Weather theoryQuestion 334 of 934

How does fog usually form?

  1. The air near the ground warms above its dew point
  2. The air near the ground cools to its dew point
  3. Rain evaporates in dry air at 5,000 feet
  4. A strong wind blows dust into the air
Show answer

Correct answer: The air near the ground cools to its dew point

Fog is a cloud on the surface. It forms when air near the ground cools to its dew point.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 12: Weather Theory — Fog, page 299

Practice weather theory

Questions last reviewed: 18 October 2026