Stratocumulus (Sc) - the name derives from the latin words stratus = flattened layer or spread out and cumulus = mass or heap. Stratocumulus is a member of the ten fundamental cloud types (or cloud genera). It is a low-level cloud, thus it usually forms within the lowest two kilometers (6,600 ft) of the atmosphere. Like its 'middle-level brother' the altocumulus cloud stratocumulus are formed by weak, shallow convection currents, perhaps triggered by turbulent airflows aloft. The convection affects a shallow zone because dry, stable air above the cloud sheet prevents further upward development.
Stratocumulus usually occur as a distinct extensive layer or sheet of grey to white low clouds, in the form of more or less regular clumbs or patches often arranged in bands or rolls that lie across the wind. Each cloud patch consists of a more or less well defined rounded mass which is not fibrous. Typically stratocumulus cloud fields have a somewhat uniform base and cover the entire sky, but between the patches blue sky can be seen. Sometimes the patches are merged.
What do stratocumulus tell about the weather?
Sc stratiformis during winter indicate high pressure and stable winter weather without or only light precipitation. If patches of blue sky are expanding in a sheet of Sc perlucidus, the weather will substantially improve. If Sc lacunosusdisplay a mosaic pattern they may only indicate a transitional weather improvement.