What parts is the atmosphere divided into? Chemical composition of the Earth's atmosphere. Composition of the Earth's atmosphere in percent
Everyone who has flown on an airplane is accustomed to this kind of message: “our flight takes place at an altitude of 10,000 m, the temperature outside is 50 ° C.” It seems nothing special. The farther from the surface of the Earth heated by the Sun, the colder it is. Many people think that the temperature decreases continuously with altitude and that the temperature gradually drops, approaching the temperature of space. By the way, scientists thought so until the end of the 19th century.
Let's take a closer look at the distribution of air temperature over the Earth. The atmosphere is divided into several layers, which primarily reflect the nature of temperature changes.
The lower layer of the atmosphere is called troposphere, which means “sphere of rotation.” All changes in weather and climate are the result of physical processes occurring precisely in this layer. The upper boundary of this layer is located where the decrease in temperature with height is replaced by its increase - approximately at an altitude of 15-16 km above the equator and 7-8 km above the poles. Like the Earth itself, the atmosphere, under the influence of the rotation of our planet, is also somewhat flattened above the poles and swells above the equator. However, this effect is much more pronounced in the atmosphere than in the solid shell of the Earth in the direction from the Earth's surface to. At the upper boundary of the troposphere, the air temperature decreases. Above the equator, the minimum air temperature is about -62 ° C, and above the poles - about -45 ° C. In temperate latitudes, more than 75% of the mass of the atmosphere is in the troposphere. In the tropics, about 90% is located within the troposphere. mass of the atmosphere.
In 1899, a minimum was found in the vertical temperature profile at a certain altitude, and then the temperature increased slightly. The beginning of this increase means the transition to the next layer of the atmosphere - to stratosphere, which means “layer sphere.” The term stratosphere means and reflects the previous idea of the uniqueness of the layer lying above the troposphere. The stratosphere extends to an altitude of about 50 km above the earth’s surface. Its peculiarity is, in particular, a sharp increase in air temperature. This increase in temperature is explained ozone formation reaction is one of the main chemical reactions occurring in the atmosphere.
The bulk of ozone is concentrated at altitudes of approximately 25 km, but in general the ozone layer is a highly extended shell, covering almost the entire stratosphere. The interaction of oxygen with ultraviolet rays is one of the beneficial processes in the earth’s atmosphere that contributes to the maintenance of life on Earth. The absorption of this energy by ozone prevents its excessive flow to the earth's surface, where exactly the level of energy that is suitable for the existence of terrestrial life forms is created. The ozonosphere absorbs some of the radiant energy passing through the atmosphere. As a result, a vertical air temperature gradient of approximately 0.62°C per 100 m is established in the ozonosphere, i.e., the temperature increases with altitude up to the upper limit of the stratosphere - the stratopause (50 km), reaching, according to some data, 0°C.
At altitudes from 50 to 80 km there is a layer of the atmosphere called mesosphere. The word "mesosphere" means "intermediate sphere", where the air temperature continues to decrease with height. Above the mesosphere, in a layer called thermosphere, the temperature rises again with altitude up to about 1000°C, and then drops very quickly to -96°C. However, it does not drop indefinitely, then the temperature increases again.
Thermosphere is the first layer ionosphere. Unlike the previously mentioned layers, the ionosphere is not distinguished by temperature. The ionosphere is an area of electrical nature that makes many types of radio communications possible. The ionosphere is divided into several layers, designated by the letters D, E, F1 and F2. These layers also have special names. The separation into layers is caused by several reasons, among which the most important is the unequal influence of the layers on the passage of radio waves. The lowest layer, D, mainly absorbs radio waves and thereby prevents their further propagation. The best studied layer E is located at an altitude of approximately 100 km above the earth's surface. It is also called the Kennelly-Heaviside layer after the names of the American and English scientists who simultaneously and independently discovered it. Layer E, like a giant mirror, reflects radio waves. Thanks to this layer, long radio waves travel further distances than would be expected if they propagated only in a straight line, without being reflected from the E layer. The F layer has similar properties. It is also called the Appleton layer. Together with the Kennelly-Heaviside layer, it reflects radio waves to terrestrial radio stations. Such reflection can occur at various angles. The Appleton layer is located at an altitude of about 240 km.
The outermost region of the atmosphere, the second layer of the ionosphere, is often called exosphere. This term refers to the existence of the outskirts of space near the Earth. It is difficult to determine exactly where the atmosphere ends and space begins, since the density increases with height. atmospheric gases decreases gradually and the atmosphere itself gradually turns into almost a vacuum, in which only individual molecules occur. Already at an altitude of approximately 320 km, the density of the atmosphere is so low that molecules can travel more than 1 km without colliding with each other. The outermost part of the atmosphere serves as its upper boundary, which is located at altitudes from 480 to 960 km.
More information about processes in the atmosphere can be found on the website “Earth Climate”
The world around us is formed from three very different parts: land, water and air. Each of them is unique and interesting in its own way. Now we'll 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 Greek origin, translated into Russian they mean “steam” and “ball”. And if you look precise definition, then 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 known already in 1774. They were installed by Antoine Lavoisier. He discovered that the composition of the atmosphere was largely 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 globe 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 Sun 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 any 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 upper layers, never reaching the surface of the Earth. 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 points accounts for 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.
List harmful substances, which daily replenish the composition of 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 such chemical elements: sulfur dioxide, hydrocarbon and hydrogen sulfide, ammonia and phenol, chlorine and fluorine. If the process continues, the questions will soon be answered: “What is the atmosphere? What does it consist of? will be completely different.
- the air shell of the globe, rotating together with the Earth. The upper boundary of the atmosphere is conventionally drawn at altitudes of 150-200 km. The lower boundary is the Earth's surface.
Atmospheric air is a mixture of gases. Most of its volume in the surface layer of air accounts for nitrogen (78%) and oxygen (21%). In addition, the air contains inert gases (argon, helium, neon, etc.), carbon dioxide (0.03), water vapor and various solid particles (dust, soot, salt crystals).
The air is colorless, and the color of the sky is explained by the characteristics of the scattering of light waves.
The atmosphere consists of several layers: the troposphere, stratosphere, mesosphere and thermosphere.
The lower ground layer of air is called troposphere. At different latitudes its power is not the same. The troposphere follows the shape of the planet and participates together with the Earth in axial rotation. At the equator, the thickness of the atmosphere varies from 10 to 20 km. At the equator it is greater, and at the poles it is less. The troposphere is characterized by maximum air density; 4/5 of the mass of the entire atmosphere is concentrated in it. The troposphere determines weather conditions: various air masses, clouds and precipitation form, intense horizontal and vertical air movement occurs.
Above the troposphere, up to an altitude of 50 km, is located stratosphere. It is characterized by lower air density and lacks water vapor. In the lower part of the stratosphere at altitudes of about 25 km. there is an “ozone screen” - a layer of the atmosphere with a high concentration of ozone, which absorbs ultraviolet radiation, which is fatal to organisms.
At an altitude of 50 to 80-90 km it extends mesosphere. With increasing altitude, the temperature decreases with an average vertical gradient of (0.25-0.3)°/100 m, and the air density decreases. The main energy process is radiant heat transfer. The atmospheric glow is caused by complex photochemical processes involving radicals and vibrationally excited molecules.
Thermosphere located at an altitude of 80-90 to 800 km. The air density here is minimal, and the degree of air ionization is very high. Temperature changes depending on the activity of the Sun. Due to big amount charged particles, polar lights and magnetic storms are observed here.
The atmosphere is of great importance for the nature of the Earth. Without oxygen, living organisms cannot breathe. Its ozone layer protects all living things from harmful ultraviolet rays. The atmosphere smoothes out temperature fluctuations: the Earth's surface does not get supercooled at night and does not overheat during the day. In dense layers of atmospheric air, before reaching the surface of the planet, meteorites burn from thorns.
The atmosphere interacts with all layers of the earth. With its help, heat and moisture are exchanged between the ocean and land. Without the atmosphere there would be no clouds, precipitation, or winds.
Human economic activities have a significant adverse impact on the atmosphere. Atmospheric air pollution occurs, which leads to an increase in the concentration of carbon monoxide (CO 2). And this contributes to global warming and increases the “greenhouse effect”. Ozone layer The earth is destroyed due to industrial waste and transport.
The atmosphere needs protection. In developed countries, a set of measures is being implemented to protect atmospheric air from pollution.
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The atmosphere is what makes life possible on Earth. We receive the very first information and facts about the atmosphere back in primary school. In high school, we become more familiar with this concept in geography lessons.
Concept of earth's atmosphere
Not only the Earth, but also other celestial bodies have an atmosphere. This is the name given to the gaseous shell surrounding the planets. The composition of this gas layer varies significantly between planets. Let's look at the basic information and facts about otherwise called air.
Its most important component is oxygen. Some people mistakenly think that the earth's atmosphere consists entirely of oxygen, but in fact, air is a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, and water vapor. Even though the percentage of these gases is small, they perform an important function - they absorb a significant part of the solar radiant energy, thereby preventing the luminary from turning all life on our planet into ashes. The properties of the atmosphere change depending on altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.
Composition of the Earth's atmosphere
- Carbon dioxide necessary for plant nutrition. It appears in the atmosphere as a result of the process of respiration of living organisms, rotting, and combustion. Its absence in the atmosphere would make the existence of any plants impossible.
- Oxygen- a vital component of the atmosphere for humans. Its presence is a condition for the existence of all living organisms. It makes up about 20% of the total volume of atmospheric gases.
- Ozone is a natural solar absorber ultraviolet radiation, which has a detrimental effect on living organisms. Most of it forms a separate layer of the atmosphere - the ozone screen. IN Lately Human activity leads to the fact that it begins to gradually collapse, but since it is of great importance, active work is being carried out to preserve and restore it.
- water vapor determines air humidity. Its content may vary depending on various factors: air temperature, territorial location, season. At low temperatures there is very little water vapor in the air, maybe less than one percent, and at high temperatures its amount reaches 4%.
- In addition to all of the above, the composition earth's atmosphere there is always a certain percentage solid and liquid impurities. This is soot, ash, sea salt, dust, water drops, microorganisms. They can get into the air both naturally and anthropogenically.
Layers of the atmosphere
And temperature, and density, and high-quality composition air is not the same different heights. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristics. Let's find out what layers of the atmosphere are distinguished:
- Troposphere - this layer of the atmosphere is closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. 90% of all water vapor in the atmosphere is located here, so active cloud formation occurs. Also in this layer processes such as air (wind) movement, turbulence, and convection are observed. Temperatures range from +45 degrees at midday to warm time years in the tropics down to -65 degrees at the poles.
- The stratosphere is the second most distant layer of the atmosphere. Located at an altitude of 11 to 50 km. In the lower layer of the stratosphere the temperature is approximately -55; moving away from the Earth it increases to +1˚С. This region is called an inversion and is the boundary of the stratosphere and mesosphere.
- The mesosphere is located at an altitude of 50 to 90 km. The temperature at its lower boundary is about 0, at the upper it reaches -80...-90 ˚С. Meteorites entering the Earth's atmosphere completely burn up in the mesosphere, causing airglows to occur here.
- The thermosphere is approximately 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the influence of cosmic radiation and radiation emanating from the Sun.
- The exosphere is the zone of air dispersion. Here the concentration of gases is small and they gradually escape into interplanetary space.
The boundary between the earth's atmosphere and outer space is considered to be 100 km. This line is called the Karman line.
Atmospheric pressure
When listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how can it affect us?
We figured out that air consists of gases and impurities. Each of these components has its own weight, which means that the atmosphere is not weightless, as was believed until the 17th century. Atmospheric pressure is the force with which all layers of the atmosphere press on the surface of the Earth and on all objects.
Scientists carried out complex calculations and proved that one square meter area the atmosphere presses 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 this? He saves us internal pressure, which balances the external. You can feel the pressure of the atmosphere while on an airplane or high in the mountains, since the atmospheric pressure at altitude is much less. In this case, physical discomfort, blocked ears, and dizziness are possible.
A lot can be said about the surrounding atmosphere. We know a lot about her interesting facts, and some of them may seem surprising:
- The weight of the earth's atmosphere is 5,300,000,000,000,000 tons.
- It promotes sound transmission. At an altitude of more than 100 km, this property disappears due to changes in the composition of the atmosphere.
- The movement of the atmosphere is provoked by uneven heating of the Earth's surface.
- A thermometer is used to determine the air temperature, and a barometer is used to determine the pressure of the atmosphere.
- The presence of an atmosphere saves our planet from 100 tons of meteorites every day.
- The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
- The atmosphere is believed to extend upward to a height of 3000 km.
The importance of the atmosphere for humans
The physiological zone of the atmosphere is 5 km. At an altitude of 5000 m above sea level, a person begins to experience oxygen starvation, which is expressed in a decrease in his performance and deterioration in well-being. This shows that a person cannot survive in a space where there is no this amazing mixture of gases.
All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, it became possible to develop life on Earth. Already today, having assessed the scale of harm that humanity is capable of causing through its actions to the life-giving air, we should think about further measures to preserve and restore the atmosphere.
10.045×10 3 J/(kg*K) (in the temperature range from 0-100°C), C v 8.3710*10 3 J/(kg*K) (0-1500°C). The solubility of air in water at 0°C is 0.036%, at 25°C - 0.22%.
Atmospheric composition
History of atmospheric formation
Early history
Currently, science cannot trace all stages of the formation of the Earth with one hundred percent accuracy. According to the most common theory, the Earth's atmosphere has been four times over time. various compositions. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This is the so-called primary atmosphere. At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (hydrocarbons, ammonia, water vapor). This is how it was formed secondary atmosphere. This atmosphere was restorative. Further, the process of atmosphere formation was determined by the following factors:
- constant leakage of hydrogen into interplanetary space;
- chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.
Gradually these factors led to the formation tertiary atmosphere, characterized by a much lower content of hydrogen and a much higher content of nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).
The emergence of life and oxygen
With the appearance of living organisms on Earth as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide, the composition of the atmosphere began to change. There is, however, data (analysis of the isotopic composition of atmospheric oxygen and that released during photosynthesis) that indicates the geological origin of atmospheric oxygen.
Initially, oxygen was spent on the oxidation of reduced compounds - hydrocarbons, ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to increase.
In the 1990s, experiments were carried out to create a closed ecological system(“Biosphere 2”), during which it was not possible to create a stable system with a uniform air composition. The influence of microorganisms led to a decrease in oxygen levels and an increase in the amount of carbon dioxide.
Nitrogen
The formation of a large amount of N 2 is due to the oxidation of the primary ammonia-hydrogen atmosphere with molecular O 2, which began to come from the surface of the planet as a result of photosynthesis, supposedly about 3 billion years ago (according to another version, atmospheric oxygen is of geological origin). Nitrogen is oxidized to NO in the upper atmosphere, used in industry and bound by nitrogen-fixing bacteria, while N2 is released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds.
Nitrogen N 2 is an inert gas and reacts only under specific conditions (for example, during a lightning discharge). Cyanobacteria and some bacteria (for example, nodule bacteria that form rhizobial symbiosis with leguminous plants) can oxidize it and convert it into biological form.
Oxidation of molecular nitrogen by electrical discharges is used in industrial production nitrogen fertilizers, it also led to the formation of unique saltpeter deposits in the Chilean Atacama Desert.
Noble gases
Fuel combustion is the main source of polluting gases (CO, NO, SO2). Sulfur dioxide is oxidized by air O 2 to SO 3 in the upper layers of the atmosphere, which interacts with H 2 O and NH 3 vapors, and the resulting H 2 SO 4 and (NH 4) 2 SO 4 return to the Earth's surface along with precipitation. The use of internal combustion engines leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and Pb compounds.
Aerosol pollution of the atmosphere is caused by: natural causes(volcanic eruptions, dust storms, removal of drops of sea water and particles of plant pollen, etc.), and economic activity people (ore mining and building materials, fuel combustion, cement production, etc.). Intensive large-scale emission of solid particles into the atmosphere is one of the possible reasons changes in the planet's climate.
The structure of the atmosphere and characteristics of individual shells
The physical state of the atmosphere is determined by weather and climate. Basic parameters of the atmosphere: air density, pressure, temperature and composition. As altitude increases, air density and atmospheric pressure decrease. Temperature also changes with changes in altitude. The vertical structure of the atmosphere is characterized by different temperature and electrical properties, and different air conditions. Depending on the temperature in the atmosphere, the following main layers are distinguished: troposphere, stratosphere, mesosphere, thermosphere, exosphere (scattering sphere). The transitional regions of the atmosphere between neighboring shells are called tropopause, stratopause, etc., respectively.
Troposphere
Stratosphere
In the stratosphere, most of the short-wave part of ultraviolet radiation (180-200 nm) is retained and the energy of short waves is transformed. Under the influence of these rays, magnetic fields change, molecules disintegrate, ionization occurs, new formation of gases and other chemical compounds. These processes can be observed in the form of northern lights, lightning, and other glows.
In the stratosphere and higher layers under influence solar radiation gas molecules dissociate into atoms (above 80 km CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - H 2). At an altitude of 100-400 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.
Mesosphere
Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular masses; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to a decrease in gas density, the temperature drops from 0°C in the stratosphere to −110°C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200-250 km corresponds to a temperature of ~1500°C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed.
At an altitude of about 2000-3000 km, the exosphere gradually turns into the so-called near-space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas represents only part of the interplanetary matter. The other part consists of dust particles of cometary and meteoric origin. In addition to these extremely rarefied particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.
The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutronosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.
Depending on the composition of the gas in the atmosphere, they emit homosphere And heterosphere. Heterosphere- This is the area where gravity affects the separation of gases, since their mixing at such an altitude is negligible. This implies a variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere called the homosphere. The boundary between these layers is called the turbopause, it lies at an altitude of about 120 km.
Atmospheric properties
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 15 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. 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.
