In units of the International System of Units (SI), the pressure is expressed in pascals (Pa). The normal level of atmospheric pressure during physical measurements is 101.325 kPa = 1013.25 hPa; 1 hPa is the pressure exerted by a body weighing 1 g per 1 cm 2 of surface (1 hPa = 0.7501 mm Hg). To recalculate the pressure, expressed in millimeters of mercury, in hectopascals, you need to multiply the obtained value by 4/3, and when converting hectopascals to mm RT. Art. – multiply the resulting value by 3/4 (or 0.7501).
Example: aneroid barometer reading of 101,000 kPa = 1010.00 hPa. In order to determine the atmospheric pressure in mmHg. Art., the value of 1010.00 hPa is necessary to multiply by 0.7501.
1010.00 • 0.7501 = 757.6 mmHg. Art.
Study of atmospheric pressure
Atmospheric pressure is measured by instruments called barometers (from the Greek baros – gravity and metron – measure). There are two types of barometers: mercury and metal.
The barograph is designed for continuous recording of atmospheric pressure during the week. The pressure receiver consists of several aneroid boxes connected in series. Changing the configuration of the block to the box using the lever system is transmitted to the arrow with a pen, which marks the corresponding pressure on the chart tape, stretched and fixed on a rotatinga drum.