Atmospheric pressure (atm) to bar, bar to atm

Atmospheric pressure
 

The atmosphere is a gas, or more precisely, a mixture of gases, which is held near the Earth by gravity. The atmosphere gradually passes into interplanetary space, and its height is approximately 100 kilometers. How do we understand the expression 'atmospheric pressure'? Above each square meter of the earth's surface, there is a hundred-kilometer column of gas. Of course, the air is transparent and pleasant, but it has a mass that presses on the surface of the earth. This is atmospheric pressure. The normal parameter is considered to be equal to 1.01325 bar. This is the measurement at sea level at a temperature of 0 degrees Celsius. The same parameter at the same temperature is exerted on its base by a column of mercury 766 millimeters high. As altitude increases above sea level, atmospheric pressure decreases. For instance, atop Mount Everest, this atmospheric parameter is only one-fourth of the normal level. At the mountain's top, the pressure is four times lower than at its base.

 

Physical vacuum
 

In scientific terms, a vacuum refers to a space devoid of matter and pressure. To be more precise, it is an almost complete absence of both. When we talk about an absolute vacuum, we are referring to an idealized concept, similar to the idea of an ideal gas in thermodynamics or a material point in mechanics. Depending on the concentration of the substance, there are low, medium, and high vacuums. The best approximation to a physical vacuum is outer space, in which the concentration of molecules and pressure are minimal. In space, the parameter is almost completely absent. Pressure is the main thermodynamic parameter of the state of the system. You can determine the parameter of air or another gas not only by instruments but also by using equations, formulas, and the laws of thermodynamics.