Everyone knows that our planet is shrouded in the atmosphere, that is, a shell of air, consisting of various gases, whose molecules are attracted to the Earth. Thus, the upper layers of air exert pressure on the lower layers, as well as on the surface of the Earth and objects located on it. So, the mass of air determines the normal pressure of the atmosphere.
The history of the discovery of atmospheric pressure dates back to the seventeenth century, when the scientists of Torricelli conducted an experiment using mercury. As a result of this experiment, it was found that the more the height above the Earth increases, the lower the blood pressure. So a formula was developed by which it is possible to calculate the dependence of pressure on the height of rise above the Earth.
So, the normal pressure of the atmosphere is 760 mm Hg. However, atmospheric pressure on the surface of the Earth can vary, depending on the place and time. This is especially important when determining weather conditions that are associated with the development of high pressure areas and rapidly moving air masses with low pressure inside.
Thus, atmospheric pressure is a changeable element, and depends on the height and density of the air column, as well as gravity at a certain place and time interval. But, despite the variability, the monthly average value of air pressure on the Earth's surface is the same every year. The closer to the equator, the lower the blood pressure, so it can be argued that its performance is affected by the geographical location, time of year and time of day. So, the maximum value of atmospheric pressure is observed at ten in the morning and evening, while the minimum - at three in the morning and afternoon.
We can say that atmospheric pressure varies depending on the height above the Earth and weather conditions, while the normal pressure of the atmosphere is constant.
Blood pressure is measured by special devices called barometers, which in their structure are similar to the Torricelli device, which made a discovery in science. Normal pressure (mmHg) can also be measured with this instrument. The mercury barometer has the most accurate pressure indicators; fragility can be considered its only drawback. Currently, metal barometers or aneroids are widely used.
Atmospheric pressure has the ability to influence the human body. So, in the case of a decrease in air pressure in humans, there is an increase in respiration and heart rate, as well as a decrease in blood pressure. The basis of the negative effect of blood pressure on humans is oxygen starvation, since a decrease in air pressure contributes to a decrease in oxygen concentration, so it enters the human body in smaller quantities, as a result of which anoxemia develops. This phenomenon can be observed in the presence of work associated with ascents to great heights. However, normal atmospheric pressure in no way affects the state of the human body.
Oxygen starvation causes dizziness, nausea and vomiting, impaired coordination of movements and rapid fatigue. Moreover, the gases that are in the gastrointestinal tract stretch the internal organs, and the state of the diaphragm changes, which leads to shortness of breath and impaired functioning of the heart and blood vessels.
High blood pressure can cause headache, pain in the heart, increased blood pressure, which leads to angina pectoris or tachycardia. All changes in the human body occur at a high rate of change in air pressure.
Thus, the normal air pressure is one bar. The atmospheric pressure itself is not constant, it varies depending on the time of year and day, on altitude, on the geographical location of continents and oceans.