Adiabatic cooling is a process that cools air by which mechanism?

• A. Expansion
• B. Conduction
• C. Radiation
• D. Mixing with cooler air

Answer: (A)

Adiabatic cooling happens when air expands as it rises. As a parcel of air ascends, the surrounding air pressure drops, allowing the parcel to expand. Because no heat is added or removed from the parcel (an adiabatic process), the expansion does work on the surrounding air, which uses up the parcel’s internal energy and lowers its temperature. This is why rising air cools without exchanging heat with its environment. It’s not conduction, radiation, or mixing with cooler air, which involve heat transfer or mixing rather than the expansion work that reduces temperature.