Jet Standard Atmosphere is often used by jet manufactures. It assumes a mean sea level temperature of +15 C. The temperature then lapses 2 C per 1000 ft to infinity. There is no Tropopause in the jet standard atmosphere. In the standard atmosphere, the Tropopause is the height at which the temperature stops decreasing. It is also the end of the Troposphere and start of the Stratosphere.
References
Jet standard atmosphere Wikipedia(Text) CC BY-SA