Which are characteristics of a cold air mass moving over a warm surface?

A cold air mass moving over a warm surface typically leads to the formation of cumulus clouds, which are characterized by their fluffy appearance resulting from the rising warm air causing convection currents. The warm surface heats the lower layers of the cold air, leading to instability. This instability can result in turbulence as the cold air interacts with the rising warm air. Additionally, visibility is often good in these conditions, especially when cumulus clouds are present, as they typically do not produce precipitation.

In contrast, the other choices imply different weather characteristics associated with either stable or uniform air masses, rather than the active mixing and convection associated with a cold air mass moving over warmer ground. For instance, stratus clouds and fog are more often linked with stable air masses, while high winds and severe thunderstorms would likely require different atmospheric conditions, such as a significant temperature gradient. Clear skies and high pressure generally are associated with more stable conditions rather than the instability that occurs when cold air moves over a warm surface.