Private Pilot Private Exam

What type of weather is most likely to develop if the temperature/dewpoint spread is small and decreasing, with a temperature of 62ºF?

1. Thunderstorms

2. Fog or low clouds

3. Clear skies

4. Heavy rain

The correct answer is: Fog or low clouds

When the temperature and dewpoint spread is small and decreasing, it indicates a high level of moisture in the air. A narrow spread between temperature and dewpoint suggests that the air is close to saturation. This condition often leads to the formation of fog or low clouds because as the air temperature drops to near the dewpoint, the moisture in the air condenses, forming small water droplets that result in fog or stratus clouds. In this scenario, with a temperature of 62ºF, a small and decreasing spread suggests that cooling could bring the temperature down to the dewpoint, resulting in cloudy, overcast conditions or fog. These phenomena are more frequent when relative humidity is high, which is typically the case in such situations. Choosing this response reflects a solid understanding of meteorological principles related to humidity and temperature relationships and their impacts on weather conditions.