This is a complete model of the 1976 US standard atmosphere model with valid data between sea level and 1000 km. This set of functions returns Temperature, Pressure, Density, Speed of Sound, Gravity, Dynamic and Kinematic Viscosity, Coefficient of Thermal Conductivity, Gas Number Density at desired altitudes. Ability to convert to English Units as desired.
The most recent definition is the "US Standard Atmosphere, 1976" developed jointly by NOAA, NASA, and the USAF. It is an idealized, steady state representation of the earth's atmosphere from the surface to 1000 km, as it is assumed to exist during a period of moderate solar activity. The 1976 model is identical with the earlier 1962 standard up to 51 km, and with the International Civil Aviation Organization(ICAO) standard up to 32 km.
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It should also be noted that since the standard atmosphere model does not include humidity, and since water has a lower molecular weight than air, its presence produces a lower density. Under extreme circumstances, this can amount to as much as a 3% reduction, but typically is less than 1% and maybe neglected.
In his review of the Standard Atmosphere, Sissenwine (1969) suggests that the derivation of a standard for conditions through the atmosphere dates back to 1864. At that time, to aid in providing fairly realistic temperatures for ballooning and mountaineering, the French adopted a simple system. Following World War I, English-speaking countries used various standards, but it was not until 1924 that the first true standardwas proposed by the International Committee for Air Navigation (ICAN). It used a pressure profile computed...
Returning to the US Standard Atmosphere 1976 there is graphic confirmation of how the mix of atmospheric species vary up to 1,000 kilometres and that the trajectory of the total density of the atmosphere is very steep at an altitude of 1,000 kilometres.
However, my personal favourites from the US Standard Atmosphere 1976 are:i) Confirmation that solar activity influences atmospheric temperatures.ii) Confirmation that the atmosphere is a dynamic real-time system.
The 6 model atmospheres in MODTRAN differ most significantly in their temperature, H2O, and O3 profiles. The temperature profiles are illustrated in Figure 1. Not surprisingly, the Sub-Arctic Winter Atmosphere has the coolest surface temperature; the Mid-Latitude Winter Atmosphere has the next coolest surface temperature. The Tropical and Mid-Latitude Summer Atmospheres have the warmest surface temperatures. At the tropopause, the temperature of the Tropical Atmosphere is the coolest and the temperature of the Sub-Arctic Summer Atmosphere is the warmest. For all 6 atmospheres, a secondary temperature peak occurs near 50 km; here the Sub-Arctic Summer temperature is the warmest, essentially equal to that of the Mid-Latitude Summer. The Sub-Arctic Winter temperature is the coolest at this altitude. The 1976 U.S. Standard Atmosphere temperature profile provides an effective median for the set of profiles.
The U.S. Standard Atmosphere 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. The model, based on an existing international standard, was first published in 1958 by the U.S. Committee on Extension to the Standard Atmosphere, and was updated in 1962, 1966, and 1976. It is largely consistent in methodology with the International Standard Atmosphere, differing mainly in the assumed temperature distribution at higher altitudes. 2ff7e9595c
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