Temperature of the upper layers of the atmosphere. Persistent auroral red arcs
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 rise to altitude, the total atmospheric pressure drops, which leads to a decrease in partial oxygen pressure.
The human lungs contain approximately three liters of alveolar air. If atmospheric pressure is normal, then the partial oxygen pressure in the alveolar air will be 11 mm Hg. Art., carbon dioxide pressure - 40 mm Hg. Art., and water vapor - 47 mm Hg. Art. As altitude increases, oxygen pressure decreases, and the total pressure of water vapor and carbon dioxide in the lungs 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 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 physiological characteristics 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. For example, thanks to the 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, a gradual weakening and then complete disappearance of phenomena familiar to humans observed in the lower atmospheric layer will be observed:
No sound travels.
There is no aerodynamic force or 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 leveling daily rates. In the absence of an atmosphere on Earth, daily temperatures would fluctuate within +/-200C˚. The atmospheric layer is a life-giving “buffer” between the earth’s surface and space, a carrier of moisture and heat; the processes of photosynthesis and energy exchange take place in the atmosphere - the most important biosphere processes.
Layers of the atmosphere in order from the Earth's surface
The atmosphere is a layered structure consisting of the following layers of the atmosphere in order from the Earth's surface:
Troposphere.
Stratosphere.
Mesosphere.
Thermosphere.
Exosphere
Each layer does not have sharp boundaries between each other, and their height is affected by latitude and seasons. This layered structure was formed as a result of temperature changes at different altitudes. It is thanks to the atmosphere that we see twinkling stars.
Structure of the Earth's atmosphere by layers: 
What does the Earth's atmosphere consist of?
Each atmospheric layer differs in temperature, density and composition. The total thickness of the atmosphere is 1.5-2.0 thousand km. What does the Earth's atmosphere consist of? Currently, 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 with an altitude of approximately 10-15 km. The bulk of atmospheric air is concentrated here. Characteristic troposphere - temperature drops by 0.6 ˚C as you rise upward for every 100 meters. The troposphere concentrates almost all atmospheric water vapor, and this is where clouds form.
The height of the troposphere changes daily. In addition, her average value varies depending on latitude and 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 above the equator is close to +26 ˚C, and above the North Pole -23 ˚C. The upper line of the troposphere above the equator has an average annual temperature of about -70 ˚C, and above north pole in summer -45 ˚C and in winter -65 ˚C. Thus, the higher the altitude, the lower the temperature. The sun's rays pass unhindered through the troposphere, heating the Earth's surface. The heat emitted by the sun is retained by carbon dioxide, methane and water vapor.
Stratosphere
Above the troposphere layer is the stratosphere, which is 50-55 km in height. The peculiarity of this layer is that the temperature increases with height. Between the troposphere and the stratosphere lies a transition layer called the tropopause.
From approximately an altitude of 25 kilometers, the temperature of the stratospheric layer begins to increase and, upon reaching a maximum altitude of 50 km, 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 rather thin clouds, which are called “pearl clouds”. 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 nacreous clouds consists of supercooled water droplets. The stratosphere consists mainly of ozone.
Mesosphere
The height of the mesosphere layer is approximately 80 km. Here, as it rises upward, the temperature decreases and at the very top reaches values of 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 "noctilucent." The mesosphere is characterized by the most cold temperature in the atmosphere: from -2 to -138 ˚C.
Thermosphere
This atmospheric layer acquired its name due to its high temperatures. The thermosphere consists of:
Ionosphere.
Exosphere.
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 made up of charged oxygen atoms, charged molecules of nitrogen atoms, and free electrons.
Exosphere
The exospheric layer begins at an altitude of 800-1000 km. Gas particles, especially light ones, move here at tremendous speed, overcoming the force of gravity. Such particles, due to their rapid movement, fly out of the atmosphere into space and dissipate. Therefore, the exosphere is called the sphere of dispersion. Mostly hydrogen atoms, which make up the highest layers of the exosphere, fly into space. Thanks to the particles in upper layers atmosphere and solar wind particles, we can observe the northern lights.
Satellites and geophysical rockets have made it possible to establish the presence in the upper layers of the atmosphere of the planet’s radiation belt, consisting of electrically charged particles - electrons and protons.
Atmosphere (from ancient Greek ἀτμός - steam and σφαῖρα - ball) is a gas shell (geosphere) surrounding planet Earth. Its inner surface covers the hydrosphere and partially earth's crust, the outer one borders on 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.
Physical properties
The thickness of the atmosphere is approximately 120 km from the Earth's surface. The total mass of air in the atmosphere is (5.1-5.3) 1018 kg. Of these, the mass of dry air is (5.1352 ± 0.0003) 1018 kg, the total mass of water vapor is on average 1.27 1016 kg.
The molar mass of clean dry air is 28.966 g/mol, and the density of air at the sea surface is approximately 1.2 kg/m3. The pressure at 0 °C at sea level is 101.325 kPa; critical temperature- −140.7 °C (~132.4 K); critical pressure- 3.7 MPa; Cp at 0 °C - 1.0048·103 J/(kg·K), Cv - 0.7159·103 J/(kg·K) (at 0 °C). Solubility of air in water (by mass) at 0 °C - 0.0036%, at 25 °C - 0.0023%.
The following are accepted as “normal conditions” at the Earth’s surface: density 1.2 kg/m3, barometric pressure 101.35 kPa, temperature plus 20 °C and relative humidity 50%. These conditional indicators have purely engineering significance.
Chemical composition
The Earth's atmosphere arose as a result of the release of gases during volcanic eruptions. With the advent of the oceans and the biosphere, it was formed due to gas exchange with water, plants, animals and the products of their decomposition in soils and swamps.
Currently, the Earth's atmosphere consists mainly of gases and various impurities (dust, water droplets, ice crystals, sea salts, combustion products).
The concentration of gases that make up the atmosphere is almost constant, with the exception of water (H2O) and carbon dioxide(CO2).
Composition of dry air
| Nitrogen | ||
| Oxygen | ||
| Argon | ||
| Water | ||
| Carbon dioxide | ||
| Neon | ||
| Helium | ||
| Methane | ||
| Krypton | ||
| Hydrogen | ||
| Xenon | ||
| Nitrous oxide |
In addition to the gases indicated in the table, the atmosphere contains SO2, NH3, CO, ozone, hydrocarbons, HCl, HF, Hg vapor, I2, as well as NO and many other gases in small quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol).
The structure of the atmosphere
Troposphere
Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass of atmospheric air and about 90% of all water vapor present in the atmosphere. Turbulence and convection are highly developed in the troposphere, clouds arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m
Tropopause
The transition layer from the troposphere to the stratosphere, a layer of the atmosphere in which the decrease in temperature with height stops.
Stratosphere
A layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 11-25 km layer (lower layer of the stratosphere) and an increase in temperature in the 25-40 km layer from −56.5 to 0.8 ° C (upper layer of the stratosphere or inversion region). Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This area constant temperature called the stratopause and is the boundary between the stratosphere and mesosphere.
Stratopause
The boundary layer of the atmosphere between the stratosphere and mesosphere. In the vertical temperature distribution there is a maximum (about 0 °C).
Mesosphere
The mesosphere begins at an altitude of 50 km and extends to 80-90 km. Temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc. cause atmospheric luminescence.
Mesopause
Transitional layer between the mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).
Karman Line
The height above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. According to the FAI definition, the Karman line is located at an altitude of 100 km above sea level.
Boundary of the Earth's atmosphere
Thermosphere
The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values of the order of 1500 K, after which it remains almost constant to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, ionization of the air (“auroras”) occurs - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity - for example, in 2008-2009 - there is a noticeable decrease in the size of this layer.
Thermopause
The region of the atmosphere adjacent to the thermosphere. In this region, the absorption of solar radiation is negligible and the temperature does not actually change with altitude.
Exosphere (scattering sphere)
The exosphere is a zone of dispersion, outer part thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space (dissipation).
Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular weights; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200-250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed.
At an altitude of about 2000-3500 km, the exosphere gradually turns into the so-called near-space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas represents only part of the interplanetary matter. The other part consists of dust particles of cometary and meteoric origin. In addition to extremely rarefied dust particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.
The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere - about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutronosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.
Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. This implies a variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere called the homosphere. The boundary between these layers is called the turbopause; it lies at an altitude of about 120 km.
Other properties of the atmosphere and effects on the human body
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.
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 devoid 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, orbital equipment space station will not be able to cool outside in the way that 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.
History of atmospheric formation
According to the most common theory, the Earth's atmosphere has been three 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 (about four billion years ago). On next stage active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). This is how the secondary atmosphere was formed (about three billion years before the present day). This atmosphere was restorative. Further, the process of atmosphere formation was determined by the following factors:
- leakage of light gases (hydrogen and helium) into interplanetary space;
- chemical reactions occurring in the atmosphere under the influence ultraviolet radiation, lightning discharges and some other factors.
Gradually, these factors led to the formation of a tertiary atmosphere, characterized by much less hydrogen and much more nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).
Nitrogen
Education large quantity nitrogen N2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O2, which began to come from the surface of the planet as a result of photosynthesis, starting 3 billion years ago. Nitrogen N2 is also released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO in the upper atmosphere.
Nitrogen N2 reacts only under specific conditions (for example, during a lightning discharge). Oxidation of molecular nitrogen with ozone during electrical discharges in small quantities is used in industrial production nitrogen fertilizers. Oxidize it with low energy consumption and convert it into biological active form can cyanobacteria (blue-green algae) and nodule bacteria that form rhizobial symbiosis with leguminous plants, so-called green manure.
Oxygen
The composition of the atmosphere began to change radically 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. Initially, oxygen was spent on the oxidation of reduced compounds - ammonia, 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. Gradually, a modern atmosphere with oxidizing properties formed. Since this caused serious and abrupt changes in many processes occurring in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe.
During the Phanerozoic, the composition of the atmosphere and oxygen content underwent changes. They correlated primarily with the rate of deposition of organic sediment. Thus, during periods of coal accumulation, the oxygen content in the atmosphere apparently significantly exceeded the modern level.
Carbon dioxide
The CO2 content in the atmosphere depends on volcanic activity and chemical processes in the earth's shells, but most of all - on the intensity of biosynthesis and decomposition of organic matter in the Earth's biosphere. Almost the entire current biomass of the planet (about 2.4 1012 tons) is formed due to carbon dioxide, nitrogen and water vapor contained in atmospheric air. Organics buried in the ocean, swamps and forests turn into coal, oil and natural gas.
Noble gases
The source of noble gases - argon, helium and krypton - is volcanic eruptions and the decay of radioactive elements. The Earth in general and the atmosphere in particular are depleted of inert gases compared to space. It is believed that the reason for this lies in the continuous leakage of gases into interplanetary space.
Air pollution
IN Lately Man began to influence the evolution of the atmosphere. The result of his activities was a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological eras. Huge amounts of CO2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic substances of plant and animal origin, as well as due to volcanism and human industrial activity. Over the past 100 years, the CO2 content in the atmosphere has increased by 10%, with the bulk (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the next 200-300 years the amount of CO2 in the atmosphere will double and could lead to global climate change.
Fuel combustion is the main source of polluting gases (CO, NO, SO2). Sulfur dioxide is oxidized by atmospheric oxygen to SO3, and nitrogen oxide to NO2 in the upper layers of the atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H2SO4 and nitric acid HNO3 fall to the surface of the Earth in the form of the so-called. acid rain. Using motors internal combustion leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and lead compounds (tetraethyl lead) Pb(CH3CH2)4.
Aerosol pollution of the atmosphere is caused by: natural causes(volcanic eruptions, dust storms, entrainment of droplets sea water and 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.
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The air shell that surrounds our planet and rotates with it is called the atmosphere. Half of the total mass of the atmosphere is concentrated in the lower 5 km, and three-quarters of the mass is in the lower 10 km. Higher up, the air is significantly rarefied, although its particles are found at an altitude of 2000-3000 km above the earth's surface.
The air we breathe is a mixture of gases. Most of all it contains nitrogen - 78% and oxygen - 21%. Argon makes up less than 1% and 0.03% is carbon dioxide. Numerous other gases, such as krypton, xenon, neon, helium, hydrogen, ozone and others, make up thousandths and millionths of a percent. The air also contains water vapor, particles of various substances, bacteria, pollen and cosmic dust.
The atmosphere consists of several layers. The lower layer up to a height of 10-15 km above the Earth's surface is called the troposphere. It is heated by the Earth, so the air temperature here drops by 6 °C with height per 1 kilometer of rise. The troposphere contains almost all the water vapor and almost all the clouds are formed - approx. The height of the troposphere over different latitudes of the planet is not the same. Over the poles it rises to 9 km, over temperate latitudes - up to 10-12 km, and above the equator - up to 15 km. The processes occurring in the troposphere - the formation and movement of air masses, the formation of cyclones and anticyclones, the appearance of clouds and precipitation - determine the weather and climate at the earth's surface.
Above the troposphere is the stratosphere, which extends up to 50-55 km. The troposphere and stratosphere are separated by a transition layer, the tropopause, 1-2 km thick. In the stratosphere, at an altitude of about 25 km, the air temperature gradually begins to rise and at 50 km reaches + 10 +30 °C. This increase in temperature is due to the fact that there is an ozone layer in the stratosphere at altitudes of 25-30 km. At the Earth's surface, its content in the air is negligible, and at high altitudes, diatomic oxygen molecules absorb ultraviolet solar radiation, forming triatomic ozone molecules.
If ozone were located in the lower layers of the atmosphere, at a height with normal pressure, the thickness of its layer would be only 3 mm. But even in such a small number he plays very important role: absorbs part of solar radiation harmful to living organisms.
Above the stratosphere, the mesosphere extends to approximately an altitude of 80 km, in which the air temperature drops with height to several tens of degrees below zero.
The upper part of the atmosphere is characterized by very high temperatures and is called the thermosphere - approx. It is divided into two parts - the ionosphere - up to an altitude of about 1000 km, where the air is highly ionized, and the exosphere - over 1000 km. Molecules in the ionosphere atmospheric gases absorb ultraviolet radiation from the Sun, resulting in the formation of charged atoms and free electrons. Auroras are observed in the ionosphere.
The atmosphere plays a very important role in the life of our planet. It protects the Earth from strong heating by the sun's rays during the day and from hypothermia at night. Most meteorites burn up in atmospheric layers, not reaching the surface of the planet. The atmosphere contains oxygen, necessary for all organisms, an ozone shield that protects life on Earth from the harmful part of the ultraviolet radiation of the Sun.
ATMOSPHERES OF THE PLANETS OF THE SOLAR SYSTEM
The atmosphere of Mercury is so rarefied that it can be said to be practically non-existent. The air shell of Venus consists of carbon dioxide (96%) and nitrogen (about 4%), it is very dense - the atmospheric pressure at the surface of the planet is almost 100 times greater than on Earth. The Martian atmosphere also consists predominantly of carbon dioxide (95%) and nitrogen (2.7%), but its density is about 300 times less than that of Earth, and its pressure is almost 100 times less. The visible surface of Jupiter is actually the top layer of a hydrogen-helium atmosphere. The composition of the air shells of Saturn and Uranus is the same. Uranus' beautiful blue color is due to the high concentration of methane in the upper part of its atmosphere - approx. Neptune, shrouded in a hydrocarbon haze, has two main layers of clouds: one consisting of crystals of frozen methane, and the second, located below, containing ammonia and hydrogen sulfide.
Atmosphere (from Greek ατμός - “steam” and σφαῖρα - “sphere”) - gas shell celestial body, held near it by gravity. The atmosphere is the gaseous shell of the planet, consisting of a mixture of various gases, water vapor and dust. The atmosphere exchanges matter between the Earth and the Cosmos. The Earth receives cosmic dust and meteorite material, and loses the lightest gases: hydrogen and helium. The Earth's atmosphere is penetrated through and through by powerful radiation from the Sun, which determines the thermal regime of the planet's surface, causing the dissociation of molecules of atmospheric gases and the ionization of atoms.
The Earth's atmosphere contains oxygen, used by most living organisms for respiration, and carbon dioxide, consumed by plants, algae and cyanobacteria during photosynthesis. The atmosphere is also protective layer planet, protecting its inhabitants from solar ultraviolet radiation.
All massive bodies - planets - have an atmosphere. earth type, gas giants.
Atmospheric composition
The atmosphere is a mixture of gases consisting of nitrogen (78.08%), oxygen (20.95%), carbon dioxide (0.03%), argon (0.93%), a small amount of helium, neon, xenon, krypton (0.01%), 0.038% carbon dioxide, and small amounts of hydrogen, helium, other noble gases and pollutants.
The current composition of the Earth’s air was established more than a hundred million years ago, but the sharply increased production activity man nevertheless led to his change. Currently, there is an increase in CO 2 content by approximately 10-12%. The gases included in the atmosphere perform various functional roles. However, the main significance of these gases is determined primarily by the fact that they very strongly absorb radiant energy and thereby have a significant impact on temperature regime Earth's surface and atmosphere.
The initial composition of a planet's atmosphere usually depends on the chemical and temperature properties of the sun during planetary formation and the subsequent release of external gases. The composition of the gas shell then evolves under the influence of various factors.
The atmospheres of Venus and Mars are primarily composed of carbon dioxide with small additions of nitrogen, argon, oxygen and other gases. The Earth's atmosphere is largely the product of the organisms that live in it. The low-temperature gas giants - Jupiter, Saturn, Uranus and Neptune - can retain mainly low molecular weight gases - hydrogen and helium. High-temperature gas giants, such as Osiris or 51 Pegasi b, on the contrary, cannot hold it and the molecules of their atmosphere are scattered in space. This process occurs slowly and constantly.
Nitrogen, The most common gas in the atmosphere, it is chemically inactive.
Oxygen, unlike nitrogen, is a chemically very active element. The specific function of oxygen is oxidation organic matter heterotrophic organisms, rocks and under-oxidized gases released into the atmosphere by volcanoes. Without oxygen, there would be no decomposition of dead organic matter.
Atmospheric structure
The structure of the atmosphere consists of two parts: the inner one - the troposphere, stratosphere, mesosphere and thermosphere, or ionosphere, and the outer one - the magnetosphere (exosphere).
1) Troposphere– this is the lower part of the atmosphere in which 3/4 i.e. is concentrated. ~ 80% of the entire earth's atmosphere. Its height is determined by the intensity of vertical (ascending or descending) air flows caused by heating earth's surface and the ocean, therefore the thickness of the troposphere at the equator is 16–18 km, in temperate latitudes 10–11 km, and at the poles – up to 8 km. The air temperature in the troposphere at altitude decreases by 0.6ºС for every 100 m and ranges from +40 to - 50ºС.
2)Stratosphere is located above the troposphere and has a height of up to 50 km from the surface of the planet. The temperature at an altitude of up to 30 km is constant -50ºС. Then it begins to rise and at an altitude of 50 km reaches +10ºС.
The upper boundary of the biosphere is the ozone screen.
The ozone layer is a layer of the atmosphere within the stratosphere located at different heights from the Earth's surface and having a maximum ozone density at an altitude of 20-26 km.
The height of the ozone layer at the poles is estimated at 7-8 km, at the equator at 17-18 km, and the maximum height of ozone presence is 45-50 km. Life above the ozone shield is impossible due to the harsh ultraviolet radiation of the Sun. If you compress all the ozone molecules, you will get a ~ 3mm layer around the planet.
3) Mesosphere– the upper boundary of this layer is located up to a height of 80 km. Its main feature is a sharp drop in temperature -90ºС at its upper limit. Noctilucent clouds consisting of ice crystals are recorded here.
4) Ionosphere (thermosphere) - is located up to an altitude of 800 km and is characterized by a significant increase in temperature:
150 km temperature +240ºС,
200 km temperature +500ºС,
600 km temperature +1500ºС.
Under the influence of ultraviolet radiation from the Sun, gases are in an ionized state. Ionization is associated with the glow of gases and the appearance of auroras.
The ionosphere has the ability to repeatedly reflect radio waves, which ensures long-distance radio communications on the planet.
5) Exosphere– is located above 800 km and extends up to 3000 km. Here the temperature is >2000ºС. The speed of gas movement is approaching critical ~ 11.2 km/sec. The dominant atoms are hydrogen and helium, which form a luminous corona around the Earth, extending to an altitude of 20,000 km.
Functions of the atmosphere
1) Thermoregulatory - weather and climate on Earth depend on the distribution of heat and pressure.
2) Life-sustaining.
3) In the troposphere, global vertical and horizontal movements of air masses occur, which determine the water cycle and heat exchange.
4) Almost all surface geological processes are caused by the interaction of the atmosphere, lithosphere and hydrosphere.
5) Protective - the atmosphere protects the earth from space, solar radiation and meteorite dust.
Functions of the atmosphere. Without the atmosphere, life on Earth would be impossible. A person consumes 12-15 kg daily. air, inhaling every minute from 5 to 100 liters, which significantly exceeds the average daily need for food and water. In addition, the atmosphere reliably protects a person from dangers that threaten him from space: it does not allow meteorites to pass through, cosmic radiation. A person can live without food for five weeks, without water for five days, without air for five minutes. Normal human life requires not only air, but also a certain purity of it. The health of people, the state of flora and fauna, the strength and durability of building structures and structures depend on air quality. Polluted air is destructive to waters, land, seas, and soils. The atmosphere determines the light and regulates the thermal regimes of the earth, contributes to the redistribution of heat on the globe. The gas shell protects the Earth from excessive cooling and heating. If our planet were not surrounded by an air shell, then within one day the amplitude of temperature fluctuations would reach 200 C. The atmosphere saves everything living on Earth from destructive ultraviolet, X-ray and cosmic rays. The atmosphere plays a great role in the distribution of light. Her air is breaking Sun rays into a million small rays, scatters them and creates uniform illumination. The atmosphere serves as a conductor of sounds.
The structure of the Earth's atmosphere
The atmosphere is the gaseous shell of the Earth with the aerosol particles it contains, moving together with the Earth in space as a single whole and at the same time taking part in the rotation of the Earth. Most of our life takes place at the bottom of the atmosphere.
Almost all of our planets have their own atmospheres. solar system, but only the earth's atmosphere is capable of supporting life.
When our planet formed 4.5 billion years ago, it was apparently devoid of an atmosphere. The atmosphere was formed as a result of volcanic emissions of water vapor mixed with carbon dioxide, nitrogen and other chemicals from the interior of the young planet. But the atmosphere can contain a limited amount of moisture, so its excess as a result of condensation gave rise to the oceans. But then the atmosphere was devoid of oxygen. The first living organisms that originated and developed in the ocean, as a result of the photosynthesis reaction (H 2 O + CO 2 = CH 2 O + O 2), began to release small portions oxygen that began to enter the atmosphere.
The formation of oxygen in the Earth's atmosphere led to the formation of the ozone layer at altitudes of approximately 8 – 30 km. And, thus, our planet has acquired protection from the harmful effects of ultraviolet study. This circumstance served as an impetus for further evolution life forms on Earth, because As a result of increased photosynthesis, the amount of oxygen in the atmosphere began to grow rapidly, which contributed to the formation and maintenance of life forms, including on land.
Today our atmosphere consists of 78.1% nitrogen, 21% oxygen, 0.9% argon, and 0.04% carbon dioxide. Very small fractions compared to the main gases are neon, helium, methane, and krypton.
The gas particles contained in the atmosphere are affected by the force of gravity of the Earth. And, given that air is compressible, its density gradually decreases with height, passing into outer space without a clear boundary. Half of the total mass of the earth's atmosphere is concentrated in the lower 5 km, three quarters in the lower 10 km, nine tenths in the lower 20 km. 99% of the mass of the Earth's atmosphere is concentrated below an altitude of 30 km, which is only 0.5% of the equatorial radius of our planet.
At sea level, the number of atoms and molecules per cubic centimeter of air is about 2 * 10 19, at an altitude of 600 km only 2 * 10 7. At sea level, an atom or molecule travels approximately 7 * 10 -6 cm before colliding with another particle. At an altitude of 600 km this distance is about 10 km. And at sea level, about 7 * 10 9 such collisions occur every second, at an altitude of 600 km - only about one per minute!
But not only pressure changes with altitude. The temperature also changes. For example, at the foot of a high mountain it can be quite hot, while the top of the mountain is covered with snow and the temperature there is at the same time below zero. And if you take a plane to an altitude of about 10-11 km, you can hear a message that it is -50 degrees outside, while at the surface of the earth it is 60-70 degrees warmer...
Initially, scientists assumed that temperature decreases with height until it reaches absolute zero(-273.16°C). But that's not true.
The Earth's atmosphere consists of four layers: troposphere, stratosphere, mesosphere, ionosphere (thermosphere). This division into layers was also adopted based on data on temperature changes with height. The lowest layer, where air temperature decreases with height, is called the troposphere. The layer above the troposphere, where the temperature drop stops, is replaced by isotherm, and finally the temperature begins to rise, is called the stratosphere. The layer above the stratosphere in which the temperature rapidly drops again is the mesosphere. And finally, the layer where the temperature begins to rise again is called the ionosphere or thermosphere.
The troposphere extends on average to the lower 12 km. This is where our weather is formed. The highest clouds (cirrus) form in the uppermost layers of the troposphere. The temperature in the troposphere decreases adiabatically with height, i.e. The temperature change occurs due to the decrease in pressure with height. The temperature profile of the troposphere is largely determined by the amount of water reaching the Earth's surface. solar radiation. As a result of the heating of the Earth's surface by the Sun, convective and turbulent flows are formed, directed upward, which form the weather. It is worth noting that the influence of the underlying surface on the lower layers of the troposphere extends to a height of approximately 1.5 km. Of course, excluding mountainous areas.
The upper boundary of the troposphere is the tropopause - an isothermal layer. Remember characteristic appearance thunderclouds whose top is a “burst” of cirrus clouds called an “anvil.” This “anvil” just “spreads” under the tropopause, because due to isotherm, the ascending air currents are significantly weakened, and the cloud stops developing vertically. But in special, rare cases, the tops of cumulonimbus clouds can invade the lower layers of the stratosphere, breaking the tropopause.
The height of the tropopause depends on geographical latitude. Thus, at the equator it is located at an altitude of approximately 16 km, and its temperature is about –80°C. At the poles, the tropopause is located lower, at approximately 8 km altitude. In summer the temperature here is –40°C, and –60°C in winter. Thus, despite more high temperatures near the Earth's surface, the tropical tropopause is much colder than at the poles.