How does temperature change with height? The vertical structure of the atmosphere In the normal state of air, temperature with height

The temperature is definitely important element human comfort. For example, it is very difficult for me to please in this regard, in winter I complain about the cold, in summer I languish from the heat. However, this indicator is not static, because the higher the point from the surface of the Earth, the colder it is, but what is the reason for this state of affairs? I'll start with what temperature is one of the states our atmosphere, which consists of a mixture of a wide variety of gases. To understand the principle of "altitude cooling", it is not at all necessary to delve into the study of thermodynamic processes.

Why does air temperature change with altitude

I have known since school days that snow on top of mountains and rock formations even if they have the foot is warm enough. This is the main evidence that the high altitudes it can be very cold. However, not everything is so categorical and unambiguous, the fact is that when ascending, the air either cools down or heats up again. A uniform decrease is observed only up to a certain moment, then the atmosphere in the literal sense feverish going through the following steps:

1. Troposphere.
2. tropopause.
3. Stratosphere.
4. Mesosphere, etc.

Temperature fluctuations in different layers

The troposphere is responsible for most weather phenomena , because it is the lowest layer of the atmosphere, where planes fly and clouds form. While in it, the air freezes steadily, approximately every hundred meters. But, reaching the tropopause, temperature fluctuations stop and stop in the area - 60-70 degrees Celsius.

The most amazing thing is that in the stratosphere, it decreases to almost zero, since it is amenable to heating from ultraviolet radiation. In the mesosphere, the trend is again declining, and the transition to the thermosphere promises a record low - -225 Celsius. Further, the air is heated again, however, due to a significant loss in density, at these levels of the atmosphere, the temperature is felt quite differently. At least orbital flights artificial satellites nothing threatens.

To somewhat simplify the consideration of the issue, the atmosphere is divided into three main layers. Atmospheric stratification is primarily the result of uneven changes in air temperature with height. The bottom two layers are relatively homogeneous in composition. For this reason, they are usually said to form a homosphere.

Troposphere. The lower layer of the atmosphere is called the troposphere. This term itself means "sphere of turn" and is associated with the turbulence characteristics of this layer. All changes in weather and climate are the result of physical processes occurring in this layer. In the 18th century, since the study of the atmosphere was limited only to this layer, it was believed that the decrease in air temperature with height found in it was inherent in the rest of the atmosphere.

Various transformations of energy occur primarily in the troposphere. Due to the continuous contact of air with earth's surface, as well as the receipt of energy from outer space, it sets in motion. The upper boundary of this layer is located where the decrease in temperature with height is replaced by its increase - approximately at a height of 15-16 km above the equator and 7-8 km above the poles. Like the Earth itself, under the influence of the rotation of our planet, it is also somewhat flattened over the poles and swells over the equator. However, this effect is much stronger in the atmosphere than in the solid shell of the Earth.

In the direction from the Earth's surface to the upper boundary of the troposphere, the air temperature decreases. Over the equator, the minimum air temperature is about -62°C, and over the poles, about -45°C. However, depending on the measurement point, the temperature may be slightly different. Thus, over the island of Java, at the upper boundary of the troposphere, the air temperature drops to a record low of -95°C.

The upper limit of the troposphere is called the tropopause. Over 75% of the mass of the atmosphere lies below the tropopause. In the tropics, about 90% of the mass of the atmosphere is within the troposphere.

The tropopause was discovered in 1899, when its minimum was found in the vertical temperature profile at a certain altitude, and then the temperature slightly increased. The beginning of this increase means the transition to the next layer of the atmosphere - to the stratosphere.

Stratosphere. The term stratosphere means "layer sphere" and reflects the previous idea of ​​the uniqueness of the layer lying above the troposphere. The stratosphere extends to a height of about 50 km above the earth's surface. Its feature is, in particular, a sharp increase in air temperature compared to its extremely low values ​​in the tropopause In the temperature in the stratosphere rises to about -40 ° C. This increase in temperature is explained by the reaction of ozone formation - one of the main chemical reactions occurring in the atmosphere.

Ozone is a special form of oxygen. Unlike the usual diatomic oxygen molecule (O2). ozone consists of its triatomic molecules (Oz). It appears as a result of the interaction of ordinary oxygen with that entering the upper atmosphere.

The bulk of the ozone is concentrated at altitudes of about 25 km, but in general the ozone layer is a shell strongly stretched along the height, covering almost the entire stratosphere. In the ozonosphere, ultraviolet rays most often and most strongly interact with atmospheric oxygen. causes the disintegration of ordinary diatomic oxygen molecules into individual atoms. In turn, oxygen atoms often reattach to diatomic molecules and form ozone molecules. In the same way, individual oxygen atoms are combined into diatomic molecules. The intensity of ozone formation is sufficient for a layer of its high concentration to exist in the stratosphere.

The interaction of oxygen with ultraviolet rays is one of the favorable processes in the earth's atmosphere that contribute 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 such a level of energy is created that is suitable for the existence of terrestrial life forms. Perhaps in the past more energy was supplied to the Earth than now, which influenced the emergence of primary life forms on our planet. But today's living organisms would not have survived more significant amounts of ultraviolet radiation from the Sun.

The ozonosphere absorbs the part that passes 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 rises with height up to the upper limit of the stratosphere - the stratopause (50 km).

At altitudes from 50 to 80 km, there is a layer of the atmosphere called the mesosphere. The word "mesosphere" means "intermediate sphere", here the air temperature continues to decrease with height.

Above the mesosphere, in a layer called the thermosphere, the temperature rises again with altitude up to about 1000°C, and then drops very quickly to -96°C. However, it does not fall indefinitely, then the temperature rises again.

The division of the atmosphere into separate layers is quite easy to notice by the features of temperature changes with height in each layer.

Unlike the previously mentioned layers, the ionosphere is not highlighted. according to temperature. main feature ionosphere - high degree ionization of atmospheric gases. This ionization is caused by the absorption of solar energy by atoms of various gases. Ultraviolet and other solar rays, carrying high-energy quanta, entering the atmosphere, ionize the atoms of nitrogen and oxygen - electrons that are in outer orbits are torn off from the atoms. By losing electrons, an atom acquires a positive charge. If an electron is added to an atom, then the atom becomes negatively charged. Thus, the ionosphere is a region of an electrical nature, thanks to which many types of radio communication become possible.

The ionosphere is divided into several layers, designating them with the letters D, E, F1 and F2. These layers also have special names. The division 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 thus prevents their further propagation.

The best studied layer E is located at an altitude of about 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 farther distances than would be expected if they propagated only in a straight line, without being reflected from the E layer.

Layer F 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 is often called the exosphere.

This term indicates the existence of the outskirts of space near the Earth. It is difficult to determine exactly where the cosmos ends and begins, since the density of atmospheric gases gradually decreases with height and itself smoothly turns into almost a vacuum, in which only individual molecules meet. With distance from the earth's surface, atmospheric gases experience less and less attraction of the planet and, from a certain height, tend to leave the earth's gravitational field. Already at an altitude of about 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.

Public lesson

in natural history at 5

correctional class

Change in air temperature from heights

Developed

teacher Shuvalova O.T.

The purpose of the lesson:

To form knowledge about measuring air temperature with height, to acquaint with the process of cloud formation, types of precipitation.

During the classes

1. Organizing time

Having a textbook workbook, diary, pens.

2. Checking students' knowledge

We are studying the topic: air

Before we start studying new material, let's recall the material covered, what do we know about air?

Frontal survey

Composition of air

Where do these gases come from in the air nitrogen, oxygen, carbon dioxide, impurities.

Air property: occupies space, compressibility, elasticity.

Air weight?

Atmosphere pressure, changing it with height.

Air heating.

3. Learning new material

We know that heated air rises. And what happens to the heated air further, do we know?

Do you think air temperature will decrease with altitude?

Lesson topic: change in air temperature with height.

The purpose of the lesson: to find out how air temperature changes with height and what are the results of these changes.

An excerpt from the book of the Swedish writer "Nils' wonderful journey with wild geese" about a one-eyed troll who decided "I will build a house closer to the sun - let it warm me." And the troll set to work. He collected stones everywhere and piled them on top of each other. Soon the mountain of their stones rose almost to the very clouds.

Now, that's enough! - said the troll. Now I will build myself a house on top of this mountain. I will live right next to the sun. I won't freeze next to the sun! And the troll went up the mountain. Just what is it? The higher it goes, the colder it gets. Made it to the top.

"Well - he thinks - from here to the sun is a stone's throw!". And at the very cold, the tooth does not fall on the tooth. This troll was stubborn: if it already sinks into his head, nothing can knock him out. I decided to build a house on the mountain, and built it. The sun seems to be close, but the cold still penetrates to the bones. So this stupid troll froze.

Explain why the stubborn troll froze.

Conclusion: the closer to the earth's surface the air, the warmer it is, and with height it becomes colder.

When climbing to a height of 1500m, the air temperature rises by 8 degrees. Therefore, outside the aircraft at an altitude of 1000m, the air temperature is 25 degrees, and at the surface of the earth at the same time the thermometer shows 27 degrees.

What is the matter here?

The lower layers of air, heating up, expand, reduce their density and, rising up, transfer heat to the upper layers of the atmosphere. This means that the heat coming from the surface of the earth is poorly conserved. That is why it does not become warmer, but colder overboard, which is why the stubborn troll froze.

Demonstration of the card: the mountains are low and high.

What differences do you see?

Why peaks high mountains covered with snow, but there is no snow at the foot of the mountains? The appearance of glaciers and eternal snows on the tops of mountains is associated with a change in air temperature with height, the climate becomes more severe, and accordingly changes vegetable world. At the very top, near the high mountain peaks, there is a realm of cold, snow and ice. Mountain peaks and in the tropics are covered with eternal snow. The boundaries of eternal snow in the mountains are called the snow line.

Demonstration of the table: mountains.

Look at the card with the image of various mountains. Is the height of the snow line the same everywhere? What is it connected with? The height of the snow line is different. In the northern regions it is lower, and in the southern regions it is higher. This line is not drawn on the mountain. How can we define the concept of "snow line".

The snow line is the line above which the snow does not melt even in summer. Below the snow line there is a zone characterized by sparse vegetation, then there is a regular change in the composition of the vegetation as it approaches the foot of the mountain.

What do we see in the sky every day?

Why do clouds form in the sky?

As the heated air rises, it carries water vapor that is not visible to the eye into a higher layer of the atmosphere. As the air moves away from the earth's surface, the air temperature drops, the water vapor in it cools, and tiny droplets of water form. Their accumulation leads to the formation of a cloud.

TYPES OF CLOUD:

Cirrus

layered

Cumulus

Demonstration of a card with types of clouds.

Cirrus clouds are the tallest and thinnest. They swim very high above the ground, where it is always cold. These are beautiful and cold clouds. The blue sky shines through them. They look like long feathers of fabulous birds. Therefore, they are called cirrus.

Stratus clouds are solid, pale gray. They cover the sky with a monotonous gray veil. Such clouds bring bad weather: snow, drizzling rain for several days.

Rain cumulus clouds - large and dark, they rush one after another as if in a race. Sometimes the wind carries them so low that it seems that the clouds touch the roofs.

Rare cumulus clouds are the most beautiful. They resemble mountains with dazzling white peaks. And they are interesting to watch. Cheerful cumulus clouds are running across the sky, constantly changing. They look either like animals, or like people, or like some kind of fabulous creatures.

Demonstration of a card with different types of clouds.

What clouds are shown in the pictures?

Under certain conditions atmospheric air precipitation falls from the clouds.

What kind of precipitation do you know?

Rain, snow, hail, dew and others.

The smallest droplets of water that make up the clouds, merging with each other, gradually increase, become heavy and fall to the ground. In summer it's raining, snow in winter.

What is snow made of?

Snow is made up of ice crystals. different shapes- snowflakes, mostly six-pointed stars, fall out of the clouds when the air temperature is below zero degrees.

Often in the warm season, during a downpour, hail falls - precipitation in the form of pieces of ice, most often of irregular shape.

How is hail formed in the atmosphere?

Droplets of water, falling to a great height, freeze, ice crystals grow on them. Falling down, they collide with drops of supercooled water and increase in size. The hail is capable of causing great damage. He knocks out crops, exposes forests, knocking down foliage, destroying birds.

4.Total lesson.

What new did you learn in the lesson about air?

1. Decrease in air temperature with height.

2. Snow line.

3. Types of precipitation.

5. Homework.

Learn the notes in your notebook. Observation of the clouds with a sketch of them in a notebook.

6. Consolidation of the past.

Independent work with text. Fill in the gaps in the text using the words for reference.

Before considering the distribution of air temperature on the earth's surface in the coldest and warmest months, it is necessary to say about the change in temperature with height, since the isotherms of all localities are reduced to sea level; you need to know how this process of reduction takes place.
So far, we have been talking about the heating of the earth's surface, now we will consider the conditions for heating the air envelope in contact with this surface.
The heating of the atmosphere occurs, as we have already said, partly directly by the sun: water vapor, carbon dioxide and dust particles absorb part of the sun's rays. But, mainly, air heating occurs by transferring heat from the heated surface of the earth, by thermal conductivity and radiation. The lower the thermal transparency of the atmosphere (for example, at in large numbers water vapor or carbon dioxide in the air), the more it retains the heat emitted by the earth's surface, and the more, consequently, it heats up from the earth.
For many reasons, one would expect that the temperature in the upper layers of the air would be lower than in the lower ones: 1) the upper layers of the atmosphere are more rarefied, therefore they retain less heat received directly from the sun, and 2) air heating mainly occurs from below . But at the same time, air, like water, tends to settle down so that there are warmer and lighter layers above, and colder and heavier layers below. Indeed, the air that comes into contact with the earth's surface, when heated, expands, becomes less dense and rises, while the denser and colder air sinks. As a result of such a circulation, one would expect that the atmosphere above and below would have the same temperature (at least at some points in the day), or the temperature would rise upward. In fact, observations and experience have shown that the temperature generally decreases with height, but the reason for this decrease lies elsewhere, namely: the rising warm particles of air fall into rarer layers, therefore they gradually expand during their rise, and a certain amount of energy is spent on expansion. the amount of heat, i.e., the work of air expansion occurs due to its heat. When a mass of air in the atmosphere rises without heat from outside, or, as they say, during an adiabatic process, the temperature of this mass decreases (due to expansion) by 1 ° per 100 m rise. This provision applies to dry air, as well as to air, containing water vapor, when, upon cooling, their condensation does not yet begin. Air, steamy water, loses less: when raised by 100 m, it cools not by 1 °, but by approximately 0.5-0.4 °. This is explained by the following: if air saturated with vapor rises, then when the temperature drops (due to the expansion of air), the vapors thicken and some of them pass into a liquid state, and the latent heat of vaporization is released.
As the air descends, it heats up, because it is compressed more and more, and heat is developed due to compression. When lowering both dry and water-saturated air, the heating value is the same and equal to 1 ° for every 100 m. Observations on the change in air temperature with height are made on the mountains, on high buildings, in addition, experiments balloons, kites and airplanes, which were supplied with meteorographs - instruments that automatically record not only temperature, but also pressure, air humidity and wind speed at different heights. IN last years the temperature at altitude is studied with the help of radiosondes, as well as during flights on stratospheric balloons.
Initially, observations were made on eiffel tower, which is exposed to the action of more or less free air, and thermometers were installed so that direct radiant solar energy does not act directly on them. They were installed at a height of 2 m, 123 m. 197 m, 302 m. It turns out that during the day in lower layers atmosphere is constantly warmer than in the upper layers, and in summer, when the earth, and consequently the lower layers of the atmosphere, are very hot, the temperature decreases with every 100 m rise more than an adiabatic value, i.e. more than 1 °.
In summer, air circulation is especially vigorous and even noticeable (by eye); on a hot summer day, we see that the air seems to flow over very hot surfaces.
In this state, the air is said to be in an unstable equilibrium, being heated from the underlying surface. At night, as observations on the Eiffel Tower have shown, the air below the surface of the earth is colder than in the upper layers. Such a temperature distribution is called the lower temperature inversion, in contrast to another inversion that has become known relatively recently and is called the upper one. The lower inversion is explained by the fact that the earth radiates a lot of heat during the night and therefore cools greatly. This cooling is transferred to the lower layers of air, which become denser and flow down, trying to fill the depressions. Therefore, in mountainous areas in the valleys in winter it is very cold, and on the slopes of the mountains it is somewhat warmer. The inversion is especially pronounced during clear winter nights.
Observations at a higher altitude (about 3-4 km), where the earth's temperature no longer plays such a role, have shown that inversions exist much less frequently there. The drop in temperature with height, calculated for 100 m (vertical temperature gradient), when rising in layers of the atmosphere exceeding 2-3 km, gradually increases and reaches its maximum at altitudes of 7-10 km. There are no inversions in these high layers, and the temperature is mainly due to convection ascending and descending currents. Ascending currents give for air not saturated with water vapor, a temperature drop of 1 ° per 100 m of elevation; for air saturated with water vapor, the temperature drop is much smaller (see above). For this reason, at these altitudes, temperature gradients in winter, when there is little water vapor in the atmosphere, are greater than in summer.
At even higher altitudes (above 7-10 km), the temperature gradient begins to fall rapidly, then the temperature drop stops completely, and even a slight increase in temperature occurs ( superior inversion). Thus, the thickness of the atmosphere can be divided into two layers: the lower one, in which the temperature decreases with height, and then the upper one, where there is no such decrease, but, on the contrary, a slight increase is observed. The first - lower - layers are given the name of the troposphere, and the second - upper - the stratosphere.
On average, the boundary of the stratosphere is at an altitude of 11 km. Observations have shown that the boundary of the stratosphere rises towards the equator and falls towards the poles. So, in polar countries, the boundary of the stratosphere is at an altitude of 8-10 km, in middle Europe 11-12 km, while under the tropics it is at an altitude of 16-18 km. As a result, under the tropics in the high layers, the temperature at the same height is lower than above the poles. Obviously, the higher the boundary of the stratosphere is, the greater will be the decrease in temperature with height. The lowest temperature in the upper troposphere was found near the equator.
Observations at Batavia, a few degrees south of the equator, gave figures of about -87°, once at an altitude of 17 km even -91.9.
This is the lowest temperature ever observed in the atmosphere. Over Europe the most low temperatures rarely fall below -70°. The height of the boundary of the stratosphere also changes during the year. Its minimum height is observed in winter or in early spring, it reaches its maximum by the end of summer.
All of the above applies to upper layers atmosphere, but for an atmospheric thickness of 4-5 km, it can be assumed that the decrease in temperature with height, when raised by 100 m, is on average 0.5-0.6 per year, and this value is taken into account when the temperature is given to sea level. In the mountains and on the plateaus, when the temperature changes with height, various side circumstances matter, for example, whether the slope of the mountain faces the sun or is in the shade. Moreover, where winters are severe, the peaks often have a warmer temperature than the valleys, and this temperature inversion does not only exist at night, but continues throughout the cold period. Yes, in Eastern Siberia in winter there is a lull due to high barometric pressure, and the surface of the earth is covered with snow, which reflects a lot of heat; cold air there, due to its greater density, fills the valleys and depressions and lingers in them, while on the tops of the ridges at this time more heat. A similar phenomenon was observed in many alpine valleys protected by mountains from prevailing winds. But in general, even for mountains, one can take a decrease in temperature for every 100 m of elevation equal to 0.5 on average per year, and in summer and spring the temperature drop is faster, in winter and autumn more slowly.

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Blue planet...

This topic was supposed to appear on the site one of the first. After all, helicopters are atmospheric aircraft. Earth's atmosphere- their, so to speak, habitat :-). A physical properties air just determine the quality of this habitat :-). So that's one of the basics. And the basis is always written first. But I just realized this now. However, it is better, as you know, late than never ... Let's touch on this issue, but without getting into the wilds and unnecessary difficulties :-).

So… Earth's atmosphere. This is the gaseous shell of our blue planet. Everyone knows this name. Why blue? Simply because the "blue" (as well as blue and violet) component sunlight(spectrum) is most well scattered in the atmosphere, thus coloring it in bluish-bluish, sometimes with a hint of violet (on a sunny day, of course :-)).

Composition of the Earth's atmosphere.

The composition of the atmosphere is quite wide. I will not list all the components in the text, there is a good illustration for this. The composition of all these gases is almost constant, with the exception of carbon dioxide (CO 2 ). In addition, the atmosphere necessarily contains water in the form of vapors, suspended droplets or ice crystals. The amount of water is not constant and depends on temperature and, in lesser degree, on air pressure. In addition, the Earth's atmosphere (especially the current one) also contains a certain amount, I would say "all sorts of filth" :-). These are SO 2, NH 3, CO, HCl, NO, in addition there are mercury vapors Hg. True, all this is there in small quantities, thank God :-).

Earth's atmosphere It is customary to divide into several zones following each other in height above the surface.

The first, closest to the earth, is the troposphere. This is the lowest and, so to speak, the main layer for life. different kind. It contains 80% of the mass of all atmospheric air (although by volume it makes up only about 1% of the entire atmosphere) and about 90% of all atmospheric water. The bulk of all winds, clouds, rains and snows 🙂 come from there. The troposphere extends to altitudes of about 18 km. tropical latitudes and up to 10 km in the polar ones. The air temperature in it drops with a rise of about 0.65º for every 100 m.

atmospheric zones.

The second zone is the stratosphere. I must say that another narrow zone is distinguished between the troposphere and stratosphere - the tropopause. It stops the temperature drop with height. The tropopause has an average thickness of 1.5-2 km, but its boundaries are indistinct and the troposphere often overlaps the stratosphere.

So the stratosphere has an average height of 12 km to 50 km. The temperature in it up to 25 km remains unchanged (about -57ºС), then somewhere up to 40 km it rises to about 0ºС and further up to 50 km it remains unchanged. The stratosphere is a relatively quiet part of the earth's atmosphere. Adverse weather it is practically absent. It is in the stratosphere that the famous ozone layer at altitudes from 15-20 km to 55-60 km.

Next comes a small boundary layer stratopause, in which the temperature remains around 0ºС, and then the next zone is the mesosphere. It extends to altitudes of 80-90 km, and in it the temperature drops to about 80ºС. In the mesosphere, small meteors usually become visible, which begin to glow in it and burn out there.

The next narrow gap is the mesopause and beyond it the thermosphere zone. Its height is up to 700-800 km. Here the temperature again begins to rise and at altitudes of about 300 km it can reach values ​​of the order of 1200ºС. Thereafter, it remains constant. The ionosphere is located inside the thermosphere up to a height of about 400 km. Here the air is highly ionized due to the impact solar radiation and has a high electrical conductivity.

The next and, in general, the last zone is the exosphere. This is the so-called scatter zone. Here, mainly very rarefied hydrogen and helium (with a predominance of hydrogen) are present. At altitudes of about 3000 km, the exosphere passes into the near space vacuum.

It's like that somewhere. Why about? Because these layers are rather conditional. Various changes in altitude, composition of gases, water, temperature, ionization, and so on are possible. In addition, there are many more terms that define the structure and state of the earth's atmosphere.

For example homosphere and heterosphere. In the first, the atmospheric gases are well mixed and their composition is quite homogeneous. The second is located above the first and there is practically no such mixing there. The gases are separated by gravity. The boundary between these layers is located at an altitude of 120 km, and it is called turbopause.

Let's finish with the terms, but I will definitely add that it is conventionally accepted that the boundary of the atmosphere is located at an altitude of 100 km above sea level. This border is called the Karman Line.

I will add two more pictures to illustrate the structure of the atmosphere. The first, however, is in German, but it is complete and easy enough to understand :-). It can be enlarged and well considered. The second shows the change in atmospheric temperature with altitude.

The structure of the Earth's atmosphere.

Change in air temperature with altitude.

Modern manned orbital spacecraft fly at altitudes of about 300-400 km. However, this is no longer aviation, although the area, of course, is in a certain sense closely related, and we will certainly talk about it again :-).

The aviation zone is the troposphere. Modern atmospheric aircraft can also fly in the lower layers of the stratosphere. For example, the practical ceiling of the MIG-25RB is 23000 m.

Flight in the stratosphere.

And exactly physical properties of air tropospheres determine how the flight will be, how effective the aircraft control system will be, how the turbulence in the atmosphere will affect it, how the engines will work.

The first main property is air temperature. In gas dynamics, it can be determined on the Celsius scale or on the Kelvin scale.

Temperature t1 at a given height H on the Celsius scale is determined:

t 1 \u003d t - 6.5N, Where t is the air temperature at the ground.

Temperature on the Kelvin scale is called absolute temperature Zero on this scale is absolute zero. Stops at absolute zero thermal motion molecules. Absolute zero on the Kelvin scale corresponds to -273º on the Celsius scale.

Accordingly, the temperature T on high H on the Kelvin scale is determined:

T \u003d 273K + t - 6.5H

Air pressure. Atmospheric pressure is measured in Pascals (N / m 2), in the old system of measurement in atmospheres (atm.). There is also such a thing as barometric pressure. This is the pressure measured in millimeters of mercury using a mercury barometer. Barometric pressure (pressure at sea level) equal to 760 mm Hg. Art. called standard. In physics, 1 atm. just equal to 760 mm Hg.

Air density. In aerodynamics, the most commonly used concept is the mass density of air. This is the mass of air in 1 m3 of volume. The density of air changes with height, the air becomes thinner.

Air humidity. Shows the amount of water in the air. There is a concept " relative humidity ". This is the ratio of the mass of water vapor to the maximum possible at a given temperature. The concept of 0%, that is, when the air is completely dry, can exist in general only in the laboratory. On the other hand, 100% humidity is quite real. This means that the air has absorbed all the water it could absorb. Something like an absolutely "full sponge". High relative humidity reduces air density, while low relative humidity increases it accordingly.

Due to the fact that aircraft flights take place under different atmospheric conditions, their flight and aerodynamic parameters in one flight mode may be different. Therefore, for a correct assessment of these parameters, we introduced International Standard Atmosphere (ISA). It shows the change in the state of the air with the rise in altitude.

The main parameters of the state of air at zero humidity are taken as:

pressure P = 760 mm Hg. Art. (101.3 kPa);

temperature t = +15°C (288 K);

mass density ρ \u003d 1.225 kg / m 3;

For the ISA, it is assumed (as mentioned above :-)) that the temperature drops in the troposphere by 0.65º for every 100 meters of altitude.

Standard atmosphere (example up to 10000 m).

ISA tables are used for calibrating instruments, as well as for navigational and engineering calculations.

Physical properties of air also include such concepts as inertness, viscosity and compressibility.

Inertia is a property of air that characterizes its ability to resist changes in the state of rest or uniform rectilinear motion. . The measure of inertia is the mass density of air. The higher it is, the higher the inertia and drag force of the medium when the aircraft moves in it.

Viscosity. Determines the frictional resistance against air as the aircraft moves.

Compressibility measures the change in air density as pressure changes. At low speeds aircraft(up to 450 km / h) there is no change in pressure when the air flow flows around it, but when high speeds the effect of compressibility begins to appear. Its influence on supersonic is especially pronounced. This is a separate area of ​​​​aerodynamics and a topic for a separate article :-).

Well, it seems that's all for now ... It's time to finish this slightly tedious enumeration, which, however, cannot be dispensed with :-). Earth's atmosphere, its parameters, physical properties of air are as important for the aircraft as the parameters of the apparatus itself, and it was impossible not to mention them.

For now, until the next meetings and more interesting topics 🙂 …

P.S. For dessert, I suggest watching a video filmed from the cockpit of a MIG-25PU twin during its flight into the stratosphere. Filmed, apparently, by a tourist who has money for such flights :-). Filmed mostly through the windshield. Notice the color of the sky...