From mmHg to pa. Normal atmospheric pressure for humans. Low atmospheric pressure and well-being

03.05.2020

Read also

What is the chief accountant responsible for and to whom?

Why do you dream about your dead father-in-law being alive?

Every person knows that air pressure is measured in millimeters of mercury, since this is the unit of measurement that is used in everyday life. In physics, in the SI system of units, pressure is measured in pascals. The article will tell you how to convert millimeters of mercury into pascals.

Air pressure

First, let's look at the question of what air pressure is. This value is understood as the pressure that the atmosphere of our planet exerts on any objects located on the surface of the Earth. It is easy to understand the reason for the appearance of this pressure: for this you need to remember that each body of finite mass has a certain weight, which can be determined by the formula: N = m*g, where N is the weight of the body, g is the value of the acceleration due to gravity, m is the mass of the body . The presence of weight in the body is due to gravity.

The atmosphere of our planet is a large gaseous body that also has some mass and therefore has weight. It has been experimentally established that the mass of air that exerts pressure on 1 m 2 of the earth's surface at sea level is approximately equal to 10 tons! The pressure exerted by this air mass is 101,325 pascals (Pa).

Converting millimeters of mercury to pascals

When viewing a weather forecast, barometric pressure information is usually presented in millimeters of mercury (mmHg). To understand how mmHg. Art. convert to pascals, you just need to know the relationship between these units. And remembering this ratio is easy: 760 mm Hg. Art. corresponds to a pressure of 101,325 Pa.

Knowing the above numbers, you can obtain a formula for converting millimeters of mercury into pascals. The easiest way to do this is to use a simple proportion. For example, a certain pressure H in mm Hg is known. Art., then the pressure P in pascals will be equal to: P = H*101325/760 = 133.322*H.

The given formula is easy to use. For example, at the top of Mount Elbrus (5642 m) the air pressure is approximately 368 mm Hg. Art. Substituting this value into the formula, we get: P = 133.322*H = 133.322*368 = 49062 Pa, or approximately 49 kPa.

In which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturated vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mmHg. Art.

Standard atmospheric pressure is taken to be (exactly) 760 mmHg. Art. , or 101,325 Pa, hence the definition of a millimeter of mercury (101,325/760 Pa). Previously, a slightly different definition was used: the pressure of a column of mercury with a height of 1 mm and a density of 13.5951·10 3 kg/m³ with a free fall acceleration of 9.806 65 m/s². The difference between these two definitions is 0.000014%.

Millimeters of mercury are used, for example, in vacuum technology, in weather reports and in measuring blood pressure. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum engineers to microns (microns) is carried out, as a rule, also without indicating “mercury column pressure”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the maximum vacuum created by this pump, measured in microns of mercury. Of course, no one uses a Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, McLeod pressure gauge (vacuum gauge). 1 Sometimes millimeters of water column are used ( 13,5951 mmHg Art. = mm water Art. ). In the USA and Canada, the unit of measurement “inch of mercury” (designation - inHg) is also used. 1 = 3,386389 inHg

kPa at 0 °C.

	Pressure units Pascal	(Pa, Pa) Bar	(bar, bar) Technical atmosphere	(at, at) Physical atmosphere	(atm, atm) Millimeter of mercury	(mm Hg, mmHg, Torr, torr) Water column meter	(m water column, m H 2 O) Pound-force per sq. inch
(psi)	1 / 2	10 −5	1 Pa	10.197 10 −6	9.8692 10 −6	7.5006 10 −3	1.0197 10 −4
145.04 10 −6	10 5	1 bar	1,0197	0,98692	750,06	10,197	14,504
1 10 6 din/cm 2	98066,5	0,980665	1 at	0,96784	735,56	10	14,223
1 kgf/cm 2	101325	1,01325	1,033	1 kgf/cm 2	760	10,33	14,696
1 atm	133,322	1 mmHg	1.3332 10 −3	1.3595 10 −3	1 1.3158 10 −3	mmHg.	13.595 10 −3
19.337 10 −3	9806,65	1 m water Art.	0,1	0,096784	73,556	9.80665 10 −2	1,4223
1 m water Art.	6894,76	1 psi	68.948 10 −3	70.307 10 −3	51,715	0,70307	68.046 10 −3

1 lbf/in 2

see also

Wikimedia Foundation.

2010. Physical encyclopedia

Non-system units pressure, app. when measuring atm. water vapor pressure, high vacuum, etc. Designation: Russian. - mmHg art., int. — mm Hg. 1 mmHg Art. equal to hydrostatic pressure of a column of mercury with a height of 1 mm and a density of 13.5951... ... Technical Translator's Guide

Big Encyclopedic Dictionary

- – non-system units. pressure; 1 mmHg art. = 133.332 Pa = 1.35952 10 3 kgf/cm2 = 13.595 mm water. Art. [Physical encyclopedia. In 5 volumes. M.: Soviet Encyclopedia. Editor-in-chief A. M. Prokhorov. 1988.] Term heading: General terms... ... Encyclopedia of terms, definitions and explanations of building materials

Off-system unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 Pa = 13.5951 mm water column. * * * MILLIMETER OF MERCURY COLUMN MILLIMETER OF MERCURY, non-systemic unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322... encyclopedic Dictionary

Torr, an off-system unit of pressure used when measuring atmospheric pressure of water vapor, high vacuum, etc. Designation: Russian mm Hg. Art., international mm Hg. 1 mm of mercury is equal to hydrostatic... Encyclopedic Dictionary of Metallurgy

- (mmHg) unit of pressure, as a result of which mercury in the column rises by 1 millimeter. 1 mmHg Art. = 133.3224 Pa... Explanatory dictionary of medicine

Torr, a non-systemic unit of pressure used in measurements of atmospheric pressure, partial pressure of water vapor, high vacuum, etc. Designations: Russian mm Hg. Art., international mm Hg. 1 mmHg see equal... ... Great Soviet Encyclopedia

Non-system units not subject to use. pressure. Designation mm Hg. Art. 1 mmHg Art. = 133.322 Pa (see Pascal) ... Big Encyclopedic Polytechnic Dictionary

Off-system unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 Pa = 13.5951 mm water. st... Natural science. encyclopedic Dictionary

In which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturated vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mmHg. Art.

kPa at 0 °C.

	Pressure units Pascal	(Pa, Pa) Bar	(bar, bar) Technical atmosphere	(at, at) Physical atmosphere	(atm, atm) Millimeter of mercury	(mm Hg, mmHg, Torr, torr) Water column meter	(m water column, m H 2 O) Pound-force per sq. inch
(psi)	1 / 2	10 −5	1 Pa	10.197 10 −6	9.8692 10 −6	7.5006 10 −3	1.0197 10 −4
145.04 10 −6	10 5	1 bar	1,0197	0,98692	750,06	10,197	14,504
1 10 6 din/cm 2	98066,5	0,980665	1 at	0,96784	735,56	10	14,223
1 kgf/cm 2	101325	1,01325	1,033	1 kgf/cm 2	760	10,33	14,696
1 atm	133,322	1 mmHg	1.3332 10 −3	1.3595 10 −3	1 1.3158 10 −3	mmHg.	13.595 10 −3
19.337 10 −3	9806,65	1 m water Art.	0,1	0,096784	73,556	9.80665 10 −2	1,4223
1 m water Art.	6894,76	1 psi	68.948 10 −3	70.307 10 −3	51,715	0,70307	68.046 10 −3

1 lbf/in 2

see also

Rodchenko, Alexander Mikhailovich
Shaikhet, Arkady Samoilovich

Wikimedia Foundation.

2010. Physical encyclopedia

Big Encyclopedic Dictionary

- (mmHg) unit of pressure, as a result of which mercury in the column rises by 1 millimeter. 1 mmHg Art. = 133.3224 Pa... Explanatory dictionary of medicine

Non-system units not subject to use. pressure. Designation mm Hg. Art. 1 mmHg Art. = 133.322 Pa (see Pascal) ... Big Encyclopedic Polytechnic Dictionary

Off-system unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 Pa = 13.5951 mm water. st... Natural science. encyclopedic Dictionary

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 over the years, stress and environmental conditions will have a sufficient impact on us. And the concept of “geodependence” will no longer seem nonsense, because pressure surges and headaches 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 live on.

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 vary in different regions. 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 the ideal conditions for which the mentioned 760 mm Hg are relevant. Art., is a temperature of 0 ° C and the 45th parallel.

In the international system of units, it is customary 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 the 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 do not even 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” (Moscow or any populated area on the planet is not important) 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 medications 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. And the maximum value in the city 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’s ventilation system and the constant operation of air conditioners, it becomes obvious that employees of such offices turn out to be 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, the characteristics of the human body make it easy to experience pressure changes if they happen rather slowly. Thirdly, the healthier lifestyle we lead and the more often we manage to maintain a daily routine (getting up at the same time, getting a long night's sleep, following a basic diet, etc.), the less susceptible we are to weather dependence. This means they are more energetic and cheerful.

For normal atmospheric pressure, it is customary to take the air pressure at sea level at a latitude of 45 degrees at a temperature of 0°C. Under these ideal conditions, the column of air presses on each area with the same force as a column of mercury 760 mm high. This figure is an indicator of normal atmospheric pressure.

Atmospheric pressure depends on the altitude of the area above sea level. At higher elevations, the indicators may differ from ideal, but they will also be considered the norm.

Atmospheric pressure standards in different regions

As altitude increases, atmospheric pressure decreases. So, at an altitude of five kilometers, pressure indicators will be approximately two times less than below.

Due to the location of Moscow on a hill, the normal pressure level here is considered to be 747-748 mm column. In St. Petersburg, normal pressure is 753-755 mm Hg. This difference is explained by the fact that the city on the Neva is located lower than Moscow. In some areas of St. Petersburg you can find a pressure norm of an ideal 760 mm Hg. For Vladivostok, normal pressure is 761 mmHg. And in the mountains of Tibet – 413 mmHg.

Impact of atmospheric pressure on people

A person gets used to everything. Even if normal pressure readings are low compared to the ideal 760 mmHg, but are the norm for the area, people will.

A person’s well-being is affected by sharp fluctuations in atmospheric pressure, i.e. decrease or increase in pressure by at least 1 mmHg within three hours

When pressure decreases, a lack of oxygen occurs in a person’s blood, hypoxia of body cells develops, and the heartbeat increases. Headaches appear. There are difficulties with the respiratory system. Due to poor blood supply, a person may experience pain in the joints and numbness in the fingers.

Increased pressure leads to an excess of oxygen in the blood and tissues of the body. The tone of blood vessels increases, which leads to their spasms. As a result, the body's blood circulation is disrupted. Visual disturbances may occur in the form of spots before the eyes, dizziness, and nausea. A sharp increase in pressure to large values can lead to rupture of the eardrum.