Stratocumulus (hybrids of layered stratus and cellular cumulus)
When the atmosphere has both convective and advective forces happening at the same time, stratocumulus clouds result. Stratocumulus clouds often occur in a shallow layer of unstable air near the surface that is overlain by stable air.
Stratocumulus are frequent in certain geographic regions, such as along coasts and in valleys. Cold air passing over warmer water will also produce stratocumulus. This is why this cloud is common in the winter near the Great Lakes. Stratocumulus also accompany cold fronts. When associated with a large weather system, stratocumulus are often the last cloud to appear before the skies clear.