FAA Ground School Practice Test

What are the characteristics of unstable air?

1. Clear skies and high pressure

2. Turbulence and good surface visibility

3. Consistent temperatures

4. Low humidity levels

The correct answer is: Turbulence and good surface visibility

Unstable air is characterized by its tendency to rise and create turbulence, which is an important consideration for pilots. When air is unstable, it is typically warmer at lower altitudes and cooler aloft, leading to vertical movement and the formation of convective currents. This movement can result in turbulence, a common occurrence in unstable atmospheric conditions. The mention of good surface visibility aligns with the fact that unstable air often leads to clear skies at lower levels, although this clarity can easily change due to the development of clouds and precipitation from rising air. The overall behavior of unstable air, with its propensity for turbulence, makes it distinct from stable air, which is more uniform and less prone to vertical movement. In contrast, consistent temperatures, low humidity levels, and conditions associated with high pressure such as clear skies are characteristics commonly associated with stable air. Stable air resists vertical movement, which does not support the turbulence described in the correct answer. Understanding these dynamics is vital for effective flight operations and anticipating potential weather-related challenges.