List of cloud types

The list of cloud types groups all genera as high, middle, multi-level, and low. These groupings are determined by the altitude level or levels in the troposphere at which each of the various cloud types are normally found. Small cumulus are commonly grouped with the low clouds because they do not show significant vertical extent. Of the multi-level genus-types, those with the greatest convective activity are often grouped separately as towering vertical. The genus types all have Latin names.
The genera are also grouped into five physical forms. These are, in approximate ascending order of instability or convective activity: stratiform sheets; cirriform wisps and patches; stratocumuliform patches, rolls, and ripples; cumuliform heaps, and cumulonimbiform towers that often have complex structures. Most genera are divided into species with Latin names, some of which are common to more than one genus. Most genera and species can be subdivided into varieties, also with Latin names, some of which are common to more than one genus or species. The essentials of the modern nomenclature system for tropospheric clouds were proposed by Luke Howard, a British manufacturing chemist and an amateur meteorologist with broad interests in science, in an 1802 presentation to the Askesian Society. Very low stratiform clouds that touch the Earth's surface are given the common names fog and mist, which are not included with the Latin nomenclature of clouds that form aloft in the troposphere.
Above the troposphere, stratospheric and mesospheric clouds have their own classifications with common names for the major types and alpha-numeric nomenclature for the subtypes. They are characterized by altitude as very high level and extreme level. Three of the five physical forms in the troposphere are also seen at these higher levels, stratiform, cirriform, and stratocumuliform, although the tops of very large cumulonimbiform clouds can penetrate the lower stratosphere.

Cloud identification and classification: Order of listed types

In section two of this page, height ranges are sorted in approximate descending order of altitude expressed in general terms. On the cross-classification table, forms and genus types are shown from left to right in approximate ascending order of instability.
In sections three to five, terrestrial clouds are listed in descending order of the altitude range of each atmospheric layer in which clouds can form:

mesospheric layer;
stratospheric layer;
tropospheric layer.
* Within the troposphere, the cloud levels are listed in descending order of altitude range.
** Non-vertical genus types are sorted into approximate descending order of altitude of the cloud bases.
** Vertical or multi-level genera and genus sub-types can be based in the low or middle levels and are therefore placed between the non-vertical low and mid-level genus types and sub-types. These thick clouds are listed in approximate descending order of altitude of the cloud tops.
*** The species associated with each genus type are listed in approximate ascending order of instability where applicable.
*** The constituent varieties and associated supplementary features and mother clouds for each genus or species are arranged in approximate order of frequency of occurrence.

In section six, the cloud types in the general lists and the mother clouds in the applicable classification table are sorted in alphabetical order except where noted. The species table shows these types sorted from left to right in approximate ascending order of the convective instability of each species. The table for supplementary features has them arranged in approximate descending order of frequency of occurrence.
In section seven, extraterrestrial clouds can be found in the atmospheres of other planets in the Solar System and beyond. The planets with clouds are listed in order of their distance from the Sun, and the clouds on each planet are in approximate descending order of altitude.

Cloud cross-classification throughout the homosphere

[Image:Wolkenstockwerke.png|right|thumb|200px|Cloud chart showing major tropospheric cloud types identified by standard two-letter abbreviations and grouped by altitude and form. See table below for full names and classification.]
The table that follows is very broad in scope much like the cloud genera template near the bottom of the article and upon which this table is partly based. There are some variations in styles of nomenclature between the classification scheme used for the troposphere and the higher levels of the homosphere. However, the schemes presented here share a cross-classification of physical forms and altitude levels to derive the 10 tropospheric genera, the fog and mist that forms at surface level, and several additional major types above the troposphere. The cumulus genus includes four species that indicate vertical size which can affect the altitude levels.

	Stratiform non-convective	Cirriform mostly non-convective	Stratocumuliform limited-convective	Cumuliform free-convective	Cumulonimbiform strong-convective
Extreme-level	Noctilucent veils	Noctilucent billows or whirls	Noctilucent bands
Very high-level	Nitric acid & water stratospheric cloud\|polar stratospheric]	Cirriform nacreous PSC	Lenticular nacreous PSC
High-level	Cirrostratus	Cirrus	Cirrocumulus
Mid-level	Altostratus		Altocumulus
Towering vertical				Cumulus congestus	Cumulonimbus
Multi-level or moderate vertical	Nimbostratus			Cumulus mediocris
Low-level	Stratus		Stratocumulus	Cumulus humilis or fractus
Surface-level	Fog or mist

Mesospheric cloud identification and classification

Clouds that form in the mesosphere come in a variety of forms such as veils, bands, and billows, but are not given Latin names based on these characteristics. These clouds are the highest in the atmosphere and are given the Latin-derived name noctilucent which refers to their illumination during deep twilight rather than their physical forms. They are sub-classified alpha-numerically and with common terms according to specific details of their physical structures.

Extreme-level stratiform, stratocumuliform, and cirriform

Noctilucent clouds are thin clouds that come in a variety of forms based from about and occasionally seen in deep twilight after sunset and before sunrise.
;Type 1 : Veils, very tenuous stratiform; resembles cirrostratus or poorly defined cirrus.
;Type 2 : Long stratocumuliform bands, often in parallel groups or interwoven at small angles. More widely spaced than cirrocumulus bands.
;Type 3: Billows. Clearly spaced, fibrous cirriform, roughly parallel short streaks.
;Type 4 : Whirls. Partial cirriform rings with dark centers.

Stratospheric cloud identification and classification

Polar stratospheric clouds form at very high altitudes in polar regions of the stratosphere. Those that show mother-of-pearl colors are given the name nacreous.

Very high-level stratiform

;Nitric acid and water polar stratospheric : Sometimes known as type 1, a thin sheet-like cloud resembling cirrostratus or haze. Contains supercooled nitric acid and water droplets; sometimes also contains supercooled sulfuric acid in ternary solution.

Very high-level cirriform and stratocumuliform

;Nacreous polar stratospheric cloud : Sometimes known as type 2, a thin usually cirriform or lenticular looking cloud based from about and seen most often between sunset and sunrise. Consists of ice crystals only.

Troposphere cloud identification and classification

Tropospheric clouds are divided into physical forms defined by structure, and levels defined by altitude range. These divisions are cross-classified to produce ten basic genus-types. They have Latin names as authorized by the World Meteorological Organization that indicate physical structure, altitude or étage, and process of formation.

High-level cirriform, stratocumuliform, and stratiform

High clouds form in the highest and coldest region of the troposphere from about 5 to 12 km in temperate latitudes. At this altitude water almost always freezes so high clouds are generally composed of ice crystals or supercooled water droplets.

Genus cirrus

Abbreviation: Ci
Cirriform clouds tend to be wispy and are mostly transparent or translucent. Isolated cirrus do not bring rain; however, large amounts of cirrus can indicate an approaching storm system eventually followed by fair weather.
There are several variations of clouds of the cirrus genus based on species and varieties:

Species

; Cirrus fibratus: High clouds having the traditional "mare's tail" appearance. These clouds are long, fibrous, and curved, with no tufts or curls at the ends.
; Cirrus uncinus: Filaments with up-turned hooks or curls.
; Cirrus spissatus: Dense and opaque or mostly opaque patches.
; Cirrus [castellanus cloud|Cirrus castellanus]: A series of dense lumps, or "towers", connected by a thinner base.
; Cirrus floccus: Elements which take on a rounded appearance on the top, with the lower part appearing ragged.

Varieties

; Opacity-based: None; always translucent except species spissatus which is inherently opaque.
; Fibratus pattern-based:
; Pattern-based variety radiatus: Large horizontal bands that appear to converge at the horizon; normally associated with fibratus and uncinus species.
; Pattern-based variety duplicatus: Sheets at different layers of the upper troposphere, which may be connected at one or more points; normally associated with fibratus and uncinus species.
; Spissatus, castellanus, or floccus: Varieties are not commonly associated.

Supplementary features

; Precipitation-based: Not associated with cirrus.
; Cloud-based:
; Genitus mother clouds:
; Mutatus mother cloud:

Genus cirrocumulus

Abbreviation: Cc.
High-level stratocumuliform clouds of the genus cirrocumulus form when moist air at high tropospheric altitude reaches saturation, creating ice crystals or supercooled water droplets. Limited convective instability at the cloud level gives the cloud a rolled or rippled appearance. Despite the lack of a strato- prefix, layered cirrocumulus is physically a high stratocumuliform genus.

High stratocumuliform species

; Cirrocumulus stratiformis: Sheets or relatively flat patches of cirrocumulus.
; Cirrocumulus lenticularis: Lenticular, or lens-shaped high cloud.
; Cirrocumulus castellanus: Cirrocumulus layer with "towers", or turrets joined at the bases.
; Cirrocumulus floccus: Very small white heaps with ragged bases and rounded tops.

Varieties

; Opacity-based varieties: None.
; Pattern-based varieties:

Supplementary features

; Precipitation-based supplementary feature:
; Cloud-based supplementary feature:
; Genitus mother clouds: No genitus types.
; Mutatus mother clouds:

Genus cirrostratus

Abbreviation: Cs
Clouds of the genus cirrostratus consist of mostly continuous, wide sheets of cloud that covers a large area of the sky. It is formed when convectively stable moist air cools to saturation at high altitude, forming ice crystals. Frontal cirrostratus is a precursor to rain or snow if it thickens into mid-level altostratus and eventually nimbostratus, as the weather front moves closer to the observer.

Species

; Cirrostratus fibratus: Cirrostratus sheet with a fibrous appearance, but not as detached as cirrus.
; Cirrostratus nebulosus: Featureless, uniform sheet.

Varieties

; Opacity-based varieties: None
; Fibratus pattern-based varieties:
; Varieties are not commonly associated with Cs species nebulosus.

Supplementary features

; Genitus mother clouds:
; Mutatus mother clouds:

Mid-level stratocumuliform and stratiform

Middle cloud forms from 2 to 7 km in temperate latitudes, and may be composed of water droplets or ice crystals depending on the temperature profile at that altitude range.

Genus altocumulus

Abbreviation: Ac
Mid-level stratocumuliform clouds of the genus altocumulus are not always associated with a weather front but can still bring precipitation, usually in the form of virga which does not reach the ground. Layered forms of altocumulus are generally an indicator of limited convective instability, and are therefore mainly stratocumuliform in structure.

Mid-level stratocumuliform species

; Altocumulus stratiformis: Always dividable into opacity-based varieties. Sheets or relatively flat patches of altocumulus.
; Altocumulus lenticularis: Lens-shaped middle cloud. Includes informal variant altocumulus Kelvin–Helmholtz cloud, lenticular spiral indicative of severe turbulence.
; Altocumulus volutus: Elongated, tube shaped, horizontal stratocumuliform cloud.
; Altocumulus castellanus: Turreted layer cloud.
; Altocumulus floccus: Tufted stratocumuliform clouds with ragged bases.

Varieties

; Opacity-based varieties:
; Pattern-based varieties:

Supplementary features

; Precipitation-based supplementary feature:
; Cloud-based supplementary feature:
; Genitus mother clouds:
; Mutatus mother clouds:

Genus altostratus

Abbreviation: As
Stratiform clouds of the genus altostratus form when a large convectively stable air mass is lifted to condensation in the middle level of the troposphere, usually along a frontal system. Altostratus can bring light rain or snow. If the precipitation becomes continuous, it may thicken into nimbostratus which can bring precipitation of moderate to heavy intensity.

Species

No differentiated species.

Varieties

; Opacity-based varieties:
; Pattern-based variety radiatus: Bands that appear to converge at the horizon.
; Pattern-based variety duplicatus: Altostratus in closely spaced layers, one above the other.
; Pattern-based variety undulatus: Altostratus with wavy undulating base.

Supplementary features

; Precipitation-based supplementary features:
; Cloud-based supplementary feature:
; Accessory cloud: Seen mostly with opacus varieties
; Genitus mother clouds:
; Mutatus mother clouds:

Towering vertical cumulonimbiform and cumuliform (low to mid-level cloud base)

Clouds with upward-growing vertical development usually form below, but can be based as high as in temperate climates, and often much higher in arid regions.

Genus cumulonimbus: Towering vertical

Abbreviation: Cb
Clouds of the genus cumulonimbus have very-dark-gray-to-nearly-black flat bases and very high tops that can penetrate the tropopause. They develop from cumulus when the air mass is convectively highly unstable. They generally produce thunderstorms, rain or showers, and sometimes hail, strong outflow winds, and/or tornadoes at ground level.

Species

; Cumulonimbus calvus: Cumulonimbus with high domed top.
; Cumulonimbus capillatus: Towering vertical cloud with high cirriform top.

Varieties

No varieties.

Supplementary features

; Precipitation-based supplementary features: Associated with calvus and capillatus species.
; Cloud-based supplementary features:
; Accessory clouds: Seen with species and capillatus except where noted.
; Genitus mother clouds:
; Mutatus mother cloud:

Genus cumulus: Towering vertical

Abbreviations: Cu con or '''Tcu'''

Species

; Cumulus congestus: These large cumulus clouds have flat dark grey bases and very tall tower-like formations with tops mostly in the high level of the troposphere. The International Civil Aviation Organization designates this species as towering cumulus.

Varieties

; Opacity-based varieties: None.
; Pattern-based variety: None.

Supplementary features

; Precipitation-based supplementary features:
; Cloud-based supplementary features:
; Accessory clouds:
; Mother clouds:

Multi-level stratiform and moderate vertical cumuliform (low to mid-level cloud base)

Genus nimbostratus: Multi-level

Abbreviation: Ns
Clouds of the genus nimbostratus tend to bring constant precipitation and low visibility. This cloud type normally forms above from altostratus cloud but tends to thicken into the lower levels during the occurrence of precipitation. The top of a nimbostratus deck is usually in the middle level of the troposphere.

Species

No differentiated species.

Varieties

No varieties.

Supplementary features

; Precipitation-based supplementary features:
; Accessory cloud:
; Genitus mother clouds
; Mutatus mother clouds:

Genus cumulus: Moderate vertical

Abbreviation: Cu
Moderate vertical cumulus is the product of free convective air mass instability. Continued upward growth suggests showers later in the day.

Species

; Cumulus mediocris: Moderate vertical clouds with flat medium grey bases and higher tops than cumulus humilis.

Varieties

; Pattern-based variety:

Supplementary features

; Cloud-based supplementary feature:
; Accessory clouds:
; Mother clouds: Genitus and mutatus types are the same as for cumulus of little vertical extent.

Low-level stratocumuliform, cumuliform, and stratiform

Low cloud forms from near surface to ca. and are generally composed of water droplets.

Genus stratocumulus

Abbreviation: Sc
Clouds of the genus stratocumulus are lumpy, often forming in slightly unstable air, and they can produce very light rain or drizzle.

Species

; Stratocumulus stratiformis: Always dividable into opacity-based varieties. Sheets or relatively flat patches of stratocumulus
; Stratocumulus lenticularis: Lens-shaped low cloud.
; Stratocumulus volutus: Elongated, low-level, tube shaped, horizontal stratocumuliform cloud.
; Stratocumulus floccus: Scattered or isolated stratocumulus tufts with domed tops and ragged bases.
; Stratocumulus castellanus: Layer of turreted stratocumulus cloud with tower-like formations protruding upwards.

Varieties

; Stratocumuliform opacity-based varieties:
; Pattern-based variety radiatus: Stratocumulus arranged in parallel bands that appear to converge on the horizon; normally associated with stratiformis species.
; Pattern-based variety duplicatus: Closely spaced layers of stratocumulus, one above the other; normally associated with stratiformis and lenticularis species.
; Pattern-based variety undulatus: Stratocumulus with wavy undulating base; normally associated with stratiformis and lenticularis species.
; Pattern-based variety lacunosus: Sc with circular holes caused by localized downdrafts; normally associated with stratiformis and castellanus species.

Supplementary features

; Precipitation-based supplementary features: Usually associated with species stratiformis and castellanus.
; Cloud-based supplementary feature:
; Genitus mother clouds:
; Mutatus mother clouds:

Genus cumulus (little vertical extent)

Abbreviation: Cu
These are fair weather cumuliform clouds of limited convection that do not grow vertically. The vertical height from base to top is generally less than the width of the cloud base. They appear similar to stratocumulus but the elements are generally more detached and less wide at the base.

Species

; Cumulus fractus: Ragged shreds of cumulus clouds.
; Cumulus humilis: "Fair weather clouds" with flat light grey bases and small white domed tops.

Varieties

; Opacity-based varieties: None.
; Humilis pattern-based variety:

Supplementary features and accessory clouds

Not commonly seen with cumulus fractus or humilis.
; Genitus mother clouds
; Mutatus mother clouds
;; Cumulus cataractagenitus: Generated by the spray from waterfalls.

Genus stratus

Abbreviation: St
Clouds of the genus stratus form in low horizontal layers having a ragged or uniform base. Ragged stratus often forms in precipitation while more uniform stratus forms in maritime or other moist stable air mass conditions. The latter often produces drizzle. Stratus that touches the Earth's surface is given the common name, fog, rather than a Latin name that applies only to clouds that form and remain aloft in the troposphere.

Species

; Stratus nebulosus: Uniform fog-like low cloud.
; Stratus fractus: Ragged shreds of stratus clouds usually under base of precipitation clouds.

Varieties

; Nebulosus opacity-based varieties:
; Pattern-based variety undulatus: Wavy undulating base.
; Varieties are not commonly associated with St species fractus.

Supplementary features

; Precipitation-based supplementary feature:
; Accessory clouds: Not usually seen with stratus.
; Genitus mother clouds and other mother sources:
; Mutatus mother cloud:

Tropospheric cloud types with Latin etymologies where applicable

Cloud types are sorted in alphabetical order except where noted.

WMO genera

; Altocumulus : Latin for "high heap": Applied to mid-level stratocumuliform.
; Altostratus : "High sheet": Applied to mid-level stratiform.
; Cirrocumulus : "Hair-like heap": Applied to high-level stratocumuliform.
; Cirrostratus : "Hair-like sheet": Applied to high-level stratiform.
; Cirrus: "Hair-like": Applied to high-level cirriform.
; Cumulonimbus : "Precipitation-bearing heap": Applied to vertical/multi-level cumulonimbiform.
; Cumulus: "Heap": Applied to low-level and vertical/multi-level cumuliform.
; Nimbostratus : "Precipitation-bearing sheet": Applied to multi-level stratiform with vertical extent that produces precipitation of significant intensity.
; Stratocumulus : "Sheet-like heap": Applied to low-level stratocumuliform.
; Stratus: "Sheet": Applied to low-level mostly shallow stratiform.

WMO species

; Castellanus : Latin for "castle-like": Applies to stratocumuliform and dense cirriform with a series of turret shapes – indicates air mass instability.
; Congestus : Latin for "congested": Applies to cumuliform with great vertical development and heaped into cauliflower shapes – indicates considerable air mass instability and strong upcurrents.
; Fibratus : "Fibrous": Cirriform or high stratiform in the form of filaments, can be straight or slightly curved; indicates strong, continuous upper winds.
; Floccus : "Tufted": Applies to stratocumuliform and high cirriform ; indicates some mid or high-level instability.
; Fractus : "Broken": Low stratiform or cumuliform with an irregular shredded appearance – forms in precipitation and/or gusty winds.
; Humilis : "Small": Applies to cumuliform with little vertical extent; indicates relatively slight air mass instability.
; Lenticularis : "Lens–like": Stratocumuliform having a lens-like appearance – formed by standing waves of wind passing over mountains or hills.
; Mediocris : "Medium-size": Cumuliform with moderate vertical extent; indicates moderate instability and upcurrents.
; Nebulosus : "Nebulous": Indistinct low and high stratiform without features; indicates light wind if any and stable air mass.
; Spissatus : "Dense": Thick cirriform with a grey appearance; indicates some upward movement of air in the upper troposphere.
; Stratiformis : "Sheet-like": Horizontal cloud sheet of flattened stratocumuliform ; indicates very slight air mass instability.
; Uncinus : "Hook-like": Cirriform with a hook shape at the top; indicates a nearby backside of a weather system.
; Volutus : "Rolled": Elongated, low or mid-level, tube shaped, stratocumuliform.
The division of genus types into species is as shown in the following table. The genus types are arranged from top to bottom in the left column in approximate descending order of average overall altitude range. The species are sorted from left to right in approximate ascending order of instability or vertical extent of the forms to which each belongs:

Stratiform species,
Cirriform species,
Stratocumuliform species,
Cumuliform species,
Cumulonimbiform species.

These ordinal instability numbers appear in each box where a particular genus has a particular species.

Level

Species

Abbrev.

Neb

Fib

Unc

Spi

Str

Len

Vol

Flo

Cas

Fra

Hum

Med

Con

Cal

Cap

Level

Genus
name

Species
name L-R

Nebulosus

Fibratus

Uncinus

Spissatus

Stratiformis

Lenticularis

Volutus

Floccus

Castellanus

Fractus

Humilis

Mediocris

Congestus

Calvus

Capillatus

High

Cirrus

High

Cirrocumulus

High

Cirrostratus

Middle

Altocumulus

Middle

Altostratus

Towering
vertical

Cumulonimbus

Towering
vertical

Cumulus
congestus

Cu con
or Tcu

Moderate
vertical

Nimbostratus

Moderate
vertical

Cumulus
mediocris

Cu med

Low

Stratocumulus

Low

Cumulus
humilis

Cu hum

Low

Stratus

WMO varieties

; Opacity-based:
; Pattern-based:
The following table shows the cloud varieties arranged across the top of the chart from left to right in approximate descending order of frequency of appearance. The genus types and some sub-types associated with each variety are sorted in the left column from top to bottom in approximate descending order of average overall altitude range. Where applicable, the genera and varieties are cross-classified to show the species normally associated with each combination of genus and variety. The exceptions comprise the following: Altostratus that have varieties but no species so the applicable boxes are marked without specific species names; cumulus congestus, a species that has its own altitude characteristic but no varieties; cumulonimbus that have species but no varieties, and nimbostratus that has no species or varieties. The boxes for genus and species combinations that have no varieties are left blank.

Level	Name	Abbrev.	Tra	Per	Opa	Dup	Und	Rad	Lac	Int	Ver
Level	Name	Abbrev.	Translucidus	Perlucidus	Opacus	Duplicatus	Undulatus	Radiatus	Lacunosus	Intortus	Vertebratus
High	Cirrus	Ci				Fib Unc		Fib Unc		Fib	Fib
High	Cirrocumulus	Cc					Str Len		Str, Cas Flo
High	Cirrostratus	Cs				Fib	Fib
Middle	Altocumulus	Ac	Str	Str	Str	Str Len	Str Len	Str	Str, Cas Flo
Middle	Altostratus	As	+		+	+	+	+
Towering vertical	Cumulonimbus	Cb
Towering vertical	Cumulus congestus	Cu con or Tcu
Moderate vertical	Nimbostratus	Ns
Moderate vertical	Cumulus mediocris	Cu med						Med
Low	Stratocumulus	Sc	Str	Str	Str	Str Len	Str Len	Str	Str, Cas Flo
Low	Cumulus humilis	Cu hum						Hum
Low	Stratus	St	Neb		Neb		Neb

WMO supplementary features

; Precipitation-based supplementary features:
; Cloud-based supplementary features:
; Accessory clouds:
The supplementary features are associated with particular genera as follows. They are sorted from left to right in approximate decreasing order of frequency of occurrence for each of three categories. The genus types and some sub-types are arranged from top to bottom in approximate descending order of average overall altitude range. Each box is marked where a particular genus or sub-type has a particular supplementary feature.

Genitus mother clouds

; Altocumulogenitus: Formed by the partial transformation of altocumulus mother cloud.
; Altostratogenitus: Formed by the partial transformation of altostratus.
; Cirrogenitus: Partial transformation of cirrus.
; Cirrocumulogenitus: Partial transformation of cirrocumulus.
; Cirrostratogenitus: Partial transformation of cirrostratus.
; Cumulogenitus: Spreading out or partial transformation of cumulus.
; Cumulonimbogenitus: Spreading out or partial transformation of cumulonimbus.
; Nimbostratogenitus: Partial transformation of nimbostratus.
; Stratogenitus: Partial transformation of stratus.
; Stratocumulogenitus: Partial transformation of stratocumulus.

Other genitus clouds

; Cataractagenitus : Formed from the mist at a waterfall, the downdraft caused from the cloud is counteracted by the ascending air displacement from the waterfall and may go on to form other types of clouds such as cumulus cataractagenitus.
; Flammagenitus : Formed by convection associated with large wildfires.
; Homogenitus : Formed as a result of human activities, particularly aircraft at high altitudes and heat-generating industrial activities at surface level. If a homogenitus cloud of one genus changes to another genus type, it is then termed a homomutatus cloud.
; Silvagenitus : Formed by low-level condensation of water vapor released by vegetation, especially forest canopies.

Mutatus mother clouds

Nomenclature works the same way as for genitus mother clouds except for the mutatus suffix to indicate the complete rather than the partial transformation of the original cloud type. e.g. Altocumulomutatus – formed by the complete transformation of altocumulus mother cloud.
The possible combinations of genera and mother clouds can be seen in this table. The genitus and mutatus clouds are each sorted from left to right in alphabetical order. The genus types and some sub-types are arranged from top to bottom in approximate descending order of average overall altitude range. Each box is marked where a particular genus or sub-type has a particular genitus or mutatus mother cloud.

Informal terms recently accepted for WMO classification with Latin nomenclature

; Aviaticus cloud: Persistent condensation trails formed by ice crystals originating from water vapor emitted by aircraft engines. Usually resembles cirrus; recognized as a WMO genitus cloud cirrus homogenitus. Further transformation into cirrus, cirrocumulus, or cirrostratus homomutatus is possible depending on atmospheric stability and wind shear.
; Fallstreak hole: Supercooled altocumulus or cirrocumulus distinguished by a hole with ragged edges and virga or wisps of cirrus. Accepted as a WMO supplementary feature to be named cavum.
; Kelvin–Helmholtz cloud: Crested wave-like clouds formed by wind-shear instability that may occur at any altitude in the troposphere. Accepted as a WMO supplementary feature with the Latin name fluctus.
; Pyrocumulus and Pyrocumulonimbus: Cumulus and cumulonimbus clouds formed by quickly generated ground heat; including forest fires, volcanic eruptions and low level nuclear detonation. Accepted as a WMO genitus cloud with the Latin name flammagenitus, or homogenitus in the case of small cumulus formed by contained human activity.
; Roll cloud: Elongated, low-level, tube shaped, horizontal formation not associated with a parent cloud. Accepted as a WMO stratocumulus or altocumulus species with the Latin name volutus.

WMO and informal terms related to free-convective cloud types and storms

Accessory cloud – secondary cloud that is associated with but separate from a main cloud.
Anvil – the anvil top of a cumulonimbus cloud.
Anvil dome – the overshooting top on a Cb that is often present on a supercell.
Anvil rollover – circular protrusion attached to underside of anvil.
Arcus cloud – arch or a bow shape, attached to cumulus, thick with ragged edges.
Backsheared anvil – anvil that spreads upwind, indicative of extreme weather.
Clear slot or dry slot – an evaporation of clouds as a rear flank downdraft descends and dries out cloud and occludes around a mesocyclone.
Cloud tags – ragged detached portions of cloud.
Collar cloud – ring shape surrounding upper part of wall cloud.
Condensation funnel – the cloud of a funnel cloud aloft or a tornado.
Altocumulus castellanus – castle crenellation-shaped altocumulus clouds.
Cumulus – heaped clouds.
Cumulus castellanus – cumulus with tops shaped like castle crenellations.
Cumulus congestus – considerable vertical development and heaped into cauliflower shapes.
Cumulus fractus – ragged detached portions of cumulus cloud.
Cumulus humilis – small, low, flattened cumulus, early development.
Cumulus mediocris – medium-sized cumulus with bulges at the top.
Cumulus pileus – capped, hood-shaped cumulus cloud.
Cumulus praecipitatio – cumulus whose precipitation reaches the ground.
Cumulus radiatus – cumulus arranged in parallel lines that appear to converge near the horizon.
Cumulus tuba – column hanging from the bottom of cumulus.
Cumulonimbus – heaped towering rain-bearing clouds that stretch to the upper levels of the troposphere.
Cumulonimbus calvus – cumulonimbus with round tops like cumulus congestus.
Cumulonimbus capillatus – Cb with cirriform top.
Cumulonimbus incus – Cb capillatus with anvil top.
Cumulonimbus mamma – Cb with pouch-like protrusions that hang from under anvil or cloud base.
Cumulonimbus pannus – shredded sections attached to main Cb cloud.
Cumulonimbus pileus – capped, hood-shaped cloud above a cumulonimbus cloud.
Cumulonimbus praecipitatio – Cb whose precipitation reaches the ground.
Cumulonimbus tuba – column hanging from the bottom of cumulonimbus.
Debris cloud – rotating "cloud" of debris or dust, often surrounding the base of a tornado, beneath a condensation funnel.
Funnel cloud – rotating funnel of cloud hanging from under Cb, not making contact with ground.
Hail fog – a shallow surface layer of fog that sometimes forms in vicinity of deep hail accumulation, can be very dense.
Hot tower – a tropical cumulonimbus cloud that penetrates the tropopause.
Inflow band – a laminar band marking inflow to a Cb, can occur at lower or mid levels of the cloud.
Inverted cumulus – cumulus which has transferred momentum from an exceptionally intense Cb tower and is convectively growing on the underside of an anvil.
Knuckles – lumpy protrusion that hangs from edge or underside of anvil.
Marine layer
Overcast
Pyrocumulus and Pyrocumulonimbus– intense ground-heat cloud proposed for WMO classification.
Rope – narrow, sometimes twisted funnel type cloud seen after a tornado dissipates.
Rope cloud – A narrow, long, elongated line of cumulus clouds that sometimes develop at the leading edge of an advancing cold front that is often visible in satellite imagery.
Scud cloud – ragged detached portions of cloud that usually form in precipitation.
Sea of clouds
Shelf cloud – wedge-shaped cloud often attached to the underside of Cb.
Stratus fractus – ragged detached portions of stratus cloud that usually form in precipitation.
Striations – a groove or band of clouds encircling an updraft tower, indicative of rotation.
Tail cloud – an area of condensation consisting of laminar band and cloud tags extending from a wall cloud towards a precipitation core.
Towering cumulus -aviation term for WMO genus and species cumulus congestus, a large cumulus cloud with great vertical development, usually with a cauliflower-like appearance, but lacking the characteristic anvil of a Cb.
Wall cloud – distinctive fairly large lowering of the rain-free base of a Cb, often rotating.

Other planets

Venus

Thick overcast clouds of sulfur dioxide and carbon dioxide in three main layers at altitudes of 45 to 65 km that obscure the planet's surface and can produce virga.
; Stratiform: Overcast opaque clouds sheets.
; Stratocumuliform: Wave clouds with clear gaps through which lower stratiform layers may be seen.
; Cumuliform and cumulonimbiform: Embedded convective cells that can produce lightning.

Mars

Clouds resembling several terrestrial types can be seen over Mars and are believed to be composed of water-ice.
; Extremely high cirriform: Noctilucent clouds are known to form near the poles at altitudes similar to or higher than the same type of clouds over Earth.
; High cirriform: Thin scattered wispy cloud resembling cirrus through which the planet's surface can be seen.
; High stratocumuliform: Thin scattered wave-cloud resembling cirrocumulus.
; Low stratocumuliform: Wave-cloud resembling stratocumulus, especially as a polar cap cloud over the winter pole which is mostly composed of suspended frozen carbon dioxide.
; Surface-based: Morning fog of water and/or carbon dioxide commonly forms in low areas of the planet.

Jupiter and Saturn

Cloud decks in parallel bands of latitude at and below the tropopause alternately composed of ammonia crystals and ammonium hydrosulfate.
; Cirriform: Bands of cloud resembling cirrus located mainly in the highest of three main layers that cover Jupiter.
; Stratiform and stratocumuliform: Wave and haze clouds that are seen mostly in the middle layer.
; Cumuliform and cumulonimbiform: Convective clouds in the lowest layer that are capable of producing thunderstorms and may be composed at least partly of water droplets. an intermediate deck of ammonium hydrosulfide, and an inner deck of cumulus water clouds.

Uranus and Neptune

Cloud layers composed mainly of methane gas.
; Cirriform: High wispy formations resembling cirrus.
; Stratiform: Layers of haze-cloud that lack any distinct features.
; Cumuliform and cumulonimbiform: Lower-based convective clouds that can produce thunderstorms.