Sections :
International Standard Atmosphere (ISA)
Sea Level Conditions
ISA Variation with Altitude
Variation due to Local Ground Conditions
Variation of Density due to Humidity
Variation of Density with Extremely High Altitude
Tabulated Data :
Table of Atmosphere Properties.
Software :
Atmosphere Properties Web Calculator
Atmosphere Properties Calculator (MS Windows Executable)

International Standard Atmosphere (ISA)
The International Standard Atmosphere (ISA) has been agreed to by many representative countries and
entities in the aviation field. It is a representative model of the atmosphere and not an average.
Most of the participants in aviation are in the northern hemisphere so this standard is based on the
range of local weather conditions that occur in their locations. The standard results will need to be
adjusted to suit weather conditions elsewhere.
SEA LEVEL CONDITIONS
Property

Metric unit

Imperial Unit

Pressure, $P$ 
101.3 kPa 
2116.7 lb_{f}/ft^{2} 
Density, $ρ$ 
1.225 Kg/m^{3} 
0.002378 slug/ft^{3} 
Temperature, $T$ 
15 ^{o}C , 288.2 K 
59 ^{o}F , 518 ^{o}R 
Speed of Sound, $a$ 
340.3 m/s 
1116.4 ft/s 
Viscosity, $μ$ 
1.789 x 10^{5} Kg/m/s 
3.737 x 10^{7} slug/ft/s 
Kinematic Viscosity, $ν$ 
1.460 x 10^{5}m^{2}/s 
1.5723 x 10^{4}ft^{2}/s 
Thermal Conductivity, $k$ 
0.02596 W/m/K 
0.015 BTU/hr/ft/^{o}R 
Gas Constant, $R$ 
287.1 J/Kg/K 
1715.7 ft lb_{f}/slug/^{o}R 
Specific Heat, $C_p$ 
1005 J/Kg/K 
6005 ft lb_{f}/slug/^{o}R 
Specific Heat, $C_v$ 
717.98 J/Kg/K 
4289 ft lb_{f}/slug/^{o}R 
Ratio of Specific Heats, $γ$ 
1.40 

Gravitational Acceleration, $g$ 
9.80665 m/s^{2} 
32.174 ft/s^{2} 
