What type of air mass produces stable air that is associated with smooth air, poor visibility, and stratiform clouds?

A warm air mass moving over a cold surface is known to produce stable air conditions. This stability occurs because the warm air is less dense than the cold air below, preventing significant vertical movement. As a result, the air remains smooth with minimal turbulence, leading to poor visibility and the formation of stratiform clouds. These clouds form in layers and indicate that the atmosphere is stable since the warm air cannot rise forcefully to create cumulus or cumulonimbus clouds, which are associated with instability and turbulent conditions. The combination of these factors leads to the characteristic weather conditions associated with this type of air mass.