FAA Aircraft Dispatcher (ADX)MeteorologyEasy
A dispatcher is planning a flight into a coastal airport during the late morning. A weather analysis indicates a prevailing onshore flow of moist, stable air over cooler land surfaces. Which type of fog is most likely to form or persist under these conditions?
- AAdvection fog
- BUpslope fog
- CRadiation fog
- DSteam fog
Show answer & explanationAnswer & explanation
Correct answer: A. Advection fog
Advection fog forms when moist, stable air moves horizontally over a cooler surface, cooling the air to its dew point. An onshore flow of moist air over cooler land is a classic scenario for advection fog.
Why the other options are wrong
- B. Upslope fog forms when moist, stable air is forced up a topographic slope, not primarily due to horizontal movement over a cool surface.
- C. Radiation fog forms on clear, calm nights as the ground cools by radiation, not typically during late morning with onshore flow.
- D. Steam fog forms when cold, dry air moves over warmer water, causing evaporation and subsequent condensation.
Advection Fog
Fog formed when moist air moves horizontally over a cooler surface, cooling the air to its dew point and causing condensation.
- Requires horizontal air movement (advection).
- Forms over land or water, often along coastlines.
- Common when warm, moist air moves over cold ocean currents or cold land.
Memory trick: Advection: Air ADDS to the COLD surface.