Which type of fog forms when air flows upslope along a terrain and cools as it rises?

Which type of fog forms when air flows upslope along a terrain and cools as it rises?

• A. Radiation fog
• B. Upslope fog
• C. Sea fog
• D. Advection fog

Answer: (C)

Upslope fog forms when moist air is lifted up sloping terrain and cools as it rises. As the air ascends, it expands because pressure decreases with height, causing adiabatic cooling. If the air cools to its dew point, water vapor condenses into tiny droplets, creating fog that sits along the hillside or along the terrain's slope. This is the characteristic effect of lifting along terrain, which is why it’s called upslope (or orographic) fog. Radiation fog forms from ground cooling after sunset, not from air being lifted uphill. Advection fog happens when warm, moist air moves horizontally over a cooler surface, causing cooling at the boundary layer. Sea fog develops when moist air over the ocean moves over relatively cold sea surfaces or cools near the water, not from terrain lifting.

Upslope fog forms when moist air is lifted up sloping terrain and cools as it rises. As the air ascends, it expands because pressure decreases with height, causing adiabatic cooling. If the air cools to its dew point, water vapor condenses into tiny droplets, creating fog that sits along the hillside or along the terrain's slope. This is the characteristic effect of lifting along terrain, which is why it’s called upslope (or orographic) fog.

Radiation fog forms from ground cooling after sunset, not from air being lifted uphill. Advection fog happens when warm, moist air moves horizontally over a cooler surface, causing cooling at the boundary layer. Sea fog develops when moist air over the ocean moves over relatively cold sea surfaces or cools near the water, not from terrain lifting.