Presenting a sunset photograph looking west from an overlook in Shenandoah National Park in central Virginia in September 2019. It was a warm afternoon and as the sun began to set, some puffy clouds appeared rolled in.
Summary: These clouds are examples of particularly puffy and somewhat ragged low-altitude layer cloud, classified as stratocumulus floccus (Sc flo).
Cloud Type. First, let’s think about the cloud level and its features to help us determine the cloud type. The clouds are puffy, somewhat ragged, and not very high in altitude. Because they’re a low altitude cloud, and they’re nowhere close to threatening rain, you can narrow down the cloud type to either cumulus, stratus, or stratocumulus.
Stratus clouds are featureless layer clouds, like a blanket over the sky. Meanwhile, these clouds have some detail to them, kind of resembling a cotton ball. They’re definitely not stratus.
So it’s down to cumulus or stratocumulus. Both cumulus and stratocumulus clouds can be puffy, and both clouds show detail. Cumulus clouds are particularly puffy… like the clouds that you’d draw as an elementary student in a landscape illustration.
Stratocumulus clouds are almost a mix of stratus and cumulus clouds. They’re somewhat puffy and somewhat layer-like. In this case, the clouds are low-level conjoined cloud heaps. It’s safe to say the type of cloud present is a stratocumulus cloud.
Cloud Species. The more you practice cloud identification, the more you’ll realize that there lots of variations in stratocumulus clouds. Stratocumulus clouds are associated with five of the fifteen cloud species: castellanus, floccus, lenticularis, stratiformis, and volutus. When classifying a cloud species, keep in mind you don’t have to classify a species if it isn’t appropriate. But let’s see if any of these five species fit the bill.
First, the cloud species lenticularis refers to clouds that are smooth, or lens-shaped, sometimes described as resembling a UFO. They’re very distinct, and it doesn’t look like this species applies here.
Next, the cloud species volutus refers to a roll cloud. Again, a very recognizable cloud species. Cross it off the list.
The cloud species stratiformis is a pretty common cloud species in stratocumulus clouds, which refers to a horizontal layer form that covers the sky. But that’s not the case here.
That leaves us with either the castellanus (rising towers, turrets) or floccus (puffy, ragged tufts) species. The stratocumulus clouds pictured aren’t particularly towered, but they’re certainly ragged and puffy. Almost as if they were conjoined balls of cotton that were pulled apart a bit.
In this case, it’s fair to classify this as the floccus cloud species.
Cloud Varieties. Stratocumulus clouds can be associated with a whopping seven of the total nine cloud species: duplicatus, lacunosus, opacus, perlucidus, radiatus, translucidus, and undulatus.
This cloud isn’t multilayered, it doesn’t have holes in it, it’s not particularly light or dark where the sun is or isn’t visible, it doesn’t have small gaps within its cloud heaps, it’s not lined up and radiating from the horizon, and it’s not undulating. This cloud has no associated cloud varieties.
Supplementary Features. Stratocumulus clouds can be associated with six supplementary features: asperitas (chaotic wavy underside), cavum (fallstreak hole), fluctus (Kelvin-Helmholtz waves), mamma (mammatus clouds), praecipitatio (precipitation), and virga (evaporating precipitation). Sure enough, there aren’t signs of any of those either.
Cloud Accessories & Other Clouds. Finally, class is dismissed a little extra early today. Stratocumulus clouds don’t have any accessory clouds or other clouds associated with it.
In this lesson, we determined the cloud classification starting from the cloud type and working our way down through its species, varieties, features, and accessories taxonomy. The vote is in and we’ve arrived at our official classification: Stratocumulus floccus (Sc flo).