FAA Ground School Practice Test

In which situation is advection fog most likely to form?

1. An air mass moving inland from the coast in winter

2. A cool breeze on a warm day

3. Warm air rising over a cold surface

4. Stable air at high altitudes

The correct answer is: An air mass moving inland from the coast in winter

Advection fog typically forms when moist air moves over a cooler surface, which causes the temperature of the air to drop to its dew point and thus leads to condensation. When an air mass moves inland from the coast, particularly in winter, it can be carrying a significant amount of moisture while encountering lower temperatures on land, especially in cooler seasons. This temperature difference can lead to the formation of fog as the warmer, moist air moves over the cooler ground, effectively cooling the air to its dew point and causing condensation. In this scenario, the air mass being influenced by the cold coastal waters. Thus, as it moves inward, the temperature difference between the warm, moist air and the cooler surface leads to the development of advection fog.