Which cloud formation is least likely to cause turbulence?

Stratus clouds are characterized by their uniform, gray appearance and typically cover the sky in a thick, extensive layer. They generally form at low altitudes and are associated with stable air conditions, which contribute to smooth flight experiences. The formation of stratus clouds often indicates overcast conditions and can lead to light precipitation, but they do not usually generate significant vertical movement in the atmosphere.

In contrast, towering cumulus clouds, cumulus clouds, and cumulonimbus clouds are associated with vertical development and unstable atmospheric conditions. Towering cumulus clouds can indicate rising air and turbulent conditions, while cumulonimbus clouds are linked to severe weather phenomena such as thunderstorms, heavy turbulence, and strong updrafts and downdrafts. Cumulus clouds, although generally more benign than cumulonimbus, can still produce varying degrees of turbulence depending on their development and the atmospheric conditions surrounding them.

Thus, while stratus clouds are typically associated with stable weather and minimal turbulence, the other types of clouds mentioned are more likely to foster turbulent conditions due to their vertical development and the instability associated with them.