Stratocumulus, sometimes abbreviated Sc, is a meteorological term used to describe low-lying clouds that form thick masses. Stratocumulus clouds can come in over a dozen varieties, depending on the shape, density, and uniformity of the cloud. Generally associated with overcast weather, these low, lumpy clouds bring little chance of precipitation, but can be the harbinger of larger storms.
The term “stratocumulus” is created from two Latin words, stratus and cumulus. The first word roughly translates as “flattened,” while the second denotes a heap or mass. The combined term thus refers to a type of cloud that is low in the sky, flattened over a widespread area, but also well defined as opposed to wispy. Stratocumulus clouds are often responsible for fully overcast skies, though small breaks in the clouds and different levels of opacity may allow sunlight to filter through. This kind of cloud is one of the ten primary types used in cloud identification.
There are several different varieties of stratocumulus, each with a distinct appearance. Sc opacus clouds are a thick, unbroken layer of clouds that allows little light to penetrate. Sc undulatus clouds form wide, rolling bands across the sky, often making for a dramatic skyscape. Sc castellanus is notable for a vertical, turret-like shape that expands upward above the flattened base of the cloud.
These fairly common form of clouds frequently form near bodies of water. If a front of cool air rolls over the top of a rising column of moist air, these clouds can be formed near the point of contact. Since marine bodies tend to create a low level of warm, wet air, Sc clouds tend to form over marine areas. They are also common in sub-tropical regions, or areas with high humidity levels.
While Sc clouds rarely carry significant amounts of rain or snow, they can form just before or after a larger storm. If weather is clear and warm, and becomes overcast with an Sc layer, it may be a sign that a storm is approaching. Conversely, if a rain or snow storm is present, stratocumulus clouds may form as the storm system moves out of the region. The presence of an Sc layer does not always relate to the existence of a nearby storm; in general, these clouds bring temperate weather with them, as they can dampen down hot temperatures or reduce the impact of a cold front.