Which type of fog forms on clear nights when the ground loses heat through radiation, cooling the air near the ground?

Which type of fog forms on clear nights when the ground loses heat through radiation, cooling the air near the ground?

• A. Radiation Fog
• B. Advection Fog
• C. Fog
• D. Cirrocumulus

Answer: (A)

When clear skies at night allow the ground to radiate heat away, the air near the surface cools to its dew point. This cooling causes water vapor to condense into tiny droplets right at the surface, creating fog that forms from radiational cooling of the ground. This specific process is Radiation Fog, the fog you get under calm, clear nighttime conditions as the surface loses heat. Advection fog would require moist air moving horizontally over a cooler surface, which isn’t described here. Cirrocumulus are high-altitude clouds, not ground-level fog. The broad term fog is too general for this particular mechanism, so Radiation Fog is the best fit.

When clear skies at night allow the ground to radiate heat away, the air near the surface cools to its dew point. This cooling causes water vapor to condense into tiny droplets right at the surface, creating fog that forms from radiational cooling of the ground. This specific process is Radiation Fog, the fog you get under calm, clear nighttime conditions as the surface loses heat. Advection fog would require moist air moving horizontally over a cooler surface, which isn’t described here. Cirrocumulus are high-altitude clouds, not ground-level fog. The broad term fog is too general for this particular mechanism, so Radiation Fog is the best fit.