Instrument Flight Rules (IFR) Practice Exam 2025 – The All-in-One Guide to Master Your IFR Certification!

Advection fog typically forms when warm, moist air moves horizontally over a cooler surface, resulting in cooling of the air to its dew point. This scenario is most clearly represented when an air mass moves inland from the coast in winter. Coastal areas often have moist air due to proximity to water, and as this warmer, moist air moves over the cooler land, it cools and can reach saturation, thus forming fog.

The other scenarios do not align as closely with the characteristics necessary for advection fog. When a front pushes warm air out to sea, the process does not involve the warm, moist air coming into contact with a colder surface to induce cooling necessary for fog formation. Cool, moist air moving over warm water might lead to different types of fog, like steam fog, rather than advection fog. Lastly, warm, moist air settling over a warmer surface typically would not cool sufficiently to form fog, especially under no wind conditions, as the air would remain above its dew point.