What are characteristics of unstable air?

Unstable air is characterized by significant vertical movement, leading to conditions that are often turbulent. When the air is unstable, it can rise rapidly, which frequently results in turbulence. This turbulence is a hallmark of unstable air, as the continuous movement causes air to swirl and create unpredictability in flight.

Additionally, unstable air can imply good surface visibility under certain conditions, particularly when it is conducive to good weather phenomena. While there may be periods where visibility fluctuates due to turbulence, the overall conditions associated with unstable air can allow for clearer visibility, especially when there are not significant obstacles or weather systems like clouds that obscure the view.

The other choices present characteristics generally associated with different atmospheric conditions. For instance, nimbostratus clouds, which are associated with stable air, typically indicate poor weather conditions, and clear skies and calm winds are more reflective of stable atmospheric conditions. Therefore, the option that combines turbulence with the possibility of good visibility accurately encapsulates the nature of unstable air.