Weather A Guide to Cloud Types  

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We live with clouds every day, but most of us don't realize that knowing your clouds and the differences between the types can tell you about the weather that might be coming. This is a guide to all the common (and some uncommon) cloud types that you might see on any given day.

Cirrus is listed (or ranked) 1 on the list A Guide to Cloud Types
High Level Cloud

These clouds are the wispy, feathery ones you see way high up. They are composed entirely of ice crystals and they usually are the first sign of an approaching warm front.

Cirrostratus is listed (or ranked) 2 on the list A Guide to Cloud Types

High Level Cloud

These cirrus-type clouds form more of a veil or a thin-looking, uniform sheet over the sky. You can get that sun-halo effect when there are cirrostratus clouds overhead. They are also the next phase of cloud after cirrus as the warm front draws closer.

Cirrocumulus Clouds is listed (or ranked) 3 on the list A Guide to Cloud Types
Cirrocumulus Clouds

High Level Cloud

The last type of cirrus clouds are the cirroculmulus, which are layered clouds with cumuliform lumps. They can also present in rows across the sky.

Altostratus is listed (or ranked) 4 on the list A Guide to Cloud Types

Mid Level Cloud

Lower to the ground than cirrus, these clouds look flat and uniform. They often mean the warm front is close and will generally thicken into stratus or nimbostratus. These strato type clouds do not normally produce significant precipitation at the surface, although a light shower may occur from a particularly thick alto-stratus layer.  

Altocumulus is listed (or ranked) 5 on the list A Guide to Cloud Types

Mid Level Clouds

These clouds exhibit less strato (flat and uniform) characteristics and more cumulo (this means fluffier). They usually indicate localized areas of rising, moist air with clear areas between them of sinking, drier air. In the morning especially, these clouds indicate instability in the air, which could then be released into deep convection by the afternoon or evening.

Stratus is listed (or ranked) 6 on the list A Guide to Cloud Types

Low Level Clouds

These are the uniform, flat, grey common clouds you see hanging around on a cold, dismal, grey day. Often meaning you will see some level of precipitation.

Stratocumulus is listed (or ranked) 7 on the list A Guide to Cloud Types
Low Level Clouds
These guys are hybrids of stratus and cumulus all clumped together continuously just like strato clouds. Stratocumulus also can be thought of as a layer of cloud clumps with thick and thin areas. These clouds tend to appear frequently, either before or after a frontal system.

Nimbostratus is listed (or ranked) 8 on the list A Guide to Cloud Types

Low Level Clouds

Nimbostratus are thick, dense stratus or stratocumulus clouds producing steady rain or snow. Unlike layered, horizontal stratus, cumulus clouds are more individual-looking. They have flat bottoms and rounded tops, and grow upwards. Their name, Nimbo, depends on the degree of verticality

Cumulus is listed (or ranked) 9 on the list A Guide to Cloud Types

Low Level Cloud

These are the clouds that little kids draw when they draw clouds. Puffy and fuffy, cumulus clouds are cellular (look like individual clouds) in nature, have flat bottoms and rounded tops, and grow vertically. Scattered cumulus clouds showing little vertical growth on an otherwise sunny day are referred to as cumulus or flat cumulus.

Cumulus Congestus is listed (or ranked) 10 on the list A Guide to Cloud Types
Cumulus Congestus

Low Level Cloud
(Storm Cloud)

A cumulus cloud that gets super tall (but is not yet a thunderstorm) is called cumulus congestus or towering cumulus. It will lead to a thunderstorm cloud if enough instability, moisture, and lift are present. Only then can strong updrafts develop in the cumulus cloud leading to a mature, deep cumulonimbus cloud.

Cumulonimbus is listed (or ranked) 11 on the list A Guide to Cloud Types

Low Level Clouds
(Serious Thunderstorm)

If a Cumulus Congestus gets big and tall enough due to enough instability, moisture, and lift, then strong updrafts can develop leading to a mature, deep cumulonimbus cloud. Lightning and thunder results when electrically charged water droplets, graupel (ice-water mix), and ice crystal particles collide. These are the bad-boys of the weather world.

Wall Clouds is listed (or ranked) 12 on the list A Guide to Cloud Types
Wall Clouds

Low Level Cloud
(Storm Cloud)

Wall clouds, or Pedestal clouds, take on many shapes and sizes. Some exhibit strong upward motion and cyclonic rotation, leading to tornados, while others do not rotate and essentially are harmless. Still, if you see one, it's good to up your level of concern.  It is typically found beneath the rain-free portion of a thunderstorm, and indicates the area of the strongest updraft of the storm.

Arcus Clouds is listed (or ranked) 13 on the list A Guide to Cloud Types
Arcus Clouds

Low Level Clouds
(Storm Cloud)

These clouds look pretty awesome and scary, but rarely produce the tornadoes they seem to be threatening. There are two types of Arcus clouds: Shelf clouds, which are low, horizontal, sometimes wedge-shaped cloud associated with the leading edge of a thunderstorm's potentially strong winds; and Roll clouds, which are low, horizontal, tube-shaped, and a relatively rare type of arcus cloud.

Fractus is listed (or ranked) 14 on the list A Guide to Cloud Types

Low Level Clouds
(Storm Clouds)

These are low, ragged strato or cumulo cloud elements that, normally, are unattached to larger thunderstorms. Also known as scud, fractus clouds can look scary, but by themselves are not dangerous. Fractus have irregular patterns, looking like torn shreds of cotton candy. They change constantly, often forming and dissipating rapidly. They do not have clearly defined bases. Sometimes they are persistent and form close to the surface. 

Mammatus is listed (or ranked) 15 on the list A Guide to Cloud Types

Low Level Clouds
(Storm Cloud)

Mammatus clouds are most often are seen hanging from the anvil of a severe thunderstorm, but do not produce severe weather. True to their ominous appearance, mammatus clouds are often harbingers of a coming storm or other extreme weather system. Usually made mostly of ice, they can stretch for hundreds of miles in each direction. While they may appear foreboding they are merely the messengers - appearing around, before or even after severe weather.

When seen accompanying cumulonimbus, the drooping lobes oftentimes indicate a particularly strong storm or maybe even a tornadic storm. Due to the intensely sheared environment in which mammatus form, pilots know to avoid any cumulonimbus with mammatus present.

Fog is listed (or ranked) 16 on the list A Guide to Cloud Types

Low Level Clouds

Fog forms when the difference between temperature and dew point is generally less than 2.5 °C or 4 °F. Like its slightly elevated cousin stratus, fog is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. Different types include radiation fog ( the sort that forms overnight and burns off in the morning) and advection fog.

Contrails is listed (or ranked) 17 on the list A Guide to Cloud Types

Low Level Clouds
(Not naturally forming)

We see these every day and think nothing of them. When planes fly overhead, aircraft exhaust condenses in cold air at high altitudes, forming these long, narrow tracks in the sky. They are indicative of upper level humidity and wind drift.