What is the temperature of an air parcel that goes down from a height of 2 km to sea level....?

Question

assume that the temperature of the air parcel at the start is 6 degrees celcius and the process is adiabatic.

Answer 1

Well...no doubt you've learned about adiabatic lapse rates.  Depending on whether the air is dry or moist, the temperature will decrease a certain amount for every km.  The dry adiabatic lapse rate is 9.8 deg Celcius/km...while the moist adiabatic lapse rate is near 4.9 deg Celcius/km.  Now you haven't told us the moisture content of the air, but if the process is adiabatic, there can be no heat transfer, which implies that we are probably dealing with dry air.  So I would use the dry adiabatic lapse rate the calculate the answer.