Which term describes air that is typically humid and stable?

The term that describes air that is typically humid and stable is "stable air." In meteorology, stable air refers to a condition where the atmosphere resists vertical motion. In stable air, the weather tends to be calm, and cloud formation is limited, resulting in a lack of turbulence. This stability is often associated with high humidity because stable air holds moisture more effectively, which can lead to overcast skies but not necessarily active weather systems like thunderstorms.

Stable air contrasts with the other options, which describe different characteristics. Dry air refers to air with low moisture content and is generally not characterized by stability. Unstable air is conducive to vertical motion, often resulting in cumulus cloud formation and turbulence due to rising, warmer air. Cool air can be stable or unstable, depending on other atmospheric conditions and not necessarily tied to humidity levels. Thus, "stable air" accurately captures the essence of humid and stable conditions.