Certified Flight Instructor - Flight Instructor Airplane Practice Exam

When warm air moves over a cold lake, what is likely to occur on the leeward side?

1. Fog

2. Showers

3. Cloudiness

The correct answer is: Fog

When warm air moves over a cold lake, the interaction between the warm, moist air and the cold water leads to a cooling of the air just above the lake's surface. As this warm air cools, it can reach its dew point, causing the moisture in the air to condense into tiny water droplets, which results in the formation of fog. Fog typically forms in conditions where warm, moist air moves over a cooler surface, and since the lake is significantly colder than the warmer air above it, the moisture condenses and creates fog on the leeward side. This phenomenon is especially prevalent when the temperature difference is substantial, as the colder water can rapidly cool the air directly in contact with it, promoting condensation. While cloudiness and showers could also result from other atmospheric conditions, they are less directly related to the specific scenario of warm air moving over cold water compared to fog. Cloudiness typically indicates an overall moist atmosphere and may not necessarily be immediate or localized like fog would be in this context. Showers usually require instability and additional lifting mechanisms, which are not directly linked to the cooling effect of the cold water.