Search results
Results from the WOW.Com Content Network
The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, [1] 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. [2] The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is ...
In aviation, pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is 29.921 inches of mercury (1,013.2 mbar; 14.696 psi) as measured by a barometer. [2] It indicates altitude obtained when an altimeter is set to an agreed baseline pressure under certain circumstances ...
the ideal gas law in molar form, which relates pressure, density, and temperature: P = ρ R s p e c i f i c T {\displaystyle \ P=\rho R_{\rm {specific}}T} at each geopotential altitude, where g is the standard acceleration of gravity , and R specific is the specific gas constant for dry air (287.0528J⋅kg −1 ⋅K −1 ).
Altimeter setting. Altimeter setting is the value of the atmospheric pressure used to adjust the scale of a pressure altimeter so that it indicates the height of an aircraft above a known reference surface. [1] This reference can be the mean sea level pressure (QNH), the pressure at a nearby surface airport (QFE), or the "standard pressure ...
Flight level. In aviation, a flight level (FL) is an aircraft's altitude as determined by a pressure altimeter using the International Standard Atmosphere. It is expressed in hundreds of feet or metres. The altimeter setting used is the ISA surface pressure of 1013 hPa or (29.92 inHg).
The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar). [1][2] By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth ...
Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 10 5 Pa (100 kPa, 1 bar). NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). [ 3 ] This standard is also called normal temperature and pressure (abbreviated as NTP).
Barometer. A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to help find surface troughs, pressure systems and frontal boundaries.