What is mm Hg. Normal atmospheric pressure for a person. pressure in the metropolis

17.04.2020

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 saturation vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mm Hg. Art. Standard atmospheric pressure is assumed to be (exactly) 760 mm Hg. Art. , or 101 325 Pa, hence the definition of a millimeter mercury column(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, meteorological reports and blood pressure measurements. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the transition to microns (microns) that is natural for vacuum engineers is also carried out, as a rule, without indicating “pressure of mercury”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the ultimate 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, a McLeod pressure gauge (vacuum gauge).

Sometimes millimeters of water column are used ( 1 mmHg Art. = 13,5951 mm w.c. Art. ). In the United States and Canada, the unit of measure is "inch of mercury" (symbol - inHg). one inHg = 3,386389 kPa at 0 °C.

Pressure units

	Pascal (Pa, Pa)	Bar (bar, bar)	technical atmosphere (at, at)	physical atmosphere (atm, atm)	millimeter of mercury (mmHg,mmHg, Torr, Torr)	Water column meter (m water column, m H 2 O)	Pound-force per sq. inch (psi)
1 Pa	1 / 2	10 −5	10.197 10 −6	9.8692 10 −6	7.5006 10 −3	1.0197 10 −4	145.04 10 −6
1 bar	10 5	1 10 6 dynes / cm 2	1,0197	0,98692	750,06	10,197	14,504
1 at	98066,5	0,980665	1 kgf / cm 2	0,96784	735,56	10	14,223
1 atm	101325	1,01325	1,033	1 atm	760	10,33	14,696
1 mmHg	133,322	1.3332 10 −3	1.3595 10 −3	1.3158 10 −3	1 mmHg.	13.595 10 −3	19.337 10 −3
1 m water Art.	9806,65	9.80665 10 −2	0,1	0,096784	73,556	1 m water Art.	1,4223
1psi	6894,76	68.948 10 −3	70.307 10 −3	68.046 10 −3	51,715	0,70307	1lbf/in2

normal atmospheric pressure

Air pressure at sea level at a latitude of 45° and at a temperature of 0°C is conventionally taken as normal atmospheric pressure. In this case, the atmosphere 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 Torricelli Experience

The value of 760 mm was first obtained in 1644. Evangelista Torricelli(1608-1647) and Vincenzo Viviani(1622-1703) - students of the brilliant Italian scientist Galileo Galilei.

E. Torricelli soldered a long glass tube with graduations from one end, filled it with mercury and lowered it into a cup with mercury (this is how the first mercury barometer was invented, which was called the Torricelli tube). The level of mercury in the tube dropped as some of the mercury spilled into the cup and settled at 760 millimeters. A void formed above the column of mercury, which was called Torricelli's void(Fig. 2).

E. Torricelli believed that the pressure of the atmosphere on the surface of the mercury in the cup is balanced by the weight of the mercury column in the tube. The height of this column above sea level is 760 mm Hg. Art.

Rice. 2. Torricelli experience

1 Pa = 10 -5 bar; 1 bar = 0.98 atm.

High and low atmospheric pressure

Air pressure on our planet can vary widely. If the air pressure is greater than 760 mm Hg. Art., then it is considered increased smaller - lowered.

Since the air becomes more and more rarefied with ascent, atmospheric pressure decreases (in the troposphere, on average, 1 mm for every 10.5 m of ascent). Therefore, for territories located at different heights above sea level, the average value of atmospheric pressure will be different. For example, Moscow lies at an altitude of 120 m above sea level, so the average atmospheric pressure for it is 748 mm Hg. Art.

Atmospheric pressure rises twice during the day (morning and evening) and falls twice (after noon and after midnight). These changes are associated with the change and movement of air. 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 pronounced zonal character. This is due to uneven heating of the earth's surface, and consequently, a change in pressure.

On the globe, there are three belts with a predominance of low atmospheric pressure (minimums) and four belts with a predominance of high pressure (maximums).

In the equatorial latitudes, the surface of the Earth warms up strongly. The heated air expands, becomes lighter and therefore rises. As a result, low atmospheric pressure is established near the earth's surface near the equator.

At the poles, under the influence of low temperatures, the air becomes heavier and sinks. Therefore, at the poles, atmospheric pressure is increased by 60-65 ° compared to latitudes.

In the high layers of the atmosphere, on the contrary, over hot areas the pressure is high (although lower than at the Earth's surface), and over cold areas it is low.

General scheme the distribution of atmospheric pressure is as follows (Fig. 3): there is a low-pressure belt along the equator; at 30-40 ° latitude of both hemispheres - belts high pressure; 60-70 ° latitude - low pressure zones; in the polar regions - areas of high pressure.

As a result of the fact that in the temperate latitudes of the Northern Hemisphere in winter the atmospheric pressure over the continents greatly increases, the low pressure belt is interrupted. It persists only over the oceans in the form of closed regions. reduced pressure- Icelandic and Aleutian lows. Over the continents, on the contrary, winter maxima are formed: Asian and North American.

Rice. 3. General scheme of distribution of atmospheric pressure

In summer, in the temperate latitudes of the Northern Hemisphere, the low atmospheric pressure belt is restored. A huge area of low atmospheric pressure centered in tropical latitudes - the Asian Low - is forming over Asia.

In tropical latitudes, the continents are always hotter than the oceans, and the pressure over them is lower. Thus, over the oceans throughout the year there are maxima: North Atlantic (Azores), North Pacific, South Atlantic, South Pacific and South Indian.

Lines that connect points of equal atmospheric pressure on a climate map are called isobars(from the Greek isos - equal and baros - heaviness, weight).

The closer the isobars are to each other, the faster atmospheric pressure changes over distance. The amount of change in atmospheric pressure per unit distance (100 km) is called pressure gradient.

The formation of atmospheric pressure belts near the earth's surface is influenced by the uneven distribution solar heat and the rotation of the earth. Depending on the season, both hemispheres of the Earth are heated by the Sun in different ways. This causes some movement of atmospheric pressure belts: in summer - to the north, in winter - to the south.

The unit of pressure in SI-pascal (Russian designation: Pa; international: Pa) \u003d N / m 2
Conversion table for pressure units. Pa; MPa; bar; atm; mmHg.; mm w.st.; m w.st., kg / cm 2; psf; psi inches Hg; in.st. below
Note, there are 2 tables and a list. Here's another useful link:

Conversion table for pressure units. Pa; MPa; bar; atm; mmHg.; mm w.st.; m w.st., kg / cm 2; psf; psi inches Hg; in.st. The ratio of pressure units.

	In units:
	Pa (N / m 2)	MPa	bar	atmosphere	mmHg Art.	mm w.st.	m w.st.	kgf / cm 2
	Should be multiplied by:
Pa (N / m 2) - pascal, SI unit of pressure	1	1*10 -6	10 -5	9.87*10 -6	0.0075	0.1	10 -4	1.02*10 -5
MPa, megapascal	1*10 6	1	10	9.87	7.5*10 3	10 5	10 2	10.2
bar	10 5	10 -1	1	0.987	750	1.0197*10 4	10.197	1.0197
atm, atmosphere	1.01*10 5	1.01* 10 -1	1.013	1	759.9	10332	10.332	1.03
mmHg Art., mmHg	133.3	133.3*10 -6	1.33*10 -3	1.32*10 -3	1	13.3	0.013	1.36*10 -3
mm w.st., mm water column	10	10 -5	0.000097	9.87*10 -5	0.075	1	0.001	1.02*10 -4
m w.st., meter of water column	10 4	10 -2	0.097	9.87*10 -2	75	1000	1	0.102
kgf / cm 2, kilogram-force per square centimeter	9.8*10 4	9.8*10 -2	0.98	0.97	735	10000	10	1
	47.8	4.78*10 -5	4.78*10 -4	4.72*10 -4	0.36	4.78	4.78 10 -3	4.88*10 -4
	6894.76	6.89476*10 -3	0.069	0.068	51.7	689.7	0.690	0.07
Inches Hg / inches Hg	3377	3.377*10 -3	0.0338	0.033	25.33	337.7	0.337	0.034
inches w.st. / inchesH2O	248.8	2.488*10 -2	2.49*10 -3	2.46*10 -3	1.87	24.88	0.0249	0.0025

Conversion table for pressure units. Pa; MPa; bar; atm; mmHg.; mm w.st.; m w.st., kg / cm 2; psf; psi inches Hg; in.st.

To convert pressure in units:	In units:
	pounds per sq. pound square feet (psf)	pounds per sq. inch / pound square inches (psi)	Inches Hg / inches Hg	inches w.st. / inchesH2O
	Should be multiplied by:
Pa (N / m 2) - SI unit of pressure	0.021	1.450326*10 -4	2.96*10 -4	4.02*10 -3
MPa	2.1*10 4	1.450326*10 2	2.96*10 2	4.02*10 3
bar	2090	14.50	29.61	402
atm	2117.5	14.69	29.92	407
mmHg Art.	2.79	0.019	0.039	0.54
mm w.st.	0.209	1.45*10 -3	2.96*10 -3	0.04
m w.st.	209	1.45	2.96	40.2
kgf / cm 2	2049	14.21	29.03	394
pounds per sq. pound square feet (psf)	1	0.0069	0.014	0.19
pounds per sq. inch / pound square inches (psi)	144	1	2.04	27.7
Inches Hg / inches Hg	70.6	0.49	1	13.57
inches w.st. / inchesH2O	5.2	0.036	0.074	1

Detailed list of pressure units, one pascal is:

1 Pa (N / m 2) \u003d 0.0000102 Atmosphere "metric" / Atmosphere (metric)
1 Pa (N/m 2) = 0.0000099 Atmosphere (standard) = Standard atmosphere
1 Pa (N / m 2) \u003d 0.00001 Bar / Bar
1 Pa (N / m 2) \u003d 10 Barad / Barad
1 Pa (N / m 2) \u003d 0.0007501 Centimeters of mercury. Art. (0°C)
1 Pa (N / m 2) \u003d 0.0101974 Centimeters in. Art. (4°C)
1 Pa (N / m 2) \u003d 10 dyne / square centimeter
1 Pa (N/m 2) = 0.0003346 Foot of water / Foot of water (4 °C)
1 Pa (N / m 2) \u003d 10 -9 Gigapascals
1 Pa (N / m 2) \u003d 0.01
1 Pa (N / m 2) \u003d 0.0002953 Dumov Hg / Inch of mercury (0 °C)
1 Pa (N / m 2) \u003d 0.0002961 Inches of mercury. Art. / Inch of mercury (15.56 °C)
1 Pa (N / m 2) \u003d 0.0040186 Dumov w.st. / Inch of water (15.56 °C)
1 Pa (N / m 2) \u003d 0.0040147 Dumov w.st. / Inch of water (4 °C)
1 Pa (N / m 2) \u003d 0.0000102 kgf / cm 2 / Kilogram force / centimetre 2
1 Pa (N / m 2) \u003d 0.0010197 kgf / dm 2 / Kilogram force / decimetre 2
1 Pa (N / m 2) \u003d 0.101972 kgf / m 2 / Kilogram force / meter 2
1 Pa (N / m 2) \u003d 10 -7 kgf / mm 2 / Kilogram force / millimeter 2
1 Pa (N / m 2) \u003d 10 -3 kPa
1 Pa (N / m 2) \u003d 10 -7 Kilopound force / square inch / Kilopound force / square inch
1 Pa (N / m 2) \u003d 10 -6 MPa
1 Pa (N / m 2) \u003d 0.000102 Meters w.st. / Meter of water (4 °C)
1 Pa (N / m 2) \u003d 10 Microbar / Microbar (barye, barrie)
1 Pa (N / m 2) \u003d 7.50062 Microns of mercury / Micron of mercury (millitorr)
1 Pa (N / m 2) \u003d 0.01 Milibar / Millibar
1 Pa (N/m 2) = 0.0075006 (0 °C)
1 Pa (N / m 2) \u003d 0.10207 Millimeters of w.st. / Millimeter of water (15.56 °C)
1 Pa (N / m 2) \u003d 0.10197 Millimeters w.st. / Millimeter of water (4 °C)
1 Pa (N / m 2) \u003d 7.5006 Millitorr / Millitorr
1 Pa (N/m2) = 1N/m2 / Newton/square meter
1 Pa (N / m 2) \u003d 32.1507 Daily ounces / sq. inch / Ounce force (avdp)/square inch
1 Pa (N / m 2) \u003d 0.0208854 Pounds of force per sq. foot / Pound force/square foot
1 Pa (N / m 2) \u003d 0.000145 Pounds of force per sq. inch / Pound force/square inch
1 Pa (N / m 2) \u003d 0.671969 Poundals per sq. foot / Poundal/square foot
1 Pa (N / m 2) \u003d 0.0046665 Poundals per sq. inch / Poundal/square inch
1 Pa (N / m 2) \u003d 0.0000093 Long tons per sq. foot / Ton (long)/foot 2
1 Pa (N / m 2) \u003d 10 -7 Long tons per sq. inch / Ton(long)/inch 2
1 Pa (N / m 2) \u003d 0.0000104 Short tons per sq. foot / Ton (short)/foot 2
1 Pa (N / m 2) \u003d 10 -7 Tons per sq. inch / Ton/inch 2
1 Pa (N / m 2) \u003d 0.0075006 Torr / Torr

pressure in pascals and atmospheres, convert pressure to pascals
atmospheric pressure is equal to XXX mm Hg. express it in pascals
gas pressure units - translation
liquid pressure units - translation

Atmospheric pressure is created by the air shell and all objects on the surface of the Earth experience it. The reason is that air, like everything else, is attracted to the globe through gravity. In weather reports, atmospheric pressure information is given in millimeters of mercury. But this is an off-system unit. Officially, pressure, as a physical quantity, in SI since 1971 is expressed in "pascals", equal to a force of 1 N acting on a surface of 1 m2. Accordingly, there is a transition "mm. rt. Art. in pascals.

The origin of this unit is associated with the name of the scientist Evangelista Torricelli. It was he who in 1643, together with Viviani, measured atmospheric pressure using a tube from which air was pumped out. It was filled with mercury, which has the highest density among liquids (13,600 kg/m3). Subsequently, a vertical scale was attached to the tube, and such an instrument was called a mercury barometer. In Torricelli's experiment, the mercury column, balancing the external air pressure, was set at a height of 76 cm or 760 mm. It was taken as a measure of air pressure. Value 760 mm. rt. st is considered normal atmospheric pressure at 0°C at sea level latitude. It is known that atmospheric pressure is very variable and fluctuates during the day. This is due to temperature change. It also decreases with height. Indeed, in the upper layers of the atmosphere, the density of air becomes less.

Using a physical formula, it is possible to convert millimeters of mercury to pascals. To do this, you need the density of mercury (13600kg / m3) multiplied by the acceleration of gravity (9.8 kg / m3) and multiplied by the height of the mercury column (0.6m). Accordingly, we obtain a standard atmospheric pressure of 101325 Pa or approximately 101 kPa. Hectopascals are still used in meteorology. 1 hPa = 100 Pa. And how many pascals will be 1 mm. rt. st? To do this, divide 101325 Pa by 760. We get the desired dependence: 1 mm. rt. st \u003d 3.2 Pa or about 3.3 Pa. Therefore, if required, for example, translate 750 mm. rt. Art. in pascals, you just need to multiply the numbers 750 and 3.3. The resulting answer will be the pressure measured in pascals.

Interestingly, in 1646, the scientist Pascal used a water barometer to measure atmospheric pressure. But since the density of water is less than the density of mercury, the height of the water column was much higher than that of mercury. Scuba divers are well aware that atmospheric pressure is the same as at a depth of 10 meters underwater. Therefore, the use of a water barometer causes some inconvenience. Although the advantage is that water is always at hand and is not poisonous.

Non-systemic units of pressure are widely used today. In addition to meteorological reports, millimeters of mercury are used in many countries to measure blood pressure. In the human lungs, pressure is expressed in centimeters of water column. In vacuum technology, millimeters, micrometers, and inches of mercury are used. Moreover, vacuum workers most often omit the words "mercury column" and talk about pressure, measured in millimeters. But mm. rt. Art. no one translates to pascals. Vacuum systems suggest too low pressures, compared to atmospheric. After all, vacuum means "airless space."

Therefore, here we already have to talk about a pressure of several micrometers or microns of mercury. And the actual measurement of pressure is carried out using special pressure gauges. So the McLeod vacuum gauge compresses the gas with a modified mercury manometer, maintaining a stable state of the gas. The device technique has the highest accuracy, but the measurement method takes a lot of time. Not always translation into pascals is of practical importance. After all, thanks to the once conducted experience, the existence of atmospheric pressure was clearly proven, and its measurement became publicly available. So on the walls of museums, art galleries, libraries you can find simple devices - barometers that do not use liquids. And their shala is graduated for convenience both in millimeters of mercury and in pascals.

Many people are subject to change in environment. A third of the population is affected by the attraction of air masses to the earth. Atmospheric pressure: the norm for a person, and how deviations from the indicators affect the general well-being of people.

Changes in the weather can affect the human condition

What atmospheric pressure is considered normal for a person

Atmospheric pressure is the weight of air that presses on the human body. On average, this is 1.033 kg per 1 cubic cm. That is, 10-15 tons of gas control our mass every minute.

The norm of atmospheric pressure is 760 mmHg or 1013.25 mbar. Conditions in which the human body feels comfortable or adapted. In fact, the ideal weather indicator for any inhabitant of the Earth. In reality, everything is not so.

Atmospheric pressure is not stable. Its changes are daily and depend on the weather, relief, level above the sea, climate and even the time of day. Fluctuations are not noticeable to humans. For example, at night, the mercury column rises 1-2 divisions higher. Minor changes do not affect well-being healthy person. Drops of 5-10 or more units are painful, and sharp significant jumps are fatal. For comparison: loss of consciousness from altitude sickness occurs already when the pressure drops by 30 units. That is, at the level of 1000 m above the sea.

A continent and even a separate country can be divided into conditional areas with different norms of average pressure. Therefore, the optimal atmospheric pressure for each person is determined by the region of permanent residence.

High air pressure adversely affects hypertension

Such weather conditions are generous for strokes and heart attacks.

Persons who are vulnerable to the vagaries of nature are advised by doctors to stay out of the zone on such days. active work and deal with the consequences of weather dependence.

Meteorological dependence - what to do?

The movement of mercury by more than one division in 3 hours is a reason for stress in a strong organism of a healthy person. Each of us feels such fluctuations in the form of a headache, drowsiness, fatigue. More than a third of people suffer from weather dependence in varying degrees of severity. In the zone of high sensitivity, the population with diseases of the cardiovascular, nervous and respiratory system, elderly people. How to help yourself if a dangerous cyclone is approaching?

15 Ways to Survive a Weather Cyclone

Not much new advice has been collected here. It is believed that together they alleviate suffering and teach the right way of life with meteorological vulnerability:

See your doctor regularly. Consult, discuss, ask for advice in case of deterioration of health. Have your prescribed medications handy at all times.
Buy a barometer. It is more productive to track the weather by the movement of the mercury column, rather than knee pain. So you will be able to anticipate the impending cyclone.
Watch the weather forecast. Forewarned is forearmed.
On the eve of a change in weather, get enough sleep and go to bed earlier than usual.
Set up a sleep schedule. Get yourself a full 8-hour sleep, getting up and falling asleep at the same time. This has a powerful restorative effect.
The meal schedule is equally important. Follow a balanced diet. Potassium, magnesium and calcium are essential minerals. Overeating ban.
Drink vitamins in a course in spring and autumn.
Fresh air, walking outside - light and regular exercise strengthens the heart.
Don't overstress. Postponing household chores is not as dangerous as weakening the body before a cyclone.
Accumulate favorable emotions. An oppressed emotional background fuels the disease, so smile more often.
Clothing made of synthetic threads and fur is harmful to static current.
store folk ways relieving symptoms in a prominent place. The recipe for herbal tea or compress is hard to remember when whiskey ache.
office workers in high-rise buildings suffer from weather changes more often. Take a day off if possible, or better yet, change jobs.
A long cyclone is discomfort for several days. Is it possible to go to a quiet region? Forward.
Prevention at least a day before the cyclone prepares and strengthens the body. Do not give up!

Don't Forget to Take Vitamins for Health

Atmosphere pressure- This is a phenomenon that is absolutely independent of a person. Moreover, our body obeys him. What should be the optimal pressure for a person determines the region of residence. People with chronic diseases are especially susceptible to meteorological dependence.