color of the sky in the mesosphere appears black, 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 a height of 150 km it reaches 220-240 °C; at an altitude of 500-600 km it exceeds 1500 °C.

In the mesosphere and thermosphere, under the action of cosmic rays, gas molecules break up 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, nitric oxide molecules and free electrons. This layer is characterized by high electrification, and long and medium radio waves are reflected from it, as from a mirror.

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

Exosphere

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

Composition of the atmosphere

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 the content of CO 2 by about 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 thus have a significant effect 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
	0 to 0.00001
Sulfur dioxide	from 0 to 0.000007 in summer; 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, chemically little active.

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

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

A characteristic property of the atmosphere can be called the fact that the content of the main gases (nitrogen, oxygen, argon) changes slightly with height: at an altitude of 65 km in the atmosphere, the nitrogen content 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, air contains water vapor and solid particles. The latter can have both natural and artificial (anthropogenic) origin. These are flower pollen, tiny salt crystals, road dust, aerosol impurities. When the sun's rays penetrate the window, they can be seen with the naked eye.

There are especially many particulate matter 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 the solar radiation reaching the Earth's surface. The largest aerosols are condensation nuclei (from lat. condensatio- compaction, thickening) - contribute to the transformation of water vapor into water droplets.

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

The amount of water vapor in the atmosphere varies over time and space. Thus, the concentration of water vapor near 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 (the layer of condensed water vapor will have such a thickness). Information about water vapor in different layers of the atmosphere is contradictory. It was assumed, for example, that in the altitude range from 20 to 30 km, the specific humidity strongly increases with height. However, subsequent measurements indicate a greater dryness of the stratosphere. Apparently, the specific humidity in the stratosphere depends little on height and amounts to 2–4 mg/kg.

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

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

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

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 °С - no more than 9 g; at +30 °С - no more than 30 g of water.

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

Air can be rich and not saturated steam. 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- this is the amount of water vapor contained in 1 m 3 of air. It is expressed in grams. For example, if they say "absolute humidity is 15", then this means that 1 mL contains 15 g of water vapor.

Relative humidity- this is the ratio (in percent) 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 a weather report is broadcast over the radio that the relative humidity is 70%, this means that the air contains 70% of the water vapor that it can hold at a given temperature.

The greater the relative humidity of the air, t. the closer the air is to saturation, the more likely it is to fall.

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

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

To measure 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 in itself, it thickens (condenses), turning into droplets of fog. Fog can be observed in the summer on a clear cool night.

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

involved in the formation of clouds particulate matter suspended in the troposphere.

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

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

families	Kinds of clouds	Appearance
A. Upper clouds - above 6 km	I. Pinnate	Threadlike, fibrous, white
	II. cirrocumulus	Layers and ridges of small flakes and curls, white
	III. Cirrostratus	Transparent whitish veil
B. Clouds of the middle layer - above 2 km	IV. Altocumulus	Layers and ridges of white and gray
	V. Altostratus	Smooth veil of milky gray color
B. Lower clouds - up to 2 km	VI. Nimbostratus	Solid shapeless gray layer
	VII. Stratocumulus	Opaque layers and ridges of gray
	VIII. layered	Illuminated gray veil
D. Clouds of vertical development - from the lower to the upper tier	IX. Cumulus	Clubs and domes 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 automobiles. In large cities, the problem of gas contamination of the main transport routes is very acute. That is why in many large cities of the world, including our country, environmental control of the toxicity of car exhaust gases has been introduced. According to experts, smoke and dust in the air can halve the flow of solar energy to the earth's surface, which will lead to a change in natural conditions.