Pressure- This physical quantity, showing the force per unit area of a surface perpendicular to this surface.
Pressure is defined as P = F / S, where P is pressure, F is pressure force, S is surface area. From this formula it is clear that pressure depends on the surface area of the body acting with a certain force. The smaller the surface area, the greater the pressure.
The unit of measurement for pressure is newton per square meter(H/m2). We can also convert pressure units N/m 2 to pascals, units named after the French scientist Blaise Pascal, who developed the so-called Pascal's Law. 1 N/m 2 = 1 Pa.
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Pressure measurement
Pressure of gases and liquids - manometer, differential pressure gauge, vacuum gauge, pressure sensor.Atmospheric pressure - barometer.
Blood pressure - tonometer.
And so, once again the pressure is defined as P = F / S. The force in the gravitational field is equal to the weight - F = m * g, where m is the mass of the body; g is the acceleration of free fall. Then the pressure is
P = m * g / S . Using this formula, you can determine the pressure exerted by the body on the surface. For example, a person to the ground.
Atmospheric pressure decreases with altitude. The dependence of atmospheric pressure on altitude is determined barometric formula -
P = Po*exp(- μgh/RT) . Where, μ = 0.029 kg/m3 - molecular mass gas (air); g = 9.81 m/s2 - free fall acceleration; h - h o - difference in altitude above sea level and the accepted altitude at the beginning of the report (h=h o); R = 8.31 - J/mol K - gas constant; Ro - Atmosphere pressure at the height taken as the starting point; T - temperature in Kelvin.
Caused by the weight of air. 1 m³ of air weighs 1.033 kg. For every meter of the earth's surface there is an air pressure of 10033 kg. This refers to a column of air from sea level to the upper atmosphere. If we compare it with a column of water, the diameter of the latter would have a height of only 10 meters. That is, atmospheric pressure is created by its own air mass. The amount of atmospheric pressure per unit area corresponds to the mass of the air column located above it. As a result of an increase in air in this column, pressure increases, and as air decreases, a decrease occurs. Normal atmospheric pressure is considered to be air pressure at t 0°C at sea level at a latitude of 45°. In this case, the atmosphere presses with a force of 1.033 kg for every 1 cm² of earth's area. The mass of this air is balanced by a column of mercury 760 mm high. Atmospheric pressure is measured using this relationship. It is measured in millimeters mercury or millibars (mb), as well as in hectopascals. 1mb = 0.75 mm Hg, 1 hPa = 1 mm.
Measuring atmospheric pressure.
measured using barometers. They come in two types.
1. A mercury barometer is a glass tube, which is sealed at the top, and the open end is immersed in a metal bowl with mercury. A scale indicating the change in pressure is attached next to the tube. The mercury is acted upon by air pressure, which balances the column of mercury in the glass tube with its weight. The height of the mercury column changes with pressure changes.
2. A metal barometer or aneroid is a corrugated metal box that is hermetically sealed. Inside this box there is rarefied air. The change in pressure causes the walls of the box to vibrate, pushing in or out. These vibrations by a system of levers cause the arrow to move along a graduated scale.
Recording barometers or barographs are designed to record changes atmospheric pressure. The pen picks up the vibration of the walls of the aneroid box and draws a line on the tape of the drum, which rotates around its axis.
What is atmospheric pressure?
Atmospheric pressure on the globe varies widely. Its minimum value - 641.3 mm Hg or 854 mb was recorded over Pacific Ocean in Hurricane Nancy, and the maximum was 815.85 mm Hg. or 1087 MB in Turukhansk in winter.
Air pressure on the earth's surface changes with altitude. Average atmospheric pressure value above sea level - 1013 mb or 760 mm Hg. The higher the altitude, the lower the atmospheric pressure, as the air becomes more and more rarefied. IN bottom layer in the troposphere to a height of 10 m it decreases by 1 mmHg. for every 10 m or 1 mb for every 8 meters. At an altitude of 5 km it is 2 times less, at 15 km - 8 times, 20 km - 18 times.
Due to air movement, temperature changes, seasonal changes Atmosphere pressure constantly changing. Twice a day, in the morning and in the evening, it increases and decreases the same number of times, after midnight and after noon. During the year, due to the cold and compacted air, atmospheric pressure is at its maximum in winter and at its minimum in summer.
Constantly changing and distributed across the earth's surface zonally. This occurs due to uneven heating by the Sun. earth's surface. The change in pressure is affected by the movement of air. Where there is more air, the pressure is high, and where the air leaves - low. The air, having warmed up from the surface, rises and the pressure on the surface decreases. At altitude, the air begins to cool, becomes denser and sinks to nearby cold areas. Atmospheric pressure increases there. Consequently, the change in pressure is caused by the movement of air as a result of its heating and cooling from the earth's surface.
Atmospheric pressure in equatorial zone constantly reduced, and in tropical latitudes- increased. This happens due to constant high temperatures air at the equator. The heated air rises and moves towards the tropics. In the Arctic and Antarctic, the surface of the earth is always cold and the atmospheric pressure is high. It is caused by air that comes from temperate latitudes. In turn, in temperate latitudes due to the outflow of air, a zone is formed low blood pressure. Thus, there are two belts on Earth atmospheric pressure- low and high. Decreased at the equator and in two temperate latitudes. Raised on two tropical and two polar. They may shift slightly depending on the time of year following the Sun towards the summer hemisphere.
Polar belts high pressure exist all year round, however, in summer they shrink, and in winter, on the contrary, they expand. All year round areas of low pressure remain near the Equator and in southern hemisphere in temperate latitudes. In the northern hemisphere, things happen differently. In temperate latitudes northern hemisphere the pressure over the continents increases greatly and the field low pressure as if “broken”: it is preserved only over the oceans in the form of closed areas low atmospheric pressure- Icelandic and Aleutian minimums. Over the continents, where the pressure has noticeably increased, winter maximums form: Asian (Siberian) and North American (Canadian). In summer, the low pressure field in the temperate latitudes of the northern hemisphere is restored. At the same time, a vast area of low pressure is formed over Asia. This is the Asian low.
In the belt increased atmospheric pressure- the tropics - the continents are heating up stronger than the oceans and the pressure above them is lower. Because of this, subtropical highs are distinguished over the oceans:
- North Atlantic (Azores);
- South Atlantic;
- South Pacific;
- Indian.
Despite large-scale seasonal changes their indicators, belts of low and high atmospheric pressure of the Earth- formations are quite stable.
About a third of our planet's population is sensitive to change environment. Most of all, a person’s well-being is influenced by atmospheric pressure - the attraction of air masses to the Earth. What atmospheric pressure is considered normal for a person depends on the area in which he spends the vast majority of the time. Everyone will find their familiar conditions comfortable.
What is atmospheric pressure
The planet is surrounded by an air mass, which, under the influence of gravity, presses on any object, including human body. The force is called atmospheric pressure. Each square meter is pressed by a column of air weighing approximately 100,000 kg. Atmospheric pressure is measured using a special device - a barometer. It is measured in pascals, millimeters of mercury, millibars, hectopascals, atmospheres.
The normal atmospheric pressure is 760 mm Hg. Art., or 101 325 Pa. The discovery of the phenomenon belongs to the famous physicist Blaise Pascal. The scientist formulated a law: at the same distance from the center of the earth (it doesn’t matter, in the air, at the bottom of a reservoir), the absolute pressure will be the same. He was the first to propose measuring heights using the barometric alignment method.
Atmospheric pressure standards by region
It is impossible to find out what atmospheric pressure is considered normal for a healthy person - there is no definite answer. By different regions impact varies across the globe. Within a relatively small area, this value can vary noticeably. For example, in Central Asia Slightly elevated numbers are considered standard (on average 715-730 mm Hg). For middle zone In Russia, normal atmospheric pressure is 730-770 mm Hg. Art.
Indicators are related to the elevation of the surface above sea level, wind direction, humidity and ambient temperature. Warm air weighs less than cold. Above the area with elevated temperature or humidity, the compression of the atmosphere is always less. People living in high mountain areas are not sensitive to such barometer readings. Their body was formed under these conditions, and all organs underwent appropriate adaptation.
How pressure affects people
The ideal value is 760 mmHg. Art. What awaits when the mercury column fluctuates:
- A change in optimal indicators (up to 10 mm/h) already leads to a deterioration in well-being.
- With a sharp increase or decrease (on average by 1 mm/h), even in healthy people there is a significant deterioration in health. Appears headache, nausea, loss of performance.
Meteor dependence
Human sensitivity to weather conditions - wind changes, geomagnetic storms- called weather dependence. The influence of atmospheric pressure has not yet been fully studied. It is known that when changing weather conditions internal tension is created inside the vessels and cavities of the body. Meteorological dependence can be expressed:
- irritability;
- pain of various localization;
- exacerbation of chronic diseases;
- general deterioration of health;
- problems with blood vessels.
In most cases, people with the following diseases suffer from weather dependence:
- illnesses respiratory tract;
- metabolic disorders;
- hypo- and hypertension.
Reaction to high blood pressure
A decrease in barometer readings by at least 10 units (770 mm Hg and below) has Negative influence to your health. People with long-standing cardiovascular and cardiovascular diseases are especially affected by weather changes. digestive system. On such days, doctors recommend reducing physical activity, spending less time on the street, and not abusing heavy foods and alcohol. Among the main reactions.
Also in ancient times people noticed that air exerts pressure on ground objects, especially during storms and hurricanes. He used this pressure, forcing the wind to move sailing ships and rotate the wings of windmills. However, for a long time it was not possible to prove that air has weight. Only in the 17th century was an experiment carried out that proved the weight of air. The reason for this was an accidental circumstance.
In Italy in 1640, the Duke of Tuscany decided to build a fountain on the terrace of his palace. The water for this fountain had to be pumped from a nearby lake, but the water did not flow higher than 32 feet. The Duke turned to Galileo, then already a very old man, for clarification. The great scientist was confused and did not immediately find how to explain this phenomenon. And only Galileo’s student, Torricelli, after long experiments, proved that air has weight, and the pressure of the atmosphere is balanced by a column of water of 32 feet. He went even further in his research and in 1643 invented a device for measuring atmospheric pressure - barometer.
So, on 1 cm² of the earth's surface, air exerts a pressure equal to 1.033 kg. All objects on Earth, as well as the human body, experience this pressure per 1 cm². If we take the average surface area of the human body to be about 15,000 cm², then it is obvious that it is under pressure of about 15,500 kg.
Why doesn’t a person experience any inconvenience and feel this heaviness? And this happens because the pressure is distributed evenly over the entire surface of the body and the external pressure is balanced by the internal air pressure that fills all our organs. The human body (and not only it, but many other representatives of the fauna) is adapted to atmospheric pressure, all organs have developed under it, and only under it can they function normally. With systematic and long-term training, a person can adapt and live with low blood pressure.
Atmospheric pressure can be measured in millimeters of mercury (mmHg) and also in millibars (mb), but currently the SI unit of atmospheric pressure is Pascal and hectoPascal (hPa). HectoPascal is numerically equal to a millibar (mb). Atmospheric pressure is 760 mm. rt. Art. = 1,013.25 hPa = 1,013.25 mbar. is considered normal.
But this does not mean at all that this value of atmospheric pressure is the climatic norm for all regions and throughout the year.
Residents of Vladivostok are lucky: the average atmospheric pressure for the year is about 761 mm. rt. Art., although the residents of the mountain village of Tok Jalung in Tibet at an altitude of 4,919 m also do not suffer, and the atmospheric pressure there at a temperature of 0˚C is only 413 mm. rt. Art.
Every morning, weather reports transmit data on atmospheric pressure for Vladivostok and, at the request of radio listeners, not in hPa, but in mm. rt. Art. at sea level.
Why is atmospheric pressure measured on land most often translated to sea level?
The fact is that atmospheric pressure decreases with altitude and quite significantly. So, at an altitude of 5,000 m it is already approximately two times lower. Therefore, to obtain an idea of the real spatial distribution of atmospheric pressure and to compare its value in different areas and on different heights, for compiling synoptic maps, etc., the pressure is brought to a single level, i.e. to sea level.
Measured at the weather station site, located at an altitude of 187 m above sea level, the atmospheric pressure is on average 16-18 mm. rt. Art. lower than below on the seashore.
The figure shows annual course average monthly atmospheric pressure according to Vladivostok. Such a course of atmospheric pressure (with a winter maximum and a summer minimum) is typical for continental regions, and in magnitude annual amplitude(about 12 mmHg) can be attributed to transitional type: from continental to oceanic.
For comparison, the amplitude in and is 15-19 mm. rt. Art., and in and only 3.75 mm. rt. Art.
On the well-being of a person who has lived in a certain area for quite a long time, normal (characteristic) pressure should not cause a particular deterioration in well-being, but failure occurs most often with sharp non-periodic fluctuations in atmospheric pressure, and, as a rule, ≥2-3 mm. rt. Art. / 3 hours. In these cases even In practically healthy people, performance decreases, a heaviness is felt in the body, and a headache appears.
We are not able to influence the weather, but it is not at all difficult to help our body survive this difficult period.
How to survive fluctuations in atmospheric pressure during the day?
When forecasting a significant deterioration in weather conditions, that is, sudden changes in atmospheric pressure, first of all you should not panic, calm down, and reduce as much as possible. physical activity. For those whose adaptation reactions are quite difficult, it is necessary to consult a doctor about prescribing appropriate medications.
Especially for Primpogoda, leading climatologist of Primhydromet E. A. Mendelson
Atmospheric air has physical density, as a result of which it is attracted to the Earth and creates pressure. During the development of the planet, both the composition of the atmosphere and its atmospheric pressure changed. Living organisms were forced to adapt to the existing air pressure, changing their physiological characteristics. Deviations from average atmospheric pressure cause changes in a person’s well-being, and the degree of sensitivity of people to such changes varies.
Normal atmospheric pressure
The air extends from the Earth's surface to heights of the order of hundreds of kilometers, beyond which interplanetary space begins, while the closer to the Earth, the more compressed the air is under the influence of own weight, accordingly, atmospheric pressure is highest at the earth's surface, decreasing with increasing altitude.
At sea level (from which all altitudes are usually measured), at a temperature of +15 degrees Celsius, the atmospheric pressure averages 760 millimeters of mercury (mmHg). This pressure is considered normal (from a physical point of view), which does not mean that this pressure is comfortable for a person under any conditions.
Atmospheric pressure is measured by a barometer, graduated in millimeters of mercury (mmHg), or in other physical units, such as pascals (Pa). 760 millimeters of mercury corresponds to 101,325 pascals, but in everyday life the measurement of atmospheric pressure in pascals or derived units (hectopascals) has not taken root.
Previously, atmospheric pressure was also measured in millibars, which fell out of use and were replaced by hectopascals. Normal atmospheric pressure is 760 mm Hg. Art. corresponds to the standard atmospheric pressure of 1013 mbar.
Pressure 760 mm Hg. Art. corresponds to the action of a force of 1.033 kilograms on each square centimeter of the human body. In total, air presses on the entire surface of the human body with a force of about 15-20 tons.
But a person does not feel this pressure, since it is balanced by air gases dissolved in tissue fluids. This balance is disrupted by changes in atmospheric pressure, which a person perceives as a deterioration in well-being.
For some areas, the average atmospheric pressure differs from 760 mm. rt. Art. So, if in Moscow the average pressure is 760 mm Hg. Art., then in St. Petersburg it is only 748 mm Hg. Art.
At night, the atmospheric pressure is slightly higher than during the day, and at the Earth’s poles, fluctuations in atmospheric pressure are more pronounced than in the equatorial zone, which only confirms the pattern that the polar regions (Arctic and Antarctic) as a habitat are hostile to humans.
In physics, the so-called barometric formula is derived, according to which, with an increase in altitude for every kilometer, atmospheric pressure drops by 13%. The actual air pressure distribution follows barometric formula not entirely accurate, since temperature, atmospheric composition, water vapor concentration and other indicators change depending on the altitude.
Atmospheric pressure also depends on the weather when air masses move from one area to another. All living things on Earth also respond to atmospheric pressure. Thus, fishermen know that the standard atmospheric pressure for fishing is reduced, because when the pressure drops predatory fish prefers to go hunting.
Weather-dependent people, and there are 4 billion of them on the planet, are sensitive to changes in atmospheric pressure, and some of them can quite accurately predict weather changes, guided by their well-being.
It is quite difficult to answer the question of what standard of atmospheric pressure is most optimal for a person’s place of stay and life, since people adapt to life in different climatic conditions. Typically the pressure is between 750 and 765 mmHg. Art. does not worsen a person’s well-being; these atmospheric pressure values can be considered within the normal range.
When atmospheric pressure changes, weather-dependent people may feel:
headache; vascular spasms with circulatory disorders; weakness and drowsiness with increased fatigue; joint pain; dizziness; feeling of numbness in the limbs; decreased heart rate; nausea and intestinal disorders; shortness of breath; decreased visual acuity.
The first thing to react to changes in pressure are those located in the cavities of the body, joints and blood vessels baroreceptors.
When pressure changes, weather-sensitive people experience disturbances in the functioning of the heart, heaviness in the chest, pain in the joints, and in case of digestive problems, also flatulence and intestinal disorders. With a significant decrease in pressure, a lack of oxygen in brain cells leads to headaches.
Also, changes in pressure can lead to mental disorders - people feel anxious, irritated, sleep restlessly, or generally cannot sleep.
Statistics confirm that with sudden changes in atmospheric pressure, the number of crimes, accidents in transport and production increases. The influence of atmospheric pressure on arterial pressure is traced. In hypertensive patients, increased atmospheric pressure can cause a hypertensive crisis with headache and nausea, despite the fact that at this moment clear sunny weather sets in.
On the contrary, hypotensive patients react more sharply to a decrease in atmospheric pressure. The reduced concentration of oxygen in the atmosphere causes circulatory disorders, migraines, shortness of breath, tachycardia and weakness.
Weather sensitivity can be a consequence of an unhealthy lifestyle. The following factors can lead to weather sensitivity or aggravate its severity:
low physical activity; poor nutrition with accompanying excess weight; stress and constant nervous tension; poor state of the external environment.
Elimination of these factors reduces the degree of meteosensitivity. For weather dependent people follows:
include foods high in vitamin B6, magnesium and potassium in your diet (vegetables and fruits, honey, lactic acid products); limit the consumption of meat, salty and fried foods, sweets and spices; stop smoking and drinking alcohol; increase physical activity, take walks on fresh air; organize your sleep, sleep at least 7-8 hours.
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Atmospheric pressure is the force with which a column of air presses on a certain unit of area of the Earth; it is often measured in kilograms per square meter, and from there it is converted to other units. By to the globe atmospheric pressure varies, it depends on geographical location. Normal habitual blood pressure is extremely important to the human body for full functioning. You need to figure out what atmospheric pressure is normal for a person, and how its changes can affect well-being.
When you rise to a height, the atmospheric pressure decreases, and when you go down, it increases. Also this indicator may depend on the time of year and humidity in a particular area. In everyday life it is measured using a barometer; it is customary to indicate atmospheric pressure in millimeters of mercury.
The ideal atmospheric pressure is considered to be 760 mmHg, but in Russia and most of the planet in general, this figure is far from this ideal.
The normal force of air pressure is considered to be that at which a person feels comfortable. Moreover, for people from different habitats, the pressure indicators at which normal health remains will be different. A person usually gets used to the indicators of the area in which he lives. If a resident of highlands moves to a lowland, he will experience discomfort for some time and gradually get used to it.
However, even at permanent place During residence, atmospheric pressure may change, usually with changing seasons and sudden changes in weather. In this case, people with a number of pathologies and congenital weather dependence may experience discomfort, and old diseases may begin to worsen.
It is worth knowing how you can improve your condition if there is a sharp drop or increase in atmospheric pressure. You don’t have to immediately run to the doctor; there are home techniques that have been tested by many people that can help you start feeling better.
Important! It is worth noting that people sensitive to changing weather conditions should be more careful when choosing places to spend their holidays or move.
What atmospheric pressure is considered normal for humans?
Many experts say: normal pressure for a person the figure will be 750 – 765 mmHg. It is easiest to adapt to indicators within these limits; for most people living on plains, small hills, and lowlands, they will be suitable.
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It is worth noting that the most dangerous thing is not increased or decreased indicators, but their sudden change. If changes happen gradually, most people won't notice them. Abrupt change can lead to negative consequences: Some people may faint during a sharp climb uphill.
Pressure norm table
In different cities of the country, the indicators will be different, this is the norm. Usually detailed weather reports tell you whether the atmospheric pressure is above or below normal. this moment time. You can always calculate the norm for your place of residence yourself, but it’s easier to contact ready-made tables. For example, here are the indicators for several cities in Russia:
| City name | Normal atmospheric pressure (in millimeters of mercury) |
| In Moscow | 747 – 748 |
| In Rostov-on-Don | 740 – 741 |
| In St. Petersburg | 753 – 755, in some places up to 760 |
| In Samara | 752 – 753 |
| In Ekaterinburg | 735 – 741 |
| In Perm | 744 – 745 |
| In Tyumen | 770 – 771 |
| In Chelyabinsk | 737 – 744 |
| In Izhevsk | 746 – 747 |
| In Yaroslavl | 750 – 752 |
It is worth noting that for some cities and regions large pressure drops are normal. Locals usually well adapted to them, bad feeling will arise for a visitor.
Important! If weather dependence occurs suddenly and has never been observed before, you should consult a doctor, this may indicate heart disease.
The influence of atmospheric pressure on the body
For people with certain diseases or hypersensitivity, changes in weather pressure changes can have a negative impact, in some cases limiting their ability to work. Experts note: women are slightly more likely than men to react to weather changes.
People with sensitivity to change have different reactions to changes. Some people feel slight discomfort that easily goes away on its own after some time. Others require an appointment special drugs to avoid exacerbation of any disease that may arise due to changing weather conditions.
The following groups of people are most prone to negative experiences during pressure changes:
People with various diseases lungs, these include bronchial asthma, obstructive bronchitis, Chronical bronchitis. People with various diseases of the heart and blood vessels, especially hypertension, hypotension, atherosclerosis, and other disorders. People with brain diseases, rheumatic diseases, diseases of the musculoskeletal system, especially osteochondrosis.
It is also believed that changes in weather conditions provoke allergy attacks in allergy sufferers. In completely healthy people, the changes usually have no significant effect.
People with weather dependence experience headaches, drowsiness, a feeling of fatigue, and pulse irregularities that are not observed during normal times. However, it is advised to consult a doctor to exclude the development of diseases of the heart and nervous system.
In addition to headaches and fatigue, people with various diseases may experience joint pain, changes blood pressure, numbness in lower limbs, muscle pain. In case of exacerbation of chronic diseases, you should take medications prescribed by your doctor.
What to do if you are weather dependent
If increased sensitivity to a change in weather conditions, but there are no diseases leading to it, then the following recommendations will help you cope with unpleasant sensations.
In the morning it is advised to take a contrast shower, then drink a cup good coffee to keep yourself in good shape. During the day it is advised to drink more tea, green tea with lemon is recommended. It is recommended to do exercises, several times a day.
Towards evening, on the contrary, they advise you to relax, they will help herbal teas and decoctions with honey, valerian infusion and other mild sedatives. They advise you to go to bed early and eat less salty foods during the day.
According to statistics, about 7 million annual deaths can be attributed to high level blood pressure. But studies show that 67% of hypertensive patients do not even suspect that they are sick! How can you protect yourself and overcome the disease? Dr. Alexander Myasnikov told in his interview how to forget about hypertension forever...
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