Final answer:
c) Clear skies and calm conditions The characteristics of stable air include clear skies and calm conditions, which occur under high barometric pressure and are ideal for minimizing atmospheric turbulence.
Step-by-step explanation:
The characteristics of stable air include clear skies and calm conditions. Stable air typically arises when the atmosphere experiences high barometric pressure, leading to less air movement and reduced potential for storm development.
Such conditions inhibit upwards air movement, which means there is little to no convection and, therefore, less cloud formation or precipitation.
Moreover, stable air can result from air that has travelled over water for great distances before reaching land, as seen in regions where astronomers find minimal atmospheric turbulence.
Conversely, unstable air is marked by conditions such as turbulent flow, strong winds, and even the potential for tornado formation when there is significant atmospheric rotation.