Which statement about standard atmosphere is true regarding how temperature behaves with altitude?

• A. Temperature decreases with altitude according to the standard lapse rate.
• B. Temperature increases with altitude.
• C. Temperature remains constant with altitude.
• D. Temperature is unpredictable with altitude.

Answer: (A)

Temperature in the standard atmosphere generally falls as you climb in the lower atmosphere, following the standard lapse rate. The conventional lapse rate is about 2°C decrease per 1,000 feet (roughly 6.5°C per 1,000 meters). This cooling happens because air pressure drops with height, causing the air to expand and lose heat. The standard atmosphere uses this fixed rate to provide a reference profile for flight planning and performance calculations. It’s worth noting that above the lower layers the temperature profile changes in different layers, but the basic, commonly cited behavior is that temperature decreases with altitude according to that standard lapse rate.