Clouds : Names, Shapes and Altitudes

Clouds are a complex product of our atmosphere.A cloud is made of water drops or ice crystals floating in the sky. There are many kinds of clouds. Clouds are an important part of Earth's weather.

How Do Clouds Form?

The sky can be full of water. But most of the time you can't see the water. The drops of water are too small to see. They have turned into a gas called water vapor. As the water vapor goes higher in the sky, the air gets cooler. The cooler air causes the water droplets to start to stick to things like bits of dust, ice or sea salt.

Types of Clouds:

Clouds are classified into four basic categories, depending largely on the height of their bases above the ground. It is very hard to just look up in the sky and determine a cloud's altitude.

High-level clouds, called cirrus clouds, can reach heights of 20,000 feet (6,000 meters) and are typically thin. They do not produce rain and often indicate fair weather. They are usually made up of ice. There are three types of clouds found in the high altitude category.

Midlevel clouds form between 6,500 feet (2,000 meters) and cirrus level. They are referred to as "alto-" clouds and Alto is a cloud name means the cloud is found at middle altitude  bear such names as altostratus or altocumulus, depending on their shape. (Altostratus clouds are flat; altocumulus clouds are puffy.) They frequently indicate an approaching storm. They themselves sometimes produce virga, which is rain or snow that does not reach the ground.

Low-level clouds lie below 6,500 feet (2,000 meters). Meteorologists refer to them as stratus clouds. They're often dense, dark, and rainy (or snowy) though they can also be cottony white clumps interspersed with blue sky.

Clouds can have a patchy of puffy (or lumpy, wavy, splotchy or ripply) appearance.  These are cumuliform clouds and will have cumulo or cumulus in their name.  In an unstable atmosphere cumuliform clouds will grow vertically.  Strong thunderstorms can produce dangerous severe weather.

Stratiform clouds grow horizontally and form layers.  They form when the atmosphere is stable.

 

HIGH CLOUDS:

 

High altitude clouds are thin because the air at high altitudes is very cold and cold air can't contain much moisture (the saturation mixing ratio for cold air is very small).  These clouds are also often blown around by fast high altitude winds.  Filamentary means "stringy" or "streaky".

Cirrus :  

Cirrus clouds are the highest of all clouds and are composed entirely of ice crystals.Cirrus clouds are precipitating clouds, although the ice crystals evaporate high above the earth’s surface.

Cirrus clouds in the form of white, delicate filaments, mostly white patches or narrow bands. They may have a fibrous (hair-like) and/or silky sheen appearance. Cirrus clouds are always composed of ice crystals, and their transparent character depends upon the degree of separation of the crystals. As a rule when these clouds cross the sun's disk they hardly diminish its brightness. Before sunrise and after sunset, cirrus is often colored bright yellow or red. These clouds are lit up long before other clouds and fade out much later.

Fast Facts:

Typical Altitude: 16,500-45,000 ft.

Location: Worldwide

Precipitation: None that reaches ground

Composition: Ice crystals

Formation: Fall streaks of ice crystals in upper troposphere winds

Cirrostratus (Cs) :

Cirrostratus clouds are difficult to spot and appear as  a pale, milky lightening of the sky. These are white layer clouds . Thin enough to ne pretty transparent, whitish veil clouds with a fibrous smooth appearance. can see the sun or moon clearly. Cirrostratus clouds never block out the sun  completely, but rather produce a variety of optical effects.

 A sheet of cirrostratus which is very extensive, nearly always ends by covering the whole sky. A cirrostratus cloud is a thin uniform white layer cloud  covering part or all of the sky.  They're so thin you can sometimes see blue sky through the cloud layer. Haloes are a pretty sure indication that a cirrostratus cloud is overhead. 

Fast Facts:

Typical Altitude: 20,000-42,000 ft.

Location: Worldwide

Precipitation: None

Composition: Ice crystals

Formation: Spreading and joining of cirrus clouds.

  Cirrocumulus (cc):

Cirrocumulus clouds are usually a transitional phase  between cirrus and cirrostratus clouds. Large numbers of cirrocumulus clouds may indicate  poor weather is approaching

Thin, white patch, sheet, or layered of clouds without shading. They are composed of very small elements in the form of more or less regularly arranged grains or ripples. In general Cirrocumulus represents a degraded state of cirrus and cirrostratus both of which may change into it and is an uncommon cloud. There will be a connection with cirrus or cirrostratus and will show some characteristics of ice crystal clouds. At sunset, cirrocumulus clouds may resemble the scales on fish-“mackerel sky”.

Fast Facts:

Typical Altitude: 16,500-45,000 ft.

Location: Worldwide

Precipitation: None that reaches ground

Composition: Ice crystals

Formation: Cloudlets formed by choppy  winds and high moisture  levels in upper troposphere.

.

MID CLUDS:

Altostratus:

Gray or bluish cloud sheets or layers of striated or fibrous clouds that totally or partially covers the sky. They are thin enough to regularly reveal the sun as if seen through ground glass. Altostratus clouds do not produce a halo phenomenon nor are the shadows of objects on the ground visible but they do make for nice

Sunsets.  Sometime virga is seen hanging from Altostratus, and at times may even reach the ground causing very light precipitation.

Fast Facts:

Typical Altitude: 6,500-16,500 ft.

Location: Worldwide, common in middle  latitudes

Precipitation: Occasional light rain, snow

Composition: Both  liquid water, and ice crystals

Formation: Usually formed from the thickening and lowering of a  cirrostratus cloud on its way  to becoming a nimbostratus  cloud.

Altocumulus:

Since altocumulus clouds are high in the sky, they are  generally above the influence of thermals, and form  very differently from cumulus and stratocumulus clouds, who share similar names.

Altocumulus clouds are pretty common.White and/or gray patch, sheet or layered clouds, generally composed of laminae (plates), rounded masses or rolls. They may be partly fibrous or diffuse. When the edge or a thin semitransparent patch of altocumulus passes in front of the sun or moon a corona appears. This colored ring has red on the outside and blue inside and occurs within a few degrees of the sun or moon.The most common mid cloud, more than one layer of Altocumulus often appears at different levels at the same time. Many times Altocumulus will appear with other cloud types.

Fast Facts:

Typical Altitude: 6,500-18,000 ft.

Location: Worldwide

Precipitation: Very occasional light rain

Composition: Mostly liquid water, may  also contain ice crystals

Formation: Mid-level atmospheric  disturbances and wave  propagation (from e.g.–

mountatins.

Nimbostratus:

The nimbostratus cloud has no species or varieties. It is a thick, wet blanket with a ragged base caused by  the continual precipitation.

  

Nimbostratus clouds tend to produce fairly light precipitation over a large area.The continuous rain cloud. Resulting from thickening Altostratus, This is a dark gray cloud layer diffused by falling rain or snow. It is thick enough throughout to blot out the sun. The cloud base lowers into the low level of clouds as precipitation continues.Also, low, ragged clouds frequently occur beneath this cloud which sometimes merges with its base.

Fast Facts:

Typical Altitude: 2,000-18,000 ft.

Location: Worldwide,common in middle latitudes

Precipitation: Moderate to heavy rain or snow, which is generally steady and prolonged

Composition: Liquid water, raindrops snowflakes and ice crystals

Formation: Usually formed from the thickening and lowering of a altostratus cloud.

LOW CLOUDS:w Clouds

Cumulus:

Cumulus clouds come with different degrees of vertical development.  The fair weather cumulus clouds don't grow much vertically at all.  A cumulus congestus cloud is an intermediate stage between fair weather cumulus and a thunderstorm. Detached, generally dense clouds and with sharp outlines that develop vertically in the form of rising mounds, domes or towers with bulging upper parts often resembling a cauliflower.The sunlit parts of these clouds are mostly brilliant white while their bases are relatively dark and horizontal.Over land cumulus develops on days of clear skies, and is due diurnal convection; it appears in the morning, grows, and then more or less dissolves again toward evening.

Here are three species of cumulus clouds:

•Humilis are wider than they are tall

•mediocrisare as wide as they are tall

•congestusare taller than they are wideOften called “fair-weather” clouds, cumulus clouds are common over land on sunny days, when the sun heats the land creating thermal convection currentsEach thermal is distinct, and, consequently, each cumulus cloud is a distinct puff

Fast Facts:

Typical Altitude: 2,000-3,000 ft.

Location: Worldwide (except in Antartica, where it’s too cold)

Precipitation: Generally none, except for brief showers from congestus

Composition: Liquid water

Formation: Thermal convection currents.

Stratus:

          Stratus clouds are the lowest forming and are often called fog or mists when they are earth-bound Stratus clouds are formed when a large air mass cools at the same time (e.g. – a warm air parcel drifts into or above a cooler region.

A generally gray cloud layer with a uniform base which may, It is thick enough to completely hide the sun from view. If it  thick enough, produce drizzle, ice prisms, or snow grains. When the sun is visible through this cloud, its outline is clearly discernible.Often when a layer of Stratus breaks up and dissipates blue sky is seen.

Fast Facts:

Typical Altitude: 0-6,500 ft.

Location: Worldwide, but especially common around coasts and mountains

Precipitation: No more than light drizzle

Composition: Liquid water

Formation: Advective or radiative cooling.

Cumulonimbus:

Cumulonimbus clouds produce heavy showers over localized areas.  Thunderstorm clouds can also produce hail, lightning, and tornadoes. This is a heavy and dense cloud in the form of a mountain or huge tower. The upper portion is usually smoothed, fibrous or striated and nearly always flattened in the shape of an anvil or vast plume.Under the base of this cloud which is often very dark, there are often low ragged clouds that may or may not merge with the base. They produce precipitation, which sometimes is in the form of virga.Cumulonimbus clouds also produce hail and tornadoes. Three critical conditions for cumulonimbus

formation:

• Ready supply of warm, moist air, which rises at speeds of up to 25-70 mph

• Tropospheric winds need to increase considerably with height to encourage it to slant forward

• The atmosphere around the cloud needs to be “unstable” – no temp. inversions here

Fast Facts:

Typical Altitude: 2,000-45,000 ft.

Location: Commonin tropics and temperate regions, rare at poles

Precipitation: Heavy downpours, hail

Composition: Liquid water throughout, ice crystals at the top

Formation: Upwardly mobile cumulus congestus clouds.

Stratocumulus:

Similar to cumulus clouds in form and composition, stratocumulus clouds are textured and puffy, but also joined into a semi-continuous layer.Stratocumulus clouds usually form from cumulus or stratus clouds

This cloud name is a little unusual because the two key words for cloud appearance have been combined, but that's a good description of this cloud type - a "lumpy layer cloud".  Gray or whitish patch, sheet, or layered clouds which almost always have dark tessellations (honeycomb appearance), rounded masses or rolls. Except for virga they are non-fibrous and may or may not be merged.They also have regularly arranged small elements with an apparent width of more than five degrees (three fingers - at arm's length).

Fast Facts:

Typical Altitude: 2,000-6,500 ft.

Location: Worldwide – very common.

Precipitation: Occasional light rain, snow

Composition: Liquid water

Formation: Spreading and joining of cumulus clouds below a temperature inversion, wind turbulence in a stratus layer.

STORM CLOUDS

The most dramatic types of clouds are cumulus and cumulonimbus, or thunderheads. Rather than spreading out in bands at a fairly narrow range of elevations, like other clouds, they rise to dramatic heights, sometimes well above the level of transcontinental jetliner flights.

Cumulus clouds are fair-weather clouds. When they get big enough to produce thunderstorms, they are called cumulonimbus. These clouds are formed by upwelling plumes of hot air, which produce visible turbulence on their upper surfaces, making them look as though they are boiling.

Just as it takes heat to evaporate water from the surface of the Earth, heat is released when water condenses to form clouds. In thunderheads, this energy can produce hail, damaging winds, lightning, torrential rain, and sometimes tornadoes.

As thunderheads reach high elevations, their tops encounter high winds that cause them to spread out sideways, earning them the nickname "anvil tops." They can reach elevations of 50,000 feet (15,000 meters).