Encyclopedic YouTube
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✪ Spaceship Earth (Episode 14) - Atmosphere
✪ Why wasn’t the atmosphere pulled into the vacuum of space?
✪ Entry of the Soyuz TMA-8 spacecraft into the Earth’s atmosphere
✪ Atmosphere structure, meaning, study
✪ O. S. Ugolnikov "Upper Atmosphere. Meeting of Earth and Space"
Subtitles
Atmospheric boundary
The atmosphere is considered to be that region around the Earth in which the gaseous medium rotates together with the Earth as a single whole. The atmosphere passes into interplanetary space gradually, in the exosphere, starting at an altitude of 500-1000 km from the Earth's surface.
According to the definition proposed by the International Aviation Federation, the boundary of the atmosphere and space is drawn along the Karman line, located at an altitude of about 100 km, above which aviation flights become completely impossible. NASA uses the 122 kilometers (400,000 ft) mark as the atmospheric limit, where the shuttles switch from powered maneuvering to aerodynamic maneuvering.
Physical properties
In addition to the gases indicated in the table, the atmosphere contains Cl 2, SO 2, NH 3, CO, O 3, NO 2, hydrocarbons, HCl, HBr, vapors, I 2, Br 2, as well as many other gases in minor amounts quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is radon (Rn).
The structure of the atmosphere
Atmospheric boundary layer
The lower layer of the troposphere (1-2 km thick), in which the state and properties of the Earth's surface directly affect the dynamics 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 ° (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 region of constant temperature is 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
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 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 above the thermosphere. In this region, the absorption of solar radiation is negligible and the temperature does not actually change with altitude.
Exosphere (scattering sphere)
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 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 rare 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.
Review
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 electrical properties in the atmosphere, they distinguish neutrosphere And ionosphere .
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.
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.
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 passes 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 (that is, 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.
History of atmospheric formation
According to the most common theory, the Earth's atmosphere has had three different compositions throughout its history. 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 (carbon dioxide, 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:
- leakage of light gases (hydrogen and helium) 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).
Nitrogen
The formation of a large amount of 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 N 2 reacts only under specific conditions (for example, during a lightning discharge). The oxidation of molecular nitrogen by ozone during electrical discharges is used in small quantities in the industrial production of nitrogen fertilizers. Cyanobacteria (blue-green algae) and nodule bacteria, which form rhizobial symbiosis with leguminous plants, which can be effective green manures - plants that do not deplete, but enrich the soil with natural fertilizers, can oxidize it with low energy consumption and convert it into a biologically active form.
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.
Noble gases
Air pollution
Recently, humans have begun to influence the evolution of the atmosphere. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological eras. Enormous amounts of CO 2 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 content of CO 2 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 CO 2 in the atmosphere will double and could lead to global climate change.
Fuel combustion is the main source of polluting gases (CO, SO2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3, and nitrogen oxide to NO 2 in the upper layers of the atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H 2 SO 4 and nitric acid HNO 3 fall to the surface of the Earth in the form so-called acid rain. Usage
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 region of constant temperature is 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. 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, a noticeable decrease in the size of this layer occurs.
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)
Atmospheric layers up to an altitude of 120 km
The exosphere is a dispersion zone, the outer part of the 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 masses; 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.
The exact size of the atmosphere is unknown, since its upper boundary is not clearly visible. However, the structure of the atmosphere has been studied enough for everyone to get an idea of how the gaseous envelope of our planet is structured.
Scientists who study the physics of the atmosphere define it as the region around the Earth that rotates with the planet. FAI gives the following definition:
- The boundary between space and the atmosphere runs along the Karman line. This line, according to the definition of the same organization, is an altitude above sea level located at an altitude of 100 km.
Everything above this line is outer space. The atmosphere gradually moves into interplanetary space, which is why there are different ideas about its size.
With the lower boundary of the atmosphere, everything is much simpler - it passes along the surface of the earth's crust and the water surface of the Earth - the hydrosphere. In this case, the border, one might say, merges with the earth and water surfaces, since the particles there are also dissolved air particles.
What layers of the atmosphere are included in the size of the Earth?
Interesting fact: in winter it is lower, in summer it is higher.
It is in this layer that turbulence, anticyclones and cyclones arise, and clouds form. It is this sphere that is responsible for the formation of weather; approximately 80% of all air masses are located in it.
The tropopause is a layer in which the temperature does not decrease with height. Above the tropopause, at an altitude above 11 and up to 50 km is located. The stratosphere contains a layer of ozone, which is known to protect the planet from ultraviolet rays. The air in this layer is thin, which explains the characteristic purple hue of the sky. The speed of air flows here can reach 300 km/h. Between the stratosphere and mesosphere there is a stratopause - a boundary sphere in which the temperature maximum occurs.
The next layer is . It extends to heights of 85-90 kilometers. The color of the sky in the mesosphere is black, so stars can be observed even in the morning and afternoon. The most complex photochemical processes take place there, during which atmospheric glow occurs.
Between the mesosphere and the next layer, there is a mesopause. It is defined as a transition layer in which a temperature minimum is observed. Higher up, at an altitude of 100 kilometers above sea level, is the Karman line. Above this line are the thermosphere (altitude limit 800 km) and the exosphere, which is also called the “dispersion zone”. At an altitude of approximately 2-3 thousand kilometers it passes into the near-space vacuum.
Considering that the upper layer of the atmosphere is not clearly visible, its exact size is impossible to calculate. In addition, in different countries there are organizations that have different opinions on this matter. It should be noted that Karman line can be considered the boundary of the earth’s atmosphere only conditionally, since different sources use different boundary markers. Thus, in some sources you can find information that the upper limit passes at an altitude of 2500-3000 km.
NASA uses the 122 kilometer mark for calculations. Not long ago, experiments were carried out that clarified the border as located at around 118 km.
Probably those who dream of space have probably wondered why there is an atmosphere only on Venus and Earth and nowhere else (we are not taking into account the satellite for now)? And how to make it appear there. Where is the reason why it is impossible to breathe deeply without a spacesuit, either on Mars or on the Moon?
To understand this, we will have to study the concept of second cosmic velocity, and also study the relationship between molecular mass and speed.
Earth's air consists mainly of the following elements: oxygen (O) and nitrogen (N).
At the second escape velocity, a body whose size/mass is negligible compared to the planet will fly away forever into interplanetary space.
Now, knowing the most probable speed of a nitrogen molecule and the second escape velocity, it is easy to determine the conditions under which a gas molecule will remain in orbit around the planet.
The condition must be met
or if the radius of the planet is expressed in kilometers then
Nitrogen turns into a liquid state around -200 degrees Celsius, or in Kelvin T=73 degrees.
So, substituting here the already known values, we get that nitrogen in a gaseous state can be on the surface of the planet in the case when
For the Earth, this ratio is 62435>21681 - which means nitrogen can be retained near the Earth not only at a temperature of 73 degrees Kelvin, but also at a temperature no higher than 210 degrees Kelvin (that is, about 400 degrees Celsius). If the temperature of the gas is higher, then the speed of the molecules will be higher than the second escape velocity and they will begin to fly into interplanetary space and the Earth will begin to lose its atmosphere.
What about other planets and nitrogen?
We will take the data from the summary table. Main characteristics of the planets of the solar system
For Venus (radius=6052, free fall acceleration=8.6) 52047>21681. Nitrogen can be retained by the planet.
For Mars (radius=3398, free fall acceleration=3.72) 12641<21681. Азот can't to be held by the planet.
Since Venus holds nitrogen with a molecular mass of 14 g/mol, then all the more the planet will also hold gases with a higher mass (which means, for example, oxygen, as well as methane, carbon dioxide and other derivatives..
Well - you say - but what about the heaviest gas - radon? There molecular weight is 226 g/mol!
The gas constant for radon is 36.8
Mars can retain radon with its mass if the gas temperature does not exceed 343 degrees Kelvin. Therefore, yes, Mars holds and possibly attracts radon molecules to itself, but this will not help us organize life on the planet.
At the beginning of the article, we talked about a satellite that has an atmosphere. It is a natural satellite of Saturn - Titanium. It is noteworthy that its radius is 2575 km, and the acceleration of gravity is 1.352.
That is, according to the above rules, the satellite should not have an atmosphere, but it does.
So, are our calculations wrong? I don’t think so, otherwise many fundamental formulas would have to be revised.
The reason is most likely that the satellite is close to its “mother” Saturn and the derived correspondence between the average speed of molecules and the second cosmic velocity in the presence of such a “neighbor” is not so unambiguous.
Or as a third option, that the atmosphere is “leaking” into space on the satellite, but what generates such an amount of gas is still impossible to find out.
There is some unsaidness left... so
What should we do on Mars so that there is an atmosphere there?
The generation of oxygen by powerful stations, as was the case in the science-fiction film starring Schwarzenegger, will not work... the atmosphere will eventually evaporate.
The same unfortunate option would be if you explode something on the planet, such as thermonuclear charges, as some suggest.
In order for nitrogen to remain on Mars, we need to increase either the radius of the planet or its acceleration of gravity by almost two times.
It’s impossible to increase the radius, but what about acceleration?
In the section on the question Weight of the Earth's atmosphere?? given by the author Gregory the best answer is Galileo proved the weight of air. How much does the entire atmosphere weigh? According to Pascal's calculations, it is the same as a copper ball with a diameter of 10 km would weigh - 5 quadrillion tons!
The entire atmosphere weighs 5.15 x 10 to the 15th power tons. link
Knowing the atmospheric pressure allows you to calculate the total mass of the atmosphere. Average atmospheric pressure at sea level is equivalent to the weight of a column of mercury 760 mm high. Paragraph 11 shows that the mass of a column of mercury 760 mm high above one square centimeter of the earth's surface is 1033.2 g; the same will be the weight of this column of mercury in grams. The same, obviously, will be the average weight of the atmospheric column above one square centimeter of surface at sea level. Knowing the area of the earth's surface and the elevation of the continents above sea level, we can calculate the total weight of the entire atmosphere. Neglecting changes in gravity with height, we can consider this weight to be numerically equal to the mass of the atmosphere.
The total mass of the atmosphere is slightly more than 5 10 to 21 grams, or 5 10 to 15 tons. This is about a million times less than the mass of the Earth itself. At the same time, half of the total mass of the atmosphere is in the lower 5 km, three quarters in the lower 10 km and 95% in the lower 20 km.
The Earth's atmosphere is a mixture of gases. Nitrogen 78.08%, carbon dioxide 0.03%, argon 0.9325%, oxygen 20.95%, neon 0.0018%, helium 0.0005%, hydrogen 0.00005%, krypton 0.000108%, xenon 0.000008%, ozone 0.000001%, radon 0.000000000000000006%
Source:
Reply from skinny[guru]
ATMOSPHERE OF THE EARTH (from the Greek atmos - steam and sphere), the air environment around the Earth, rotating with it; weight approx. 5.15·1015 t. Its composition at the surface of the Earth: 78.1% nitrogen, 21% oxygen, 0.9% argon, in small fractions of a percent carbon dioxide, hydrogen, helium, neon and other gases. The lower 20 km contains water vapor (near the earth's surface - from 3% in the tropics to 2·10-5% in Antarctica), the amount of which quickly decreases with height.
Reply from European[guru]
Knowing the atmospheric pressure, we determine that it is almost exactly ten tons for every square meter of the earth’s surface.
so ten tons per square meter multiplied by 511 million square kilometers = 5111859325225255.3092562483408718 tons.
I can add the following:
It is believed that for the Earth the thickness of the equivalent layer of the atmosphere is about eight kilometers
(equivalent layer of the atmosphere is an imaginary value - the thickness that the planet’s atmosphere would have if it had an atmospheric pressure of 760 mm Hg from top to bottom)
on Venus this layer is approximately 800 km; the moon has maybe one and a half to two centimeters.
