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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). The solution is given by the barometric formula. Air density must be calculated in order to solve for the pressure, and is used in calculating dynamic pressure for moving vehicles.
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 ]
To allow modeling conditions below mean sea level, the troposphere is actually extended to −2,000 feet (−610 m), where the temperature is 66.1 °F (18.9 °C), pressure is 15.79 pounds per square inch (108,900 Pa), and density is 0.08106 pounds per cubic foot (1.2985 kg/m 3).
Decrease in air pressure when going from Earth sea level to 1000 m elevation [citation needed] +13 kPa +1.9 psi High air pressure for human lung, measured for trumpet player making staccato high notes [48] < +16 kPa +2.3 psi Systolic blood pressure in a healthy adult while at rest (< 120 mmHg) (gauge pressure) [44] +19.3 kPa +2.8 psi
Pressure as a function of the height above the sea level. The human body can perform best at sea level, [7] where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition). The concentration of oxygen (O 2) in sea-level air is 20.9%, so the partial pressure of O 2 (pO 2) is 21.136 kilopascals (158.
Therefore, a pressure altitude of 32,000 ft (9,800 m) is referred to as "flight level 320". In metre altitudes the format is Flight Level xx000 metres. Flight levels are usually designated in writing as FLxxx , where xxx is a two- or three-digit number indicating the pressure altitude in units of 100 feet (30 m).
A standard reference value for air pressure: Standard atmosphere (unit), a standard pressure that approximates atmospheric pressure value at sea level; Standard atmospheric pressure, other reference values; One of various static atmospheric models of how atmospheric pressure, density, and temperature vary with altitude, such as:
= molar mass of Earth's air: 0.0289644 kg/mol The value of subscript b ranges from 0 to 6 in accordance with each of seven successive layers of the atmosphere shown in the table below. The reference value for ρ b for b = 0 is the defined sea level value, ρ 0 = 1.2250 kg/m 3 or 0.0023768908 slug/ft 3 .