Who measured atmospheric pressure for the first time? As a result, atmospheric pressure is created

Atmospheric pressure is one of the most important climatic characteristics that influence humans. It contributes to the formation of cyclones and anticyclones, and provokes the development of cardiovascular diseases in people. Evidence that air has weight was obtained back in the 17th century; since then, the process of studying its fluctuations has been one of the central ones for weather forecasters.

What is atmosphere

The word “atmosphere” is of Greek origin, literally translated as “steam” and “ball”. This is a gas shell around the planet, which rotates with it and forms a single cosmic body. It extends from earth's crust, penetrating the hydrosphere and ending in the exosphere, gradually flowing into interplanetary space.

The atmosphere of a planet is its most important element, ensuring the possibility of life on Earth. It contains necessary for a person oxygen, weather indicators depend on it. The boundaries of the atmosphere are very arbitrary. It is generally accepted that they begin at a distance of about 1000 kilometers from the surface of the earth and then, at a distance of another 300 kilometers, smoothly move into interplanetary space. According to theories followed by NASA, this gas shell ends at an altitude of about 100 kilometers.

It arose as a result of volcanic eruptions and the evaporation of substances in cosmic bodies falling onto the planet. Today it consists of nitrogen, oxygen, argon and other gases.

History of the discovery of atmospheric pressure

Until the 17th century, humanity did not think about whether air had mass. There was no idea what atmospheric pressure was. However, when the Duke of Tuscany decided to equip the famous Florentine gardens with fountains, his project failed miserably. The height of the water column did not exceed 10 meters, which contradicted all ideas about the laws of nature at that time. This is where the story of discovery begins atmospheric pressure.

Galileo’s student, the Italian physicist and mathematician Evangelista Torricelli, began studying this phenomenon. Using experiments on a heavier element, mercury, a few years later he was able to prove that air has weight. He created the first vacuum in the laboratory and developed the first barometer. Torricelli imagined a glass tube filled with mercury, in which, under the influence of pressure, such an amount of substance remained that would equalize the pressure of the atmosphere. For mercury, the column height was 760 mm. For water - 10.3 meters, this is exactly the height to which the fountains rose in the gardens of Florence. It was he who discovered for humanity what atmospheric pressure is and how it affects human life. in the tube was named the "Torricelli void" in his honor.

Why and as a result of which atmospheric pressure is created

One of the key tools of meteorology is the study of the movement and movement of air masses. Thanks to this, you can get an idea of ​​what causes atmospheric pressure. After it was proven that air has weight, it became clear that it, like any other body on the planet, is subject to the force of gravity. This is what causes the appearance of pressure when the atmosphere is under the influence of gravity. Atmospheric pressure can fluctuate due to differences in air mass in different areas.

Where there is more air, it is higher. In a rarefied space, a decrease in atmospheric pressure is observed. The reason for the change lies in its temperature. It is heated not by the rays of the Sun, but by the surface of the Earth. As the air heats up, it becomes lighter and rises, while the cooled air masses sink down, creating a constant, continuous movement. Each of these flows has different atmospheric pressure, which provokes the appearance of winds on the surface of our planet.

Influence on weather

Atmospheric pressure is one of the key terms in meteorology. The weather on Earth is formed due to the influence of cyclones and anticyclones, which are formed under the influence of pressure changes in the gaseous envelope of the planet. Anticyclones are characterized by high rates (up to 800 mm mercury and above) and low speed movements, while cyclones are areas with lower rates and high speed. Tornadoes, hurricanes, and tornadoes are also formed due to sudden changes in atmospheric pressure - inside the tornado it rapidly drops, reaching 560 mm Hg.

Air movement causes changes in weather conditions. Winds occurring between areas with at different levels pressure, overtake cyclones and anticyclones, as a result of which atmospheric pressure is created, forming certain weather conditions. These movements are rarely systematic and are very difficult to predict. In areas where high and low atmospheric pressure collide, climate conditions change.

Standard indicators

The average in ideal conditions the level is considered to be 760 mmHg. The level of pressure changes with altitude: in lowlands or areas located below sea level, the pressure will be higher; at altitudes where the air is thin, on the contrary, its indicators decrease by 1 mm of mercury with every kilometer.

Low atmospheric pressure

It decreases with increasing altitude due to distance from the Earth's surface. In the first case, this process is explained by a decrease in the influence of gravitational forces.

Heated by the Earth, the gases that make up the air expand, their mass becomes lighter, and they rise to higher levels. The movement occurs until the neighboring air masses are less dense, then the air spreads to the sides and the pressure equalizes.

The tropics are considered traditional areas with lower atmospheric pressure. In equatorial areas there is always low pressure. However, zones with high and low indicators are distributed unevenly over the Earth: in one geographical latitude There may be areas with different levels.

Increased atmospheric pressure

Most high level on Earth it is observed at the South and North Poles. This is explained by the fact that the air above a cold surface becomes cold and dense, its mass increases, therefore, it is more strongly attracted to the surface by gravity. It descends, and the space above it is filled with warmer air masses, as a result of which atmospheric pressure is created at an increased level.

Impact on humans

Normal indicators characteristic of a person’s area of ​​residence should not have any impact on his well-being. At the same time, atmospheric pressure and life on Earth are inextricably linked. Its change - increase or decrease - can provoke the development of cardiovascular diseases in people with increased blood pressure. A person may experience pain in the heart area, attacks of causeless headaches, and decreased performance.

For people suffering from respiratory diseases, anticyclones that bring high blood pressure can become dangerous. The air descends and becomes denser, and the concentration of harmful substances increases.

During fluctuations in atmospheric pressure, people's immunity and the level of leukocytes in the blood decrease, so it is not recommended to strain the body physically or intellectually on such days.

Atmosphere surrounding globe, exerts pressure on the surface of the earth and on all objects located above the ground. In a resting atmosphere, the pressure at any point is equal to the weight of the overlying column of air, extending to the outer periphery of the atmosphere and having a cross section of 1 cm 2.

Atmospheric pressure was measured for the first time by an Italian scientist Evangelista Torricelli in 1644. The device is a U-shaped tube about 1 m long, sealed at one end and filled with mercury. Since there is no air in the upper part of the tube, the pressure of the mercury in the tube is created only by the weight of the mercury column in the tube. Thus, atmospheric pressure is equal to the pressure of the mercury column in the tube and the height of this column depends on the atmospheric pressure of the surrounding air: the higher the atmospheric pressure, the higher the mercury column in the tube and, therefore, the height of this column can be used to measure atmospheric pressure.

Normal atmospheric pressure (at sea level) is 760 mmHg (mmHg) at 0°C. If the atmospheric pressure is, for example, 780 mm Hg. Art., this means that the air produces the same pressure as that produced by a vertical column of mercury 780 mm high.

Observing the height of the mercury column in the tube day after day, Torricelli discovered that this height was changing, and changes in atmospheric pressure were somehow related to changes in weather. By attaching a vertical scale next to the tube, Torricelli obtained a simple device for measuring atmospheric pressure - a barometer. Later, pressure was measured using an aneroid ("liquidless") barometer, which does not use mercury, and the pressure is measured using a metal spring. In practice, before taking readings, you need to lightly tap your finger on the glass of the device to overcome friction in the lever transmission.

Based on a Torricelli tube station cup barometer, which is the main instrument for measuring atmospheric pressure on weather stations currently. It consists of a barometric tube with a diameter of about 8 mm and a length of about 80 cm, lowered with its free end into a barometric cup. The entire barometric tube is enclosed in a brass frame, in the upper part of which a vertical section is made to observe the meniscus of the mercury column.

At the same atmospheric pressure, the height of the mercury column depends on the temperature and the acceleration of gravity, which varies somewhat depending on the latitude and altitude above sea level. To exclude the dependence of the height of the mercury column in the barometer on these parameters, the measured height is reduced to a temperature of 0 ° C and the acceleration of gravity at sea level at a latitude of 45 ° and, by introducing an instrumental correction, the pressure at the station is obtained.

According to international system units (SI system) the basic unit for measuring atmospheric pressure is the hectopascal (hPa), however, in the service of a number of organizations it is allowed to use the old units: millibar (mb) and millimeter of mercury (mm Hg).

1 mb = 1 hPa; 1 mmHg = 1.333224 hPa

The spatial distribution of atmospheric pressure is called pressure field. The pressure field can be visually represented using surfaces at all points of which the pressure is the same. Such surfaces are called isobaric. To obtain a visual representation of the pressure distribution on the earth's surface, isobar maps are constructed at sea level. To do this on geographical map show atmospheric pressure measured at meteorological stations and normalized to sea level. Then points with the same pressure are connected by smooth curved lines. Areas of closed isobars with high blood pressure in the center are called pressure maxima or anticyclones, and areas of closed isobars with low blood pressure in the center are called baric lows or cyclones.

Atmospheric pressure at every point on the earth's surface does not remain constant. Sometimes the pressure changes very quickly over time, sometimes it remains almost unchanged for quite a long time. In the daily variation of pressure, two maxima and two minima are detected. Maximums are observed around 10 and 22 hours local time, minimums around 4 and 16 hours. The annual variation of pressure strongly depends on physical and geographical conditions. This move is more noticeable over continents than over oceans.

We will answer the following questions.

1. What is atmospheric pressure called?

Air has weight and presses on the earth's surface and objects on it. The force with which air presses on the earth's surface is called atmospheric pressure. A column of air from the Earth's surface to the upper boundary of the atmosphere presses on the Earth's surface with a force equal to approximately 1.033 kg/cm2. In technology, this value is taken as a unit of pressure and is called 1 atmosphere.

2. Who and how first measured atmospheric pressure?

Atmospheric pressure was first measured by the Italian scientist Evangelista Torricelli in 1644. The device is a U-shaped tube about 1 m long, sealed at one end and filled with mercury. Since there is no air in the upper part of the tube, the pressure of the mercury in the tube is created only by the weight of the mercury column in the tube. Thus, atmospheric pressure is equal to the pressure of the mercury column in the tube and the height of this column depends on the atmospheric pressure of the surrounding air: the higher the atmospheric pressure, the higher the mercury column in the tube and, therefore, the height of this column can be used to measure atmospheric pressure.

3. What instruments are used to measure atmospheric pressure?

To measure atmospheric pressure, a mercury barometer, aneroid barometer and barograph are used (from Greek grapho - I write).

If we attach a scale to a tube, similar to the one Torricelli used in his experiment, we get the simplest device for measuring atmospheric pressure - a mercury barometer.

The main part of the aneroid barometer is round corrugated metal boxes that are interconnected; a vacuum is created inside the boxes (the pressure in them is less than atmospheric pressure); with an increase in atmospheric pressure, the boxes compress and pull the spring attached to them; the movement of the end of the spring is transmitted through special devices to the arrow, which moves along the scale (the scale has divisions and the value of atmospheric pressure). When atmospheric pressure increases, the box contracts, and when atmospheric pressure decreases, it expands; these vibrations affect the spring, which is connected to the arrow. The arrow shows the pressure value on a dial scale.

Aneroid barometer is one of the main instruments used by meteorologists to forecast the weather for the coming days, since changes in weather are associated with changes in atmospheric pressure.

A barograph is used to automatically and continuously record changes in atmospheric pressure. In addition to metal corrugated boxes, this device has a mechanism for moving a paper tape, on which a grid of pressure values ​​and days of the week is printed. Using such tapes, you can determine how atmospheric pressure changed during any week. Atmospheric pressure is measured in millimeters of mercury (mmHg).

4. Why is the atmospheric pressure different in different places?

On the earth's surface, atmospheric pressure varies from place to place and over time. Particularly important are non-periodic changes in atmospheric pressure that determine the weather, associated with the emergence, development and destruction of slow-moving regions high pressure(anticyclones) and relatively fast moving huge eddies (cyclones), in which low pressure prevails. The colder the air, the higher its density. The density of the air above it depends on the heating of the underlying surface. If the air is dense, then its mass is greater, and therefore it presses harder on the surface.

5. How does atmospheric pressure change with altitude?

Atmospheric pressure decreases with altitude. This is due to two reasons. Firstly, the higher we are, the lower the height of the air column above us, and, therefore, the less weight presses on us. Secondly, with height the density of air decreases, it becomes more rarefied, that is, there are fewer gas molecules in it, therefore it has less mass and weight.

If we imagine a column of air from the surface of the Earth to upper layers atmosphere, then the weight of such an air column will be equal to weight a column of mercury 760 mm high. This pressure is called normal atmospheric pressure. This is the air pressure at parallel 45° at a temperature of 0°C at sea level. If the height of the column is more than 760 mm, then the pressure is increased, less - decreased. Atmospheric pressure is measured in millimeters of mercury (mmHg).

6. How do maps show the distribution of air temperature and atmospheric pressure near the earth’s surface?

To analyze the weather, experts use maps on which the values ​​of meteorological quantities are plotted. When processing meteorological maps, meteorologists connect points with the same values ​​of air temperature and atmospheric pressure with lines called isotherms (lines of the same temperature) and isobars (lines of the same pressure). This method allows you to find out the position of areas of high and low pressure, areas with high and low temperatures.

1. What is atmospheric pressure. How atmospheric pressure was measured in the distant past.

Atmospheric pressure is the force with which a column atmospheric air presses on the earth's surface.

In Fig. 1 Use arrows to show the direction and average value the pressure of a column of mercury in the tube and a column of atmospheric air on the surface of the mercury in the cup. (The cross-sectional area of ​​the tube with mercury is 1 cm2.)

In Fig. 2 write the height of the mercury column in the tube if it is known that the atmospheric pressure is 760 mm Hg. Art.

Fill in the missing words to describe the changes in atmospheric pressure over the sea and over land during the day.

In the morning hours, the surface of land and sea practically does not heat up sun rays.

During the night, the temperatures of the surface and surface air layers have almost cooled down, so there are no noticeable differences between the atmospheric pressure over land (Рс) and over the sea (Рм).

During the day, the land surface is intensely heated by the sun's rays and earth's surface gives off heat to the ground layer of air, which becomes less dense.

Thus, the atmospheric pressure is higher over land. The surface of the water during the day is also heated by the sun's rays, but the heat is transferred to deeper layers and “accumulates” in the water column. Consequently, the surface layer of air is less dense than the surface layer, it heats up later. Relatively low atmospheric pressure forms over the sea.

In the evening, as in the morning, the air temperature and atmospheric pressure over land and over the sea are almost the same.

At night, the earth's surface (land and sea) is not heated by the sun's rays.

The land surface cools down than the sea surface, gives up its heat to the surface layer of air, its temperature decreases faster than the temperature of the surface layer of air. Consequently, the air over land is less dense than over the sea, and over land less dense than over the sea.

2. Atmospheric pressure changes with altitude

Under the same air heating conditions, atmospheric pressure decreases with altitude.

Using the textbook text, determine the values ​​of atmospheric pressure in two populated areas Earth.

The Tibetan Buddhist monastery of Rongbuk (founded in 1902) is the highest place on Earth where people live permanently. The legendary monastery is located on the northern side of the Himalayas, at the foot of Everest at an altitude of 5029 m. Climbers pass through Rongbuk to the base camp, from where the conquest of the highest peak in the world, Mount Everest, begins. Monks come to the camp to pray for the brave souls and perform rituals.

If at the level of the World Ocean the atmospheric pressure is 760 mm Hg, then at the level of the Rongbuk Monastery it is 292 mm Hg.

In Bolivia ( South America) at an altitude of 3660 m in the Andes is the city of La Paz with a population of one million, which is called the highest capital in the world. The official capital of Bolivia is the small town of Sucre, where only Supreme Court countries. The actual capital, political, economic and cultural center of the country is the city of La Paz. Here are the executive and legislative powers of Bolivia, the parliament building, the residence of the president and ministries. The city was founded in 1548. Spanish conquistador Alonso Mendoza and was named in honor of the reconciliation of the Spanish conquerors who had been at war for a long time.

If at the level of the World Ocean the atmospheric pressure is 760 mm Hg. Art., then at the level of the city of La Paz 418 mm Hg. Art.

Fill in the missing words in the definition.

Lines connecting points with the same air temperature values ​​are called isotherms.

Lines connecting points with the same values ​​of atmospheric pressure are called isobars.

Geographer-Pathfinder School

Determine the amount of atmospheric pressure in the geography classroom, on the first and top floors school building. (individually)

This pressure is called atmospheric pressure. How big is it?

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