Dry adiabatic lapse rate

• As a parcel of air rises, it cools, but at what rate???

• rate of temperature change with height is called the lapse rate

• units of lapse rate are °C km^-1

• Let's first consider an unsaturated parcel of air

• unsaturated parcels cool at a rate of 10°C km^-1 - this is called the dry-adiabatic lapse rate -->>

• What will be the parcel's temperature be at 1 km? ANSWER

QUESTION FOR THOUGHT:

Suppose the air pressure outside a conventional jet airliner flying at an altitude of 10 km is 250 mb. Further, suppose the air inside the aircraft is pressurized to 1000mb. If the outside air temperature is -50 ºC, what would be the temperature of this air if brought inside the aircraft and compressed at the dry adiabatic rate to a pressure of 1000mb (assume that a pressure of 1000mb is equivalent to an altitude of 0 m).