Which characteristic is associated with stable air?

Stable air is characterized by a tendency to resist vertical motion. This resistance leads to specific weather conditions associated with stable air masses. Poor low-level visibility and the presence of stratus clouds are common indicators of stable air. Stratus clouds form when warm, moist air rises slowly over cooler surfaces, often resulting in a widespread cloud layer that can lead to fog or lower visibility. This is typical of stable atmospheric conditions where the air does not rise significantly and, consequently, does not support the development of towering cumulus clouds or substantial turbulence.

In contrast, high visibility and cumulus clouds, along with strong turbulence and rapid temperature changes, are generally more aligned with unstable air conditions. Clear skies and descending air are also indicative of certain weather patterns but do not specifically communicate the state of stability in the atmosphere as effectively as poor visibility and stratus clouds do. Thus, the association of poor visibility and stratus clouds makes it the correct characteristic of stable air.