The air surrounding the Earth has a mass, and despite the fact that the mass of the atmosphere is about a million times less than the mass of the Earth (the total mass of the atmosphere is 5.2 * 10 21 g, and 1 m 3 of air at the earth's surface weighs 1.033 kg), this air mass exerts pressure on all objects on the earth's surface. The force with which the air presses on the earth's surface is called atmospheric pressure.

Each of us is pressed by a column of air of 15 tons. Such pressure can crush all living things. Why don't we feel it? This is explained by the fact that the pressure inside our body is equal to atmospheric.

Thus, the internal and external pressures are balanced.

Barometer

Atmospheric pressure is measured in millimeters of mercury (mmHg). To determine it, use a special device - a barometer (from the Greek. Baros - gravity, weight and metreo - I measure). There are mercury and liquid-free barometers.

Liquid-free barometers are called aneroid barometers(from the Greek. a - negative particle, nerys - water, that is, acting without the aid of a liquid) (Fig. 1).

Rice. 1. Aneroid barometer: 1 - metal box; 2 - spring; 3 - transmission mechanism; 4 - arrow-pointer; 5 - scale

Normal atmospheric pressure

The 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 column of mercury 760 mm high.

The Torricelli Experience

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

E. Torricelli sealed 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 named the Torricelli tube). The mercury level in the tube dropped as some of the mercury poured into the cup and settled at 760 millimeters. A void formed above the column of mercury, which was named Torricellian 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 column of mercury in the tube. The height of this pillar above sea level is 760 mm Hg. Art.

Rice. 2. Torricelli's experience

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

High and low atmospheric pressure

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

Since the air becomes more and more rarefied with the rise upward, the atmospheric pressure decreases (in the troposphere, on average, 1 mm for every 10.5 m of rise). Therefore, for territories located at different heights above sea level, the average value of atmospheric pressure will be. 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.

The atmospheric pressure rises twice during the day (in the morning and in the evening) and decreases twice (in the afternoon 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 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, pressure changes.

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

In equatorial latitudes, the Earth's surface warms up strongly. The heated air expands, becomes lighter and therefore rises upward. As a result, a 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 in comparison with latitudes by 60-65 °.

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

The general scheme of atmospheric pressure distribution is as follows (Fig. 3): a low pressure belt is located along the equator; at 30-40 ° latitude of both hemispheres - high pressure belts; 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 atmospheric pressure over the continents rises strongly, the low-pressure belt is interrupted. It persists only over the oceans in the form of closed areas of low pressure - the Icelandic and Aleutian minima. Over the continents, on the contrary, winter highs are formed: Asian and North American.

Rice. 3. General diagram of the distribution of atmospheric pressure

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

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

The lines that connect points with the same atmospheric pressure on the climate map are called isobars(from the Greek isos - equal and baros - heaviness, weight).

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

The formation of belts of atmospheric pressure near the earth's surface is influenced by the uneven distribution of 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 the belts of atmospheric pressure: in the summer - to the north, in the winter - to the south.

Everyone knows that air pressure is measured in millimeters of mercury, since this unit of measurement 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 translate millimeters of mercury into pascals.

Air pressure

To begin with, let's deal with the question of what constitutes air pressure. This value is understood as the pressure that the atmosphere of our planet exerts on any objects 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 body weight, g is the value of the acceleration due to gravity, m is the body weight ... The presence of weight in the body is due to gravity.

The atmosphere of our planet is a large gaseous body, which 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).

Pascal conversion of millimeters of mercury

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

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

This 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 in the formula, we get: P = 133.322 * H = 133.322 * 368 = 49062 Pa, or approximately 49 kPa.

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1 pascal [Pa] = 0.00750063755419211 millimeter mercury (0 ° C) [mmHg]

Initial value

Converted value

pascal exapascal petapascal terapascal gigapascal megapascal kilopascal hectopascal decapascal decapascal santipascal millipascal micropascal nanopascal picopascal femtopascal attopascal newton per sq. meter newton per sq. centimeter newton per sq. millimeter kilonewtons per square meter meter bar millibar microbar dyne per sq. centimeter kilogram-force per sq. meter kilogram-force per sq. centimeter kilogram-force per sq. millimeter gram-force per sq. centimeter ton-force (short) per sq. ft ton-force (short) per sq. inch ton-force (dl) per sq. ft ton-force (long) per sq. inch kilopound-force per square foot inch kilopound-force per square foot in lbf / sq. ft lbf / sq. inch psi poundal per sq. foot torr centimeter mercury (0 ° C) millimeter mercury (0 ° C) inch mercury (32 ° F) inch mercury (60 ° F) centimeter water column (4 ° C) mm wg. column (4 ° C) inH2O column (4 ° C) foot of water (4 ° C) inch of water (60 ° F) foot of water (60 ° F) technical atmosphere physical atmosphere decibar walls per square meter piezoe of barium (barium) Planck pressure meter seawater feet sea ​​water (at 15 ° C) water meter. column (4 ° C)

More about pressure

General information

In physics, pressure is defined as the force acting on a unit of surface area. If two equal forces act on one large and one smaller surface, then the pressure on the smaller surface will be greater. Agree, it is much more terrible if the owner of the stiletto heels steps on your feet than the owner of the sneakers. For example, if you press down on a tomato or carrot with a sharp knife, the vegetable will be cut in half. The surface area of ​​the blade in contact with the vegetable is small, so the pressure is high enough to cut the vegetable. If you press with the same force on a tomato or carrot with a blunt knife, then, most likely, the vegetable will not be cut, since the surface area of ​​the knife is now larger, which means the pressure is less.

In SI, pressure is measured in pascals, or newtons per square meter.

Relative pressure

Sometimes pressure is measured as the difference between absolute and atmospheric pressure. This pressure is called relative or gauge and it is it that is measured, for example, when checking the pressure in car tires. Gauges often, though not always, show exactly the relative pressure.

Atmosphere pressure

Atmospheric pressure is the air pressure at a given location. It usually refers to the pressure of a column of air per unit surface area. A change in atmospheric pressure affects weather and air temperature. People and animals suffer from severe pressure drops. Low blood pressure causes problems of varying severity in humans and animals, from mental and physical discomfort to fatal diseases. For this reason, aircraft cockpits are kept above atmospheric pressure at a given altitude, because atmospheric pressure at cruising altitude is too low.

Atmospheric pressure decreases with altitude. People and animals living high in the mountains, such as the Himalayas, adapt to these conditions. Travelers, on the other hand, must take the necessary precautions so as not to fall ill due to the fact that the body is not used to such low pressure. Mountain climbers, for example, can get sick with altitude sickness associated with a lack of oxygen in the blood and oxygen starvation of the body. This disease is especially dangerous if you are in the mountains for a long time. An exacerbation of altitude sickness leads to serious complications such as acute mountain sickness, high-altitude pulmonary edema, high-altitude cerebral edema, and an acute form of mountain sickness. The danger of altitude and mountain sickness begins at an altitude of 2,400 meters above sea level. To avoid altitude sickness, doctors advise not to use depressants such as alcohol and sleeping pills, drink plenty of fluids, and climb gradually, for example, on foot, rather than by transport. It is also beneficial to eat a lot of carbohydrates and rest well, especially if the climb is fast. These measures will allow the body to become accustomed to oxygen deprivation caused by low atmospheric pressure. If you follow these guidelines, your body can make more red blood cells to transport oxygen to your brain and internal organs. For this, the body will increase the pulse and respiratory rate.

First aid in such cases is provided immediately. It is important to move the patient to a lower altitude, where the atmospheric pressure is higher, preferably to an altitude lower than 2400 meters above sea level. Medicines and portable hyperbaric chambers are also used. They are lightweight, portable chambers that can be pressurized with a foot pump. An altitude sickness patient is placed in a chamber that maintains a pressure corresponding to a lower altitude. Such a camera is used only for first aid, after which the patient must be lowered below.

Some athletes use low blood pressure to improve circulation. Usually for this, training takes place in normal conditions, and these athletes sleep in a low pressure environment. Thus, their bodies become accustomed to high altitude conditions and begin to produce more red blood cells, which, in turn, increases the amount of oxygen in the blood, and allows them to achieve better results in sports. For this, special tents are produced, the pressure in which is regulated. Some athletes even change the pressure in the entire bedroom, but sealing the bedroom is an expensive process.

Spacesuits

Pilots and astronauts have to work in a low pressure environment, so they work in spacesuits to compensate for the low ambient pressure. Space suits completely protect a person from the environment. They are used in space. Altitude compensation suits are used by pilots at high altitudes - they help the pilot to breathe and counteract the low barometric pressure.

Hydrostatic pressure

Hydrostatic pressure is the pressure of a fluid caused by gravity. This phenomenon plays a huge role not only in technology and physics, but also in medicine. For example, blood pressure is the hydrostatic pressure of blood against the walls of blood vessels. Blood pressure is the pressure in the arteries. It is represented by two values: systolic, or highest pressure, and diastolic, or lowest pressure during the heartbeat. Blood pressure monitors are called sphygmomanometers or tonometers. The unit of blood pressure is taken in millimeters of mercury.

The Pythagorean mug is an entertaining vessel that uses hydrostatic pressure, and more specifically, the siphon principle. According to legend, Pythagoras invented this cup to control the amount of wine consumed. According to other sources, this cup was supposed to control the amount of water drunk during a drought. Inside the mug is a curved U-shaped tube hidden under the dome. One end of the tube is longer and ends with a hole in the leg of the mug. The other, shorter end, is connected with a hole to the inner bottom of the mug so that water in the mug fills the tube. The principle of the mug is similar to that of a modern toilet cistern. If the level of the liquid rises above the level of the tube, the liquid flows into the other half of the tube and flows out due to the hydrostatic pressure. If the level, on the contrary, is lower, then the mug can be safely used.

Geology pressure

Pressure is an important concept in geology. Formation of precious stones, both natural and artificial, is impossible without pressure. High pressure and high temperature are also necessary for the formation of oil from the remains of plants and animals. Unlike gemstones, which are mainly formed in rocks, oil forms at the bottom of rivers, lakes, or seas. Over time, more and more sand accumulates over these remains. The weight of water and sand presses on the remains of animals and plant organisms. Over time, this organic material sinks deeper and deeper into the earth, reaching several kilometers below the earth's surface. Temperatures increase by 25 ° C for every kilometer below the earth's surface, so temperatures reach 50–80 ° C at depths of several kilometers. Depending on the temperature and temperature difference in the formation medium, natural gas may form instead of oil.

Natural gems

The formation of gemstones is not always the same, but pressure is one of the main ingredients in this process. For example, diamonds are formed in the Earth's mantle, under conditions of high pressure and high temperature. During volcanic eruptions, diamonds are transported to the upper layers of the Earth's surface thanks to magma. Some diamonds come to Earth from meteorites, and scientists believe they formed on planets similar to Earth.

Synthetic gemstones

The production of synthetic gemstones began in the 1950s and has been gaining popularity in recent years. Some buyers prefer natural gemstones, but artificial gemstones are becoming more and more popular due to the low price and lack of problems associated with mining natural gemstones. For example, many buyers choose synthetic gemstones because their extraction and sale is not associated with human rights violations, child labor and the financing of wars and armed conflicts.

One of the technologies for growing diamonds in the laboratory is the method of growing crystals at high pressure and high temperature. In special devices, carbon is heated to 1000 ° C and subjected to a pressure of about 5 gigapascals. Typically, a small diamond is used as the seed crystal, and graphite is used for the carbon base. A new diamond grows from it. It is the most common method for growing diamonds, especially as gemstones, due to its low cost. The properties of diamonds grown in this way are the same or better than those of natural stones. The quality of synthetic diamonds depends on the method of growing them. Compared to natural diamonds, which are most often transparent, most artificial diamonds are colored.

Due to their hardness, diamonds are widely used in manufacturing. In addition, their high thermal conductivity, optical properties and resistance to alkalis and acids are appreciated. Cutting tools are often coated with diamond dust, which is also used in abrasives and materials. Most of the diamonds in production are of artificial origin due to the low price and because the demand for such diamonds exceeds the ability to mine them in nature.

Some companies offer services to create memorial diamonds from the ashes of the dead. To do this, after cremation, the ashes are cleaned until carbon is obtained, and then a diamond is grown on its basis. Manufacturers advertise these diamonds as a memory of the departed, and their services are popular, especially in countries with a large percentage of wealthy citizens, such as the United States and Japan.

High pressure and high temperature crystal growing method

The high pressure, high temperature crystal growth method is mainly used to synthesize diamonds, but more recently, this method has been helping to refine natural diamonds or change their color. Different presses are used for the artificial cultivation of diamonds. The most expensive to maintain and the most difficult of them is the cube press. It is mainly used to enhance or change the color of natural diamonds. Diamonds grow in the press at a rate of approximately 0.5 carats per day.

Do you find it difficult to translate a unit of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and you will receive an answer within a few minutes.

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

The atmospheric pressure at sea level is approximately 760 mm Hg. Art. Standard atmospheric pressure is taken to be (exactly) 760 mm Hg. Art. , or 101 325 Pa, hence the definition of a millimeter of mercury (101 325/760 Pa). Earlier, 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 at an acceleration of gravity of 9.806 65 m / s². The difference between these two definitions is 0.00014%.

Millimeters of mercury are used, for example, in vacuum technology, in meteorological reports and in measuring blood pressure. Since in vacuum technology very often the pressure is measured simply in millimeters, omitting the words "mercury column", the transition to microns (microns) natural for vacuum specialists is carried out, as a rule, also without indicating the "pressure of the mercury column". 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. Needless to say, no one uses a Torricelli gauge to measure such low pressures. Other devices are used to measure low pressures, for example, a McLeod manometer (vacuum gauge).

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

see also

Wikimedia Foundation. 2010.

• Rodchenko, Alexander Mikhailovich
• Shaikhet, Arkady Samoilovich

See what "Millimeter of mercury" is in other dictionaries:

- (mm Hg. Art., mm Hg), off-system units. pressure; 1 mmHg st. = 133.332 Pa = 1.35952 10 3 kgf / cm2 = 13.595 mm of water. Art. Physical encyclopedic dictionary. M .: Soviet encyclopedia. Chief editor A.M. Prokhorov. 1983. MILLIME ... Physical encyclopedia

Non-systemic unit. pressure, applied. at meas. atm. pressure of water vapor, high vacuum, etc. Designation: rus. - mm Hg. Art., Intern. - mm Hg. 1 mmHg Art. equal to hydrostatic. pressure of a column of mercury 1 mm high and a density of 13.5951 ... ... Technical translator's guide

Big Encyclopedic Dictionary

- - off-system unit. pressure; 1 mmHg st. = 133.332 Pa = 1.35952 10 3 kgf / cm2 = 13.595 mm of water. Art. [Physical encyclopedia. In 5 volumes. M .: Soviet encyclopedia. Chief editor 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 POST MILLIMETER OF MERCURY POST, non-systemic unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 ... encyclopedic Dictionary

Torr, a non-systemic unit of pressure used to measure atmospheric pressure of water vapor, high vacuum, etc. Designation: Russian mm Hg. Art., international mm Hg. 1 mm Hg is equal to hydrostatic ... Encyclopedic Dictionary of Metallurgy

- (mmHg) unit of pressure, as a result of which the 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 to measure atmospheric pressure, partial pressure of water vapor, high vacuum, etc. Abbreviations: Russian mm Hg. Art., international mm Hg. 1 mmHg see equals ... ... Great Soviet Encyclopedia

Non-systemic unit not applicable. pressure. Designation mmHg 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 of water. st ... Natural science. encyclopedic Dictionary

Length and Distance Converter Mass Converter Bulk and Food Volume Converter Area Converter Culinary Recipe Volume and Units Converter Temperature Converter Pressure, Stress, Young's Modulus Converter Energy and Work Converter Power Converter Force Converter Time Converter Linear Velocity Converter Flat Angle Converter Thermal Efficiency and Fuel Efficiency Numeric Conversion Systems Converter of Information Measurement Systems Currency Rates Women's Clothing and Shoes Sizes Men's Clothing and Shoes Sizes Angular Velocity and Rotation Rate Converter Acceleration Converter Angular Acceleration Converter Density Converter Specific Volume Converter Moment of Inertia Converter Moment of Force Converter Torque converter Specific calorific value (mass) converter Energy density and specific calorific value (volume) converter Temperature difference converter Coefficient converter Thermal expansion coefficient Thermal resistance converter Thermal conductivity converter Specific heat capacity converter Thermal exposure and radiation power converter Heat flux density converter Heat transfer coefficient converter Volumetric flow rate converter Mass flow rate Molar flow rate converter Mass flux density converter Molar concentration converter Mass concentration in solution converter absolute) viscosity Kinematic viscosity converter Surface tension converter Vapor permeability converter Water vapor flux density converter Sound level converter Microphone sensitivity converter Sound pressure level (SPL) converter Sound pressure level converter with selectable reference pressure Luminance converter Luminous intensity converter Illumination converter Computer graphics resolution converter Frequency and Wavelength Converter Optical Power in Diopters and Focal distance Diopter power and lens magnification (×) Electric charge converter Linear charge density converter Surface charge density converter Bulk charge density converter Electric current linear current density converter Surface current density converter Electric field strength converter Electrostatic potential and voltage converter Electrostatic potential and voltage converter Electrical resistance converter Converter electrical resistivity Electrical conductivity converter Electrical conductivity converter Electrical capacitance Inductance converter American wire gauge converter Levels in dBm (dBm or dBmW), dBV (dBV), watts, etc. units Magnetomotive force converter Magnetic field strength converter Magnetic flux converter Magnetic induction converter Radiation. Ionizing Radiation Absorbed Dose Rate Converter Radioactivity. Radioactive decay Radiation converter. Exposure Dose Converter Radiation. Absorbed Dose Converter Decimal Prefixes Converter Data Transfer Typography and Image Processing Unit Converter Timber Volume Unit Converter Calculating Molar Mass Periodic Table of Chemical Elements D. I. Mendeleev

1 pascal [Pa] = 0.00750063755419211 millimeter mercury (0 ° C) [mmHg]

Initial value

Converted value

pascal exapascal petapascal terapascal gigapascal megapascal kilopascal hectopascal decapascal decapascal santipascal millipascal micropascal nanopascal picopascal femtopascal attopascal newton per sq. meter newton per sq. centimeter newton per sq. millimeter kilonewtons per square meter meter bar millibar microbar dyne per sq. centimeter kilogram-force per sq. meter kilogram-force per sq. centimeter kilogram-force per sq. millimeter gram-force per sq. centimeter ton-force (short) per sq. ft ton-force (short) per sq. inch ton-force (dl) per sq. ft ton-force (long) per sq. inch kilopound-force per square foot inch kilopound-force per square foot in lbf / sq. ft lbf / sq. inch psi poundal per sq. foot torr centimeter mercury (0 ° C) millimeter mercury (0 ° C) inch mercury (32 ° F) inch mercury (60 ° F) centimeter water column (4 ° C) mm wg. column (4 ° C) inH2O column (4 ° C) foot of water (4 ° C) inch of water (60 ° F) foot of water (60 ° F) technical atmosphere physical atmosphere decibar walls per square meter piezoe of barium (barium) Planck pressure meter seawater feet sea ​​water (at 15 ° C) water meter. column (4 ° C)

More about pressure

General information

In physics, pressure is defined as the force acting on a unit of surface area. If two equal forces act on one large and one smaller surface, then the pressure on the smaller surface will be greater. Agree, it is much more terrible if the owner of the stiletto heels steps on your feet than the owner of the sneakers. For example, if you press down on a tomato or carrot with a sharp knife, the vegetable will be cut in half. The surface area of ​​the blade in contact with the vegetable is small, so the pressure is high enough to cut the vegetable. If you press with the same force on a tomato or carrot with a blunt knife, then, most likely, the vegetable will not be cut, since the surface area of ​​the knife is now larger, which means the pressure is less.

In SI, pressure is measured in pascals, or newtons per square meter.

Relative pressure

Sometimes pressure is measured as the difference between absolute and atmospheric pressure. This pressure is called relative or gauge and it is it that is measured, for example, when checking the pressure in car tires. Gauges often, though not always, show exactly the relative pressure.

Atmosphere pressure

Atmospheric pressure is the air pressure at a given location. It usually refers to the pressure of a column of air per unit surface area. A change in atmospheric pressure affects weather and air temperature. People and animals suffer from severe pressure drops. Low blood pressure causes problems of varying severity in humans and animals, from mental and physical discomfort to fatal diseases. For this reason, aircraft cockpits are kept above atmospheric pressure at a given altitude, because atmospheric pressure at cruising altitude is too low.

Atmospheric pressure decreases with altitude. People and animals living high in the mountains, such as the Himalayas, adapt to these conditions. Travelers, on the other hand, must take the necessary precautions so as not to fall ill due to the fact that the body is not used to such low pressure. Mountain climbers, for example, can get sick with altitude sickness associated with a lack of oxygen in the blood and oxygen starvation of the body. This disease is especially dangerous if you are in the mountains for a long time. An exacerbation of altitude sickness leads to serious complications such as acute mountain sickness, high-altitude pulmonary edema, high-altitude cerebral edema, and an acute form of mountain sickness. The danger of altitude and mountain sickness begins at an altitude of 2,400 meters above sea level. To avoid altitude sickness, doctors advise not to use depressants such as alcohol and sleeping pills, drink plenty of fluids, and climb gradually, for example, on foot, rather than by transport. It is also beneficial to eat a lot of carbohydrates and rest well, especially if the climb is fast. These measures will allow the body to become accustomed to oxygen deprivation caused by low atmospheric pressure. If you follow these guidelines, your body can make more red blood cells to transport oxygen to your brain and internal organs. For this, the body will increase the pulse and respiratory rate.

First aid in such cases is provided immediately. It is important to move the patient to a lower altitude, where the atmospheric pressure is higher, preferably to an altitude lower than 2400 meters above sea level. Medicines and portable hyperbaric chambers are also used. They are lightweight, portable chambers that can be pressurized with a foot pump. An altitude sickness patient is placed in a chamber that maintains a pressure corresponding to a lower altitude. Such a camera is used only for first aid, after which the patient must be lowered below.

Some athletes use low blood pressure to improve circulation. Usually for this, training takes place in normal conditions, and these athletes sleep in a low pressure environment. Thus, their bodies become accustomed to high altitude conditions and begin to produce more red blood cells, which, in turn, increases the amount of oxygen in the blood, and allows them to achieve better results in sports. For this, special tents are produced, the pressure in which is regulated. Some athletes even change the pressure in the entire bedroom, but sealing the bedroom is an expensive process.

Spacesuits

Pilots and astronauts have to work in a low pressure environment, so they work in spacesuits to compensate for the low ambient pressure. Space suits completely protect a person from the environment. They are used in space. Altitude compensation suits are used by pilots at high altitudes - they help the pilot to breathe and counteract the low barometric pressure.

Hydrostatic pressure

Hydrostatic pressure is the pressure of a fluid caused by gravity. This phenomenon plays a huge role not only in technology and physics, but also in medicine. For example, blood pressure is the hydrostatic pressure of blood against the walls of blood vessels. Blood pressure is the pressure in the arteries. It is represented by two values: systolic, or highest pressure, and diastolic, or lowest pressure during the heartbeat. Blood pressure monitors are called sphygmomanometers or tonometers. The unit of blood pressure is taken in millimeters of mercury.

The Pythagorean mug is an entertaining vessel that uses hydrostatic pressure, and more specifically, the siphon principle. According to legend, Pythagoras invented this cup to control the amount of wine consumed. According to other sources, this cup was supposed to control the amount of water drunk during a drought. Inside the mug is a curved U-shaped tube hidden under the dome. One end of the tube is longer and ends with a hole in the leg of the mug. The other, shorter end, is connected with a hole to the inner bottom of the mug so that water in the mug fills the tube. The principle of the mug is similar to that of a modern toilet cistern. If the level of the liquid rises above the level of the tube, the liquid flows into the other half of the tube and flows out due to the hydrostatic pressure. If the level, on the contrary, is lower, then the mug can be safely used.

Geology pressure

Pressure is an important concept in geology. Formation of precious stones, both natural and artificial, is impossible without pressure. High pressure and high temperature are also necessary for the formation of oil from the remains of plants and animals. Unlike gemstones, which are mainly formed in rocks, oil forms at the bottom of rivers, lakes, or seas. Over time, more and more sand accumulates over these remains. The weight of water and sand presses on the remains of animals and plant organisms. Over time, this organic material sinks deeper and deeper into the earth, reaching several kilometers below the earth's surface. Temperatures increase by 25 ° C for every kilometer below the earth's surface, so temperatures reach 50–80 ° C at depths of several kilometers. Depending on the temperature and temperature difference in the formation medium, natural gas may form instead of oil.

Natural gems

The formation of gemstones is not always the same, but pressure is one of the main ingredients in this process. For example, diamonds are formed in the Earth's mantle, under conditions of high pressure and high temperature. During volcanic eruptions, diamonds are transported to the upper layers of the Earth's surface thanks to magma. Some diamonds come to Earth from meteorites, and scientists believe they formed on planets similar to Earth.

Synthetic gemstones

The production of synthetic gemstones began in the 1950s and has been gaining popularity in recent years. Some buyers prefer natural gemstones, but artificial gemstones are becoming more and more popular due to the low price and lack of problems associated with mining natural gemstones. For example, many buyers choose synthetic gemstones because their extraction and sale is not associated with human rights violations, child labor and the financing of wars and armed conflicts.

One of the technologies for growing diamonds in the laboratory is the method of growing crystals at high pressure and high temperature. In special devices, carbon is heated to 1000 ° C and subjected to a pressure of about 5 gigapascals. Typically, a small diamond is used as the seed crystal, and graphite is used for the carbon base. A new diamond grows from it. It is the most common method for growing diamonds, especially as gemstones, due to its low cost. The properties of diamonds grown in this way are the same or better than those of natural stones. The quality of synthetic diamonds depends on the method of growing them. Compared to natural diamonds, which are most often transparent, most artificial diamonds are colored.

Due to their hardness, diamonds are widely used in manufacturing. In addition, their high thermal conductivity, optical properties and resistance to alkalis and acids are appreciated. Cutting tools are often coated with diamond dust, which is also used in abrasives and materials. Most of the diamonds in production are of artificial origin due to the low price and because the demand for such diamonds exceeds the ability to mine them in nature.

Some companies offer services to create memorial diamonds from the ashes of the dead. To do this, after cremation, the ashes are cleaned until carbon is obtained, and then a diamond is grown on its basis. Manufacturers advertise these diamonds as a memory of the departed, and their services are popular, especially in countries with a large percentage of wealthy citizens, such as the United States and Japan.

High pressure and high temperature crystal growing method

The high pressure, high temperature crystal growth method is mainly used to synthesize diamonds, but more recently, this method has been helping to refine natural diamonds or change their color. Different presses are used for the artificial cultivation of diamonds. The most expensive to maintain and the most difficult of them is the cube press. It is mainly used to enhance or change the color of natural diamonds. Diamonds grow in the press at a rate of approximately 0.5 carats per day.

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