http://en.wikipedia.org/wiki/Interna...ard_Atmosphere
At Sea Level on a Standard Day
Temperature 15C (288.15 Kelvin)
Pressure 29.92126 "Hg, 1013.25 mB, 760 mmHg, 14.69595 psi
Air Density 1.225 kg/m^3, .002376892 slugs/ft^3
Standard Lapse Rate
Below the Tropopause (36089.24 ft) 1.9812C/1000 ft
Above the Tropopause -56.5C to an altitude of 20km