FAA Ground School Practice Test

What feature is associated with a temperature inversion?

1. A stable layer of air

2. Low-level turbulence

3. Increased wind speeds

4. Cumulonimbus development

The correct answer is: A stable layer of air

A temperature inversion is characterized by a stable layer of air, which occurs when warmer air overlays cooler air near the surface. This phenomenon creates a cap that inhibits vertical air movement. In typical atmospheric conditions, air temperature decreases with altitude; however, during an inversion, the normal lapse rate is reversed. Because of this stability, the cooler air often becomes trapped at lower elevations, leading to poor mixing and can contribute to fog or haze conditions. Inversions can lead to significant differences in temperature and density, which prevents turbulence from developing in the lower atmosphere. While low-level turbulence, increased wind speeds, and cumulonimbus development are associated with unstable atmospheric conditions that promote vertical movement and convection, these are not features of a temperature inversion. The inversion itself suppresses these processes, reinforcing the presence of a stable layer of air.