The norm of atmospheric pressure for humans

Since ancient times, people have noticed that air, being a substance "incorporeal", still affects the condition of various bodies. The flight of an arrow or dart, the hovering of a bird, the movement of objects during strong winds and hurricanes caused undisguised interest. But also from time immemorial, probably not understanding the very nature of the phenomenon, people have learned and take advantage of the advantages that created atmospheric pressure.

Initially, scientists who were interested in this issue formulated it in such a way that air has a weight, under the influence of which all atmospheric phenomena occur.

It was very difficult to prove the weightiness of air, it took a long time until scientists were able to experimentally establish this physical fact. And this case was favored by the case. In the middle of the 17th century, fashion in fountains was widespread in European cities. They were a kind of symbol of wealth and respectability of a city, castle or estate. Guided by just such considerations, the decision to equip the fountain in his palace took the Duke of Tuscany, a city in Italy. The fountain's design included taking water from a reservoir that was not far from the fountain itself, but at start-up the water could not rise above 10 meters. Such a phenomenon could not immediately explain even the great Galileo. And only his student - Torricelli - was able not only to prove the presence of "weight" in the air, but also was able to measure what the magnitude of normal atmospheric pressure. He invented a special instrument for such measurements - a barometer. And then using this device, I measured that the optimum atmospheric pressure is such that it can be balanced by a certain volume of water of 32 feet. Then it was found that the air per square centimeter of the Earth weighs in at 1.033 kg.

This applies to all objects that are on the earth's surface, including the body itself. If we measure its area, we get a value of about 15,000 cm², which means that the body is exposed to air pressure of about 15500 kg. Since this pressure is spreading all over the surface evenly, a person does not experience any discomfort from such a "burden".

Atmospheric pressure is measured in such quantities as millimeters of mercury. The unit of measurement of millibar (mb) is also used, but recently the most common is the use of Pascal (or hectoPascal, hPa), which is equal to one millibar. If you compare all three units, then the ratio between them is: 760 mm Hg. = 1013 hPa = 1013.25 mbar. All these values are taken as the norm of atmospheric pressure for a person. The human body is able to reconfigure, adapting to changes in atmospheric pressure. In addition, the ability to behave normally with other pressures a person can form with himself through training.

At the same time, it should be understood that such a norm of atmospheric pressure for a person does not at all mean that it will be a climatic norm, because at many points of the Earth there are many factors that significantly influence this index. So, for example, in Vladivostok, the climatic pressure in the average annual measurement is 761 mm Hg, and this is practically the norm of atmospheric pressure for humans. At the same time, in some places in Tibet, where the height of the location of settlements exceeds 5000 meters, the pressure is only 413 mm Hg. This value, as it is easy to calculate, is 1.8 times less than the norm of atmospheric pressure for a person.

And the fact is that the magnitude of the atmospheric pressure depends very much on the altitude. That is why, in order to harmonize the indications of instruments and statistical data, it is customary, when pressure is reflected, to indicate its value at a certain level-sea level.