List of cloud types

g
Tropospheric cloud classification by altitude of occurrence.

The list of cloud types is a summarisation of the modern systems of cloud classification used in the troposphere, stratosphere, and mesosphere. The ten basic genus-types in the troposphere have Latin names derived from 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 tufts, and cumulonimbiform towers that often have complex structure. The forms are cross-classified by altitude range or étage into high-level, middle, low, and multi-level. Some of the resultant genus types are common to more than one form or more than one level, as illustrated in the stratocumuliform and cumuliform columns of the classification table below. Most genera are divided into species, 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. Since 1890, clouds have been classified and illustrated in cloud atlases. Mesospheric and stratospheric clouds have their own classifications with common names for the major types and alpha-numeric nomenclature for the subtypes.

Cloud classification: Order of listed types

In section two of this page (Classification of major types), height ranges are sorted in approximate descending order of altitude expressed in general terms. Within the troposphere, forms and genus types (including some genus sub-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:


In section six, the cloud types in the general lists and the mother clouds in the applicable classification table are sorted in alphabetical order. 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 our solar system and beyond. The planets with clouds are listed (not numbered) in order of their distance from the sun, and the clouds on each planet are in approximate descending order of altitude.

Classification of major types

Level/Form (1) Stratiform(2) Cirriform(3) Stratocumuliform(4) Cumuliform(5) Cumulonimbiform
Extreme level Noctilucent
Very high level Nacreous
High-level CirrostratusCirrusLayered CirrocumulusTufted Cirrocumulus
Mid-level Altostratus Layered AltocumulusTufted Altocumulus
Towering vertical Towering CumulusCumulonimbus
Vertical/multi-level Nimbostratus Moderate Cumulus
Low-level Stratus StratocumulusSmall Cumulus

Polar mesospheric classification

Clouds that form above the mesosphere have a generally cirriform structure, but are not given Latin names based on that characteristic. Polar mesospheric clouds are the highest in the atmosphere and are given the Latin name noctilucent which refers to their illumination during deep twilight. They are sub-classified alpha-numerically according to specific details of their cirriform physical structure.

Extremely high cirriform

Noctilucent cloud over Estonia

Noctilucent clouds are thin, mostly cirriform-looking clouds, based from about 264,000 to 280,000 feet (80–85 km) and occasionally seen in deep twilight after sunset and before sunrise.[1][2]

Type 1 
Very tenuous; resembles cirrus.
Type 2 
Bands. Long streaks, often in parallel groups or interwoven at small angles.
Subtypes
2A 
Streaks with diffuse, blurred edges.
2B 
Streaks with sharply defined edges.
Type 3
Billows. Clearly spaced, roughly parallel short streaks.
Subtypes
3A 
Short, straight, narrow streaks.
3B 
Wave-like structures with undulations.
Type 4 
Whirls. Partial (or, more rarely, complete) rings with dark centers.
Subtypes
4A 
Whirls possessing a small angular radius of curvature, sometimes resembling light ripples on a water surface.
4B 
Simple curve of medium angular radius with one or more bands.
4C 
Whirls with large-scale ring structures.

Polar stratospheric 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.[3] Both these and non-nacreous types are classified alpha-numerically according to their physical state and chemical makeup.

Very high cirriform

Nacreous (mother of pearl) and non-nacreous

Stratospheric nacreous clouds over Antarctica

A thin usually cirriform-looking cloud based from about 60,000 to 100,000 feet (18–30 km) and seen most often between sunset and sunrise.[3]

Type 1 (non-nacreous) 
Contains supercooled nitric acid and water droplets.
Subtypes
1A 
Crystals of nitric acid and water.
1B 
Additionally contains supercooled sulfuric acid in ternary solution.
Type 2 (nacreous) 
Consists of ice crystals only.

Columnar clouds – rare, column-shaped.

Tropospheric classification

Tropospheric clouds are divided into physical forms defined by structure, and étages 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 (WMO) that indicate physical structure, altitude or étage, and process of formation

High étage cirriform, stratocumuliform, cumuliform, and stratiform

High clouds form in the highest and coldest region of the troposphere from about 16,500 to 40,000 ft (5 to 12 km) in temperate latitudes.[4][5] At this altitude water almost always freezes so high clouds are generally composed of ice crystals or supercooled water droplets.

Genus cirrus

Cirrus uncinus clouds (2)
Cirrus spissatus (3) clouds
Cirrus fibratus radiatus (8)

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
Opacity-based varieties
  • None; always translucent except species spissatus which is inherently opaque.[7]
Fibratus pattern-based varieties
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.
  • Varieties are not commonly associated with Ci species spissatus, castellanus, or floccus.[6][7]
Precipitation-based supplementary features
  • Not associated with cirrus.
Cloud-based supplementary feature
  • Mamma
    Bubble-like downward protuberances; mostly seen with species castellanus.[8]
Genitus mother clouds
  • Cirrus cirrocumulogenitus
  • Cirrus altocumulogenitus
  • Cirrus cumulonimbogenitus
Mutatus mother cloud
  • Cirrus cirrostratomutatus

Genus cirrocumulus

A A large field of cirrocumulus clouds in a blue sky, beginning to merge near the upper left.
A large field of cirrocumulus stratiformis (V-12)

Abbreviation: Cc.[4]

High stratocumuliform and cumuliform 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. However, tufted cirrocumulus with its detached heaps fall more within the cumuliform category.[9]

High stratocumuliform species
Opacity-based varieties
  • None (always translucent)
Stratocumuliform pattern-based variety undulatus
Cirrocumulus with an undulating base; normally associated with stratiformis and lenticularis species.
Pattern-based variety lacunosus
Cirrocumulus with large clear holes; normally associated with stratiformis and castellanus species (also with cumuliform floccus species).
Stratocumuliform lacunosus
High cumuliform species
Opacity-based varieties
  • None (always translucent)[7]
Cumuliform lacunosus
  • Cirrocumulus floccus lacunosus [7] (V-20)
Precipitation-based supplementary feature
  • Virga
    Light precipitation that evaporates well above ground level; mostly seen with species stratiformis, castellanus, and floccus.[8]
Cloud-based supplementary feature
  • Mamma
    Bubble-like downward protuberances; mostly seen with species castellanus.
Genitus mother clouds
  • None associated with cirrocumulus.
Mutatus mother clouds
  • Cirrocumulus cirromutatus
  • Cirrocumulus cirrostratomutatus
  • Cirrocumulus altocumulomutatus

Genus cirrostratus

Cirrostratus nebulosus (V-22) merging into darker altostratus translucidus (V-47)

Abbreviation: Cs[4]

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.[11] 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
Opacity-based varieties
  • None (always translucent)[7]
Fibratus pattern-based varieties
  • Cirrostratus fibratus duplicatus[7] (V-23)
    Separate or semi-merged sheets with one layer slightly above the other.
  • Cirrostratus fibratus undulatus[7] (V-24)
    Undulating waves.
Varieties are not commonly associated with Cs species nebulosus.[7]
Supplementary features/accessory clouds
  • Not associated with cirrostratus.[8]
Genitus mother clouds
  • Cirrostratus cirrocumulogenitus
  • Cirrostratus cumulonimbogenitus
Mutatus mother clouds
  • Cirrostratus cirromutatus
  • Cirrostratus cirrocumulomutatus
  • Cirrostratus altostratomutatus.

Middle étage stratocumuliform, cumuliform, and stratiform

Middle cloud forms from 6,500 to about 23,000 ft (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.[5]

Genus altocumulus

Altocumulus castellanus (V-26)
Altocumulus floccus (V-27)
Altocumulus lenticularis duplicatus (V-37)
Altocumulus stratiformis translucidus undulatus (V-39)
Altocumulus stratiformis perlucidus undulatus (V-39) clouds merging into altostratus opacus (48), with higher layer of cirrus fibratus (V-1)
Fallstreak hole -altocumulus stratiformis translucidus lacunosus (V-42)

Abbreviation: Ac[4]

Mid-level stratocumuliform and cumuliform 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. Tufted altocumulus has a little more instability, and its detached heaps have a distinct cumuliform structure.

Mid-level stratocumuliform species
Stratocumuliform opacity-based varieties
  • Altocumulus stratiformis translucidus (V-27)
    Translucent altocumulus through which the sun or moon can be seen.
  • Altocumulus stratiformis perlucidus (V-28)
    Opaque middle clouds with translucent breaks.
  • Altocumulus stratiformis opacus (V-29)
    Opaque altocumulus that obscures the sun or moon.[7]
Stratocumuliform pattern-based variety radiatus
Rows of altocumulus that appear to converge at the horizon; normally associated with stratiformis species.
  • Altocumulus stratiformis translucidus radiatus (V-30)
  • Altocumulus stratiformis perlucidus radiatus (V-31)
  • Altocumulus stratiformis opacus radiatus (V-32)
Stratocumuliform pattern-based variety duplicatus
Altocumulus in closely spaced layers, one above the other; normally associated with stratiformis and lenticularis species.
  • Altocumulus stratiformis translucidus duplicatus (V-33)
  • Altocumulus stratiformis perlucidus duplicatus (V-34)
  • Altocumulus stratiformis opacus duplicatus (V-35)
  • Altocumulus lenticularis duplicatus (V-36)
Stratocumuliform pattern-based variety undulatus
Altocumulus with wavy undulating base; normally associated with stratiformis and lenticularis species.[7]
Pattern-based variety lacunosus
Altocumulus with circular holes caused by localized downdrafts; normally associated with stratiformis and castellanus species (also with cumuliform floccus species).[7]
Stratocumuliform lacunosus
  • Altocumulus stratiformis translucidus lacunosus (V-41)
  • Altocumulus stratiformis perlucidus lacunosus (V-42)
  • Altocumulus stratiformis opacus lacunosus (V-43)
  • Altocumulus castellanus lacunosus (V-44)
Mid-level cumuliform species
Cumuliform lacunosus
  • Altocumulus floccus lacunosus [6] (V-46)
Precipitation-based supplementary feature
  • Virga
    Altocumulus producing precipitation that evaporates before reaching the ground; usually associated with species stratiformis, castellanus, and floccus.
Cloud-based supplementary feature
  • Mamma
    Altocumulus (usually species castellanus) with downward facing bubble-like protuberances caused by localized downdrafts within the cloud.[8]
Genitus mother clouds
  • Altocumulus cumulogenitus
  • Altocumulus cumulonimbogenitus
Mutatus mother clouds
  • Altocumulus cirrocumulomutatus
  • Altocumulus altostratomutatus
  • Altocumulus nimbostratomutatus
  • Altocumulus stratocumulomutatus

Genus altostratus

Altostratus translucidus (V-47) near top of photo merging into altostratus opacus (48) near bottom

Abbreviation: As[4]

Stratiform clouds of the genus altostratus form when a large convectively stable airmass is lifted to condensation in the middle étage 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
Opacity-based varieties
  • Altostratus translucidus (V-47)
    Altostratus through which the sun can be seen.
  • Altostratus opacus (V-48)
    Altostratus that completely blocks out the sun.[7]
Pattern-based variety radiatus
Bands that appear to converge at the horizon.
  • Altostratus translucidus radiatus (V-49)
  • Altostratus opacus radiatus (V-50)
Pattern-based variety duplicatus
Altostratus in closely spaced layers, one above the other.
  • Altostratus translucidus duplicatus (V-51)
  • Altostratus opacus duplicatus (V-52)
Pattern-based variety undulatus
Altostratus with wavy undulating base.
Precipitation-based supplementary features
  • Virga
    Accompanied by precipitation that evaporates before reaching the ground. Seen mostly with opacus varieties.
  • Praecipitatio
    Produces precipitation that reaches the ground; associated with opacus varieties.[8]
Cloud-based supplementary feature
  • Mamma
    Altostratus with downward facing bubble-like protuberances caused by localized downdrafts within the cloud.
Accessory cloud
Seen mostly with opacus varieties
  • Pannus
    Accompanied by ragged lower layer of fractus species clouds forming in precipitation.[8]
Genitus mother clouds
  • Altostratus altocumulogenitus
  • Altostratus cumulonimbogenitus
Mutatus mother clouds
  • Altostratus cirrostratomutatus
  • Altostratus nimbostratomutatus

Vertical or multi-étage cumulonimbiform, cumuliform, and stratiform (low to middle cloud base)

Clouds with upward-growing vertical development usually form below 6,500 feet (2.0 km),[5] but can be based as high as 8,000 feet (2.4 km) in temperate climates, and often much higher in arid regions. Downward-growing cloud forms mostly above 6,500 feet (2.0 km) and achieves vertical extent as the base subsides into the low altitude range during precipitation.

Genus cumulonimbus: Towering vertical

Cumulonimbus calvus (V-55)
Single-cell Cumulonimbus capillatus (V-56) incus

Abbreviation: Cb[4]

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 airmass is convectively highly unstable. They generally produce thunderstorms, rain or showers, and sometimes hail, strong outflow winds, and/or tornadoes at ground level.

Species

Varieties
  • No varieties (always opaque and does not form in patterns visible from surface level).[6][7]
Precipitation-based supplementary features
Associated with calvus and capillatus species.
  • Virga
    Precipitation that evaporates before reaching the ground.
  • Praecipitatio
    Precipitation that reaches the ground.[8]
Cloud-based supplementary features
  • Incus (species capillatus only)
    Cumulonimbus with flat anvil-like cirriform top caused by wind shear where the rising air currents hit the inversion layer at the tropopause.[8][12]
  • Mamma
    Also sometimes called Mammatus, consisting of bubble-like protrusions on the underside caused by localized downdrafts.
  • Arcus (including roll and shelf clouds)
    Low, horizontal cloud formation associated with the leading edge of thunderstorm outflow.
  • Tuba
    Column hanging from the cloud base which can develop into a funnel cloud or tornado.[8]
Accessory clouds
Seen with species and capillatus except where noted.
  • Pannus
    Accompanied by a lower layer of fractus species cloud forming in precipitation.
  • Pileus (species calvus only)
    Small cap-like cloud over parent cumulonimbus.
  • Velum
    A thin horizontal sheet that forms around the middle of a cumulonimbus.[8]
Genitus mother clouds
  • Cumulonimbus altocumulogenitus
  • Cumulonimbus altostratogenitus
  • Cumulonimbus nimbostratogenitus
  • Cumulonimbus stratocumulogenitus
  • Cumulonimbus cumulogenitus
Mutatus mother cloud
  • Cumulonimbus cumulomutatus

Genus cumulus: Towering vertical

Cumulus congestus (V-57)

Abbreviations: Cu con (cumulus congestus) or Tcu (towering cumulus)[13]

Species

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 (ICAO) designates this species as towering cumulus (Tcu).
Opacity-based varieties
  • None (always opaque).
Pattern-based variety
  • None (not generally discerned with highly unstable cumulus congestus).
Precipitation-based supplementary features
  • Virga
    Accompanied by precipitation that evaporates before reaching the ground.
  • Praecipitatio
    Produces precipitation that reaches the ground.[8]
Cloud-based supplementary features
  • Mamma
    Downward facing bubble-like protuberances caused by localized downdrafts within the cloud.
  • Arcus (including roll and shelf clouds)
    Low horizontal cloud formation associated with the leading edge of a thunderstorm outflow.
  • Tuba
    Column hanging from the cloud base which can develop into a small funnel cloud.[8]
Accessory clouds
  • Pannus
    Accompanied by a lower layer of fractus species cloud forming in precipitation.
  • Pileus
    Small cap-like cloud over parent cumulus cloud.
  • Velum
    A thin horizontal sheet that forms around the middle of a cumulus cloud.[8]
Mother clouds
  • Genitus and mutatus types are the same as for small and moderate cumulus.

Genus nimbostratus: Moderate or deep vertical

Nimbostratus virga

Abbreviation: Ns[4] (V-58)

Clouds of the genus nimbostratus tend to bring constant precipitation and low visibility. This cloud type normally forms above 6,500 feet (2.0 km)[5] 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
Varieties
  • No varieties (always opaque and never forms in patterns).[6][7]
Precipitation-based supplementary features
  • Virga
    Accompanied by precipitation that evaporates before reaching the ground.
  • Praecipitatio
    Produces precipitation that reaches the ground.[8]
Accessory cloud
  • Pannus
    Nimbostratus with lower layer of fractus species cloud forming in precipitation.[8]
Genitus mother clouds
  • Nimbostratus cumulogenitus
  • Nimbostratus cumulonimbogenitus
Mutatus mother clouds
  • Nimbostratus altostratomutatus
  • Nimbostratus altocumulomutatus
  • Nimbostratus stratocumulomutatus

Genus cumulus: Moderate vertical

Cumulus mediocris (V-56) from above
Cumulus mediocris (V-56) pileus
Cumulus mediocris (V-56) arcus

Abbreviation: Cu[4]

Moderate vertical cumulus is the product of free convective airmass instability. Continued upward growth suggests showers later in the day.

Species
Moderate vertical clouds with flat medium grey bases and higher tops than cumulus humilis.[6]
Opacity-based varieties
  • None (always opaque)
Pattern-based variety
  • Cumulus mediocris radiatus [14](V-60)
    Moderate cumulus clouds arranged in parallel lines that appear to converge at the horizon.[6][7]
Precipitation-based supplementary features
  • Virga
    Accompanied by precipitation that evaporates before reaching the ground.
  • Praecipitatio
    Produces precipitation that reaches the ground.[8]
Cloud-based supplementary feature
  • Mamma
    Downward facing bubble-like protuberances caused by localized downdrafts within the cloud.[8]
Accessory clouds
  • Pileus
    Small cap-like cloud over parent cumulus cloud.[8]
  • Velum
    A thin horizontal sheet that forms around the middle of a cumulus cloud.
Mother clouds
  • Genitus and mutatus types are the same as for cumulus of little vertical extent.

Low étage stratocumuliform, cumuliform, and stratiform

Low cloud forms from near surface to ca. 6,500 feet (2.0 km) and are generally composed of water droplets.[5]

Genus stratocumulus

Stratocumulus castellanus (V-62)

Abbreviation: Sc[4]

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

Species
Stratocumuliform opacity-based varieties
  • Stratocumulus stratiformis translucidus (V-63)
    Thin translucent stratocumulus through which the sun or moon can be seen.
  • Stratocumulus stratiformis perlucidus (V-64)
    Opaque low clouds with translucent breaks.
  • Stratocumulus stratiformis opacus (V-65)
    Opaque stratocumulus clouds.[7]
Pattern-based variety radiatus
Stratocumulus arranged in parallel bands that appear to converge on the horizon; normally associated with stratiformis species..
  • Stratocumulus stratiformis translucidus radiatus (V-66)
  • Stratocumulus stratiformis perlucidus radiatus (V-67)
  • Stratocumulus stratiformis opacus radiatus (V-68)
Pattern-based variety duplicatus
Closely spaced layers of stratocumulus, one above the other; normally associated with stratiformis and lenticularis species.
  • Stratocumulus stratiformis translucidus duplicatus (V-69)
  • Stratocumulus stratiformis perlucidus duplicatus (V-70)
  • Stratocumulus stratiformis opacus duplicatus (V-71)
  • Stratocumulus lenticularis duplicatus (V-72)
Pattern-based variety undulatus
Stratocumulus with wavy undulating base; normally associated with stratiformis and lenticularis species.[7]
  • Stratocumulus stratiformis translucidus undulatus (V-73)
  • Stratocumulus stratiformis perlucidus undulatus (V-74)
  • Stratocumulus stratiformis opacus undulatus (V-75)
  • Stratocumulus lenticularis undulatus (V-76)
Pattern-based variety lacunosus
Sc with circular holes caused by localized downdrafts; normally associated with stratiformis and castellanus species.
  • Stratocumulus stratiformis translucidus lacunosus (V-77)
  • Stratocumulus stratiformis perlucidus lacunosus (V-78)
  • Stratocumulus stratiformis opacus lacunosus (V-79)
  • Stratocumulus castellanus lacunosus[6] (V-80)
Precipitation-based supplementary features
Usually associated with species stratiformis and castellanus:
  • Virga
    Low cloud producing precipitation that evaporates before reaching the ground.
  • Praecipitatio
    Stratocumulus clouds producing precipitation that reaches the ground.[8]
Cloud-based supplementary feature
  • Mamma
    Stratocumulus with bubble-like protrusions on the underside; usually associated with species castellanus.[8]
Stratocumulus cumulogenitus with higher layer of altocumulus stratiformis
Genitus mother clouds
  • Stratocumulus cumulogenitus
  • Stratocumulus nimbostratogenitus
  • Stratocumulus cumulonimbogenitus
  • Stratocumulus altostratogenitus
Mutatus mother clouds
  • Stratocumulus nimbostratomutatus
  • Stratocumulus altocumulomutatus
  • Stratocumulus stratomutatus

Genus cumulus (little vertical extent)

Cumulus humilis (V-82)

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
Opacity-based varieties
  • None (always opaque except species fractus which is always translucent).[7]
Humilis pattern-based variety
  • Cumulus humilis radiatus (V-83)
    Small cumulus clouds arranged in parallel lines that appear to converge at the horizon.[15]
Supplementary features/accessory clouds
  • Not commonly seen with cumulus fractus or humilis.[8]
Genitus mother clouds
  • Cumulus stratocumulogenitus
Mutatus mother clouds
  • Cumulus stratocumulomutatus
  • Cumulus stratomutatus

Genus stratus

At level with stratus nebulosus (V-81) clouds
Stratus fractus (V-84) cloud

Abbreviation: St[4]

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.

Species
Nebulosus opacity-based varieties
  • Stratus nebulosus translucidus (V-85)
    Thin translucent stratus.
  • Stratus nebulosus opacus (V-86)
    Opaque stratus that obscures the sun or moon.[7]
Pattern-based variety undulatus
Wavy undulating base.
  • Stratus nebulosus translucidus undulatus (V-87)
  • Stratus nebulosus opacus undulatus (V-88)
  • Varieties are not commonly associated with St species fractus.[6][7]
Precipitation-based supplementary feature
  • Praecipitatio
    Stratus (usually species nebulosus) producing precipitation.[8]
Accessory clouds
  • Not usually seen with stratus.[8]
Genitus mother clouds
  • Stratus nimbostratogenitus
  • Stratus cumulogenitus
  • Stratus cumulonimbogenitus
Mutatus mother cloud
  • Stratus stratocumulomutatus

Alphabetical lists of tropospheric cloud types with Latin etymologies where applicable

WMO genera

Nimbus and Altus, not genera but used in combination, are Latin for "raincloud" and "high" respectively.

WMO species

The division of genus types into species is as shown in the following table. The species are sorted from left to right in approximate ascending order of instability or vertical extent. The genus types are arranged from top to bottom in the same ascending order for each étage. (1)=Stratiform types, (2)=Cirriform types, (3)=Stratocumuliform types, (4)=Cumuliform types, (5)=Cumulonimbiform types.

Species (L-R) Abbrev. (1) Neb (1) Fib (1,2) Unc (2) Spi (2) Str (3) Len (3) Cas (2,3) Flo (2,4) Fra (1,4) Hum (4) Med (4) Con (4) Cal (5) Cap (5)
Etage Genus
name
Species
name L-R
(no species) Nebulosus Fibratus Uncinus Spissatus Stratiformis Lenticularis Castellanus Floccus Fractus Humilis Mediocris Congestus Calvus Capillatus
High Cirrostratus (1) Cs + (1) + (1)
Cirrus (2) Ci + (2) + (2) + (2) + (2) + (2)
Cirrocumulus (3,4) Cc + (3) + (3) + (3) + (4)
Mid Altostratus (1) As + (1)
Altocumulus (3,4) Ac + (3) + (3) + (3) + (4)
Vert Nimbostratus-MV (1) Ns + (1)
Cumulus-MV (4) Cu + (4)
Cumulus-TV (4) Tcu + (4)
Cumulonimbus-TV (5) Cb + (5) + (5)
Low Stratus (1) St + (1) + (1)
Stratocumulus (3) Sc + (3) + (3) + (3)
Cumulus (4) Cu + (4) + (4)

Vert=Vertical or multi-étage, MV=Moderate or deep vertical, TV=Towering vertical.

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 associated with each variety are sorted from top to bottom in the left column 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 include altostratus that has varieties but no species, towering cumulus and cumulonimbus that have species but no varieties, and nimbostratus has no species or varieties.

Abbrev. Tra Per Opa Dup Und Rad Lac Int Ver
Etage Name Abbrev. Translucidus Perlucidus Opacus Duplicatus Undulatus Radiatus Lacunosus Intortus Vertebratus
High Cirrus Ci + Fib
+ Unc
+ Fib
+ Unc
+ Fib + Fib
Cirrocumulus Cc + Str
+ Len
+ Str + Cas
+ Flo
Cirrostratus Cs + Fib + Fib
Mid Altocumulus Ac + Str + Str + Str + Str
+ Len
+ Str
+ Len
+ Str + Str + Cas
+ Flo
Altostratus As + + + + +
Vert Cumulonimbus (TV) Cb
Cumulus (TV) Tcu
Nimbostratus (MV) Ns
Cumulus (MV) Cu + Med
Low Stratocumulus Sc + Str + Str + Str + Str
+ Len
+ Str
+ Len
+Str +Str
+ Cas
Cumulus Cu + Hum
Stratus St + Neb + Neb + Neb

WMO supplementary features

A translucent wave cloud -altocumulus lenticularis

Precipitation-based supplementary features

Cloud-based supplementary features

Mammatus over Squaw Valley

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 (including some cumulus sub-types) are arranged from top to bottom in approximate descending order of average overall altitude range.

Class Precipitation-based Cloud-based Accessory cloud
Etage Name Abbrev. Virga Praecipitatio Incus Mamma Arcus Tuba Pannus Pileus Velum
High Cirrus Ci +
Cirrocumulus Cc + +
Cirrostratus Cs
Mid Altocumulus Ac + +
Altostratus As + + + +
Vert Cumulonimbus (TV) Cb + + + + + + + + +
Cumulus (TV) Tcu + + + + + + +
Nimbostratus (MV) Ns + + +
Cumulus (MV) Cu + + + + +
Low Stratocumulus Sc + + +
Cumulus Cu +
Stratus St

Mother clouds

and so on....

Mutatus mother cloud

and so on...

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 (including some cumulus sub-types) are arranged from top to bottom in the left column in approximate descending order of average overall altitude range.

Class Genitus mother Mutatus mother
Abbrev. Ac As Ci Cc Cs Cu Cb Ns St Sc Ac As Ci Cc Cs Cu Cb Ns St Sc
Etage Name Abbrev. altocumulo altostrato cirro cirrocumulo cirrostrato cumulo cumulonimbo nimbostrato strato stratocumulo altocumulo altostrato cirro cirrocumulo cirrostrato cumulo cumulonimbo nimbostrato strato stratocumulo
High Cirrus Ci + + + +
Cirrocumulus Cc + + +
Cirrostratus Cs + + + + +
Mid Altocumulus Ac + + + + + +
Altostratus As + + + +
Vert Cumulonimbus (TV) Cb + + + + + +
Cumulus (TV) Tcu
Nimbostratus (MV) Ns + + + + +
Cumulus (MV) Cu + + + +
Low Stratocumulus Sc + + + + + + +
Cumulus Cu + + + +
Stratus St + + + +

Informal terms officially proposed for WMO classification

Roll cloud over Wisconsin

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

Other planets

Venus

Thick overcast clouds of sulfur dioxide in three main layers at altitudes of 45 to 65 km that obscure the planet's surface and can produce virga.[18]

Stratiform

Overcast opaque clouds sheets.

Stratocumuliform

Wave clouds with clear gaps through which lower stratiform layers may be seen.[19]

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.[20][21]

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.[22]

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.[20][21]

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 latitudinal bands at and below the tropopause alternatingly 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.[23]

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.[24] an intermediate deck of ammonium hydrosulfide, and an inner deck of cumulus water clouds.[25][26]

Uranus and Neptune

Clouds layers made mostly of methane gas.[27]

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.[27]

Notes and references

  1. World Meteorological Organization, ed. (1975). Noctilucent, International Cloud Atlas (PDF). I. p. 66. ISBN 92-63-10407-7. Retrieved 26 August 2014.
  2. Michael Gadsden & Pekka Parviainen (September 2006). Observing Noctilucent Clouds (PDF). International Association of Geomagnetism & Aeronomy. p. 9. Retrieved 31 January 2011.
  3. 1 2 Les Cowley (2011). "Nacreous and polar stratospheric clouds". Atmospheric optics, atoptics.co.uk. Retrieved 7 November 2014.
  4. 1 2 3 4 5 6 7 8 9 10 Clouds Online (2012). "Cloud Atlas". Retrieved 1 February 2012.
  5. 1 2 3 4 5 JetStream (5 January 2010). "Cloud Classifications". National Weather Service. Retrieved 31 January 2011.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Boyd, Sylke (2008). "Clouds – Species and Varieties". University of Minnesota. Archived from the original on December 30, 2010. Retrieved 4 February 2012.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Aerographer/Meteorology (2012). "Cloud Variety". meteorologytraining.tpub.com. Retrieved 2 July 2012.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 World Meteorological Organization, ed. (1975). Features, International Cloud Atlas (PDF). I. pp. 22–24. ISBN 92-63-10407-7. Retrieved 26 August 2014.
  9. Burroughs, William James; Crowder, Bob (January 2007). Weather, p.216. Fog City Press, San Francisco. ISBN 978-1-74089-579-8.
  10. 1 2 3 4 5 6 World Meteorological Organization, ed. (1975). Species, International Cloud Atlas (PDF). I. pp. 17–20. ISBN 92-63-10407-7. Retrieved 26 August 2014.
  11. Burroughs, William James; Crowder, Bob (January 2007). Weather, p.215. Fog City Press, San Francisco. ISBN 978-1-74089-579-8.
  12. "Cumulonimbus Incus". Universities Space Research Association. 5 August 2009. Retrieved 23 October 2012.
  13. Paul de Valk; Rudolf van Westhrenen & Cintia Carbajal Henken (2010). "Automated CB and TCU detection using radar and satellite data: from research to application" (PDF). Retrieved 2011-09-15.
  14. World Meteorological Organization (1995). "Cloud Atlas" (PDF). Retrieved 2014-08-26.
  15. Cumulus-skynews (2013). "Clouds: Their curious natures". Retrieved 26 August 2014.
  16. Task Team On Revision of the International Cloud Atlas (2013). "Final Report" (PDF). World Meteorological Organization. Retrieved 2014-10-06.
  17. http://cimss.ssec.wisc.edu/goes/blog/archives/555
  18. Franck Montmessin (2013). "Clouds in the terrestrial planets" (PDF). Retrieved 2013-11-05.
  19. David Shiga (2006). "Mysterious waves seen in Venus's clouds". New Scientist. Retrieved 2013-11-05.
  20. 1 2 "Clouds Move Across Mars Horizon". Phoenix Photographs. National Aeronautics and Space Administration. 19 September 2008. Retrieved 15 April 2011.
  21. 1 2 "NASA SP-441: Viking Orbiter Views of Mars". National Aeronautics and Space Administration. Retrieved 26 January 2013.
  22. SPACE.com staff (2006-08-28). "Mars Clouds Higher Than Any On Earth". SPACE.com. Retrieved 2008-10-19.
  23. Phillips, Tony (20 May 2010). "Big Mystery: Jupiter Loses a Stripe". Nasa Headline News – 2010. National Aeronautics and Space Administration. Retrieved 15 April 2011.
  24. Dougherty & Esposito 2009, p. 118
  25. A.P. Ingersoll; T.E. Dowling; P.J. Gierasch; G.S. Orton; P.L. Read; A. Sanchez-Lavega; A.P. Showman; A.A. Simon-Miller; A.R. Vasavada. "Dynamics of Jupiter's Atmosphere" (PDF). Lunar & Planetary Institute. Retrieved 2007-02-01.
  26. Monterrey Institute for Research in Astronomy (2006-08-11). "Saturn". Retrieved 2011-01-31.
  27. 1 2 Nola Taylor Redd (2012). "Neptune's Atmosphere: Composition, Climate, & Weather". Space.com. Retrieved 2013-11-05.

See also

Cloud species

External links

This article is issued from Wikipedia - version of the 11/16/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.