The World Meteorological Organization lists over 100 different types of clouds in its International Cloud Atlas. But, clouds are grouped into four main genera: cumulus, stratus, cirrus, and nimbus. These combine and form 10 basic cloud types. Here is an overview of the types of clouds, how to recognize them, and what kind of weather they produce.
- Cumulus clouds look like fluffy cotton balls. Low to the ground, they indicate fair weather, but when they tower into the sky they produce storms.
- Stratus clouds are sheets or layers of clouds. They can produce an overcast day or light rain or snow.
- Cirrus clouds are white wisps high in the sky.
- Nimbus clouds are either cumulus or stratus clouds that produce precipitation. Rain and snow clouds tend to be gray rather than white.
Quick Cloud Identification Guide
- Fluffy and puffy, like cotton → Cumulus
- Flat gray layer covering the sky → Stratus
- Thin, wispy, feather-like → Cirrus
- Tall, towering storm cloud → Cumulonimbus
- Low, lumpy gray patches → StratocumulusHigh ripples like fish scales → Cirrocumulus
How Are Clouds Classified?
Clouds get classified according to the altitude at which they form, their upper height, and their shape. The names come from Latin words. Four common types are cumulus, stratus, nimbus, and cirrus. Alternatively, clouds get names from their height: high (cirrus or ciro-), middle (alto-), low (stratus, strato-), and multilevel (cumulus, cumulo-, nimbo-). In terms of shape, stratiform describes flattened sheets, cirriform describes wisps or patches, and cumuliform clouds are masses or heaps. Nimbus clouds are ones that produce precipitations.
Types of Clouds
Cloud Types at a Glance
| Cloud Type | Altitude | Appearance | Weather |
|---|---|---|---|
| Cumulus | Low | Puffy, white | Fair weather |
| Stratus | Low | Flat, gray | Overcast, drizzle |
| Cirrus | High | Wispy, thin | Fair, changing weather |
| Cumulonimbus | Vertical | Tall, anvil | Storms |
| Nimbostratus | Low/mid | Thick, dark | Steady rain/snow |
Cumulus Clouds
Cumulus clouds are the puffy popcorn shapes you produce when asked to draw clouds. They are puffy with rounded tops. Cumulus clouds appear white when well-lit, but have flattened, darker bases.
You’ll see cumulus clouds form on clear, sunny days as the ground heats up. They often appear mid-morning, develop, and vanish as the sun sets. They indicate the presence of moisture in the air, but don’t necessarily produce rain or snow.
Stratus Clouds
Stratus clouds are flat, uniform, gray clouds. Usually, they are gray and resemble fog, rather fog forms at ground level.
Stratus clouds produce overcast days. Sometimes they produce mist or a light drizzle. Altostratus (and altocumulus) clouds sometimes produce virga, which is precipitation that evaporates before it reaches the ground.
Nimbus Clouds
Nimbus clouds produce precipitation in the form of rain, hail, or snow. Both cumulus and stratus clouds can be nimbus clouds, which go by the names cumulonimbus and stratonimbus.
Cumulonimbus clouds are thunderheads that tower from the troposphere into the stratosphere. The cloud top often flattens into an anvil shape. The cloud’s bottom is dark.
Nimbostratus clouds are less ominous. They are gray, multi-level clouds that yield the occasional rain shower or snow flurry.
Cirrus Clouds
Cirrus clouds are patchy or wispy white clouds high in the atmosphere. Because of their altitude, these clouds consist of ice crystals rather than liquid water droplets.
Combining Cloud Names
Some clouds have multiple features and have combination names.
- Cirrostratus: Cirrostratus clouds are thin veils high in the atmosphere.
- Cirrocumulus: Cirrocumulus clouds appears a high white ripples, scales, or stripes.
- Altostratus: Altostratus clouds are either opaque or translucent gray clouds at intermediate altitudes.
- Altocumulus: Altocumulus clouds are irregular patches or waves of mid-level clouds.
- Stratocumulus: Stratocumulus clouds are low-level irregular gray patches or sheets.
Types of Clouds Worksheet
Practice identifying the types of clouds based on their appearance.
[Google Apps worksheet][worksheet PDF][worksheet PNG][answers PNG]
| Altitude | Cloud Type | Symbol | Features |
|---|---|---|---|
| Extremely high | Polar mesospheric clouds or noctilucent veils | PMC | Night-shining clouds |
| Very high | Nitric acid and water polar stratospheric clouds | PSC | Iridescent, most visible at twilight |
| High | Cirrostratus Cirrus Cirrocumulus | Cs Ci Cc | Thin veil Delicate wisps Pure white rounded masses or ripples |
| Mid | Altostratus Altocumulus | As Ac | Opaque or translucent gray clouds Irregular patches or sheets in groups or waves |
| Low | Stratus Stratocumulus Cumulus | St Sc Cu | Flat or ragged clouds resembling fog Irregular patches or sheets shading to gray Detached clouds with flat bases and tops |
| Multi-level | Nimbostratus | Ns | Dark gray multi-layers that appear lit from within that produce precipitation |
| Towering vertical | Cumulonimbus | Cb | Heavy, towering cloud with dark base and very high top that produces lightning, thunderstorms, snow showers, hail |
| Surface | fog or mist |
Other Types of Clouds
Other noteworthy types of clouds are lenticular clouds and mammatus clouds.
Lenticular clouds (Lenticularis or len) are lens-shaped or almond-shaped stationary clouds. They are a specific form of stratocumulus, altocumulus, or cirrocumulus clouds. These clouds form around mountains, hills, and buildings and resemble UFOs.
Mammatus clouds are cumulus clouds (usually cumulonimbus) with cellular pouches hanging from the cloud base. Clouds with “lumpy” undersides and anvil shapes are associated with extreme turbulence and severe thunderstorms.
- Lenticular → associated with strong winds over mountains
- Mammatus → linked to severe storms but not dangerous themselves
Why Clouds Form
Clouds form when warm, moist air rises, cools, and condenses into tiny water droplets or ice crystals.
Simple breakdown:
- Warm air rises
- Air cools with altitude
- Water vapor condenses
- A cloud forms
Clouds and Weather Prediction
Clouds provide valuable clues about current and upcoming weather. By recognizing cloud types, you can often predict changes before they occur.
- Cumulus clouds usually indicate fair weather, especially when they are small and scattered. However, if they grow taller and darker, they may develop into storms.
- Cumulonimbus clouds signal thunderstorms. These clouds can produce heavy rain, lightning, hail, and even tornadoes.
- Stratus clouds bring gray, overcast skies. They often produce light drizzle, mist, or fog-like conditions.
- Nimbostratus clouds indicate steady, long-lasting precipitation such as rain or snow.
- Cirrus clouds often appear before a change in the weather. They can signal that a warm front or storm system is approaching within the next day.
- Altostratus clouds frequently precede widespread precipitation, especially ahead of large storm systems.
- Stratocumulus clouds usually bring dry weather, although they may produce light rain in some cases.
Watching how clouds change over time is especially useful. For example, increasing cloud thickness or lowering cloud height often signals that precipitation is likely.
Fun Facts About Clouds
Clouds are more complex and surprising than they appear at first glance.
- A typical cumulus cloud weighs over 1 million kilograms, even though it looks light and fluffy.
- Clouds float because the tiny water droplets or ice crystals are spread out and supported by rising air currents.
- No two clouds are exactly alike, just like snowflakes.
- High-altitude clouds, such as cirrus, are made of ice crystals, not liquid water.
- Noctilucent clouds glow at night and form at the edge of space in the mesosphere.
- Pilots avoid flying through cumulonimbus clouds because of strong turbulence and lightning.
- The study of clouds is called nephology.
- Some clouds, like lenticular clouds, can look like UFOs.
- Mammatus clouds have pouch-like structures hanging underneath and are often associated with severe storms.
- Clouds play a key role in regulating Earth’s temperature by reflecting sunlight and trapping heat.
FAQs
What is the most common type of cloud?
Stratocumulus clouds are among the most common. They often cover large areas of the sky in low, lumpy layers.
What type of cloud produces thunderstorms?
Cumulonimbus clouds produce thunderstorms, lightning, heavy rain, hail, and sometimes tornadoes.
Which clouds bring steady rain?
Nimbostratus clouds are responsible for continuous, steady precipitation over long periods.
What is the highest type of cloud?
Cirrus clouds form at the highest altitudes in the troposphere, typically above 6,000 meters (20,000 feet).
Are clouds made of water or ice?
Clouds can consist of liquid water droplets, ice crystals, or a mixture of both, depending on temperature and altitude.
Why are clouds sometimes gray?
Clouds appear gray when they are thick enough to block or scatter most of the sunlight passing through them.
Can you touch a cloud?
Yes. Fog is simply a cloud at ground level, so walking through fog means you are inside a cloud.
Do clouds always mean rain?
No. Many clouds, such as cumulus and cirrus, often form without producing any precipitation.
References
- Ackerman, Steven A. (2011). Meteorology: Clouds and the Greenhouse Effect. Jones & Bartlett. ISBN 978-0-7637-8927-5.
- Burroughs, William James; Crowder, Bob (2007). Weather. San Francisco: Fog City Press. ISBN 978-1-74089-579-8.
- Miyazaki, R.; Yoshida, S.; Dobashi, Y.; Nishita, T. (2001). “A method for modeling clouds based on atmospheric fluid dynamics”. Proceedings Ninth Pacific Conference on Computer Graphics and Applications. Pacific Graphics. doi:10.1109/PCCGA.2001.962893. ISBN 978-0-7695-1227-3.
- World Meteorological Organization, ed. (1975). International Cloud Atlas. Vol. I. ISBN 978-92-63-10407-6.