Pressure 760 mm Hg. Normal atmospheric pressure for a person

atmospheric air has a 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 Atmosphere pressure. Living organisms were forced to adapt to the existing air pressure, changing their physiological characteristics. Deviations from the average atmospheric pressure cause changes in a person's well-being, while the degree of sensitivity of people to such changes is different.

normal atmospheric pressure

Air extends from the surface of the Earth to heights of the order of hundreds of kilometers, beyond which interplanetary space begins, while the closer to the Earth, the more air is compressed under the action of its own weight, respectively, atmospheric pressure is highest earth's surface decreasing with increasing altitude.

At sea level (from which it is customary to count all heights), at a temperature of +15 degrees Celsius, atmospheric pressure averages 760 millimeters of mercury (mm Hg). This pressure is considered to be normal (from a physical point of view), which does not mean at all that this pressure is comfortable for a person under any conditions.

Atmospheric pressure is measured with a barometer graduated in millimeters of mercury (mm Hg), or in other physical units, for example, in pascals (Pa). 760 millimeters of mercury correspond to 101,325 pascals, but in everyday life the measurement of atmospheric pressure in pascals or derived units (hectopascals) did not take root.

Previously, atmospheric pressure was also measured in millibars, now obsolete and replaced by hectopascals. The norm of 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 on each square centimeter of the human body by a force of 1.033 kilograms. In total, the 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 disturbed by changes in atmospheric pressure, which a person perceives as a deterioration in well-being.

For some areas, the average value of atmospheric pressure differs from 760 mm. rt. Art. So, if in Moscow the average pressure is 760 mm Hg. Art., then in St. Petersburg only 748 mm Hg. Art.

At night, atmospheric pressure is slightly higher than daytime, and at the Earth's poles, atmospheric pressure fluctuations are more pronounced than in 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 each kilometer, atmospheric pressure drops by 13%. The real distribution of air pressure does not follow the barometric formula quite accurately, since temperature, atmospheric composition, water vapor concentration and other indicators change depending on altitude.

Atmospheric pressure also depends on the weather air masses moving from one area to another. All living things on Earth also react to atmospheric pressure. So, fishermen know that the rate of atmospheric pressure for fishing is reduced, because when the pressure decreases 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 accurately predict weather changes, guided by their well-being.

It is quite difficult to answer the question of what atmospheric pressure is the most optimal for places of residence and life of a person, since people adapt to life in different climatic conditions. Usually the pressure is in the range from 750 to 765 mm Hg. Art. does not worsen the well-being of a person, these atmospheric pressure values ​​\u200b\u200bcan be considered within the normal range.

With changes in atmospheric pressure, weather-dependent people can feel:

headache; vasospasm with circulatory disorders; weakness and drowsiness with increased fatigue; pain in the joints; dizziness; feeling of numbness in the limbs; decrease in heart rate; nausea and intestinal disorders; shortness of breath decrease in visual acuity.

Baroreceptors located in the body cavities, joints and blood vessels are the first to respond to pressure changes.

With a change in pressure, weather-sensitive people experience disturbances in the work of the heart, heaviness in the chest, pain in the joints, and in case of digestive problems, flatulence and intestinal disorders are also observed. With a significant decrease in pressure, the lack of oxygen in the brain cells leads to headaches.

Also, changes in pressure can lead to mental disorders - people feel anxious, irritated, sleep restlessly or, in general, cannot fall asleep.

Statistics confirm that with sharp changes in atmospheric pressure, the number of offenses, accidents in transport and production increases. The influence of atmospheric pressure on arterial pressure is traced. In hypertensive patients, elevated atmospheric pressure can cause hypertensive crisis with headache and nausea, when the weather is clear and sunny.

On the contrary, hypotensive patients react more sharply to a decrease in atmospheric pressure. The reduced concentration of oxygen in the atmosphere causes them circulatory disorders, migraines, shortness of breath, tachycardia and weakness.

Weather sensitivity can be the result of an unhealthy lifestyle. The following factors can lead to meteosensitivity or aggravate the degree of its manifestation:

low physical activity; malnutrition with concomitant overweight; stress and constant nervous tension; bad state of the environment.

The elimination of these factors reduces the degree of meteosensitivity. Weather dependent people should:

include in the diet foods high in vitamin B6, magnesium and potassium (vegetables and fruits, honey, lactic acid products); limit the consumption of meat, salty and fried food, sweets and spices; stop smoking and drinking alcohol; increase physical activity, take walks on fresh air; streamline 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 area of ​​​​the Earth, often measured in the amount of kilograms per one square meter, from there they are already converted to other units. Atmospheric pressure varies across the globe, it depends on geographical location. Normal habitual pressure is extremely important for the human body to function properly. It is necessary to figure out what atmospheric pressure is the norm for a person, how its changes can affect well-being.

When ascending a height, the atmospheric pressure indicator decreases, when descending, it rises. Also, this indicator may depend on the time of year and on the 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 an indicator of 760 mm of mercury, however, in Russia and in general most of the planet, this indicator is far from this ideal.

The normal force of air pressure is considered to be the one at which a person feels comfortable. Moreover, for people from different places habitats, pressure indicators at which normal health is maintained will be different. A person usually gets used to the indicator of the area in which he lives. If a resident of the uplands moves to a lowland, for some time he will experience discomfort and gradually get used to it.

However, even at a permanent place of residence, atmospheric pressure can change, usually with the change of seasons and sudden changes in the weather. In this case, people with a number of pathologies and congenital weather dependence may experience discomfort, old diseases may begin to worsen.

It is worth knowing how you can improve your condition with a sharp drop or increase in atmospheric pressure. It is not necessary to immediately run to the doctor, there are home methods proven by many people that help you start feeling better.

Important! It should be noted that people who are sensitive to change weather conditions, you should be more careful in choosing places for a vacation or a move.

What atmospheric pressure is considered normal for a person

Many experts say: normal pressure for a person will be 750 - 765 mm Hg. It is easiest to adapt to indicators within these limits; for most people living on the plains, small hills, lowlands, they will be suitable.

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It is worth noting that the most dangerous thing is not increased or decreased rates, but their sharp change. If changes happen gradually, most people won't notice them. An abrupt change can lead to negative consequences: some people may faint during a sharp climb uphill.

Pressure table

AT different cities country indicators will be different, this is the norm. Usually, in detailed weather reports, they tell 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 is easier to refer to ready-made tables. For example, here are the indicators for several cities in Russia:

It should be noted that for some cities and regions large pressure drops are normal. locals usually well adapted to them, a visitor will feel unwell.

Important! If weather dependence arose suddenly, it had never been observed before, you should consult a doctor, this may indicate heart disease.

The effect of atmospheric pressure on the body

For people with certain diseases, hypersensitivity, changes in the weather, pressure drops can negatively affect, in some cases limiting performance. Experts note that women are slightly more likely than men to react to weather changes.

People with sensitivity to change have different responses to changes. Some people experience mild discomfort that goes away easily on its own after a while. Others require the use of special medications to avoid exacerbation of any disease that may occur due to changes in weather conditions.

The following groups of people are most prone to negative experiences during pressure drops:

People with various lung diseases, these include bronchial asthma, obstructive bronchitis, Chronical bronchitis. People with various diseases of the heart and blood vessels, especially with 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, changes usually do not have a pronounced effect.

People with meteorological dependence experience headaches, drowsiness, fatigue, and pulse disturbances that are not observed at 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 in blood pressure, numbness in lower limbs, muscle pain. With exacerbation of chronic diseases, you should take the medicines prescribed by your doctor.

What to do when weather dependent

If there is an increased sensitivity to changing weather conditions, but there are no diseases leading to it, then the following recommendations will help to cope with unpleasant sensations.

In the morning, it is advised to take a contrast shower, then drink a cup of 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, you can several times a day.

Toward evening, on the contrary, it is advised to relax, herbal teas and decoctions with honey, valerian infusion and other mild sedatives will help. It is advised to go to bed early, 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 suspect at all 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 ...

In the event that you have chronic headaches, chest pains, a systematic increase in blood pressure, a general deterioration in well-being due to a change in atmospheric pressure, we recommend that you read our article, take care of your health!

In each region of Russia, different atmospheric pressure is considered normal. Therefore, in weather reports, when the number of millimeters of mercury is announced, weather forecasters always say what pressure it is for this area, above or below the norm.

In addition to atmospheric pressure, many factors affect our well-being. About what to do if breathing problems have appeared? Take care of your health, this is the only thing that you can not buy for any money!

You can find out how much air density depends on temperature, it's very interesting!

Moscow is a city located on the Central Russian Upland. As we already know, atmospheric pressure depends precisely on the relief and altitude. If people are above sea level, the atmospheric column presses less.

Therefore, the normal atmospheric pressure in Moscow on the banks of the Moskva River will be guaranteed to be higher than at the source of the Moskva River in the Moscow Region. On the shore we fix a point 168 meters above sea level. And on a hill near the source of the Moscow River - 310. By the way, the highest point in the city itself is located in the area Teply Stan is 255 meters.

Meteorologists name a specific figure normal atmospheric pressure for Moscow - 747-748 mm Hg. pillar. It is, of course, like average temperature by hospital. People who permanently live in Moscow feel normal in the range 745-755 mm rt. pillar. The main thing is that the pressure drops are not serious.

Doctors believe that the danger for residents of the metropolis is fraught with, for example, work on the upper floors. If the building's tightness and ventilation system is broken in a high-rise building, then employees of such offices may feel a constant headache and problems with performance. It's all about the abnormal pressure for them.

Normal atmospheric pressure in St. Petersburg ^

For Petersburgers, the situation is different. Due to the fact that St. Petersburg is lower above sea level than Moscow, higher pressure is the norm. Average, normal atmospheric pressure for St. Petersburg is 753-755 mm Hg. pillar. However, in some sources you can see another figure - 760 mm Hg. pillar. However, it is valid only for low-lying districts of St. Petersburg.

Due to its location Leningrad region has unstable climatic indicators, and atmospheric pressure can fluctuate significantly. For example, it is not uncommon for it to rise to 780 mm Hg during an anticyclone. pillar. And in 1907, a record atmospheric pressure was recorded - 798 mm Hg. pillar. This is 30 mm more than normal.

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What is the value of normal atmospheric pressure in pascals? ^

We are used to measuring atmospheric pressure in millimeters of mercury. However international system defines the pressure in Pascals. So, standard atmospheric pressure, according to IUPAC requirements, is 100 kPa.

Let's translate our measurement of mercury barometers into pascals into pascals. So, 760 mmHg a column is 1013.25 mb. According to the SI system, 1013.25 mb is equal to 101.3 kPa.

But still, measuring pressure in Russia in pascals is a rarity. Like the standard 760 mm Hg. pillar. An ordinary resident of Russia just needs to remember what pressure is the norm for his region.

Let's summarize.

1. Normal atmospheric pressure - 760 mm Hg. pillar. However, it rarely occurs. It is quite comfortable for a person to live in the range from 750 to 765 mm Hg. pillar.
2. In each region of the country, different pressure is considered normal for this region. If a person lives in a zone low pressure, he gets used to it and adapts to it.
3. Normal atmospheric pressure for Moscow is 747-748 mm Hg. pillar, for St. Petersburg - 753-755 mm.
4. The value of normal pressure in pascals will be 101.3 kPa.

If you want to measure the atmospheric pressure in your region and find out how it corresponds to the norm, we recommend using the most modern device - an electronic barometer. In the event that you are weather dependent and suffer from a sharp change in atmospheric pressure, it is recommended to use a tonometer to check the quality of your own health.

A short video about atmospheric pressure

Have you ever thought about why on some days you feel worse and lethargic, although everything seems to be going on as always? Perhaps you even associated this with worsening weather conditions, noticing that bad weather worsens diseases. However, it remains unclear exactly how bad weather affects health. The answer is simple - it's all about the effect of atmospheric pressure on a person.

about atmospheric pressure

Atmospheric pressure is the force with which air presses on the surface of the Earth, as well as on all objects that are on it. It is constantly changing and depends on the height and mass of air, its density, temperature, direction of circulation of flows, height above sea level, latitude.

It is measured in the following units:

• torr or millimeter of mercury (mm Hg);
• pascal (Pa, Ra);
• kilogram-force per sq. cm;
• other units.

Which atmospheric pressure is low and which is high

The impact of the atmosphere decreases as the temperature rises (in summer) and increases as it falls (in winter). It also decreases after 12 hours and after 24 hours, and rises from morning to evening.

A smaller layer of air presses on high points on the Earth's surface than on low ones, so the severity of the atmosphere at such points is less. At points closer to the poles, the atmosphere presses harder due to the cold. Therefore, it became necessary to define a starting point. As a norm, it is customary to consider an indicator at sea level and a latitude of 45 °.

Important! Normal atmospheric pressure is 760 mm Hg. Art. or 101 325 Pa.

Video: atmospheric pressure Accordingly, if the pressure is more than 760 mm Hg. Art., it will be increased for meteorologists, if less - reduced. However, this statement does not apply to specific people. Normal atmospheric pressure is a conditional concept, it does not mean optimal for a person.

People live in different climate zones different latitudes, at different heights above sea level, therefore they feel different gravity of the air, so it is impossible to determine the optimal level for everyone.

One can only say that for specific person the optimal level will be the one that is the norm (taking into account the height above sea level and other factors) for the area in which he lives.

In other words, the pressure that would be considered normal for the inhabitants of Africa in the equatorial region may be lowered for the inhabitants of the Arctic if they come to Africa on an excursion.

Influence and relationship with the human body

About ¾ of the world's population are weather dependent and react to a decrease in atmospheric pressure with a deterioration in well-being. Weather-dependent people feel the fluctuations of the mercury column when it is about 10 mm.

The deterioration of well-being at low atmospheric pressure is primarily associated with a reduced oxygen content in it and an increase in air pressure inside us.

Important! An average of 12 to 15 tons of air presses on each person, which does not crush people due to the fact that there is also air inside us that presses with equal force.

The liquid boils in the presence of air resistance at +100 ° C, when it weakens, the temperature drops. If you rise to a height of 19,200 m above sea level, the blood in the body will boil.

Distinguish 3 types of addiction:

1. Straight- when blood pressure rises following an increase in atmospheric pressure, and vice versa. This type is familiar to hypotensive patients, whose blood pressure is usually below normal.
2. Reverse- when blood pressure falls when atmospheric pressure rises, and vice versa. Basically, this is typical for hypertensive patients.
3. Incomplete reverse- when only the upper or lower blood pressure changes. Thus, changes in meteorological conditions can affect people who are not normally familiar with hypertension or hypotension.

The gravity of the atmosphere decreases before the deterioration of weather conditions, this is manifested in humans by the following symptoms:

• nervousness;
• migraine;
• lethargy;
• aches in the joints;
• numbness of fingers and toes;
• labored breathing;
• accelerated heartbeat;
• vasospasm, circulatory problems;
• blurred vision;
• nausea;
• suffocation;
• dizziness;
• rupture of the eardrum.

Why is low atmospheric pressure dangerous?

The mechanism of influence of the reduced gravity of air manifests itself in the following way:

1. The humidity in the air rises and it becomes more difficult to breathe.
2. The air becomes lighter because there is less of it, that is, the amount of oxygen contained in it also decreases. Oxygen starvation sets in.
3. Brain cells, heart, blood vessels, and respiratory organs suffer from a lack of oxygen.
   
4. Oxygen starvation of brain cells causes changes in the mental state - euphoria is replaced by apathy and depression.
5. As a result, the head begins to hurt, and conventional medicines cannot relieve this pain. The person feels dizzy, nauseous, weak.
6. A reflex reaction of the body to a decrease in oxygen supply is rapid breathing.
7. On the other hand, the intense work of the respiratory organs causes an increase in oxygen demand. At the same time, due to the greater number of exhalations, more carbon dioxide. In response to this, the respiratory center weakens the load, the number of breaths decreases.
8. An accelerated heartbeat leads to an increase in the number of heart attacks. Blood starts with greater strength flow through the vessels, blood pressure rises.
9. On the other hand, in response to a decrease in oxygen in the blood, more red blood cells are produced to carry more oxygen. The blood thickens internal organs increase, it becomes more difficult for the heart to pump blood, it flows more slowly through the vessels, blood pressure drops.
   
10. A drop in blood pressure worsens the well-being of not only hypotensive patients, but also hypertensive patients who take medication to lower it.
11. Thickening of the blood impairs its flow through small vessels, the blood supply to the joints and extremities worsens, aching joints and numbness of the extremities appear.
12. The deterioration of blood supply and brain function reduces visual acuity.
13. The pressure of air inside the body increases gastrointestinal tract, this causes the diaphragm to rise and compress the lungs, that is, breathing is difficult. The same reason can cause a rupture of the eardrum.
14. The resistance of the skin increases, the body feels stress, produces more stress hormones, and the number of leukocytes in the blood increases.

Did you know? Blaise Pascal calculated that the mass of the entire atmosphere of the Earth is 5 quadrillion tons.




What to do with low atmospheric pressure

Most often, weather sensitivity problems occur in people with overweight, leading sedentary image life and malnutrition.




Did you know? If the Earth's atmosphere disappears, the air temperature will be -170° C, there will be no sound, the sky will turn black.

Thus, the indicator of reduced atmospheric pressure will be different for residents of different areas, so there is no optimal indicator for everyone.
A decrease in the gravity of the air negatively affects the well-being of most people, so such indicators should be carefully monitored. To reduce the negative influence, on such days one should lead a more calm and healthy lifestyle life.

Our Earth has an atmosphere that puts pressure on everything that is inside it. In 1634, the Italian scientist Torricelli was the first to determine the value equal to atmospheric pressure. The influence of its changes on a person is studied by scientists of various specialties.

As it turned out, atmospheric pressure depends on temperature, air density, altitude, gravity, latitude. It is subject to constant fluctuations.

What atmospheric pressure is considered normal? What does it equal? Physicists answer: 760 millimeters of mercury. The measurement must be carried out exactly at sea level, and the temperature must correspond to 15 degrees.

per square centimeter of body normal pressure acts as a weight equal to 1.033 kg, but we do not notice it. This is because air gases are dissolved in tissue fluids. They completely balance the pressure of the atmosphere. Disbalance during weather changes is perceived as a deterioration in well-being. What atmospheric pressure is considered normal? Obviously, one that does not have a negative effect on the body. According to doctors, it is equal to 750 mm. rt. Art.

However, people living in places below or above sea level in conditions of constantly high or low pressure, adapting, tolerate it well. Therefore, what atmospheric pressure is considered normal for health also depends on our adaptation.

It is not so much atmospheric pressure itself that has a negative effect, but its rapid changes. Drops or rises in pressure cause deterioration of health, heart problems. Normal atmospheric pressure is imperceptible to humans. But with a rapid change in its air, located in various cavities of the body, acts on the baroreceptors of the internal organs. Some people experience malaise, joint pain, pressure surges and other unpleasant phenomena.

For example, eardrums hurt, abdominal pains bother. This is due to the fact that the air in the body cavities presses on their walls. This is especially true during cyclones. Anticyclones have less negative impact on the body.

There may be pain in the heart, palpitations, heart rhythm disturbances. Dizziness, heart pain, difficulty breathing - these are the most typical complaints. Nervous system reacts with increased anxiety, irritability. Some people have increased aggressiveness, conflict. This is due to the impulses coming from the baroreceptors to the brain during a change in atmospheric pressure.

The dependence of well-being on the weather - that's what weather dependence is. It is most pronounced in people with chronic diseases of blood vessels, heart, lungs and joints.

What atmospheric pressure is considered normal in your area, you can find out at the weather station. Usually, meteorologists, when making forecasts, the pressure at each specific point leads to the pressure at sea level using a special formula.

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 to all objects on the earth's surface. The force exerted by air on the earth's surface is called atmospheric pressure.

A column of 15 tons of air presses on each of us. 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 pressure.

Thus, internal and external pressures are balanced.

Barometer

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

Liquid-free barometers are called aneroid barometers(from the Greek a - a negative particle, nerys - water, i.e. acting without the help 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

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 divisions 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 less - 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 the globe three belts are distinguished 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.

The general scheme of atmospheric pressure distribution 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 temperate latitudes In the northern hemisphere in winter, atmospheric pressure over the continents rises sharply, 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 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.

The lines that climate map connecting points of equal atmospheric pressure 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 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 atmospheric pressure belts: in summer - to the north, in winter - to the south.