The SI unit of atmospheric pressure is the Pascal (Pa).
Atmospheric pressure, commonly referred to as air pressure or barometric pressure, is the force per unit area exerted by the weight of the Earth's atmosphere. The International System of Units (SI) provides a standardized and universally accepted system for measurement, and within this system, pressure is measured in Pascals.
- Pascal (Pa): One Pascal is defined as one Newton per square meter (1 N/m²). It represents the force of one Newton acting on an area of one square meter.
While the Pascal is the SI unit, other units are also frequently used to measure atmospheric pressure, particularly in meteorology and aviation:
- Hectopascal (hPa): 1 hPa = 100 Pa. This unit is commonly used by meteorologists for reporting atmospheric pressure due to its convenient numerical range in typical weather conditions.
- Millibar (mbar): 1 mbar = 100 Pa. Historically, millibars were used extensively in meteorology, but hectopascals are now preferred due to their alignment with the SI system. Note that 1 hPa = 1 mbar.
- Atmosphere (atm): 1 atm is defined as 101,325 Pa. This unit is approximately equal to the average atmospheric pressure at sea level.
- Torr: 1 Torr is approximately equal to the pressure exerted by 1 millimeter of mercury (mmHg).
Therefore, while various units are used, the Pascal (Pa) is the fundamental SI unit for measuring atmospheric pressure. Using Pascals ensures consistency and compatibility in scientific and engineering applications.
