According to the standard lapse rate, how many Fahrenheit degrees are gained or lost per 1,000 feet?

• A. 3.0
• B. 3.3
• C. 3.5
• D. 4.0

Answer: (C)

The temperature in the standard atmosphere falls with altitude. The typical lapse rate is about 2°C per 1,000 feet. When you convert that to Fahrenheit, 2°C is roughly 3.6°F, and aviation practice uses 3.5°F per 1,000 feet as the standard value. So, for every 1,000 feet you climb, the air cools by about 3.5°F (and it warms by about 3.5°F per 1,000 feet if you descend). This is why the correct amount gained or lost per 1,000 feet is approximately 3.5°F.