FAA Aircraft Dispatcher Practice Exam

What role does temperature play in the formation of fog?

1. Higher temperatures prevent fog

2. Temperature has no role in fog formation

3. Low temperatures are ideal for fog

4. Warm air always leads to fog

The correct answer is: Low temperatures are ideal for fog

Temperature plays a crucial role in the formation of fog, particularly at lower temperatures. Fog typically forms when the air temperature cools to the dew point, which is the temperature at which air becomes saturated and can no longer hold all the moisture in the form of water vapor. When temperatures drop, especially during the nighttime or early morning hours, the air cools and can reach a saturation point, allowing moisture to condense into tiny water droplets, thus forming fog. In cases of radiation fog, for example, clear skies and calm winds at night result in heat loss from the ground, cooling the air near the surface. This cooler air can lead to saturation and fog development. Additionally, specific types of fog, such as steam fog, depend on lower temperatures causing warm, moist air to condense rapidly in cooler surroundings. The other considerations of temperature do not support fog formation in the same way. Higher temperatures, for example, typically prevent fog because warmer air can hold more moisture without condensing. Therefore, while various factors contribute to fog formation, low temperatures provided an ideal environment for the saturation of air, leading to the development of fog, making it the correct choice in this context.