Apassenger jet is flying at an altitude of 12 000 m where the pressure is 200 hpa and the outside temperature is -47°c. to maintain comfort for the passengers, the air must be at 700 hpa and 18°c in the cabin. does the air need to be heated or cooled to achieve this? show your reasoning. hint: when air is compressed without adding or subtracting energy (without being heated or cooled) it maintains its potential temperature.