In the troposphere the average temperature is 15°C at sea level, falling to −57°C at
the bottom of the tropopause at 11 km. This variation is much less pronounced when
expressed on the Kelvin scale, ranging from 288 K to 216 K, an average of 268 K. If we
suppose that the temperature has its average value all the way up to the tropopause,
then the pressure varies with altitude, h, according to the barometric formula