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Clouds

Clouds the driving force behind weather in the Nature API...

Cloud formation

Clouds are automatically placed and adjusted based on the following factors:

For more specific details of which factors are used for each cloud, see list of clouds further down this page.

The higher the clouds, the fairer the weather. Basically, if clouds are mostly in the high-level, weather will usually be fair due to lack of clouds capable of producing rainfall or snowfall.

"When clouds appear like rocks and towers, the earth will be washed by frequent showers." – cumulonimbus.

Cloud types

Extreme-level clouds (Mesospheric)
PhotoNameAltitudesNotes

Noctilucent

Nlc

76→85km

Appearance: Thin and often very feint layer of wispy pale blue or silvery filaments. On are occasions they can appear green or red. Stars are usually clearly visible through the clouds.

Conditions:

  • Location: Latitudes between 50° and 70° north and south of the equator
  • Air: Stable airmass, neutral or downwards buoyancy convection, low moisture content, <-120ºC.
  • Temporal: Visible during nautical and astronomical twilight during summer months of May – August (northern hemisphere, where they are most common) or November – February (southern hemisphere, where they are less common).

Precipitation: None.

Weather: Typical summer weather.

Forecast: Global climate change of the "Oh no, we're all going to die" variety.

More info: Wikipedia, Crystalinks

Very high-level clouds (Stratospheric)
PhotoNameAltitudesNotes

Nacreous

Psc

1529km

Appearance: Thin layer of clouds, glowing brightly with vivid iridescent colours similar to those found in a seashell.

Conditions:

  • Location: 60ºN→90ºN (arctic), 60ºS→90ºS (antarctic)
  • Air: Stable airmass, neutral or upwards buoyancy convection, very low moisture content, -78ºC to -119ºC.
  • Temporal: Visible during civil twilight during winter months.

Precipitation: None.

Weather: Frigidly cold and icy, often with very little moisture in the atmosphere.

Forecast: Ozone layer depletion.

More info: Wikipedia, NamesOfClouds

High-level clouds (Tropospheric)
PhotoNameAltitudesNotes

Cirrus

Ci

5→12km

Appearance: A wide variety of appearances but generally white, delicate-looking and "feathery". Usually translucent, but dense cirrus (formed from a cumulonimbus) can be opaque. Commonly move slowly in a westerly direction regardless of wind direction at ground level.

Formation:

  • General: Tend to form on days with fine weather and light winds at ground level.
  • Location: Worldwide, covering approximately 25% of the world at any given time! In polar regions, they are often larger than normal.
  • Air: Neutral or turbulent airmass stability, neutral buoyancy convection, small moisture content, -20ºC to -30ºC. Often caused by convection in unstable layers of the upper atmosphere, turbulence caused by strong changes in vertical wind direction.
  • Temporal: Occurs all year round, but more so during summertime. Can occur at any time of day, but usually only visible during daylight hours.
  • Genitus: Cumulonimbus, Altocumulus.
  • Mutatus: Cirrostratus, Cirrocumulus, Altocumulus.

Precipitation: In rare cases, after a thunderstorm Cirrus may produce hail or large water droplets and will then dissipate completely. Occasionally produces snowfall virga.

Weather: Usually fair.

Forecast: Large numbers of cirrus clouds indicate an approaching warm weather front, or upper-air disturbance and troughs of low pressure, signalling the approach of stormy weather. See specific cloud forms for more details.

Notes: When present in the jet stream, Cirrus can travel at over 100mph. However, they'll always appear to be slow moving in comparison to lower clouds even if the lower clouds are travelling much more slowly.

More info: Wikipedia, Clouds-online, Nephology, Pilotfriend

Cirrus
aviaticus

Ci avi

Variable

~5km

Appearance: Long, thin artificial clouds caused by condensation or fumes from airborne objects. Often called "contrails" (if non-persistent) or "chemtrails" (if persistent).

Formation:

  • General: ?
  • Location: Worldwide, anywhere where aircraft fly
  • Air: ?
  • Temporal: Non-persistent contrails dissipate within a matter of minutes or hours. Persistent contrails can last for many hours or even days, often seeding extensive cloud cover.
  • Genitus: Aircraft, missiles, projectiles
  • Mutatus: ?

Notes: Can be used to determine the path taken by an aircraft or projectile.

Precipitation: None.

More info: Wikipedia

Cirrus
castellanus

Ci cas

>6km

Appearance: A rarely seen series of dense lumps, or "towers" of Cirrus, connected by a thinner base. Looks a bit like crenellated battlements on old castles. Often accompanied by a thin veil of Cirrostratus.

Formation:

  • Location: Worldwide, but rare.
  • Air: Unstable airmass stability, neutral buoyancy convection, small moisture content and, most likely, a steep drop in temperature in the stratosphere.
  • Mutatus: Cirrus floccus, Cirrus unicus

Precipitation: May form snowfall virgas.

Ground weather: Usually fair.

Forecast: Impending rain or storms.

More info: Wikipedia

Cirrus
<species>
duplicatus

Ci * du

>5km

Appearance: Fairly rare form of Cirrus arranged in superposed layers at slightly different levels, sometimes merged in places.

Species: Most Cirrus fibratus and Cirrus uncinus exhibit this variety. Cirrus spissatus sometimes exhibit this variety.

Notes: They tend to "chase" fair weather.

Pictured: Cirrus fibratus duplicatus.

More info: NamesOfClouds

Cirrus
fibratus

Ci fib

>6km

Appearance: White or silvery clouds with fibrous threads or tufts at the ends. Often seen in two or more layers (duplicatus). They usually appear in small patches.

Formation:

  • Location: Worldwide, very common.
  • Air: Unstable airmass stability, upwards buoyancy convection.

Precipitation: None.

Ground weather: Usually fair.

Forecast: Thick layers can be a precursor to rain or snow due to an approaching warm front, although this is rare. Thin layers generally indicate that fair weather (eg. Cumulus humilis) will follow, and in countries with tropical weather suggest a sunny day ahead.

More info: Wikipedia, Chitambo

Cirrus
floccus

Ci flo

>5km

Appearance: Small, usually isolated, tufts of pale white cloud, usually with a rugged base. Often seen with snowfall virga.

Formation:

  • Location:
  • Air: Turbulent airmass stability

Precipitation: Usually virga, although on very rare occasions can briefly cause large rain droplets that reach the ground.

Ground weather: Usually fair.

Forecast: The presence of virga will sometimes give rise to storm cells by forming or contributing to Cumulonimbus.

Notes: Cirrus floccus are the highest and fastest tropospheric clouds, often forming in the jet stream, although they will appear to be moving slowly when viewed from ground level.

More info: Wikipedia

Cirrus
<species>
intortus

Ci * in

>5km

Appearance: Tangled and interwoven filaments (streaks) and wisps of white, pale blue cirrus cloud. Unique to the cirrus genus.

Species: Often associated with Cirrus spissatus.

Formation:

  • Location: Worldwide
  • Air: Upwards buoyancy convection.

Precipitation: None.

Ground weather: Usually fair.

Forecast: When present in large patches covering most of the sky, stormy weather will likely follow.

Notes: This variety of Cirrus is usually the last to form, using up the last remaining moisture in the stratosphere. The air above them will be incredibly dry.

More info: Wikipedia

Cirrus
<species>
radiatus

Ci * ra

>5km

Appearance: Parallel stripes or bands of pale white cloud, often covering the whole sky. They often appear to converge at a point on the horizon.

Formation:

  • Location: Worldwide
  • Temporal: Any time of year.

Ground weather: Usually fair.

Forecast:

Notes: Often accompanied by, and sometimes partly merged with, Cirrocumulus or Cirrostratus clouds.

More info: Wikipedia

Cirrus
spissatus

Ci spi

>6km (usually)

>1.5km (sometimes)

Appearance: Opaque threads or whisps, ranging in colour from white to grey with increasing density. Often obscures the sun or moon. Sometimes seen in two or more layers (duplicatus).

Notes: Unlike other Cirrus clouds, these can sometimes link to other, lower-level clouds such as Cumulonimbus, making their base drop well below the high-level part of the stratosphere (as low as 1.5km in some cases).

Formation:

  • Location: Worldwide
  • Air: Neutral airmass stability, neutral buoyancy convection, small moisture content. Often formed from the upper part of cumulonimbus clouds.
  • Genitus: Dissipation of Cumulonimbus capillatus.
  • Temporal:

Ground weather: Generally fair, although if present with cumulonimbus there may be rain or snow.

Forecast: Winds from the east travelling south will cause rainfall within 24 hours or less, winds in other directions will cause an overcast sky and often a storm within the next 48 hours.

More info: Wikipedia, NamesOfClouds

Cirrus
unicus

Ci unc

>7km

Appearance: White clouds with "hooks" at one end, often seen in two or more layers (duplicatus). They are generally more thinly distributed than other Cirrus species (for example Cirrus spissatus).

Formation:

  • Location: Worldwide
  • Air: Unstable airmass stability, upwards buoyancy convection, variable moisture content, -45ºC, warm or occluded front. Winds of 100 – 150mph cause whisps of cloud.

Precipitation: Snowfall virga

Ground weather: Usually fair.

Forecast: Indicates approach of showers, rain, or possibly snow depending on temperature.

More info: Wikipedia, Chitambo

Cirrus
<species>
(bi)undulatus

Ci * un 

>6km

Notes: Not sure this classification is correct - looks more like a Cirrostratus undulatus.

Appearance: Very rare Cirrus clouds with waves running through them. If there are two sets of waves interwoven with each other they are often referred to as "biundulatus".

Formation:

  • Location: Worldwide, usually above large open plains (generally flat land).
  • Air: Unstable buoyancy convection, variable moisture content.
  • Temporal: Usually formed during morning hours and sometimes, usually after a convective thunderstorm, during midday hours.

Precipitation:

Ground weather: Relatively cool or early stages of weather destabilisation.

Forecast:

Cirrus
vertebratus

Ci ve

>6km

Appearance: White clouds in the distinctive form of a spinal column or fish skeleton. Unique to the cirrus genus.

Conditions:

  • Location: Worldwide
  • Air: Turbulent winds at high altitude. Often found in the jet stream, where air moves in parallel to the main cloud line.
  • Mutatus: Cirrus aviaticus

Ground weather: Usually fair.

Forecast: Indication of changing weather.

More info: Wikipedia

Cirrostratus

Cs

>6km

Appearance: Milky, translucent cloud veil of ice crystals, which sometimes causes halo appearances around moon and sun. Often covers the whole sky.

Formation:

  • Location: Worldwide
  • Air: Stable airmass stability, neutral buoyancy convection, small moisture content, <0ºC
  • General: Usually preceded by Cirrus clouds, generally forms when light but increasing winds are present at ground level.

Ground weather:

  • Turbulent winds at high altitude. Deterioration of weather conditions within 12 to 24 hours.

More info: Wikipedia, Clouds-online

Cirrostratus
<species>
duplicatus

Cs * du 

>5km

>8km
(topics) 

Appearance: Cirrostratus arranged in up to 12 superposed layers, at different altitudes, sometimes partly merged. Generally the thickest form of Cirrostratus, up to 8km thick, although each layer will usually be only a few hundred metres thick.

 

Cirrostratus
fibratus

Cs fib

>6km

Appearance: A thin layer of silvery or pale white fibrous veils. Unlike it's nebulosus counterpart, it will not cause halos around the sun or moon.

Formation:

  • Location: Worldwide
  • Air: ? airmass, ? buoyancy convection, small moisture content, <0ºC.
  • Temporal: Most often seen in the morning after sunrise through to the afternoon. In the winter where they can appear at any time of day or night.

Weather: If no other clouds are present, the weather will usually be dry and mild. If other clouds are present, refer to their effects on weather conditions.

Forecast: With falling air pressure, indicates approaching rain or storms within 8 to 24 hours.

More info: Wikipedia, Clouds-online

Cirrostratus
nebulosus

Cs neb

>6km

Appearance: Very common smooth, light-grey, feint or fog-like veil that covers most of the sky. A "halo" may appear around the sun or moon due to light refraction in the ice crystals.

Formation:

  • Air: Stable airmass, neutral buoyancy convection, small moisture content, <0ºC.
  • Genitus: Cirrus

Precipitation: Does not produce precipitation or virga.

Forecast: With falling air pressure, often accompanied by halo appearance, indicates approaching rain or storms within 8 to 24 hours. This is most common if Cirrus precede them, and Nimbostratus will usually start to form and subsequently lead to a storm.

More info: Wikipedia, Clouds-online, Pilotfriend

Cirrostratus
<species>
undulatus

Cs * un

>5km

>8km
(topics)

Appearance: Quite rare

Formation:

  • Location:
  • Air: ? airmass stability, ? buoyancy convection, small moisture content, <0ºC, warm front

Precipitation:

Ground weather:

Forecast:

More info: NamesOfClouds, CloudAtlas

Cirrocumulus

Cc

 

Appearance: High level milky-white cloud with wavelike or fine, dappled cumuliform structure.

Formation:

  • General: Usually preceded by Cirrus and/or Cirrostratus. Sometimes occur as a transitional phase between Cirrus and Cirrostratus. Sometimes develops under same conditions as Altocumulus lenticularis.
  • Location: Worldwide
  • Air: Upward airmass stability, upwards buoyancy convection, small to large moisture content, <0ºC
  • Mutatus: Cirrus, Cirrostratus, Altocumulus
  • Temporal: Less frequent in peak summer.

Weather:

Forecast:

More info: Pilotfriend

 

Cirrocumulus
castellanus

Cc cas

 Cirrocumulus, some elements of which are vertically developed in the form of small turrers, rising from a common horizontal base. The apparent width of the turrets is always less than one degree, when observed at an angle of more than 30 degrees above the horizon, the presense of this cloud is an indication of instability at its level.
 

Cirrocumulus floccus

Cc flo

 Cirrocumulus composed of very small cumuliform tufts, the lower parts of which are more or less ragged. The apparent width of the tufts is always less than one degree, when observed at an angle of more than 30 degrees above the horizon. As in the case of Cirrocumulus castellanus, the presence of these clouds is an indication of instability at their level. Cirrocumulus floccus sometimes results from the evolution of Cirrocumulus castellanus the base of which has dissipated.
 

Cirrocumulus <species>
lacunosus

Cc * la

 Cirrocumulus in a patch, sheet or layer, showing small more or less regularly distributed round holes, many of them with fringed edges. Cloud elements and clear spaces are often arranged in a manner suggesting a net or a honeycomb.
 

Cirrocumulus lenticularis

Cc len

 Cirrocumulus patches shaped like lenses or almonds, often very elongated and usually with well-defined outlines. These more or less isolated clouds are mostly smooth and are very white throughout. Irisation is sometimes observed on these clouds.
 

Cirrocumulus
stratiformis

Cc str

 Cirrocumulus in the form of a relatively extensive sheet or layer, sometimes showing gaps, breaches or rifts.
 

Cirrocumulus <species>
undulatus

Cc * un

 Cirrocumulus showing one or two systems of undulations.
Middle-level clouds
PhotoNameAltitudesNotes
 

Altocumulus

Ac

 

Formation:

  • Air: Unstable airmass stability, upwards buoyancy convection, moderate moisture content, >0ºC
  • Genitus: Cumulus and Cumulonimbus in stable airmass.
  • Mutatus: Altostratus and Nimbostratus in unstable airmass.

Altocumulus
castellanus

Ac cas

 

Appearance: Cumuliform protuberances in the form of turrets which give this cloud a crenelated appearance (like the top of castle walls). The cumuliform cloud elements have a common horizontal base and appear to be arranged in lines. The castellanus character is especially evident when the cloud is seen from the side.

Conditions:

  • General: ?
  • Location: ?
  • Air: Mid-level unstable, weak shear, convective
  • Temporal: ?
  • Genitus: ?
  • Mutatus: ?

Precipitation: None (normally)

Ground Weather:

Forecast:

  • Thunderstorms are possible if surface-based convection can connect to the mid-tropospheric unstable layer

More info:

Altocumulus which presents, in at least a fraction of its upper part, cumuliform protuberances in the form of turrets which give this cloud a crenulated appearance. . The presence of this cloud is a sign of instability at its level; when it acquires a considerable vertical extent, Altocumulus castellanus becomes Cumulus congestus, and sometimes Cumulonimbis.

 

Altocumulus
<species>
duplicatus

Ac * du 

 Altocumulus comprising two or more broadly horizontal superposed patches, sheets or layers, close together, sometimes partly merged. This variety occurs in the species stratiformis and lenticularis.
 

Altocumulus
floccus

Ac flo

 Altocumulus consisting of small tufts if cumuliform appearance; the lower parts of these tufts are more or less ragged and are often accompanied by fibrous trails (virga of ice crystals). The presence of these clouds is an indication of instability at their level. Altocumulus floccus sometimes forms as a result of the dissipation of the base of Altocumulus castellanus.
 

Altocumulus
<species>
lacunosus

Ac * la

 Altocumulus, in a sheet or layer or in patches showing more or less regularly distributed round holes, many of them with fringed edges. Cloud elements and clear spaces are often arranged in a manner suggesting a net or a honeycomb. The details change rapidly.
 

Altocumulus
lenticularis

Ac len

 A patch of Altocumulus, in the shape of a lens or almond, often very elongated and usually with well-defined outlines. This patch is either composed of small elements, closely grouped together, or consists of one more or less smooth unit. In the latter cased, there are pronounced shadings. Irisation is occasionally visible.
 

Altocumulus
<species>
opacus 

Ac * op

 A patch, sheet or layer of Altocumulus, the greater part of which is sufficiently opaque to mask completely the sun or moon, most often, the base of this variety of Altocumulus is even and its apparent subdivision into merged elements results from the irregularity of its upper surface. The uder surface is sometimes uneven and the elements then stand out in true relief. The variety opacus occurs fairly often in the species stratiformis.
 

Altocumulus
<species>
perlucidus 

Ac * pe

 A patch, sheet or layer of Altocumulus in which the spaces between the elements allow the sun, the moon, the blue of the sky or higher clouds to be seen. This variety often occurs in the species stratiformis.
 

Altocumulus
<species>
radiatus 

Ac * ra

 Altocumulus showing approximately straight, parallel bands which, owing to the effect of perspective, appear to converge towards towards the horizon.
 

Altocumulus
stratiformis

Ac str

 Altocumulus in an extensive sheet or layer, composed of sperate or merged elements. This is by far the most frequent species.
 

Altocumulus
<species>
translucidus

Ac * tr

 

Appearance: A patch, sheet or layer of Altocumulus, the greater part of which is sufficiently translucent to reveal the position of the sun or moon.

Species: This variety often occurs in the species stratiformis and lenticularis.

Altocumulus
<species>
undulatus

Ac * un

 

Altocumulus composed of separate or merged elements, either elongated and broadly parallel, or arranged in ranks and files having the appearance of two distinct systems of undulations.

Altostratus undulatus is more common.

 

Altostratus

As

 

Appearance: Greyish or bluish sheet or layer of striated, fibrous or uniform appearance, totally or partly covering the sky, and having parts thin enough to reveal the sun at least vaguely, as through frosted glass. Altostratus does not show halo phenomena. Sometimes exhibits mammatus.

Notes: Due to the uniformity of Altostratus clouds, they are not split in to species.

Formation:

  • General:
  • Location:
  • Air: Stable airmass stability, neutral buoyancy convection, moderate moisture content, >0ºC, warm front.
  • Genitus: Altocumulus virga. In the tropics, may also be formed from spreading out of middle layer of Cumulonimbus.
  • Mutatus: A thickening veil of Cirrostratus, or a thinning layer of Nimbostratus.

Precipitation: Can cause rainfall or snow virga, or continuous rainfall, snowfall or hail.

 

Altostratus
duplicatus

As du 

 Altostratus composed of two or more superposed layers, at slightly different levels, sometimes partly merged.
 

Altostratus
opacus

As op 

 Altostratus, the greater part of which is sufficiently opaque to mask the position of the sun or moon.
 

Altostratus
radiatus

As ra 

 Altostratus showing broad parallel bands which appear to converge towards one point or towards two opposite points of the horizon.
 

Altostratus
translucidus

As tr 

 Altostratus, the greater part of which is sufficiently translucent to reveal the position of the sun or moon.
 

Altostratus
undulatus

As un 

 Altostratus showing undulations.
Low-level clouds
PhotoNameAltitudesNotes
Stratus 

Appearance: Low-lying formless cloud, greyish-white in colour.

Conditions:

Weather: Usually associated with cold, damp conditions in autumn, winter and spring.

Stratocumulus 

Appearance: Low layered cloud with bumpy, heap-like structure.

Conditions: Low elevation, slightly unstable airmass, slight upwards buoyancy convection, moderate moisture content, >0ºC

Weather: A sign of blustery and relatively cool conditions indicating possible showers, rain or snow.

 Cumulus  

Cumulus humilis

Cu hum

 

Appearance: Small heaps of clouds with flattish bottoms and rounded tops.

Conditions: Low elevation, slightly unstable airmass, slight upwards buoyancy convection, small moisture content, >0ºC

Weather: Usually a sign of fair (nice) weather when they appear in clear sky. If cirrostratus clouds are also present, a warm front is approaching, expect showers in the next 12-24 hours.

Forecast: If these clouds are present in the morning it is a sign of an unstable atmosphere. Larger clouds and possibly thunderstorms could form throughout the day to cause bad or severe weather in the afternoon or evening.

Temporal: Most common in the afternoon near the top of the well-mixed planetary boundary layer.

 More info: Wikipedia

 

Cumulus
mediocris

Cu med

  
Cumulus congestus 

Appearance: Very active separated heaps with flat bottoms (usually) and growing towers. Often called "summertime clouds".

Formation:

  • Air: Very unstable airmass, high upwards buoyancy convection, large moisture content, >0ºC, cold front.
  • Mutatus: Cumulis Humilis
  • Temporal: More common in the afternoon as warm air currents cause Cumulus humilis to extend vertically.

Weather: Transient showers

Forecast:

Pyrocumulus

Pc

Ground-level

Appearance: Cumuliform smoke plume, often greyish-brown in colour.

Conditions: Intense fire on the ground.

Location: Site of a laser satellite strike, nuclear explosion, plasmite bombs, etc.

Weather: Significant plumes (Pyrocumulonimbus) can cause lightning.

Forecast: As they spread they can cause other clouds to form.

More info: Wikipedia

Multi-level clouds
PhotoNameAltitudesNotes
Cumulonimbus

 

Appearance: A massive pile of cloud penetrating the freezing level and sometimes forming an anvil at the base of the stratosphere.
Nimbostratus <3km

Appearance: Generally formless dark mass of low- to middle-level storm cloud. Generally obscures the sun and moon.

Supplementary and Accessory: (praecipitatio), (virga), (pannus)

Formation:

  • General:
  • Location: Worldwide, very common in "middle" latitudes 23°26'22"→66°33'39" N & S.
  • Air: lightly unstable airmass, slight upwards buoyancy convection, moderate to high moisture content, >0ºC, occluded or warm front.
  • Genitus: Cumulus, Cumulonimbus
  • Mutatus: Altocumulus, Stratocumulus and, most commonly, Altostratus that has thickened sufficiently to produce precipitation.

Precipitation: Light to moderate, and sometimes heavy, rainfall or snowfall, which is generally steady and prolonged.

Notes: Stratus and Stratocumulus will often form below Nimbostratus, especially as it clears. The Stratocumulus clouds will sometimes thicken due to precipitation from the Nimbostratus and causing them to mutate in to Nimbostratus in the lower-level atmosphere. In addition, the conditions required for Nimbostratus also cause high-level clouds to form.

Forecast: Grim weather over prolonged period of time, often giving way to Stratus or Stratocumulus clouds when the weather clears.

More info: Wikipedia, Pilotfriend

Additional features and accessory clouds
PhotoNameHeightNotes
 

(asperatus)

* (asp)

 

http://en.wikipedia.org/wiki/Undulatus_asperatus

An additional feature sometimes found with Stratocumulus stratiformis undulatus or Altocumulus stratiformis undulatus.

 

(arcus)

* (arc)

 

Often called roll or shelf cloud: a dense, horizontal roll with more or less tattered edges, situated on the lower front part of certain clouds and having, when extensive, the appearance of a dark, menacing arc.

 

(incus)

* (inc)

 

The upper portion of a Cumulonimbus spread out in the shape of an anvil with smooth, fibrous or striated appearance.

Formation:

  • General: Normally preceded by Cirrus first, then Cirrostratus.

More info: Pilotfriend

(mammatus)

* (mam)

 

Appearance: A cellular pattern of pouches hanging underneath the base of a cloud, often a cumulus or cumulonimbus. Sometimes seen under cirrus clouds, in which case only the bottom part of the pouch is visible.

Conditions: Warm weather, moist unstable upper atmosphere over very dry lower atmosphere, upwards buoyancy convection.

Weather:

Forecast:

More info: Wikipedia

(pannus)

* (pan)

 

Ragged shreds, sometimes constituting a continuous layer, situated below another cloud and sometimes attached to it.

 

(pileus)

* (pil)

 

An accessory cloud of small horizontal extent, in the form of a cap or hood above or attached to the top of a cumuliform cloud which often penetrates it. Several pileus clouds may fairly often be observed in superposition.

 

(praecipitatio)

* (pra)

 

Precipitation (rain, drizzle, snow, ice pellets, hail, etc.) falling from a cloud and reaching the earth's surface.

 

(tuba)

* (tub)

 

Cloud column or inverted cloud cone, protruding from a cloud base; it constitutes the cloudy manifestation of more or less intense vortex, and if it touches the ground can become a tornado or waterspout.

 

(velum)

* (vel)

 

An accessory cloud veil of great horizontal extent, close above or attached to the upper part of one or several cumuliform clouds which often pierce it.

 

(virga)

* (vir)

 

Appearance: Vertical or inclined trails of precipitation ("fallstreaks") attached to the under surface of a cloud, which do not reach the earth's surface.

Conditions: Precipitation (pra) that evaporates as it encounters warmer air below.

Location: Common in the desert and in temperate climates. In North America, it is commonly seen in the Western United States and the Canadian Prairies.

Forecast: Can cause formation of Cumulonimbus clouds which in turn cause stormy weather.

More info: Wikipedia

Variants: When a virga occurs in a Cirrocumulus or Altocumulus cloud, a "fallstreak hole" may occur. Aircraft passing through the clouds often trigger the virga, a useful cue for you to start building AA defences!

More info: Crystalinks, Wikipedia

 

(fallstreak hole)

(holepunch cloud) 

  
 (wall cloud)  
 (flanking line)  

Earthquake lights

It might be possible to implement earthquakes in Warzone, using a camera shake and health damage to DEFENCE structures (walls, towers, etc). If so, an interesting associated phenomena could be earthquake lights - iridescent colouring sometimes seen in the sky before, during and after an earthquake:

Still under construction, possibly lots of errors so check interwebs for verification.