It is known that Atmosphere pressure during horse racing affects a person’s well-being and health. Every third inhabitant of the Earth is affected by the attraction of air to the surface.
Let's figure out what this concept is and why it negatively affects well-being.
What is atmospheric pressure and how is it measured?
The definition of atmospheric (barometric) pressure is the pressure of air on objects present in it and on the surface. It is measured with barometers or thermohygrometers.
The following units are used:
- bars (1 Ba = 100 thousand Pa);
- Pascals (kPa, hPa, mPa);
- mm mercury(1 mmHg = 133.3 Pa);
- atmosphere (1 at = 98066 Pa);
- kg force per cm 2 (1 kgf/cm 2 = 98066 Pa).
Assuming air temperature remains constant, pressure decreases exponentially as it rises. For altitudes up to approximately 100 km it is calculated by the formula:
p h—pressure at a certain height, Pa;
p 0—surface pressure, Pa;
ρ 0 — density of air masses at zero altitude;
h—height, m;
g is a constant equal to 9.80665;
e is the base of the natural logarithm, a constant equal to 2.71828.
This is interesting: the maximum pressure at sea level was recorded on December 31, 1968 in the village of Agata Krasnoyarsk Territory and reached 812 mm. rt. Art. Lowest value took place on September 24, 1958 in the center of the typhoon near the Philippines and did not exceed 654.8 mm. rt. Art.
Normal atmospheric pressure
Normal pressure is 760 mmHg. Art. At the same time, people feel comfortable or feel good.
The pressure is unstable and fluctuates daily. However, the body is able to calmly withstand a wide range of values. Thus, in Mexico City the average value is no more than 570 mm Hg. Art. (due to being at a significant altitude).
The changes are not felt by people. Let’s say that at night the mercury rises by 1-2 units. Jumps of 5-10 or more points can cause painful sensations, and sudden strong fluctuations can even lead to death. For example, loss of consciousness occurs when the pressure drops by 30 points, i.e. at an altitude of 1000 meters.
A continent or a specific country can be divided into zones with different rates of indicator. The optimal value is determined by the area of permanent residence. The human body is capable of adapting to unusual natural conditions.
Banal acclimatization at resorts serves as an example of this. Sometimes a person is unable to change his mind. Thus, those living in the mountains experience bad feeling in low-lying areas, no matter how long they lived there.
Thus, the value of the standard pressure is clearly established. And comfortable matters wide range. It is individual and determined by the familiar environment. With prolonged acclimatization, the negative effects are minimized.
High and low atmospheric pressure
Low values cause symptoms similar to those associated with climbing uphill. Lack of oxygen causes shortness of breath, the pulse becomes faster, and pain occurs in the temples. painful sensations and squeezes his head.
All this poses a threat to those suffering from hypertension and atherosclerosis, as it causes blood thickening, lack of oxygen and an increase in the number of blood cells. The heart and blood vessels function in an enhanced mode, which contributes to an increase in blood pressure, tachycardia and arrhythmia. Very dangerous for elderly people.
Dizziness and migraines are also common, and the risk of attacks is greater in those suffering from allergies and asthma. Less susceptible, healthy and persons young feel the desire to sleep and lack of strength.
In areas of higher values, the weather is calm, there are almost no clouds in the sky, and wind gusts are not strong. The weather is dry and hot.
In zones low pressure a lot of clouds, rainy and windy. Due to such areas, it is cool in the summer with rain, there are a lot of clouds in the sky, and in the winter it snows.
The large difference in the two zones is a factor in causing hurricanes and storms.
Elevated values have a detrimental effect on those suffering from low blood pressure blood, negatively affect digestion, heart and blood vessels.
Atmospheric pressure is normal for humans
People can get used to change. There is no need to be upset if you find out that you live in a region of low pressure. Let’s say that the inhabitants of skyscrapers do not feel a decrease, although a rapid rise of 100 m is very stressful.
In the Central Asian zone, the norm is slightly reduced (715-730 mm Hg). For middle zone RF norm will be 730-770 mmHg. Art.
The body can adapt to different heights. According to doctors, if the pressure is not extremely dangerous action on people, then this is a variant of the norm. It all depends on adaptation. Doctors often consider values from 750 to 765 mm Hg to be normal. Art.
In Moscow the norm is 747-749 mm Hg. Art.
Since Novosibirsk is located at an altitude of 120-130 m, 750 mm Hg is considered the norm. Art.
In Samara - 752-753, in St. Petersburg - 753-755 mm Hg. Art.
Norm in Nizhny Novgorod in the trans-river zone - 754 mm Hg. Art., in Nagornaya - 747.
It is worth noting: there is no overall best indicator. There are territorial norms. People are able to tolerate jumps in values without pain if it goes away gradually.
The healthier the lifestyle and the more often one manages to maintain a daily routine (getting up, sleeping long at night, following a regular diet), the less susceptible a person is to meteorological dependence.
Man is far from being the king of nature, but rather its child, an integral part of the universe. We live in a world where everything is strictly interconnected and subordinated to a single system.
Everyone knows that the Earth is surrounded by dense air mass, which is commonly called the atmosphere. And any object, including the human body, is “pressed” by an air column having a certain weight. Scientists have experimentally established that for every square centimeter human body exposed to atmospheric pressure weighing 1.033 kilograms. And if you carry out simple mathematical calculations, it turns out that the average person is under pressure of 15,550 kg.
The weight is colossal, but, fortunately, completely imperceptible. This may be due to the presence of dissolved oxygen in human blood.
What is the effect of atmospheric pressure on humans? Let's talk a little more about this.
Atmospheric pressure standard
Doctors, when talking about what atmospheric pressure is considered normal, indicate a range of 750....760 mmHg. Such a scatter is quite acceptable, since the planet’s topography is not perfectly flat.
Meteor dependence
Doctors say that some people's bodies are able to adapt to any conditions. They don’t even care about such serious tests as long-distance flights on an airplane from one climate zone to another.
At the same time, others, without leaving their apartment, feel the approach of changes in the weather. This can manifest itself in the form of severe headaches, unexplained weakness, or constantly wet palms, for example. Such people are more often diagnosed with diseases of the blood vessels and endocrine system.
It is especially difficult when atmospheric pressure makes a sharp jump over a short time. According to statistics most of people whose bodies react so violently to changes in atmospheric pressure are women living in major cities. Unfortunately, the harsh rhythm of life, overcrowding, and the environment are not the best companions for health.
If desired, you can get rid of addiction. You just need to show persistence and consistency. Everyone knows the methods. These are the basics of a healthy lifestyle: hardening, swimming, walking and running, healthy eating, adequate sleep, elimination bad habits, weight loss.
How does our body react to increased atmospheric pressure?
Atmospheric pressure (normal for humans) is ideally 760 mmHg. But this figure is very rarely maintained.
As a result of the increase in pressure in the atmosphere, clear weather, there are no sudden changes in humidity and air temperature. The body of hypertensive and allergy sufferers actively reacts to such changes.
In city conditions, in calm weather, gas pollution naturally makes itself felt. The first to feel this are patients who have problems with the respiratory organs.
An increase in atmospheric pressure also affects the immune system. Specifically, this is expressed in a decrease in leukocytes in the blood. A weakened body will not easily cope with infections.
Doctors advise:
Start your day easy morning exercises. Take a contrast shower. For breakfast, give preference to foods high in potassium (cottage cheese, raisins, dried apricots, bananas). Don't indulge in large meals. Don't overeat. This day is not the best for great physical effort and expression of emotions. When you come home, rest for an hour, do routine household chores, and go to bed earlier than usual.
Low atmospheric pressure and well-being
Low atmospheric pressure, how much is it? To answer the question, we can conditionally say if the barometer readings are lower than 750 mmHg. But it all depends on the region of residence. In particular, for Moscow the figures are 748-749 mmHg. are the norm.
Among the first to feel this deviation from the norm are “heart patients” and those who have intracranial pressure. They complain of general weakness, frequent migraines, lack of oxygen, shortness of breath, and pain in the intestines.
Doctors advise:
Bring yours back to normal arterial pressure. Reduce physical activity. Add ten minutes of rest to every working hour. Drink fluids more often, preferring green tea with honey. Drink morning coffee. Take herbal tinctures indicated for heart patients. Relax in the evenings under a contrast shower. Go to bed earlier than usual.
How changes in humidity affect the body
Low air humidity of 30–40 percent is not beneficial. It irritates the nasal mucosa. Asthmatics and allergy sufferers are the first to feel this deviation. In this case, moisturizing the mucous membrane of the nasopharynx with a slightly salted aqueous solution can help.
Frequent precipitation naturally increases air humidity to 70 - 90 percent. This also has a negative impact on health.
High air humidity can cause exacerbation of chronic kidney and joint diseases.
Doctors advise:
Change the climate to a dry one if possible. Reduce the time you spend outside in wet weather. Go out for a walk in warm clothes. Remember the vitamins
Atmospheric pressure and temperature
The optimal temperature for a person in a room is no higher than +18. This is especially true in the bedroom.
How does it work out? mutual influence atmospheric pressure and oxygen?
In the event of an increase in air temperature and a simultaneous decrease in atmospheric pressure, people with cardiovascular and respiratory diseases suffer.
If the temperature decreases and the atmospheric pressure increases, it becomes worse for hypertensive patients, asthmatics and those who have problems with the stomach and genitourinary system.
In the event of a sharp and repeated temperature fluctuation in the body, unacceptable a large number of histamine, the main trigger of allergies.
Good to know
Now you know what normal atmospheric pressure is for a person. This is 760 mmHg, but the barometer records such indicators very rarely.
It is also important to remember that the change in atmospheric pressure with altitude (at the same time it rapidly decreases) occurs quite sharply. It is precisely because of this difference that a person climbing a mountain very quickly can lose consciousness.
In Russia, atmospheric pressure is measured in mmHg. But the international system accepts pascals as a unit of measurement. In this case, normal atmospheric pressure in pascals will be equal to 100 kPa. If we convert our 760 mmHg. in pascals, then the normal atmospheric pressure in pascals for our country will be 101.3 kPa.
Atmospheric pressure units
|
Unit designation |
Relation to SI unit – pascal (Pa) and others |
|
Millimeter of mercury (mmHg.) |
1 mm. rt. Art. = 133.322 Pa |
|
Millimeter of water column (mm water column) |
1 mm water. Art. = 9.807 Pa |
|
Technical atmosphere (at) |
1 at = 9.807 10 4 Pa |
|
Physical atmosphere (atm) |
1 atm = 1.033 atm = 1.013 10 4 Pa |
|
1 torus = 1 mm Hg. Art. |
|
|
Millibar (mb) |
1 mb = 0.7501 mm Hg. Art. = 100 Pa |
Table 24
Barometric Pressure Unit Ratio
|
mmHg Art. |
mm water Art. |
||||
|
Pascal, Pa | |||||
|
The atmosphere is normal, atm | |||||
|
Millimeter of mercury, mmHg Art. | |||||
|
Millibar, mb | |||||
|
Millimeter of water column, mm water. Art. |
Of the units of measurement given in tables 23 and 24, the most widespread in Russia are mm. rt. Art. And mb. For the convenience of recalculations, in necessary cases, you can use the following ratio:
760 mmHg Art.= 1013mb= 101300Pa(36)
Easier way:
MB = mm. rt. Art.(37)
mmHg Art. = mb(38)
Instruments for measuring atmospheric pressure.
In hygienic studies, two types are used barometers:
liquid barometers;
metal barometers – aneroid.
The operating principle of various modifications of liquid barometers is based on the fact that atmospheric pressure balances a column of liquid of a certain height in a tube sealed at one end (top). The less specific gravity liquid, the higher the column of the latter, balanced by atmospheric pressure.
The most widespread mercury barometers , since the high specific gravity of liquid mercury makes it possible to make the device more compact, which is explained by balancing the atmospheric pressure with a lower column of mercury in the tube.
Three systems of mercury barometers are used:
cup-shaped;
siphon;
siphon-cup.
The indicated systems of mercury barometers are schematically presented in Figure 35.
|
Station cup barometers (Figure 35). In these barometers, a glass tube sealed on top is placed in a cup filled with mercury. A so-called toricelli void is formed in the tube above the mercury. The air, depending on its condition, causes one or another pressure on the mercury in the cup. Thus, the mercury level is set to a particular height in the glass tube. It is this height that will balance the air pressure on the mercury in the cup, and therefore reflect atmospheric pressure. The height of the mercury level corresponding to atmospheric pressure is determined using the so-called compensated scale available on the metal frame of the barometer. Cup barometers are manufactured with scales from 810 to 1110 mb and from 680 to 1110 mb. |
|
Rice. 35. Cup barometer(left) A – barometer scale; B – screw; B – thermometer; G – cup with mercury Mercury siphon barometer(on right) A – upper knee; B – lower knee; D – lower scale; E – upper scale; N – thermometer; a – hole in the tube |
In some modifications there are two scales - in mmHg. Art. and mb. Tenths of mm Hg. Art. or mb are counted on a moving scale - vernier. To do this, you need to use a screw to set the zero division of the vernier scale on the same line with the top of the meniscus of the mercury column, count the number of whole divisions of millimeters of mercury on the barometer scale and the number of tenths of a millimeter of mercury to the first mark of the vernier scale, which coincides with the division of the main scale.
Example. The zero division of the vernier scale is between 760 and 761 mmHg. Art. main scale. Therefore, the number of whole divisions is 760 mm Hg. Art. To this figure it is necessary to add the number of tenths of a millimeter of mercury, measured on a vernier scale. The first division of the main scale coincides with the 4th division of the vernier scale. Barometric pressure equals 760 + 0.4 = 760.4 mmHg. Art.
As a rule, cup barometers have a built-in thermometer (mercury or alcohol, depending on the expected range of air temperature during research), since in order to obtain the final result it is necessary to use special calculations to bring the pressure to standard conditions of temperature (0°C) and barometric pressure (760 mm Hg . Art.).
IN cup expeditionary barometers Before observation, first use a special screw located at the bottom of the device to set the mercury level in the cup to zero.
Siphon and siphon-cup barometers (Figure 35). In these barometers, the amount of atmospheric pressure is measured by the difference in the heights of the mercury column in the long (sealed) and short (open) bends of the tube. This barometer allows you to measure pressure with an accuracy of 0.05 mmHg st. Using a screw at the bottom of the devices, the mercury level in the short (open) tube bend is adjusted to zero point, and then the barometer readings are taken.
Siphon-cup inspector barometer. This device has two scales: on the left in mb and on the right in mmHg. Art. To determine tenths of mmHg. Art. serves as a vernier. The found values of atmospheric pressure, as when working with other liquid barometers, must be brought to 0°C using calculations or special tables.
On weather stations not only a temperature correction is introduced into barometer readings, but also a so-called constant correction: instrumental and gravity correction.
Barometers should be installed away from or isolated from sources of thermal radiation (solar radiation, heating devices), as well as away from doors and windows.
Metal aneroid barometer (Figure 36). This device is especially convenient when conducting research in expeditionary conditions. However, this barometer must be calibrated against a more accurate mercury barometer before use.
|
Rice. 36. Aneroid barometer |
Rice. 37. Barograph |
The principle of the design and operation of an aneroid barometer is very simple. A metal pad (box) with corrugated (for greater elasticity) walls, from which air has been removed to a residual pressure of 50-60 mm Hg. Art., under the influence of air pressure changes its volume and as a result is deformed. The deformation is transmitted through a system of levers to an arrow, which indicates atmospheric pressure on the dial. A curved thermometer is mounted on the dial of the aneroid barometer due to the need, as mentioned above, to bring the measurement results to 0°C. The dial graduation can be in mb or mmHg. Art. Some modifications of the aneroid barometer have two scales - both in mb and in mmHg. Art.
Aneroid altimeter (altimeter). In measuring altitude by the level of atmospheric pressure, there is a pattern according to which there is a relationship between air pressure and altitude that is very close to linear. That is, as you rise to a height, the atmospheric pressure decreases proportionally.
This device is designed to measure atmospheric pressure at altitude and has two scales. One of them shows pressure values in mmHg. Art. or mb, on the other - height in meters. Aircraft use altimeters with a dial on which the flight altitude is determined on a scale.
Barograph (barometer-recorder). This device is designed for continuous recording of atmospheric pressure. In hygienic practice, metal (aneroid) barographs are used (Figure 37). Under the influence of changes in atmospheric pressure, a package of aneroid boxes connected together, as a result of deformation, affects the system of levers, and through them, a special pen with non-drying special ink. As atmospheric pressure increases, the aneroid boxes compress and the lever with the feather rises upward. When the pressure decreases, the aneroid boxes expand with the help of springs placed inside them and the pen draws a line downward. A record of pressure in the form of a continuous line is drawn with a pen on a graduated line in mmHg. Art. or MB paper tape placed on a cylindrical mechanically rotating drum. Barographs with weekly or daily winding with appropriate graduated tapes are used, depending on the purpose, objectives and nature of the research. Barographs are produced with an electric drive that rotates the drum. However, in practice, this modification of the device is less convenient, since its use in expeditionary conditions is limited. To eliminate temperature influences on barograph readings, bimetallic compensators are inserted into them, which automatically correct (correct) the movement of the levers depending on the air temperature. Before starting work, the lever with the pen is set using a special screw to its initial position, corresponding to the time indicated on the tape and to the pressure level measured by an accurate mercury barometer.
Ink for recording barograms can be prepared according to the following recipe:
Bringing air volume to normal conditions (760 mmHg, 0 WITH). This aspect of barometric pressure measurement is very important when measuring the concentrations of pollutants in the air. Ignoring this aspect can lead to significant errors in concentration calculations harmful substances, which can reach 30 percent or more.
Bringing the volume of air to normal conditions is carried out according to the formula:
Example. To measure the dust concentration in the air, 200 liters of air were passed through a paper filter using an electric aspirator. The air temperature during the period of aspiration was - +26 C, barometric pressure - 752 mm Hg. Art. It is necessary to bring the air volume to normal conditions, that is, to 0°C and 760 mm Hg. Art.
We substitute the values of the corresponding parameters of the example into the formula X and calculate the required volume of air under normal conditions:
Thus, when calculating the concentration of dust in the air, it is necessary to take into account the air volume of exactly 180.69 l, not 200 l.
To simplify calculations of air volume under normal conditions, you can use correction factors for temperature and pressure (Table 25) or calculated ready-made values from formula 39 and (Table 26).
Table 25
Correction factors for temperature and pressure to bring air volume to normal conditions
(temperature 0 O
|
Barometric pressure, mm rt. Art. |
||||||||
End of table 25
|
Barometric pressure, mm rt. Art. |
||||||||
Table 26
Coefficients for bringing air volumes to normal conditions
(temperature 0 O C, barometric pressure 760 mm Hg. Art.)
|
mm rt. Art. |
mm rt. Art. | ||||||
We are taught about what atmospheric pressure is at school during natural history and geography lessons. We get acquainted with this information and safely throw it out of our heads, rightly believing that we will never be able to use it.
But after years of stress and ecological situation environment will have a sufficient impact on us. And the concept of “geodependence” will no longer seem nonsense, since pressure surges and headache will begin to poison life. At this moment you will have to remember what it is like in Moscow, for example, in order to adapt to new conditions. And move on with your life.
School basics
The atmosphere that surrounds our planet, unfortunately, literally puts pressure on all living and nonliving things. There is a term to define this phenomenon - atmospheric pressure. This is the force of the air column acting on the area. In the SI system we talk about kilograms per square centimeter. Normal atmospheric pressure (optimal indicators for Moscow have long been known) affects the human body with the same force as a weight weighing 1.033 kg. But most of us don't notice this. There are enough gases dissolved in body fluids to neutralize all unpleasant sensations.
Atmospheric pressure standards in different regions are different. But 760 mmHg is considered ideal. Art. Experiments with mercury turned out to be the most revealing at a time when scientists were proving that air has weight. Mercury barometers are the most common devices for determining pressure. It should also be remembered that ideal conditions, for which the mentioned 760 mm Hg are relevant. Art., is a temperature of 0 ° C and the 45th parallel.
IN international system units are used to define pressure in Pascals. But for us, the use of mercury column fluctuations is more familiar and understandable.
Relief features
Of course, many factors influence the value of atmospheric pressure. The most significant are the relief and proximity to the magnetic poles of the planet. The norm of atmospheric pressure in Moscow is fundamentally different from the indicators in St. Petersburg; and for residents of some remote village in the mountains, this figure may seem completely abnormal. Already at 1 km above sea level it corresponds to 734 mm Hg. Art.
As already noted, in the region of the Earth’s poles the amplitude of pressure changes is much higher than in equatorial zone. Even during the day, the atmospheric pressure changes slightly. Insignificantly, however, only by 1-2 mm. This is due to the difference between day and night temperatures. At night it is usually cooler, which means the pressure is higher.
Pressure and man
For a person, in essence, it does not matter what atmospheric pressure is: normal, low or high. These are very conditional definitions. People tend to get used to everything and adapt. The dynamics and magnitude of changes in atmospheric pressure are much more important. On the territory of the CIS countries, in particular in Russia, there are quite a lot of zones. Often local residents and don't know about it.
The norm of atmospheric pressure in Moscow, for example, may well be considered as a variable value. After all, every skyscraper is a kind of mountain, and the higher and faster you go up (or go down), the more noticeable the difference will be. Some people may well pass out while riding a high-speed elevator.
Adaptation
Doctors almost unanimously agree that the question “what atmospheric pressure is considered normal” (is it Moscow or any locality planets - not the point) is incorrect in itself. Our body adapts perfectly to life above or below sea level. And if the pressure does not have a detrimental effect on a person, it can be considered normal for the area. Doctors say that the normal atmospheric pressure in Moscow and other large cities is in the range from 750 to 765 mm Hg. pillar
The pressure drop is a completely different matter. If within a few hours it rises (falls) by 5-6 mm, people begin to experience discomfort and pain. This is especially dangerous for the heart. Its beating becomes more frequent, and a change in the frequency of breaths leads to a change in the rhythm of oxygen supply to the body. The most common ailments in such a situation are weakness, etc.
Meteor dependence
Normal atmospheric pressure for Moscow may seem like a nightmare to a visitor from the North or the Urals. After all, each region has its own norm and, accordingly, its own understanding of the stable state of the body. And since in life we do not concentrate on exact pressure indicators, weather forecasters always focus on whether the pressure is high or low for a given region.
After all, not every person can boast that they do not notice the corresponding changes. Anyone who cannot call himself lucky in this matter must systematize his feelings during pressure changes and find acceptable countermeasures. Often a cup of strong coffee or tea is enough, but sometimes more serious help in the form of medication is needed.
Pressure in the metropolis
Residents of megacities are the most weather-dependent. It is here that a person experiences more stress, lives life at a high pace and experiences environmental degradation. Therefore, knowing what the normal atmospheric pressure is for Moscow is vital.
The capital of the Russian Federation is located on the Central Russian Upland, which means that there is a priori a zone of low pressure. Why? It's very simple: the higher you are above sea level, the lower the atmospheric pressure. For example, on the banks of the Moscow River this figure will be 168 m. A maximum value in the city it was recorded in Teply Stan - 255 m above sea level.
It is quite possible to assume that Muscovites will experience abnormally low atmospheric pressure much less frequently than residents of other regions, which, of course, cannot but make them happy. And yet, what atmospheric pressure is considered normal in Moscow? Meteorologists say that it usually does not exceed 748 mm Hg. pillar This means little, since we already know that even a quick ride in an elevator can have a significant impact on a person's heart.
On the other hand, Muscovites do not feel any discomfort if the pressure fluctuates between 745-755 mm Hg. Art.
Danger
But from the point of view of doctors, not everything is so optimistic for the residents of the metropolis. Many experts quite reasonably believe that by working on the upper floors of business centers, people expose themselves to danger. Indeed, in addition to the fact that they live in a zone of low pressure, they also spend almost a third of the day in places with
If we add to this fact violations of the building ventilation system and permanent job air conditioners, it becomes obvious that the employees of such offices are the most incapacitated, sleepy and sick.
Results
Actually, there are a few things to remember. Firstly, there is no single ideal value for normal atmospheric pressure. There are regional standards that can vary significantly in absolute terms. Secondly, features human body make it easy to experience pressure changes if they happen rather slowly. Thirdly, the more healthy image life we lead and the more often we manage to maintain a daily routine (getting up at the same time, long night sleep, following a basic diet, etc.), the less we are susceptible to weather dependence. This means they are more energetic and cheerful.
The weight of air determines atmospheric pressure (1 m 3 of air weighs 1.033 kg). For every meter earth's surface air presses with a force of 10033 kg. It is a column of air from sea level to the upper atmosphere. For comparison: a column of water of the same diameter would have a height of only 10 m. In other words, the own mass of air creates atmospheric pressure, the value of which per unit area corresponds to the mass of the air column located above it. In this case, a decrease in air in this column leads to a decrease (drop) in pressure, and an increase in air leads to an increase (increase) in pressure. Normal atmospheric pressure is taken to be air pressure at sea level at a latitude of 45° and at a temperature of 0°C. In this case, it presses on every 1 cm 2 of the earth's surface with a force of 1.033 kg, and the mass of this air is balanced by a mercury column 760 mm high. The principle of pressure measurement is based on this dependence. It is measured in millimeters (mm) of mercury (or millibars (mb): 1 mb = 0.75 mmHg) and in hectopascals (hPa), when 1 mm = = 1 hPa.
Atmospheric pressure is measured using barometers. There are two types of barometers: mercury and metal (or aneroid).
A mercury cup consists of a glass tube sealed at the top and immersed with the lower open end into a metal cup containing mercury. A column of mercury in a glass tube balances with its weight the air pressure acting on the mercury in the cup. When the pressure changes, the height of the mercury column also changes. These changes are recorded by the observer on a scale attached next to the glass tube of the barometer.
A metal barometer, or aneroid, consists of a hermetically sealed thin-walled corrugated metal box, inside which the air is rarefied. When the pressure changes, the walls of the box vibrate and are pressed in or out. These vibrations are transmitted by a system of levers to the arrow, which moves along a graduated scale.
Self-recording barometers called barographs are used to record changes in pressure. The operation of the barograph is based on the fact that the vibrations of the walls of the aneroid box are transmitted, which draws a line on the tape of the drum rotating around its axis.
Pressure on globe may vary within wide limits. Thus, the maximum value is 815.85 mm Hg. (1087 mb) was registered in winter in Turukhansk, the minimum is 641.3 mm Hg. (854 MB) - in “Nancy” over the ocean.
Pressure changes with altitude. It is generally accepted that the average value of atmospheric pressure is pressure above sea level - 1013 mb (760 mm Hg). As altitude increases, the air becomes more rarefied and the pressure decreases. IN bottom layer in the troposphere to a height of 10 m it decreases by 1 mm Hg. for every 10 m, or 1 mb (hPa) for every 8 m. At an altitude of 5 km it is already two times less, 15 km - 8 times, 20 km - 18 times.
Atmospheric pressure changes continuously due to the change and movement of air. During the day it increases twice (in the morning and in the evening), and decreases twice (after noon and after midnight). During the year on the continents, the maximum pressure is observed in winter, when the air is supercooled and compacted, and the minimum pressure is observed in summer.
The distribution of atmospheric pressure over the earth's surface has a well-defined zonal character, which is due to uneven heating of the earth's surface, and consequently, changes in pressure. The change in pressure is explained by the movement of air. It is high where there is more air, low where the air leaves. Heated from the surface, the air rushes upward and the pressure on warm surface goes down. But at altitude, the air cools, becomes denser and begins to fall to neighboring cold areas, where the pressure increases. Thus, heating and cooling of air from the Earth's surface is accompanied by its redistribution and pressure changes.
IN equatorial latitudes air temperatures are constantly high, the air, heating up, rises and moves towards tropical latitudes. Therefore, in the equatorial zone the pressure is constantly low. IN tropical latitudes As a result of the air flow, increased pressure is created. Above the constantly cold surface of the poles (and) the pressure is increased, it is created by air coming from latitudes. However, in temperate latitudes the outflow of air forms a belt of low pressure. As a result, belts of low (and two moderate) and high (two tropical and two polar) pressures are formed on Earth. Depending on the season, they shift somewhat towards the summer hemisphere (following the Sun).
Polar regions high pressure They expand in winter, contract in summer, but exist all year round. Low pressure belts persist throughout the year near and in temperate latitudes southern hemisphere. The picture is different in the northern hemisphere. Here in winter, in temperate latitudes over the continents, the pressure increases greatly and the low pressure field seems to be “broken”: it is preserved only over the oceans in the form of closed areas of low pressure - the Icelandic and Aleutian lows. But over the continents, where the pressure has noticeably increased, so-called winter maxima are formed: Asian (Siberian) and North American (Canadian). Summer in temperate latitudes northern hemisphere the low pressure field is restored. At the same time, a vast area of low pressure forms over Asia - the Asian Low.
In tropical latitudes - the belt high blood pressure— continents always warm up more than the oceans, and the pressure above them is lower. This causes subtropical maxima over the oceans: North (Azores), North Pacific, South Atlantic, South Pacific and Indian.
In other words, the Earth’s belts of high and low pressure, despite large-scale seasonal changes their indicators are quite stable formations.
Loading...
