Steam fog forms under which condition?

Steam fog forms under which condition?

• A. Cold air over warm water
• B. Warm air over cold water
• C. Cold air over cold water
• D. Warm air over warm water

Answer: (A)

Fog forms when water vapor in the air condenses into tiny droplets. Steam fog is produced when a layer of cold air sits over a warm water surface. The warm water keeps evaporating, filling the cold air with water vapor. Because the air is cold, it can’t hold much of that vapor, so it quickly saturates and the vapor condenses into visible droplets right above the water, creating the fog. If the air were warm over cold water, or if both were cold or both warm, this rapid saturation near the surface doesn’t occur, so steam fog doesn’t form in those cases.

Fog forms when water vapor in the air condenses into tiny droplets. Steam fog is produced when a layer of cold air sits over a warm water surface. The warm water keeps evaporating, filling the cold air with water vapor. Because the air is cold, it can’t hold much of that vapor, so it quickly saturates and the vapor condenses into visible droplets right above the water, creating the fog.

If the air were warm over cold water, or if both were cold or both warm, this rapid saturation near the surface doesn’t occur, so steam fog doesn’t form in those cases.