What is the normal range of barometric pressure?
When barometers in the home are set to match the local weather reports, they measure pressure adjusted to sea level, not the actual local atmospheric pressure. The altimeter setting in aviation is an atmospheric pressure adjustment. Average sea-level pressure is 1013.25 mbar (101.325 kPa; 29.921 inHg; 760.00 mmHg).
A barometer measures atmospheric pressure in units of measurement called atmospheres or bars. An atmosphere (atm) is a unit of measurement equal to the average air pressure at sea level at a temperature of 15 degrees Celsius (59 degrees Fahrenheit).
- When the air pressure drops, so does the mercury level." Atmospheric pressure can also be measured in millibars (mb), with a "bar" being roughly equivalent to one atmosphere of pressure (one atmosphere equals 1.01325 bars). One bar is equivalent to 29.6 in. Hg.A barometer reading of 30 inches (Hg) is considered normal.
- A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. A simple barometer consists of a long glass tube (closed at one end, open at the other) filled with mercury and turned upside down into a container of mercury.
- “Sunny,” for instance, can usually be found in the range of high barometric pressure — 30.2 or 30.3 inches. “Stormy,” on the other hand would be found in the range of low barometric pressure — 29.2 or lower, perhaps even on occasion below 29 inches.
Measurement based on depth of water. One atmosphere (101.325 kPa or 14.7 psi) is also the pressure caused by the weight of a column of fresh water of approximately 10.3 m (33.8 ft). Thus, a diver 10.3 m underwater experiences a pressure of about 2 atmospheres (1 atm of air plus 1 atm of water).
- 'Dry' air will contain water vapor with a VP which is less than the SVP at the given temperature. A device to measure relative humidity is called a hygrometer. The simplest hygrometer - a sling psychrometer - consists of two thermometers mounted together with a handle attached on a chain. One thermometer is ordinary.
- 14.7 pounds per square inch
- Measurements from a mercury barometer are usually made in inches of Mercury (in Hg). An aneroid barometer can be used in place of a mercury barometer. It is easier to move and is often easier to read. This instrument contains sealed wafers that shrink or spread out depending on changes of atmospheric pressure.
Updated: 21st November 2019