All clouds are basically the same thing—water droplets or
ice crystals that float in the sky. They were initially named in
the early 1800s by a man named Luke Howard, who classified
the four main categories of clouds using Latin terms. Cumulus
(Latin for pile) describes heaped lumpy clouds. Cirrus (hair)
describes high-level clouds that look like wispy locks of hair.
Stratus (layer) are featureless sheet-like clouds, and Nimbus
(cloud) refers to low, gray rain clouds. The term “alto” describes
mid-level clouds while “convective” clouds are more vertical
and travel through multiple portions of the atmosphere.
Cloud names have been expanded based on where in the
sky they are located, how high they are in the air, and whether
they produce precipitation. For example, high clouds include
cirrus, cirrostratus, contrails, and cirrocumulus; Mid-level
clouds are altostratus and altocumulus, and low-level clouds
are stratus, stratocumulus, nimbostratus, and fog. Finally,
cumulonimbus clouds span all of the sky’s layers and are
classic thunderstorm clouds.
Sound complicated? Perhaps a simple visual will help.
Dense cirrus from cumulonimbus storm clouds.
Cumulus.
Once we know the different types of clouds, we can begin
to understand how we can predict the weather (hopefully
with a higher percentage probability than our local
weatherpersons!)
Rain on the way? Keep your eye out for high cirrostratus
clouds, mid-level altostratus or nimbostratus clouds, or low-
level cumulonimbus clouds. Hoping for fair weather? Watch
for altocumulus clouds in the mid-level sky or low-level
cumulus clouds. Worried about hurricanes or tornados? Be
on the lookout for low-flying cumulonimbus or upper-level
cirrocumulus clouds. Still confused? Have a look at some
real-life Lowcountry examples on the right.
So the next time you look toward the heavens, think about
the clouds you see there and remember what Rabindranath
Tagore, the 1913 Nobel Laureate for Literature, said, “Clouds
come floating into my life, no longer to carry rain or usher
storm, but to add color to my sunset sky.” NK
WINTER/SPRING 2019 • VOLUME 41
Fog.
Mammatus. (Opposite page: Nimbostratus.)
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