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clouds at playClouds and Some Things You May Want To Know About Them
by Marjorie Dorfman

What are clouds anyway and who do they think they are? Why are there so many different kinds and how do they form? These and other issues will be addressed whether your head is below, in or above the clouds.

I’ve looked at clouds from both sides now, from up and down and still somehow, it’s cloud illusions I recall. I really don’t know clouds at all.
~Judy Collins

What are clouds and how do they form?

Clouds are natural phenomena that add beauty and well as function to the atmosphere. Clouds form in the troposphere, which is the lowest portion of the earth’s atmosphere. The word derives from the Greek "tropos," meaning turning or mixing. Most daily weather phenomena occur in the troposphere. Because climate is dynamic, different conditions of turbulence give rise to many types of clouds. Many types occur so frequently that scientists name them, and it is known that some atmospheric conditions can cause the clouds to organize in distinct patterns, such as wave clouds or actinoform clouds.

The cold region of the troposphere, above 23,000 feet, is where clouds develop. At this altitude, water almost always freezes and ice crystals are the main component of the clouds that form. They are usually wispy and transparent and known as cirrus clouds, of which there are more than a dozen variations. They are known to have a traditional "mare’s tail" appearance with no tufts or curls at the ends. Large amounts of these clouds are often an indicator of an approaching storm system.

High Level Clouds

clouds at lakeClouds are divided broadly into three levels: high, medium and low. Latin words describe their different appearances. All clouds that have a ‘cir’ as a prefix are the higher-level clouds (the snobs of the sky, if you will). There are several variations, including: cirrus castellanus, cirrus duplicatus, cirrus floccus, cirrus fibratus, cirrus radiatius and cirrus intortus to name a few. (If this sounds like a roster of ancient Roman senators, it is understandable.)

Mid Level Clouds

Mid level can appear anywhere between six thousand and twenty thousand feet. Primarily composed of water droplets, if the temperature is very cold they can contain ice crystals. These clouds are known for the uniform gray sheet or layer that runs alongside them and can be very dangerous to aircraft because they can cause ice-accretion. The major types of mid level clouds are Altostratus Clouds and they include:

altostratus duplicatus
altostratus lenticularis
altostratus mammatus
altostratus opacus
altostratus praecipitatio
altostratus radiatus
altostratus undulatus
altostratus translucidus

Lower Level Clouds

Lower level clouds are less snobbish than their higher counterparts. They hang low in the air (well, duh) and resemble cauliflower on top with a flattish base. Referred to as cumulus clouds, the word is Latin for "heap." Called "the King of the Clouds" when the other clouds are distracted and unable to argue, clusters of these small, white clouds usually indicate fine weather. Sometimes, they can develop into storm clouds known as cumulonimbus. The base of a cumulonimbus cloud is often low but it can also be as high as 10 kilometers, (more than 6 miles). Some cumulus types include:

cumulus arcus
cumulus congestus (often spreads chest colds)
cumulus fractus (argumentative, stay away from)
cumulis humilis (more humble than most)
cumulus mediocris (usually can do much better)
cumulus praecipitato
cumulus radiatus (warm and informative)

Stratus Clouds

Stratus clouds are known to be layer-like and are usually associated with the widespread precipitation of ocean air. They can produce drizzle and can often be seen very low in the air. Usually light grey in color, these clouds are composed of fine water droplets that grow larger as they collide with each other. Some types of stratus clouds include:

stratus fractus (accident-prone)
stratus lenticularis (slow, dull)
stratus nebulosus (vague and uncertain)
stratus opacus (shallow, transparent)
stratus praecipitato
stratus translucidus
stratus unulatus (opinionated)

Cloud Colors and What They Mean

The color of a cloud is the primary indicator of what is happening inside of it. Traditional white clouds may be boring to some, but they occur primarily because sunlight cannot penetrate far into the cloud as tiny particles of densely packed rising and cooling water form the cloud’s structure. It is the reflection/absorption process that creates the range of cloud colors from white to grey to black. The lack of light being reflected is the reason why the undersides of large clouds and heavy overcasts so often appear to be various shades of grey. (It has nothing at all to do with indecision or ambivalence, as formerly believed.)

Some colors occur naturally in clouds. Bluish-grey, for example, results from degrees of light scattering within the cloud that are produced by rain-sized droplets. Blue and green are at the short end of light's visible wavelengths, while red and yellow are at the long end. The short rays are more easily scattered by water droplets, while the long rays are more likely to be absorbed. Green occurs in clouds when sunlight is scattered by ice. During the forest fire season from late spring to early fall, yellowish clouds may appear but they are somewhat rare. The color always indicates the presence of smoke.

Other cloud colors include red, orange and pink. They occur almost always at sunrise and/or sunset (whether that old song by Perry Como is playing or no) and are the result of the atmospheric scattering of sunlight. The colors are actually a reflection of the long unscattered rays of sunlight, which prevail at those hours.

The Morning Glory Cloud

twisterSome clouds form as a consequence of interactions with specific geographical features. One of the world’s strangest clouds of this type is the Morning Glory, a rolling cylindrical cloud, which appears unpredictably over the Gulf of Carpentaria in Northern Australia. Associated with a powerful "ripple" in the atmosphere, this cloud can actually be "surfed" in glider aircraft.


Clouds are a fascinating natural phenomenon, the subject of which could fill the pages of the thickest tome. The next time you see some minding their business in the sky above your head, stop and look at them. You may even want to salute them as you pass mindfully and respectfully by.

You never know what secret powers they may choose to yield.

Happy cloud formations to all!

© 2008 Marjorie Dorfman
Stuff in the air

Did you know . . . ?

We found this great book:

The Book of Clouds

by John A. Day

Financial Peace, Jr.

Photographer and scientist John Day, Ph.D. in cloud physics and known round the world as "The Cloudman", introduces and enthralls readers to the earth's great skyscape. A magnificent cloud chart; an explanation of clouds formation; hints on forecasting, observing, and photographing clouds; and his "Ten Reasons to Look Up" teach us to use our inner eye to really perceive those familiar fleeting forms.

Available as well in hardcover.

See this special note about Cloudman.

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