Cloud Types Table
| Level | Genus | Abbrev. | Signature look |
|---|---|---|---|
| High (ice, 6-13 km) | Cirrus | Ci | Silky filaments and hooks |
| High | Cirrocumulus | Cc | Tiny grainy ripples, mackerel sky |
| High | Cirrostratus | Cs | Milky sheet that halos sun or moon |
| Middle (2-6 km) | Altocumulus | Ac | Woolly white patches in bands |
| Middle | Altostratus | As | Gray sheet, sun as through frosted glass |
| Vertical | Cumulonimbus | Cb | Anvil-topped storm tower, dark base |
| Vertical | Cumulus congestus | Tcu | Cauliflower tower still growing |
| Vertical | Nimbostratus | Ns | Featureless dark rain layer, all day |
| Low (under 2 km) | Stratocumulus | Sc | Lumpy gray deck with gaps |
| Low | Stratus | St | Uniform fog-like layer, may drizzle |
| Low | Cumulus humilis / mediocris | Cu | Flat-based fair-weather heaps |
| Any level | Contrails & special clouds | — | Engine trails, lenticulars, nacreous |
Meteorology recognizes exactly twelve cloud genera, and the naming system decodes itself once you know four Latin roots: cirro- (high and icy), alto- (mid-level), strato- (layered) and cumulo- (heaped). The chart sorts them by the level where they live - high clouds above 6 km, mid-level between 2 and 6 km, low clouds under 2 km - plus the two vertical Developers that ignore levels entirely: nimbostratus, the featureless rain layer, and cumulonimbus, the anvil-topped thunderstorm that spans the whole troposphere.
The abbreviations are the weather chart's shorthand and worth memorizing first: Ci, Cc, Cs up high; Ac, As in the middle; Sc, St, Cu down low; Ns and Cb for the rain-makers. The genera are also the honest answer to what kind of weather is coming: cirrostratus halos often precede a warm front by a day, thickening altostratus means rain within hours, and a morning cumulus humilis that stays flat promises the picnic holds.
How to use
- Identify by height first, then shape: look for the level band (icy wisps high, gray sheets middle, lumpy bases low), then match texture - filaments mean cirrus, grainy patches mean cirrocumulus or altocumulus, uniform sheets mean the stratus family, and Cauliflower towers with dark bases mean cumulus growing toward rain.
- Use the abbreviation column to read forecasts and pilot reports: METARs and aviation weather compress every observation into these two-letter codes, so Sc spells a lumpy gray deck at a few thousand feet and Cb in a terminal aerodrome forecast means thunderstorms are an official expectation, not a maybe.
- Read the vertical Developers as time limits: nimbostratus means steady rain is already falling and will persist, while cumulonimbus carries hail, downbursts and lightning inside its anvil - the one genus where the identification rule is give it distance rather than admire it.
Frequently asked questions
What are the 12 main types of clouds?
The twelve genera, by level: high - cirrus (Ci, icy filaments), cirrocumulus (Cc, grainy ripples) and cirrostratus (Cs, the sheet that halos the sun); middle - altocumulus (Ac, woolly patches) and altostratus (As, the gray sheet that dims the sun); low - stratocumulus (Sc, lumpy deck), stratus (St, featureless fog-aloft) and cumulus (the fair-weather heaps); and the two vertical rain-makers, nimbostratus (Ns, steady rain layer) and cumulonimbus (Cb, the thunderstorm). Every cloud you will ever see is one of these or a variety of one of them.
What cloud type brings rain?
Two, reliably. Nimbostratus is the steady-rain cloud - a thick, gray, featureless layer that darkens the sky and drizzles for hours, the classic all-day soaker ahead of and behind a warm front. Cumulonimbus is the dramatic one: the anvil-topped tower that delivers downpours, hail, lightning and gust fronts in bursts. Everything else promises at most light precipitation - cirrostratus and altostratus thicken toward those two, which is why a halo tonight followed by a dimming sky tomorrow is the oldest rain forecast there is.
How high do clouds fly?
By level: high clouds ride 6 to 13 kilometers (about 20,000 to 43,000 feet), made of ice crystals because the air there is freezing - cirrus, cirrocumulus, cirrostratus. Middle clouds occupy roughly 2 to 6 km - the alto- family plus nimbostratus when it embeds there. Low clouds sit below 2 km - stratus, stratocumulus, and most cumulus. Cumulonimbus ignores the ladder, building from a low base near the surface up to the tropopause at 12 km or higher, which is why it is the only genus that touches every level at once.
Why do cloud names all sound Latin?
Because the system was set in 1803 by Luke Howard, an amateur pharmacist who proposed the Latin binomial scheme - cirrus (a curl), cumulus (a heap), stratus (a layer), nimbus (a rain-bearer) - and the scientific world adopted it wholesale. Modern names are compounds of his four roots plus the height prefixes cirro- and alto-: alto-cumulus is simply mid-level heap, nimbo-stratus the rain layer. The chart's abbreviations descend from the same convention, which is why a two-letter code like Cb carries a complete weather story in the corner of a forecast chart.