Weather theoryQuestion 329 of 934

In which condition does the greatest instability occur?

  1. When the air is moist and warm
  2. When the air is cool and dry
  3. When the air is cold and moist
  4. When the air is warm and dry
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Correct answer: When the air is moist and warm

Cool, dry air is very stable. Moist, warm air, as in the summer tropics, is the most unstable.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 12: Weather Theory — Atmospheric Stability, page 297

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Questions last reviewed: 18 October 2026