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The rarefaction of air at high altitude leads to the fact that less air enters each of the engine cylinders than under normal conditions, while the amount of fuel entering the cylinder remains practically unchanged. Thus, when working at high altitude, the mixture in the engine cylinders becomes richer. To keep the composition of the mixture unchanged, it is necessary to slightly reduce the cross section of the main jet of the carburetor. This is achieved by turning the adjusting needle of the main jet of the carburetor. The needle should be turned carefully no more than / e of a turn at a time, ensuring that the engine runs while maintaining throttle response.

Dilution of air and gases.

The rarefaction of air in the device system under the test layer should be such that the Knudsen flow regime is provided. To do this, it is necessary to check the independence of the pressure drop in the layer from the air pressure under the measured sample.

When the air is rarefied in the VZK installed on the surface of the cargo, a pressure difference is created compared to atmospheric pressure over the entire area bounded by the walls of the hermetic seal.

But one air rarefaction is not enough. The gas molecule needs to break the shackles of gravity. And for this, its speed must reach the second cosmic speed (11 3 km / sec) and be directed upwards. This speed is called parabolic, since it is known from celestial mechanics that the particles possessing it fly away along a parabolic trajectory, the focus of which is in the center of the globe.

Inside the tornado, the rarefaction of air is so great that sometimes structures that are in its path are destroyed by an explosion due to the pressure of air from the inside. The same thing happens as from the shock wave in the rarefaction phase.

To measure the rarefaction of air and other gases, a device called a vacuum gauge is usually used.

A rarefaction of air is created inside the wheel, and an increased pressure is created in the guide casing. Thus, the air suction is carried out in the axial direction, and the exhaust is carried out tangentially to the rotor.

Static and dynamic pressure. a is the work of pressure. b - head loss at the outlet.

The highest pressures or rarefactions of air are often measured in millimeters of water column. The pressure (or head), expressed in millimeters of water column, is numerically equal to the pressure in kilograms per square meter.

To measure pressure or rarefaction of air, draft pressure gauges and micromanometers are used, which are connected to the measured medium using rubber or metal (stationary connection) tubes.

When the desired degree of rarefaction of air in the fore-vacuum chamber is reached, the vacuum shutter 8 a separating the pre-chamber from the heating furnace opens and the source material is fed into furnace 8 with the help of a pusher 10, after which the shutter 8 a closes again.

Depending on the degree of rarefaction of air above the indicator liquid, a distinction is made between the aquarium method and the baroaquarium method.

In the upper atmosphere, gas is at very low pressure (the higher above the Earth's surface, the lower the pressure). Also there are very few different substances. This gas is called sparse.

technical vacuum

And a very rarefied gas is called technical vacuum.

Word check: spit

Vacuum is a certain region of space without matter.

Generally speaking, there is no ideal vacuum in nature. Indeed, even in outer space, where, it would seem, there is nothing, hydrogen atoms are still found (a couple of atoms per cubic centimeter).
But in theory, it is still possible to achieve such an ideal, on a meager scale.

A technical vacuum is a gas that is at a pressure lower than in the surrounding space. Well, for example, this is easy to achieve in some vessels or in a pipeline. There are various vacuum pumps for this purpose.

For living organisms, being in a vacuum is deadly. Death occurs within minutes due to hypoxia (lack of oxygen).

The rarefied state of the air

In addition to the fact that rarefied air does not contain enough oxygen to breathe, there are many other reasons why it is dangerous. For example, low air temperature. And so low that a person can freeze to death. It is in the most rarefied space that the lowest temperature is observed - in space (-273.15 ° C - absolute zero).

And rarefied air is dangerous with low pressure. Because of it, you can find yourself in a situation where you can not take a breath. This happens because the rarefied air has a much lower pressure than in your lungs. Because of this, one of the laws of partial pressure of gases comes into force. It states that gas will tend to flow from an area of ​​high pressure to an area of ​​low pressure. That is, from our lungs to the surrounding space. It is for this reason that it is so difficult to breathe in the mountains, because you have to make considerable efforts in order to win oxygen from the surrounding space, while it seeks to pull it out of your lungs.

How can you improve your life and help defuse tension?

• 14:04, 05 April 2014,
• Health

There are days when we seem to have everything, but something is missing. We do not understand the plans and intentions. In addition, we are in a bad mood because, for example, we got up on our left foot. Everything we don't do goes wrong.

Thin out carrots check word

Like there is no power. Hot discussions and disputes, as well as a big adventure, bring practically nothing. External factors are annoying, such as: a neighbor turned on the radio too loudly, a dog barks in the street, there is a big mess in the house and you are to blame for everything.

Such moments are best sweetened with small joys. Set aside the work you took home and haven't done yet. Just sit quietly and think. It may be that it is better to postpone important things until tomorrow, because today you will not be able to solve these problems.

It may be better, even for an hour or two, to leave the child with the grandmother and go on a shopping trip herself or just take a walk and get some fresh air.

Sometimes we need to let our nerves rest. At such times, it is best to deal with pleasure. It takes time to rest, and from tomorrow - to start all over again.
Think about when life gives you pleasant moments, what makes you relaxed, what makes you smile, imagine that you see life in other colors.

You can continue the list yourself. Each of us loves something different. You just have to discover what will save you from boredom, moments when you have a good sense of humor, when you don't have tears in your eyes, or when you really know what to do. Small pleasures can really help and make problems invisible, or look at them from a different, better side.

Here are some examples of how you can improve your life and help defuse tension:

- Drink green tea, it's really soothing, and even better when it's mint.

- Just sleep during the day;

- Go shopping, you can go shopping without a specific purpose, just look at the goods, then there is definitely no need to buy.

- Turn on your favorite music.

- Take a relaxing bath.

- Visit a hairdresser or beautician.

Eat chocolate or order something tasty to eat.

- Take care of gardening, especially mowing grass, watering flowers, feeding pets. leave a comment

Rhyming words for "air"

Discharge in the boiler furnace

When purchasing private houses, many build stoves for space heating. A stove or boiler must have a firebox or firebox. This is the zone in which the combustion of the material occurs. If there is not enough oxygen, then heating will be carried out with large heat losses. Vacuum in the boiler furnace or draft is one of the most important parameters. There are rules by which it is measured, increased, reduced if necessary.

Traction as a physical phenomenon

Before considering the design features of the furnace, you need to understand what vacuum in the furnace is. Vacuum or thrust is a decrease in the pressure of combustion products, air, due to which the flow of the medium through the channels of the structure into the low pressure zone is ensured. It is customary to distinguish between two types of traction: (See also: Do-it-yourself furnace furnace repair)

• natural - carried out under the influence of Archimedean force. Air enters the furnace or boiler directly to the burner or grate. During combustion, hot air is generated. Partly it is cooled by the influx of new air, partly by contact with the walls of the furnace. Hot air will rise up the pipe. The longer the pipe, the stronger the pull.

To control the process, you can block the hole through which new air enters. Very often in small domestic boilers and stoves, the natural draft is so good that it even needs to be reduced. The only drawback is that the higher the ambient temperature, the lower the vacuum. And also with poor adjustment of cold air there will be so much inside that the oven will not warm up;

• forced - with the help of special mechanical devices. Usually, smoke exhausters are used to create it - bladed mechanisms, fans. The disadvantage of such a device is that the vacuum drops as you move away from the mechanism, and the advantage is that by controlling the rotation speed, you can change the thrust.

(See also: Briquettes for furnaces)

The smoke exhauster requires a lot of electricity, makes noise during operation. For small stoves and boilers, it is better to choose options with fans. Usually, along with forced draft in any system, natural draft will also be present, but they are not always co-directional.

Firebox dimensions for excellent combustion

When laying out the stove yourself, you need to know how to properly arrange the firebox. Also, this knowledge may be required when choosing a firebox. The firebox is a rectangular chamber inside which fuel burns. There are always very high temperatures, and therefore special materials must be used. The standard dimensions are 25x38 cm. The height is about 80 cm. Most often, the chamber is used for burning firewood, peat, and coal.

The design is such that the vacuum in the boiler furnace is uniform. The furnace has an obligatory part - a grate, as well as a blower. The grate is located slightly below the fuel loading door. Firewood, peat, combustible materials will lie on it. Holes are made in it to ensure air flow. A blower is a hole in the furnace below the firebox, which is needed to improve traction. The lower part of the firebox under the grate is an ashpit where waste will be collected. (See also: How to increase chimney draft)

There are three subtleties that determine the size of the furnace furnace:

1. Creation of maximum temperature. The higher the temperature in the furnace, the more productive the combustion will be. Temperature is very dependent on size. A wide firebox is bad because the products of combustion in the form of soot will quickly rise up and settle on the walls of the pipe, worsening traction, and it will also not have time to warm up. Efficiency is calculated for both furnaces and boilers. Modern designs allow you to reach 90% for wood-burning fireboxes. To reproduce such conditions, you need to make the width of the firebox about 25 cm, and the length is what is needed for the log. Usually the depth ranges from 50 to 63 cm.
2. Use of refractory bricks for the inside of the firebox. It is easy to create a structure of any dimensions from this material, and the material also withstands high temperatures well.
3. Firebox height. It should be as high as the flame is possible. Usually the flame from wood is higher than the flame of coal. If the stove is used as a stove, then the height of the furnace does not exceed 40 cm, and for heating the room it is better to choose 70 cm.

Vacuum measurement

In boiler rooms, emergency situations are highly undesirable, since a lot depends on them, there may be casualties among the maintenance personnel. But even in a small house, the stove or boiler should work properly. Many sensors constantly monitor the operation of the device. There is a vacuum sensor in the furnace. There are several different designs of the sensor, the main thing is that it works properly.

The sensor can measure the resolution, or react when a certain value is exceeded. At enterprises, the signal from the sensor is transmitted to the notification device: light, sound, electromagnetic. And employees or automation take measures to stabilize the situation. For example, the flow of air or fuel may be reduced. The measures taken depend on the design of the particular boiler or furnace.

The first furnace furnace and draft test

After the stove has been folded, two things need to be done: let it dry and determine the quality of the draft. It takes a week to dry the oven. For this period, all doors are left open, the furnace blower. You can burn paper and wood chips in small quantities. If you do not let it dry qualitatively, it is possible that the material will crack in the future.

To find out how much heat the stove will give, a draft test is carried out. It depends on:

• smoothness of the inner walls, including the walls of the furnace and chimney;
• pipe height - not less than 5 meters. Usually use the recommendation that the higher it is, the better.

Trial fireboxes are carried out slowly. First they always burn paper and wood chips, and then they set fire to firewood. Smoke may occur in the room. This indicates not very good traction. Sometimes the problem is solved by burning paper or wood chips in the chimney.

Gpasnye, checked by stress (difficult cases)

Crimson flame indicates incomplete combustion of fuel. A lot of soot will form, settling in the chimney and narrowing the hole.

If the fire is straw-yellow and the smoke is colorless, then the stove is built correctly. You can check the traction using a special device. If it is not available, then plain paper can be used. A sheet or strip of paper is carefully brought to the open firebox door. If it deviates towards the firebox with an air flow, it will be pulled inward, then there are no problems. A well-built stove can be decorated with a mantel clock. It will not only heat the room, but also be aesthetically attractive.

Finished fireboxes

In order not to torment yourself with the question of choosing the size of the firebox for good traction, you can purchase ready-made options. Today the market presents a wide range of such products. The advantage of such a firebox is that it is made according to all the rules, reliable, and easy to assemble.

From the META group

As many as four options for fireplace inserts are produced by META:

• ARDENFIRE - META cast iron fireboxes made in France. This model has heat-resistant glasses for monitoring the process. They have good heat dissipation and are durable. All connectors are additionally sealed with a special cord.
• EUROKAMIN - all models are assembled from parts made in Europe. They are also equipped with special glasses. The furnace is distinguished by good heat dissipation, resistance to high temperatures.
• METAFIRE - inserts designed for fireplaces. The base is made of steel, the chamber is additionally laid out with refractory plates. The fireboxes in these models can be adjusted in height, glass is also built in. The price and quality of these models are well balanced.
• Caminetti is one of the novelties. The cast-iron fire chamber is lined with high-quality steel from within. Has heat resistant glass. It is characterized by rapid heating of the room, has small dimensions, aesthetically beautiful.

From Keddy

Swedish engineers are renowned for their ability to work with cast iron. Keddy fireboxes are distinguished by the quality of the cast iron used in the first place. The technologies for its production and processing are classified. For a very long time they have mastered the intricacies of working with this material. For this reason, each of their products is distinguished by:

• high efficiency. Heating the room begins at the moment when the fire is just kindled. In addition to cast iron, the construction uses Olivi stone, which accumulates heat and gives it away for a long time;
• reduced fuel consumption. The temperature will be maintained indoors for a long time without the need to frequently add fuel:
• durability. Any product will withstand more than one year of work, a guarantee of up to 10 years.

logical outcome

The vacuum in the furnace ensures uniform heating of the room. This is a common physical process, which is sufficient for heating in small houses. The quality of draft is largely determined by the shape and dimensions of the firebox. It can be either folded by hand or bought ready-made. The advantages of a finished one are that its design is designed to maximize efficiency. Depending on the intended fuel, the design of the furnace may vary.

A preliminary firebox is needed in order to determine the quality of traction. In the future, if constant monitoring of this parameter is required, special sensors are used. Depending on the type of boiler or furnace, sensors of different designs are used.

When the fireplace or stove is ready, they need to be decorated. Today it is not just a device for heating, but also part of the interior. Porcelain mantel clocks are often purchased. This is a durable material that is not afraid of high temperatures near the fireplace.

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Examples of the use of the word defuse in the literature.

Pantagruel Panurge Fatal madman, High note madman, natural madman, bekar and flat madman, heavenly madman, earthly madman, jovial madman, cheerful and playful madman, mercurial madman, mischievous and beautiful madman, lunatic madman, pom-pom madman, erratic madman , madcap with scalloped, eccentric madcap, madcap with bells, ethereal and youthful madcap, smiling and howling, venereal-obedient, arctic madcap, settled madcap, heroic madcap, madcap right from under the winepress, brilliant madness, first-time madness, predetermined madness, madness fermentative, august madcap, double-stranded madcap, Caesarian madness, papal madness, imperial madness, consistorial madness, royal madness, conclave madness, royal madness, bullist madness, patriarchal madness, synodal madness, loyal madness, madness d episcopal, crazy

And Panurge picked up: - Unchanging and excellent madcap, Pantagruel Panurge Fatal madcap, High note madcap, natural madcap, bekar and flat madcap, heavenly madcap, earthly madcap, jovial madcap, cheerful and playful madcap, mercurial madcap, mischievous and beautiful madcap , madcap lunatic, madcap with pom-poms, madcap erratic, madcap with festoons, eccentric madcap, madcap with bells, ethereal madcap and smiling and Juno madcap, venereobedient, arctic madcap, settled madcap, heroic madcap, madcap right from under the winepress, genius madcap , extravagant madman, predetermined madman, fermenting madness, august madness, double-stranded madness, Caesarian madness, papal madness, imperial madness, consistorial madness, royal madness, conclave madness, monarchical madness, bullist madness, patriarchal madness , synodal madman

The houses were discharged like women, buffoons and butterflies, the letters peeped out of the acanthus curls, forming a moral, and officials, in accordance with the requirements of the most rigorous realism, were twice as tall as commoners.

Soon, out of the unique mess of her bedroom, discharged like a halberdier, Virginia.

And captain Gonsovsky, having ordered to cover the carts with a tarpaulin and not to leave a single grain in the barn, returned to the apiary, saw the chain tightened under the barn, grinned, bent down, put the muzzle into the hole and discharged the whole circle.

Kroon came to laugh in the face of all this discharged a crowd of cesareans and cesareans, princes and princesses, courtiers, ministers, senators, curators, plebeian delegates and other scoundrels feasting on the blood and sweat of enslaved peoples!

An arrow whistled just above my ear, a crossbowman discharged his weapon into the silhouette that appeared on the spiral staircase - the magician already raised his hands, preparing to cast a spell.

Saying goodbye, Badmaev took from his secretary, a large, discharged as a bogdykhan of a baptized Chinese named Nikolai Ivanovich Tifontai, as he introduced him, a morocco folder with a note about his proposal and asked him to pass it on to the emperor.

Cairo minion of fate was discharged to smithereens, handsome as a rooster, - here he was buried by a Russian bullet.

Discharged The Basque, in a tailcoat, in short trousers, in white stockings and white gloves, decorated each dish with wreaths of roses before being brought to the table. Jean Valjean, showing him his bandaged hand, instructed him to explain the reason for his departure and left the house.

This neighborhood of St. Petersburg, relatively quite deaf, not yet poisoned by the railway, music, theater, crowds, discharged dacha ladies and the vain bustle of fashionable summer cottages, Voshchinin liked its silence and the proximity of the sea, and for the fifth summer he spent vacations in this place with Tanechka, his only daughter, from a short and not particularly happy marriage with her late beautiful mother.

But the main thing is that you will be warmed by the knowledge that during this night you freed yourself from such an explosive bomb in your hold that you could not discharge no spas, no costly treatments over the years.

Our ringleader was second goalkeeper Jerry Chivers, who often knew how to joke discharge environment.

Curious specimens of ocean fauna got into the net this morning: a clownfish from the family of hand-finned fish, nicknamed the clown for its comical movements, triggerfish girded with red ribbons, a poisonous pufferfish capable of inflating, olive lampreys, silver-scaled garfish, threadtails with highly developed electrical organs, not inferior in strength to the organs of the hymnot and stingray, greenish cod gobies of various species and, finally, several larger fish: fathead with a convex head, a whole meter long, many excellent mackerels, discharged in silver and azure, three magnificent tunas, which were not saved from the net by the speed of their movements.

Other indescribable machines scattered across the deserted plateau came to life, discharged their batteries and released hysteresis currents in the direction of the man rolling head over heels.

Vacuum or vacuum

"In thin air" (Into Thick Air) can be attributed to that small category of books where you should not skip the author's preface, and as you read it, it will be supplemented by revelations, rethinking, confessions of mistakes. I have already reviewed what I read earlier, which was, to an even greater extent, a literary apology and an attempt to present my vision of the tragedy that unfolded on the slopes of Everest spring 1996 of the year. Krakauer, in fairness, admits his own mistakes, especially the lack of enterprise and commitment that could have saved the life of at least one of his mountaineering colleagues. Although the book as a whole relies heavily on the emotional projection of events, the author does not make himself white and fluffy innocent. Among the numerous prerequisites for the tragedy, he refers, among other things, to his lack of zeal.

Twenty years ago, Krakauer was a freelance journalist, having the most interesting form of collaboration with Outside magazine, which found its niche in the topic of active lifestyle. It is curious to read that he was a representative of the middle class and was inferior to most of the participants in commercial ascents of Everest in social status and income. In fact, the journalist could not afford the $65,000 service and his participation was the result of a mutually beneficial arrangement. The magazine first discussed mountain climb coverage with Scott Fisher and his Mountain Madness. After a more interesting option for money offered Robb Hall, and the correspondent changed camp.

After returning home in May 1996, Krakauer, in hot pursuit, wrote quite a lot of material within a month, which became the sensational basis of one of the monthly issues of Outside. After that, he almost immediately set to work on the book, which he announced to his colleagues. Friends, among them survivors of the expedition, discouraged John from such a fleeting monograph, while the wounds were still too painful. Moreover, such serious incidents are usually not fully disclosed until years later, when all those involved have expressed their point of view. As the author himself writes in the preface, he was in a constant state of stress and guilt, and, as it seemed to him then, by publishing the book he could subjectively buy back a little of his conscience. It is likely that it is dark, and some part of the pursuit of commerce was present.

Who is to blame for the tragedy?

As in any other work of art, claiming the interest of readers and discussion, a simple presentation of events. There must be intrigue, and while millions of people die of starvation and disease every year, few can be seriously interested in the question of who is to blame for this tragedy. Eight climbers have lost their lives on the slopes of the world's highest mountain, and public opinion fueled by interest must place the blame on something or someone. In fairness, although the author is not distinguished by complete objectivity, let alone impartiality, he considers a whole set of events, a chain that led to sad consequences that year. I'm not going to spoil the impressions and retell, I'll just give brief annotations.

- Sherpas. Religiosity. Sagarmatha. Frankly, before reading Krakauer's book, I considered Sherpas and simply called all porters of Asian appearance who helped on expeditions. Here, this nationality, its history, contribution to the Himalayan ascents, its bright personalities are described quite interestingly. A separate reason for curiosity is religious prejudice. As an example, we can cite such an insider detail from Krakauer as an intimate relationship between two clients. The Sherpas considered this disrespectful to the god of the mountain and the cause of all the trouble, instead of taking matters into their own hands when needed. After the death of their compatriot, the brave Asians bring food to his body for another three days.

- Atantoliy Bukreev. I will not quote popular sayings of third parties, which can be found in every second article on the topic. Along with this, criticism of the famous Soviet climber has become one of the stumbling blocks in the criticism of Krakauer's book. A year later, Boukreev himself outlined his vision of what happened in another book, and it is the reader's prerogative to decide who was right. On the one hand, the author criticizes the guide of the "Mountain Madness" expedition for insufficient attention to clients and early descent from the summit, on the other hand, he acknowledges the heroic deed of Bukreev, who saved several lives.

— Rob Hall and Scott Fisher. To paraphrase the phrase about students and teachers, only the expedition leaders themselves can be bad. It is noteworthy that among the eight people who died that day on the mountain (including the Indian-Tibetan border guard), two are just the leaders of the hikes, one of the most experienced high-mountain guides of their time. They had different characters and different fates, which led to that day above the clouds. Whether it was a matter of a desire to earn more money, not to lose perspective, in personal grievances and ambitions - this is what the author is trying to analyze. By the way, those who watched the film remember Rob Hall's wife, played episodically by Keira Knightley. This then pregnant woman and a brave climber herself - she accompanied her husband in climbing Everest in 1993.

— Commercialization of Everest. In fact, it is this theme that is the leitmotif of the entire book and a kind of connecting link. Krakauer gives a very interesting background to the development of the Himalayan peaks and especially the Chomolungma. And not in the format of mean and boring facts, but in fascinating fiction. Already twenty years ago, commercial expeditions became a hot topic of debate among the climbing community. And agreements on the removal of tons of garbage from the slopes every season are a vivid confirmation of this. Krakauer even gives unpleasant details of the filthiness of one of the intermediate camps, where everything is literally drowning in defecation. The level of preparedness of all clients is also very different, and not always experienced climbers with eight-thousanders behind them go to storm the highest point of the roof of the world.

The amount of oxygen and nitrogen sharply decreases with height. It's all about the pressure difference between the upper and lower layers of the atmosphere. The upper layers put a lot of pressure on the lower ones, so there is much more air in the latter and its pressure is lower. Climbers, climbing to great heights, experience some difficulties.

It all depends on the height at which the person is located. If it does not exceed 1 km, the difference is almost imperceptible, and there will be no harm to the body. An altitude of 1 to 3 km also cannot harm a healthy person (the body easily compensates for the lack of oxygen). Sick people, especially those who suffer from asthma, should not go on such a dangerous journey.

At an altitude of 5 to 6 km, the body of a healthy person mobilizes all systems and makes them work in an enhanced mode due to a lack of oxygen. A trained person copes with such a height, so various research bases and observatories are often located here. Healthy sleep and proper nutrition help the body of scientists to cope with a stressful situation.

Places located at an altitude of 7 km and above are unsuitable for human life. There is so little oxygen here that the blood cannot fully deliver it to all organs. They begin to experience oxygen starvation. A person feels tired, headache, general condition worsens. At an altitude of 8 km and above, a person can spend no more than 3 days.

Life in the mountains

Mountain dwellers are much healthier and live longer than plain dwellers. What explains this? Oxygen is by nature a strong oxidizing agent. Any oxidizing agent in the body, to a greater or lesser extent, causes its aging. But a person cannot live. To improve health, you need a slightly lower oxygen content in the air than on the plains.

The optimal height for a comfortable life is about 1500 meters above sea level. The body experiences a slight oxygen starvation, which includes all systems in an enhanced mode. Improves blood circulation and ventilation of the lungs, increases the level of hemoglobin in the blood.

American scientists have noticed that people living in the mountains are characterized by guttural sounds in speech. At high altitude, it is much easier to make such sounds, since for this you need to compress the air in the throat. This is easiest to do precisely in the highlands, since the air here is thinner than on the plains.

Air density is not the same. Where it is smaller, the air is rarefied. Let's find out what rarefied air means and what features it is characterized by.

Gaseous shell of the Earth

Air is an intangible, but extremely important component of our planet. It participates in the process of energy exchange, supporting all the vital functions of organisms. It promotes the transmission of sounds, prevents the Earth from hypothermia and protects it from the excessive influence of solar radiation.

Air is the outer shell of the planet, called the atmosphere. It consists of many gases: neon, argon, hydrogen, methane, helium, krypton, etc. The main share is oxygen and nitrogen, which make up from 98% to 99% of air.

The ratio of gases and their number may vary. So, because of exhausts of cars and emissions of factories, urban air is more saturated with carbon dioxide. In forests, in areas where there are no industries, the amount of oxygen increases. But in the pasture area, the proportion of methane that cows emit during digestion is growing.

Air density

The density of the gaseous envelope is affected by many factors; it differs in different parts of the planet and at different heights. Air with low density is rarefied air (from the word "rare"). The rarer it is, the farther its molecules are from each other.

Density shows how much air is in one cubic meter of volume. The value of 1.293 kilograms per cubic meter under normal conditions and dry air is chosen as the standard for this value.

In physical science, it is customary to distinguish between specific and mass density. Specific defines, in one cubic meter. It depends on the geographic latitude and inertia from the rotation of the planet. Mass is determined based on barometric pressure, absolute temperature and specific gas constant.

The main patterns of occurrence and principles of rarefied air are described by the law of Gay-Lussac and Boyle-Mariotte. According to them, the higher the temperature and the lower the pressure, the rarer the air. At the same time, its humidity is also important: with its increase, the density decreases.

Thin air and altitude

The force of gravity of the Earth, like a magnet, attracts all the bodies available to it to itself. Therefore, we walk, and not chaotically hover in space. Therefore, more molecules of matter are collected at the bottom, which means that its density and pressure are also higher at the earth's surface. The farther away from it, the lower these figures.

Have you noticed that with climbing to great heights, for example in the mountains, it becomes harder to breathe? All because of the rarefied air. With height, the total oxygen content in one liter of air decreases. It does not saturate the blood properly, and we experience difficulty in breathing.

The height of Mount Everest is 8488 meters. At its summit, the air density is one third of the standard density at sea level. A person can notice changes already at an altitude of 1500 to 2500 meters. Further, the change in density and pressure is felt more acutely and already poses a potential health risk.

The most rarefied air is characteristic of the exosphere - the outer layer of the atmosphere. It starts from an altitude of 500-1000 kilometers above. It smoothly passes into outer space, where space is close to a state of vacuum. The pressure and density of gas in space is very low.

Helicopter and rarefied air

A lot depends on the density of the air. For example, it defines a "ceiling" for lifting above the earth's surface. For a person, it is ten thousand meters. But to rise so high, a long preparation is necessary.

Aircraft also have their limits. For helicopters, it is about 6 thousand meters. Much less than airplanes. Everything is explained by the design features and the principles of operation of this "bird".

The helicopter acquires lift with the help of propellers. They spin, dividing the air into two streams: above them and below them. In the upper part, the air moves in the direction of the screws, in the lower part - against. Thus, the density under the wing of the apparatus becomes greater than above it. The helicopter seems to rest on the air below it and takes off.

Rarefied air does not allow you to create the desired pressure. Under such conditions, it will be necessary to greatly increase the engine power and the speed of the propellers, which the materials themselves will not withstand. As a rule, helicopters fly in denser air at altitudes of 3-4 thousand meters. Only once did the pilot Jean Boulet raise his car to 12.5 thousand meters, however, the engine caught fire.