What phenomenon forms near a warm front due to evaporating rain, reducing ceilings near ground level?

What phenomenon forms near a warm front due to evaporating rain, reducing ceilings near ground level?

• A. Cumulonimbus
• B. Clear skies
• C. Frost
• D. Frontal fog

Answer: (D)

Frontal fog forms when rain falling from a warm front evaporates into the cooler air near the surface. That evaporation adds moisture to the near-surface air and brings the dew point up to the actual air temperature, causing condensation and fog right at ground level. This fog lowers ceilings and tightens visibility, which is exactly the situation described. Cumulonimbus involves tall storm clouds, not this evaporation-induced fog; clear skies would raise ceilings; frost forms from freezing temperatures, not evaporating rain.

Frontal fog forms when rain falling from a warm front evaporates into the cooler air near the surface. That evaporation adds moisture to the near-surface air and brings the dew point up to the actual air temperature, causing condensation and fog right at ground level. This fog lowers ceilings and tightens visibility, which is exactly the situation described. Cumulonimbus involves tall storm clouds, not this evaporation-induced fog; clear skies would raise ceilings; frost forms from freezing temperatures, not evaporating rain.