FAA Ground School Practice Test

The most common type of ground-based temperature inversion is produced by what?

1. High altitude clouds

2. Terrestrial radiation on a clear, relatively still night

3. Increased solar radiation

4. Cold fronts moving through

The correct answer is: Terrestrial radiation on a clear, relatively still night

A ground-based temperature inversion typically occurs when the Earth's surface cools rapidly during the night, especially under clear skies and calm conditions. This cooling effect is due to terrestrial radiation, which is the process of the Earth radiating heat back into space. As the surface cools, the air directly in contact with it also cools, becoming denser and heavier than the warmer air above it. This results in a layer of cooler air trapped below a layer of warmer air, creating an inversion. This phenomenon is most prominent on clear nights when the ground loses heat quickly, allowing for the formation of a stable atmospheric layer that can lead to reduced visibility and potential air quality issues. Understanding this process is crucial for pilots and meteorologists, as inversions can significantly affect weather patterns and aviation operations, such as the development of fog and low clouds. While high altitude clouds can influence temperature profiles, they do not create ground-based inversions. Increased solar radiation generally warms the surface, which would typically disrupt an inversion effect. Cold fronts moving through can lead to mixing of air layers, also making it less likely for a stable inversion to persist.