Which fog type is associated with wind-driven, horizontal movement of air masses?

• A. Advection fog and upslope fog
• B. Radiation fog only
• C. Steam fog only
• D. Frost fog only

Answer: (A)

Fog that forms because moist air is moved horizontally by the wind is advection fog. When that same moist air is carried upslope by the wind and cools as it rises, it condenses into fog as well, known as upslope fog. Both types arise from the horizontal movement of a moist air mass, which is exactly what wind-driven, horizontal transport describes.

Radiation fog forms when surface cooling occurs on calm, clear nights, not from horizontal air movement. Steam fog happens when cold air moves over a warm water surface, causing evaporation and condensation in the air above—it's an evaporation-driven process, not a horizontal transport one. Frost fog occurs under very cold, humid conditions near the surface and involves deposition of moisture as frost rather than being driven by horizontal air movement.