Air pressure on the ground. As a result, atmospheric pressure is created

Atmospheric pressure means the pressure of the mass atmospheric air on the surface of the Earth and objects located on it. The degree of pressure corresponds to the weight of atmospheric air with the base a certain area and configurations.

The main unit of measurement of atmospheric pressure in the SI system is Pascal (Pa). In addition to Pascals, other units of measurement are also used:

Bar (1 Ba=100000 Pa);
millimeter mercury(1 mm Hg = 133.3 Pa);
kilogram of force per square centimeter (1 kgf/cm 2 =98066 Pa);
technical atmosphere (1 at = 98066 Pa).

The above units are used for technical purposes, with the exception of millimeters of mercury, which is used for weather forecasts.

The main instrument for measuring atmospheric pressure is the barometer. Devices are divided into two types - liquid and mechanical. The design of the first is based on flasks filled with mercury and immersed with the open end in a vessel with water. The water in the vessel transmits the pressure of the atmospheric air column to mercury. Its height acts as an indicator of pressure.

Mechanical barometers are more compact. The principle of their operation lies in the deformation of a metal plate under the influence of atmospheric pressure. The deforming plate presses on the spring, which, in turn, sets the needle of the device in motion.

The influence of atmospheric pressure on the weather

Atmospheric pressure and its effect on weather conditions varies depending on place and time. It varies depending on the altitude above sea level. Moreover, there are dynamic changes associated with the movement of areas of high (anticyclones) and low pressure(cyclones).

Changes in weather associated with atmospheric pressure occur due to the movement of air masses between areas of different pressure. The movement of air masses is formed by wind, the speed of which depends on the difference in pressure in local areas, their scale and distance from each other. In addition, movements of air masses lead to temperature changes.

Standard atmospheric pressure equals 101325 Pa, 760 mm Hg. Art. or 1.01325 bar. However, a person can easily tolerate a wide range of pressures. For example, in the city of Mexico City, the capital of Mexico with a population of almost 9 million people, average atmospheric pressure is 570 mm Hg. Art.

Thus, the value of the standard pressure is determined accurately. And comfortable pressure has a significant range. This value is quite individual and completely depends on the conditions in which a particular person was born and lived. Thus, a sudden movement from an area with relatively high pressure to an area of lower pressure can affect the work circulatory system. However, with prolonged acclimatization negative influence fades away.

High and low atmospheric pressure

In zones high pressure The weather is calm, the sky is cloudless and the wind is moderate. High atmospheric pressure in summer leads to heat and drought. In low pressure areas the weather is predominantly cloudy with wind and precipitation. Thanks to such zones, cool, cloudy weather with rain occurs in summer, and snowfall occurs in winter. The high pressure difference in the two areas is one of the factors leading to the formation of hurricanes and storm winds.

Man is part of nature. It constantly influences each of us. The more time passes, the more weather-sensitive people appear. Today there are approximately 4 billion such people living on the planet. The factor that most strongly influences a person’s health and well-being is atmospheric pressure, or rather its norm. What atmospheric pressure is considered normal depends on geographical location the area where a person spends most of the time.

What is atmospheric pressure?

The Earth is habitable due to a number of factors. The first of these is the availability of breathing air. Our planet, like a dome, is covered with an atmosphere consisting of many layers, each of which performs a specific important function. The air mass exerts constant pressure on everything that is on Earth, including humans, so it is so important to know what its norm is. Every day, each of us withstands a load of approximately 15,000 kg. We do not feel this burden due to the unique structure of our body. But he can't always cope natural phenomena. Sometimes an imbalance occurs in the organ system of the human body, and then a person becomes dependent on changes in atmospheric pressure.

Atmospheric pressure, which is the norm for a person living in central Russia, is 750-760 mmHg. This is the indicator at which most people do not feel any discomfort in their health.

Any deviation of a person’s atmospheric pressure from the norm by 5-10 units or higher will be painfully accepted by our body.

Atmospheric pressure measurement

To measure the normal atmospheric pressure for a person, a specially designed device is used - a barometer. Science has established that the force of atmospheric pressure per 1 sq.cm. surface of the Earth, corresponds to the height of the mercury column of 760 mm. This indicator was taken as the norm of atmospheric pressure for humans. If the barometer reading is above this mark, it is customary to talk about increased pressure from normal. If the atmospheric pressure is below normal for a person, then it is considered low. Barometer readings in different parts of the planet differ due to differences in relief, temperature, etc.

The normal atmospheric pressure for a person is measured in mm of mercury (mmHg). Other units may be used, such as pascals (Pa). An indicator of 760 mmHg will be equal in this case to 101325 Pa. However, in everyday life, measuring normal atmospheric pressure for humans in pascals has not taken root. Any weather forecast informs us about the state of atmospheric pressure using mmHg.

What is weather sensitivity?

Many people have so-called weather sensitivity. This is a peculiar reaction of the body to a change in the normal atmospheric pressure for a person. It can be expressed, depending on the presence of various health problems, in the appearance of irritability, pain in various parts of the body, a general decrease in performance, and insomnia. A change in normal atmospheric pressure for a person can manifest itself in mental disorders, for example, a state of anxiety, depression, and unreasonable fear.

According to statistics, during sudden changes weather, even the number of offenses and transport accidents, as well as man-made disasters, grows several times.

The human body is a kind of chemical laboratory that works normally at the appropriate standard of atmospheric pressure for a person. As soon as these conditions change in any direction, the body reacts with painful manifestations. He lacks something, for example, oxygen. Or vice versa, there is something in excess.

The causes of weather sensitivity are not only health problems, but also poor lifestyle choices. Sedentary activity, poor nutrition with subsequent acquisition of excess weight, and stress play a big role.

The influence of human atmospheric pressure

In the vessels and cavities of the human body there are specific receptors that are very sensitive to any changes in atmospheric pressure standards for humans. For example, people with musculoskeletal disorders always “predict” weather changes by aching joints. Hypertensive patients due to headaches in the temples, etc.

The well-being of heart patients also worsens with changes in normal atmospheric pressure for humans. They feel pain in the heart and head, rapid heartbeat and other unpleasant symptoms.

High atmospheric pressure forces the human body to equalize the imbalance that has arisen. How does this happen? By reducing the rate blood pressure. At the same time, the vessels relax, the speed of blood flow changes. Malaise, headaches, and stuffy ears occur. With increased atmospheric pressure, changes occur in chemical composition blood, in particular, the level of leukocytes, the main fighters against infections and viruses, decreases.

Low atmospheric pressure creates conditions for the body similar to climbing a mountain. Under such conditions, there is a deficiency of oxygen, and, consequently, the brain and other organs suffer from hypoxia. The person feels difficulty breathing, pain in the temporal region, and pressure in the head.

Scientists have discovered the dependence of atmospheric pressure on air temperature. With warming, atmospheric pressure decreases. This is unfavorable for hypotensive patients and asthmatics.

With the onset of cold weather and the establishment of clear weather, the norm becomes high. Hypertension sufferers, allergy sufferers, and kidney sufferers.

The most dangerous thing is a sharp increase in atmospheric pressure (by 1 mmHg in 2-3 hours). The patient sharply feels negative symptoms and feels very bad. It is imperative to control your blood pressure and immediately take the medications prescribed by your doctor.

A person cannot influence the weather, but he can help himself survive difficult periods.

The first thing you should do as much as possible is to reduce physical activity.

Secondly, consult your doctor about prescribing normal medical supplies for those who have a particularly difficult time withstanding weather changes.

The optimal combination of weather indicators for a person is as follows:

Atmospheric pressure is normal - 760 mm Hg.
Air temperature is the norm 18-20 ͦ C.
Humidity is normal 50-55%.

At different points on the Earth, the pressure rate may be different. Recorded fluctuations at sea level are 641-816 mmHg. The average value is exactly 760 mmHg at 20 degrees Celsius. This does not mean that for every person this reading should be equal to the norm. If a person was born and raised in the mountains, the normal numbers for him will naturally be different. Climbing into the mountains will reduce the altitude by about 13% for every kilometer.

The average atmospheric pressure for St. Petersburg, located in northwestern Russia, is only 748 mmHg.

It is time that can greatly influence a patient’s barometric pressure. At night it is higher than during the day. That is why most attacks in heart patients occur at night.

Since 1982, a standard pressure of 100 kPa has been adopted.

Naturally, what to choose for yourself ideal conditions impossible. There are so many problems, so many people. Everyone is concerned about certain disturbances, so it is important to prepare yourself and your body for weather changes and take care of your health.

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

A column of air weighing 15 tons 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.

In this way, internal and external pressures are balanced.

Barometer

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

Liquidless barometers are called aneroid barometers(from Greek a - negative particle, nerys - water, i.e. acting without the help of liquid) (Fig. 1).

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

Normal atmospheric pressure

Normal atmospheric pressure is conventionally taken to be air pressure at sea level at a latitude of 45° and at a temperature of 0 °C. 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.

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 sealed a long glass tube with divisions at one end, filled it with mercury and lowered it into a cup of mercury (this is how the first mercury barometer was invented, which was called the Torricelli tube). The mercury level 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 atmospheric pressure 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 more than 760 mm Hg. Art., then it is considered elevated, less - reduced.

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

Atmospheric pressure increases twice during the day (morning and evening) and decreases twice (after noon and after midnight). These changes are due to 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, changes in pressure.

There are three zones on the globe with a predominance of low atmospheric pressure (minimums) and four zones with a predominance of high atmospheric pressure (maxima).

At equatorial latitudes, the Earth's surface warms up greatly. 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 the atmospheric pressure is increased by 60-65° compared to the 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): along the equator there is a low pressure belt; at 30-40° latitude of both hemispheres - high pressure belts; 60-70° latitude - low pressure zones; in the polar regions there are 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 increases greatly, and the low pressure belt is interrupted. It persists only over oceans as closed areas low blood pressure— Icelandic and Aleutian minimums. On the contrary, winter maximums form over the continents: Asian and North American.

Rice. 3. General diagram of atmospheric pressure distribution

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 Low—forms over Asia.

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

Lines that are on climate map connect points with the same atmospheric pressure 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 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 time of year, both hemispheres of the Earth are heated by the Sun differently. This causes some movement of atmospheric pressure belts: in summer - to the north, in winter - to the south.

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 means a column of air with a height from sea level to upper layers 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 of 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 that 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 increasingly rarefied. In the lower layer of 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 atmospheric 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 of the earth's surface by the Sun. 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 of low pressure is formed. 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 high pressure belts exist all year round, however, in summer they contract 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 low pressure field seems to “break”: it persists 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- in the tropics - the continents heat up more 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 in its performance, 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 encircled air mass, which, under the influence of gravity, presses on any object, including human body. The force is called atmospheric pressure. For each square meter crushes 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) 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 globe the impact is not the same. 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 air. 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. Headache, nausea, and loss of performance appear.

Meteor dependence

A person’s sensitivity to weather conditions – wind changes, geomagnetic storms – is 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:

respiratory tract diseases;
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 a negative impact on health. People with long-standing cardiovascular and cardiovascular diseases are especially affected by weather changes. digestive system. Doctors on such days recommend reducing physical activity, spend less time on the street, do not abuse heavy food and alcohol. Among the main reactions: