U.S. Standard Atmosphere#1962 version

The USSA mathematical model divides the atmosphere into layers with an assumed linear distribution of absolute temperature T against geopotential altitude h.Gyatt, Graham (2006-01-14): [http://nebula.wsimg.com/ab321c1edd4fa69eaa94b5e8e769b113?AccessKeyId=AF1D67CEBF3A194F66A3&disposition=0&alloworigin=1 "The Standard Atmosphere"]. A mathematical model of the 1976 U.S. Standard Atmosphere. The other two values (pressure P and density ρ) are computed by simultaneously solving the equations resulting from:

• the vertical pressure variation, which relates pressure, density and geopotential altitude (using a standard pressure of {{convert|101325|Pa|psi|sigfig=5}} at mean sea level as a boundary condition):

:: $\backslash frac\{dP\}\{dh\}\; =\; -\; \backslash rho\; g$, and

• the ideal gas law in molar form, which relates pressure, density, and temperature:

:: $\backslash \; P\; =\; \backslash rho\; R\_\{\backslash rm\; specific\}T$

at each geopotential altitude, where g is the standard acceleration of gravity, and R_specific is the specific gas constant for dry air.

Air density must be calculated in order to solve for the pressure, and is used in calculating dynamic pressure for moving vehicles. Dynamic viscosity is an empirical function of temperature, and kinematic viscosity is calculated by dividing dynamic viscosity by the density.

Thus the standard consists of a tabulation of values at various altitudes, plus some formulas by which those values were derived.

To allow modeling conditions below mean sea level, the troposphere is actually extended to {{convert|-2000|ft|m|sp=us}}, where the temperature is {{convert|66.1|F|C}}, pressure is {{convert|15.79|psi|Pa}}, and density is {{convert|1.2985|kg/m3|lb/ft3|sp=us|disp=flip}}.

The basic assumptions made for the 1962 version were:{{cite book |author=Tuve, George Lewis |author2=Bolz, Ray E. |title=CRC handbook of tables for applied engineering science |publisher=CRC Press |location=Boca Raton |date=1973 |isbn=0-8493-0252-8 |url-access=registration |url=https://archive.org/details/crchandbookoftab0000unse_y0b1 }}

• air is a clean, dry, perfect gas mixture (heat capacity = 1.40)
• molecular weight to 90 km of 28.9644 (C-12 scale)
• principal sea-level constituents are assumed to be (in mole percent):
• N₂ – 78.084%
• O₂ – 20.9476%
• Ar – 0.934%
• CO₂ – 0.0314%
• Ne – 0.001818%
• He – 0.000524%
• CH₄ – 0.0002%.
• assigned mean conditions at sea level are as follows :
• P = 14.696 psi = 2116.22 psf = 101325 Pa = 760 mm Hg = 29.92 inHg = 0.1013250 MN/m²
• T = 59 °F = 518.67 °R = 15 °C = 288.15 K
• ρ = 0.0764734 lb/(cu ft) = 1.225 0 kg/m³
• g = 32.174 1 ft/s² = 9.80665 m/s²
• R^* = 1545.31 ft⋅lb/(lbmol⋅°R) = 8.31432 J/(mol⋅K).

The Federal Aviation Regulations define Standard Atmosphere in {{CodeFedReg |14|1|1|}} by reference to the U.S. Standard Atmosphere, 1962 (Geopotential altitude tables).

This is the most recent version and differs from previous versions only above 51 km:

Image:Us standard atmosphere model.png

• Atmospheric models
• NRLMSISE-00
• Barometric formula
• Standard temperature and pressure

{{Reflist}}

• U.S. Extension to the ICAO Standard Atmosphere, U.S. Government Printing Office, Washington, D.C., 1958.
• U.S. Standard Atmosphere, 1962, U.S. Government Printing Office, Washington, D.C., 1962. [https://ntrs.nasa.gov/api/citations/19630003300/downloads/19630003300.pdf]
• U.S. Standard Atmosphere Supplements, 1966, U.S. Government Printing Office, Washington, D.C., 1966.
• [https://ntrs.nasa.gov/api/citations/19770009539/downloads/19770009539.pdf?attachment=true U.S. Standard Atmosphere], 1976, U.S. Government Printing Office, Washington, D.C., 1976 (Linked file is 17 MB).

{{Commonscat}}

• [https://web.archive.org/web/20060513194709/http://modelweb.gsfc.nasa.gov/atmos/us_standard.html NASA GSFC ModelWeb]
• [http://nebula.wsimg.com/ab321c1edd4fa69eaa94b5e8e769b113?AccessKeyId=AF1D67CEBF3A194F66A3&disposition=0&alloworigin=1 A mathematical model of the 1976 U.S. Standard Atmosphere]
• [http://www.digitaldutch.com/atmoscalc/ Online 1976 US Standard Atmosphere calculator and table generator]
• [http://www.luizmonteiro.com/StdAtm.aspx Calculate 28 properties of 1976 Standard Atmosphere]

Category:Atmosphere of Earth

Category:Atmospheric thermodynamics