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, Cp | 1005 J/Kg/K | 6005 ft lb_{f}/slug/^{o}R |
Specific Heat, Cv | 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} |