Keeping clouds simple :)
Every cloud in the sky is named using a handful of Latin words describing its shape, its height, and whether it's raining. Learn those words, and the ten official cloud types basically name themselves.
The sky in three layers
Part one
Meteorologists describe almost every cloud using combinations of these four shape words. Learn what each one looks like and means, and you're most of the way to naming any cloud you see.
Cirrus
cirro- = "curl"Thin, wispy clouds that look like feathers or curls of hair, floating around 6,000m up.
Cirrus clouds are made almost entirely of ice crystals rather than water droplets, because it's so cold at that height. Strong high-altitude winds stretch them into their curled, streaky shape — sometimes nicknamed "mares' tails". On their own they usually mean fair weather, though a growing number of them can hint that a change is on the way.
Cumulus
cumulo- = "heap"Puffy clouds that look like cotton wool or candy floss, usually floating between 300m and 2,000m.
Cumulus clouds form when warm air near the ground rises, cools, and condenses into a heap. Small, isolated ones on a sunny day are called "fair weather cumulus" — the classic cartoon cloud shape. Given enough heat and moisture, a cumulus cloud can keep growing upward all day until it becomes something much bigger (see cumulonimbus below).
Stratus
strato- = "layer"Flat, featureless clouds that don't really move, stretching across the whole sky like a blanket on overcast days.
Stratus forms when a whole layer of air cools and condenses evenly, rather than in separate rising bubbles. It sits low in the sky and can look a lot like fog that never quite reaches the ground. It rarely produces more than a light drizzle, but it's the reason a sky can stay uniformly grey for a whole day.
Nimbus
nimbo- = "rain"Not a cloud shape on its own — "nimbus" is added to a cloud's name whenever rain or snow is actually falling from it.
Unlike the other three, nimbus describes behaviour rather than shape. Attach it to stratus and you get nimbostratus, a steady rain-layer. Attach it to cumulus and you get cumulonimbus, a towering thunderstorm. If you see "nimbus" anywhere in a cloud's name, grab an umbrella.
Alto alto- = "high"
One more word worth knowing before Part two: unlike the four above, alto- doesn't describe a shape — it describes height. Confusingly, it actually marks the middle layer of the sky (roughly 2,000–6,000m), not the highest one.
This is a historical quirk, not a mistake. When clouds were first classified, the low clouds (stratus, cumulus) and the true high clouds (cirro-) were named first. The middle band then got called the "elevated" or "high" version of the low clouds — high compared to stratus and cumulus, not compared to cirrus. So the real order from low to high is: stratus/cumulus → altocumulus/stratus → cirrocumulus/stratus, even though "alto" is the Latin word for "high".
Part two
Weather scientists group almost every cloud in the sky into ten "genera". Seven of the ten combine two of the five words above; the other three (cirrus, cumulus, stratus) are just one of those words standing alone. Either way, the name tells you the shape and the height at once.
Part three
Ten names can feel like a lot to hold onto — but the table below shows the pattern that connects almost all of them.
| Puffy cumulo- |
Layer strato- |
Both mixed together | |
|---|---|---|---|
| High cirro- |
Cirrocumulus | Cirrostratus | — (cirrus alone covers it) |
| Mid alto- |
Altocumulus | Altostratus | Nimbostratus (breaks the pattern) |
| Low no prefix |
Cumulus | Stratus | Stratocumulus |
Cumulonimbus sits outside this table entirely — a low cumulus cloud that grew tall enough to tower through every layer at once.