Description & Characteristics. Translated from latin meaning piled up, the ‘congestus’ cloud species is found only in the cumulus cloud type. No other cloud type besides a cumulus cloud can be classified as congestus. A cumulus congestus cloud is fairly distinct and easy to classify in relation to other clouds: they’re cumulus clouds that are taller than they’re wide. They also go by the name of towering cumulus clouds, or cumulus towers. The proper cloud classification abbreviation for this cloud is ‘Cu con’.
As a cloudspotter, there are two variations of cumulus congestus clouds you should be aware of. First is the version that that has potential to turn into stormy weather. A cumulus congestus cloud can be a precursor to cumulonimbus clouds. When this is the case, it’s not unusual to see these clouds grow vertically, accompanied by cap cloud features (pileus cloud accessory), precipitation (praecipitatio cloud feature), and in extreme cases, shelf clouds (arcus cloud feature), horizontal cloud veils (velum cloud accessory), and evaporating rain strips (cloud feature virga). It’s also a possibility to see funnel clouds in cumulus congestus clouds, more often than not as waterspouts or landspouts.
It might be difficult to tell the difference between this cloud and a cumulonimbus calvus cloud. The key giveaway is if the cloud is producing heavier precipitation, has a darker base, is producing lightning, and is more mature, you might be better off giving it a cumulonimbus calvus classification.
It’s not to say cumulus congestus clouds are all bad news however. The second variation of a cumulus congestus is a fair-weather cumulus congestus that fits the definition of a cumulus cloud that is taller than it is wide.
While cumulus cloud formations are generally defined as low and fair-weather clouds, this is the one species of cumulus that can break the rules a bit. They can grow beyond the altitude typically associated with low clouds, typically defined as clouds less than 6,500ft in altitude. The congestus species can be common when there’s a potential for stormy weather later in the day, especially when the day starts out clear during the summer.