What is a key characteristic indicative of stable air?

A key characteristic indicative of stable air is restricted visibility. In stable air conditions, the atmosphere tends to resist vertical movement and maintains a more uniform temperature profile. This stability often leads to the development of stratus clouds or fog, which can significantly reduce visibility. When stable air is present, pollutants and moisture can become trapped near the surface, further contributing to hazy conditions and limited visibility. In contrast, rapid vertical development of clouds, frequent thunderstorms, and low humidity are typically associated with unstable air, which promotes strong upward motion and dynamic weather phenomena.