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These figures should be compared with the temperature and density of Earth's atmosphere plotted at NRLMSISE-00, which shows the air density dropping from 1200 g/m 3 at sea level to 0.125 g/m 3 at 70 km, a factor of 9600, indicating an average scale height of 70 / ln(9600) = 7.64 km, consistent with the indicated average air temperature over ...
The International Civil Aviation Organization (ICAO) published their "ICAO Standard Atmosphere" as Doc 7488-CD in 1993. It has the same model as the ISA, but extends the altitude coverage to 80 kilometers (262,500 feet). [7] The ICAO Standard Atmosphere, like the ISA, does not contain water vapor. Some of the values defined by ICAO are:
In this formulation, R * is the gas constant, and the term R * T/Mg gives the scale height (approximately equal to 8.4 km for the troposphere). (For exact results, it should be remembered that atmospheres containing water do not behave as an ideal gas. See real gas or perfect gas or gas for further understanding.)
Air pressure actually decreases exponentially with altitude, for altitudes up to around 70 km (43 mi; 230,000 ft), dropping by half every 5.6 km (18,000 ft), or by a factor of 1/e ≈ 0.368 every 7.64 km (25,100 ft), which is called the scale height. However, the atmosphere is more accurately modeled with a customized equation for each layer ...
Near the equator, the lower edge of the stratosphere is as high as 20 km (66,000 ft; 12 mi), at mid-latitudes around 10 km (33,000 ft; 6.2 mi), and at the poles about 7 km (23,000 ft; 4.3 mi). [4] Temperatures range from an average of −51 °C (−60 °F; 220 K) near the tropopause to an average of −15 °C (5.0 °F; 260 K) near the ...
Using the values T=273 K and M=29 g/mol as characteristic of the Earth's atmosphere, H = RT/Mg = (8.315*273)/(29*9.8) = 7.99, or about 8 km, which coincidentally is approximate height of Mt. Everest. For an isothermal atmosphere, ( 1 − 1 e ) {\displaystyle (1-{\frac {1}{e}})} or about 63% of the total mass of the atmosphere exists between the ...
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]
Density Altitude Computation Chart [1]. The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation.