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  2. Barometric formula - Wikipedia

    en.wikipedia.org/wiki/Barometric_formula

    Pressure as a function of the height above the sea level. There are two equations for computing pressure as a function of height. The first equation is applicable to the atmospheric layers in which the temperature is assumed to vary with altitude at a non null lapse rate of : = [,, ()] ′, The second equation is applicable to the atmospheric layers in which the temperature is assumed not to ...

  3. Atmospheric pressure - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_pressure

    Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth.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]

  4. Pressure altitude - Wikipedia

    en.wikipedia.org/wiki/Pressure_altitude

    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]

  5. International Standard Atmosphere - Wikipedia

    en.wikipedia.org/wiki/International_Standard...

    The International Standard Atmosphere (ISA) is a static atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations. It has been established to provide a common reference for temperature and pressure and consists of tables of values at various altitudes ...

  6. Bar (unit) - Wikipedia

    en.wikipedia.org/wiki/Bar_(unit)

    Atmospheric air pressure where standard atmospheric pressure is defined as 1013.25 mbar, 101.325 kPa, 1.01325 bar, which is about 14.7 pounds per square inch. Despite the millibar not being an SI unit, meteorologists and weather reporters worldwide have long measured air pressure in millibar as the values are convenient.

  7. Barometer - Wikipedia

    en.wikipedia.org/wiki/Barometer

    When atmospheric pressure is measured by a barometer, the pressure is also referred to as the "barometric pressure". Assume a barometer with a cross-sectional area A, a height h, filled with mercury from the bottom at Point B to the top at Point C. The pressure at the bottom of the barometer, Point B, is equal to the atmospheric pressure.

  8. Flight level - Wikipedia

    en.wikipedia.org/wiki/Flight_level

    The pressure setting to achieve this varies with local atmospheric pressure. It is called QNH ("barometric pressure adjusted to sea level"), or "altimeter setting", the current local value is available from various sources, including air traffic control and the local airport weather frequency or a METAR-issuing station.

  9. Scale height - Wikipedia

    en.wikipedia.org/wiki/Scale_height

    The pressure (force per unit area) at a given altitude is a result of the weight of the overlying atmosphere. If at a height of z the atmosphere has density ρ and pressure P, then moving upwards an infinitesimally small height dz will decrease the pressure by amount dP, equal to the weight of a layer of atmosphere of thickness dz.