Which of the following describes unstable air?

• A. Turbulence and good surface visibility
• B. Calm conditions with poor visibility
• C. Stable skies with high humidity
• D. No wind with clear air

Answer: (A)

Unstable air is marked by vertical air motions driven by buoyancy, which causes turbulence as rising parcels mix with the surrounding air. This convection often leads to the development of cumulus clouds and gusty, irregular air rather than smooth, calm conditions. Even though you have turbulence, surface visibility can remain good because the air is actively mixing and not forming widespread fog or low clouds that degrade visibility. The other descriptions point to stable conditions: calm conditions with poor visibility typically indicate fog or low cloud cover with little vertical mixing; stable skies with high humidity can produce fog or low clouds rather than turbulence; no wind with clear air reflects a very stable layer with almost no vertical motion. So turbulence with good surface visibility best describes unstable air.