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Atmosphere, its composition and structure. Functions of the atmosphere

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

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

What does it consist of?

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

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

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

Low but important gases

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

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

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

What else is in the air?

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

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

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

What layers is the atmosphere divided into?

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

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

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

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

Layers in which there is practically no air

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

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

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

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

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

The meaning of atmosphere

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

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

How does a person influence the atmosphere?

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

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

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

The importance of the atmosphere in the existence of the Earth is enormous. If our planet is deprived of its atmosphere, all living organisms will die. Its effect can be compared to the role of glass in a greenhouse, which allows light rays to pass through and does not release heat back. Thus, the atmosphere protects the Earth's surface from excessive heating and cooling.

The importance of the atmosphere for humans

The air envelope of the globe is a protective layer that saves all living things from corpuscular and short-wave solar radiation. All weather conditions in which people live and work arise in the atmospheric environment. Meteorological stations are being created to study this earth's shell. Around the clock, in any weather, meteorologists monitor the state of the lower atmospheric layer and record their observations. Several times a day (in some regions every hour) at the stations, temperature, air humidity, pressure are measured, the presence of cloudiness, wind direction, any sound and electrical phenomena are detected, wind speed and precipitation are measured. Meteorological stations are scattered throughout our planet: in the polar regions, in the tropics, in the highlands, and in the tundra. On the seas and oceans, observations are also made from stations located on specially constructed devices on special-purpose ships.

Measurements of environmental parameters

Since the beginning of the twentieth century, they began to measure the parameters of the state of the environment in a free atmosphere. For this purpose, radiosondes are launched. They are capable of rising to a height of 25-35 km and using radio equipment to send data on pressure, temperature, wind speed and air humidity to the surface of the Earth. In the modern world, they often resort to the use of meteorological satellites and rockets. They are equipped with television installations that accurately reproduce images of the planet's surface and clouds.

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The role of the atmosphere in the life of the Earth

The atmosphere is a gaseous shell surrounding planet Earth. Its inner surface covers the hydrosphere and partly the earth's crust, while its outer surface borders the near-Earth part of outer space.

The set of branches of physics and chemistry that study the atmosphere is usually called atmospheric physics. The atmosphere determines the weather on the Earth's surface, meteorology studies weather, and climatology deals with long-term climate variations.

Already at an altitude of 5 km above sea level, an untrained person begins to experience oxygen starvation and, without adaptation, a person’s performance is significantly reduced. The physiological zone of the atmosphere ends here. Human breathing becomes impossible at an altitude of 9 km, although up to approximately 115 km the atmosphere contains oxygen.

The atmosphere supplies us with the oxygen necessary for breathing. However, due to the drop in the total pressure of the atmosphere, as you rise to altitude, the partial pressure of oxygen decreases accordingly.

The human lungs constantly contain about 3 liters of alveolar air. The partial pressure of oxygen in alveolar air at normal atmospheric pressure is 110 mmHg. Art., carbon dioxide pressure - 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. With increasing altitude, oxygen pressure drops, and the total vapor pressure of water and carbon dioxide in the lungs remains almost constant - about 87 mm Hg. Art. The supply of oxygen to the lungs will completely stop when the ambient air pressure becomes equal to this value.

At an altitude of about 19-20 km, the atmospheric pressure drops to 47 mm Hg. Art. Therefore, at this altitude, water and interstitial fluid begin to boil in the human body. Outside the pressurized cabin at these altitudes, death occurs almost instantly. Thus, from the point of view of human physiology, “space” begins already at an altitude of 15-19 km.

Dense layers of air - the troposphere and stratosphere - protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, ionizing radiation - primary cosmic rays - has an intense effect on the body; At altitudes of more than 40 km, the ultraviolet part of the solar spectrum is dangerous for humans. atmosphere oxygen stratosphere radiation

As we rise to an ever greater height above the Earth's surface, such familiar phenomena observed in the lower layers of the atmosphere as sound propagation, the occurrence of aerodynamic lift and drag, heat transfer by convection, etc. gradually weaken and then completely disappear.

In rarefied layers of air, sound propagation is impossible. Up to altitudes of 60-90 km, it is still possible to use air resistance and lift for controlled aerodynamic flight.

But starting from altitudes of 100-130 km, the concepts of the M number and the sound barrier, familiar to every pilot, lose their meaning: there lies the conventional Karman line, beyond which the region of purely ballistic flight begins, which can only be controlled using reactive forces.

At altitudes above 100 km, the atmosphere is deprived of another remarkable property - the ability to absorb, conduct and transmit thermal energy by convection (i.e. by mixing air). This means that various elements of equipment on the orbital space station will not be able to be cooled from the outside in the same way as is usually done on an airplane - with the help of air jets and air radiators. At this altitude, as in space generally, the only way to transfer heat is thermal radiation.

(Greek atmos - steam and sphaira - ball) - the air shell of the Earth. The atmosphere does not have a sharp upper boundary. About 99.5% of its total mass is concentrated in the lower 80 km.

The atmosphere arose as a result of the release of gases at . Its formation was subsequently influenced by the emergence of oceans and.

The structure of the atmosphere

There are several main layers, differing in characteristics, density, etc. The bottom layer is the troposphere. It is heated by the Earth, which in turn is heated by the Sun. The warmest layers of the troposphere are adjacent to the Earth. Heating decreases with altitude, and this drops from +14°C at sea level to -55°C at the upper boundary of the troposphere. Scientists have calculated that the temperature here drops by an average of 0.6° for every 100 m. This value is called the vertical temperature gradient. The thickness of the troposphere is different: it is 17 km, and above the polar latitudes it is 8-9 km. Only in the troposphere do phenomena such as cloud formation, precipitation, and others occur. Above the troposphere is the stratosphere (up to 50-55 km), which is separated from the lower one by a transition layer - the tropopause. In the stratosphere, the air is in a rarefied state; clouds do not form here, since there is practically no water screen. The decrease in temperature with altitude continues, but above 25 km it begins to increase by 1-2°C per kilometer. This is apparently caused by the fact that the ozone layer absorbs and scatters solar radiation, preventing it from reaching the Earth's surface. Above the stratosphere there is also a transition zone - the stratopause, after which comes the next layer of the atmosphere - the mesosphere (up to 80-85 km). The air here is even thinner, and the temperature continues to rise. Even higher is a layer called the thermosphere. Complex chemical reactions in these layers of the atmosphere (above 50 km) make it electrically conductive. Since reactions release ions, the upper part of the atmosphere, which includes the mesosphere and thermosphere, is called the ionosphere. It is in these layers that what happens. Above 800 km is the exosphere (“exo” - external), here gas particles are very rare, and the temperature reaches +2000 ° C. The gas composition of the atmosphere has been studied for a long time. In 1774, the French scientist Antoine Lavoisier studied the main parts of air and established the presence of oxygen and nitrogen there. Subsequently, it was discovered that in addition to these gases, there are also other gases in the air. Thus, air is a mixture of gases consisting of the following components at the earth’s surface:

Nitrogen - 78%
Oxygen - 21%
Inert gases - 0.94%
Carbon dioxide - 0.03%
Water vapor and impurities - 0.03%.

The importance of atmosphere in nature and human life

thanks to the gaseous shell, the surface of the Earth does not heat up during the day and does not cool down at night as much as, for example, a surface devoid of an atmosphere;
the atmosphere protects the Earth from, most of which burns up and does not reach the surface of the planet;
the ozone screen () protects humanity from excess ultraviolet radiation, a large dose of which is harmful to the body;
oxygen contained in the atmosphere is necessary for all living organisms to breathe.

Study of the atmosphere

Humanity has been interested in the ocean of air for a long time, but only 300-400 years ago the first instruments for studying the atmosphere were invented: a thermometer, a weather vane. Currently, the study of gas is carried out under the leadership of the World Meteorological Organization (WMO), which, in addition to Russia, includes many more. A program for collecting and processing materials using the latest technical means has been developed. To monitor the state of the atmosphere, a network of ground-based meteorological stations equipped with various instruments has been created.

Temperature is measured using thermometers; it is customary to measure it in degrees Celsius. This system is based on the physical properties of water: at zero degrees it turns into a solid state - it freezes, at 100 degrees - into a gaseous state. The amount of precipitation is measured by a precipitation gauge - a container with special markings on the walls. The speed of movement of air currents is measured by a wind meter (anemometer). A weather vane is usually installed next to it, indicating the direction of the wind. At airfields and near bridges where there may be danger, wind direction indicators are installed - large cone-shaped bags made of striped fabric, open on both sides. measured by a barometer.

At meteorological stations, readings are taken at least 4 times a day. Automatic radio meteorological stations operate in hard-to-reach areas. And in the oceans, such stations are installed on floating platforms. The free atmosphere is studied using radiosondes - instruments that are attached to free-flying rubber balloons filled with hydrogen. They collect data on the state of the atmosphere at altitudes up to 30-40 km. Meteorological rockets rise even higher, up to 120 km. At a certain altitude, part of the rocket with instruments is separated and parachuted to the earth's surface. To clarify the composition of the air and study layers located at high altitudes, rockets are used that probe the atmosphere up to 500 km. Very important information about the state of the atmosphere and weather processes occurring above the Earth's surface is provided by artificial Earth satellites. Observations of atmospheric phenomena carried out by astronauts from orbital stations in space are of great value.

Video source: AirPano.ru

The end of the term is always a time of trouble for caring parents. :) Since I think it’s a shame to have a 4 in geography, I decided to improve my son in this subject and teach him a short lesson explaining to him what is called atmosphere and what its role is. By the way, the efforts were not in vain, and my son is getting an “A”!

What is atmosphere

First you need to figure out what it is. So, this is the lightest shell of all, but its role in all processes on our planet is very significant. It is heterogeneous- the higher you are from the surface of the planet, the more discharged it is, as a result of which its composition also changes. Science considers this shell in the form of several layers:

troposphere- maximum density is observed here, and all atmospheric phenomena occur here;
stratosphere- characterized by lower density, and the only phenomenon observed here is noctilucent clouds;
mesosphere- there is a significant drop in temperature here;
thermosphere- here the air density is several hundred thousand times less;
exosphere- represented by ionized gases - plasma.

What is the meaning of atmosphere

Firstly, thanks to her it became possible emergence of life. Animals cannot survive without oxygen, and plants cannot support life without another gas - carbon dioxide. It is necessary for plants main component of the photosynthesis process, as a result of which the oxygen necessary for animals is produced. It should be noted the special importance of this shell as a shield, which counteracts solar radiation and meteors - they simply burn up in its thickness. It acts as a heat regulator, leveling temperature fluctuations: excessive overheating during the day and hypothermia at night. It’s like she’s covering our planet with a blanket, delaying back radiation of heat.

Due to the fact that the planet warms up unevenly, pressure drops occur, which cause occurrence of winds and weather changes. Winds participate in processes called “weathering,” forming various relief zones. In addition, without it, another extremely important process would be impossible - the water cycle, thanks to which clouds form and precipitation falls.