Which of the following describes characteristics of a moist, unstable air mass?

The characteristics of a moist, unstable air mass are best described by the presence of turbulence and showery precipitation. When an air mass is moist and unstable, it is capable of rising rapidly, leading to convection. This rising motion can cause the formation of cumulonimbus clouds, which are associated with turbulence and can produce significant precipitation in the form of showers or thunderstorms.

In contrast, calm conditions and clear skies are typically associated with stable air masses, where the air does not rise effectively, leading to a lack of vertical development in clouds. High winds and no precipitation could occur, but this situation does not specifically describe the behaviors of a moist, unstable air mass. Lastly, stable air with fog indicates that the air is not conducive to the vertical development necessary for turbulence or showery precipitation, further highlighting why those conditions do not apply. Thus, the presence of turbulence and showery precipitation accurately captures the essence of a moist, unstable air mass.