What type of clouds typically forms in a stable air mass?

Stratiform clouds are characteristic of stable air masses because they form in conditions where there is a gradual layering of air, leading to uniform cloud coverage over a large area. In stable air, vertical movement is suppressed, which means that any moisture in the air will condense horizontally rather than rising sharply, as is the case with other types of clouds.

Stratiform clouds, such as stratus or stratocumulus, typically cover the sky in a flat, even layer, which is indicative of a stable atmosphere. This stability keeps the clouds low and prevents the strong updrafts that create more vertically developed clouds like cumulus or cumulonimbus.

In contrast, cumulus clouds usually form in unstable conditions where air masses are rising rapidly, leading to a more puffy structure. Cirrus clouds, on the other hand, form at high altitudes and are usually associated with fair weather or the approach of a warm front, but do not indicate stability in the lower atmosphere. Cumulonimbus clouds are associated with severe weather and require unstable air to develop, featuring strong vertical growth and stormy conditions.