Fascinating and Beautiful Clouds!

"I wandered as lonely as a cloud, that floats on high o'er vales and hills"
Daffodils by William Wordsworth

Before we look at the various types of cloud, let's begin with how clouds are formed. Clouds are a combination of water vapour or ice crystals and microscopic dust particles that are found in rising warm air. These billions of tiny droplets of water or ice are so light they float in the Earth's Troposphere - causing the clouds you see everyday.

In 1802 Luke Howard, a British amateur meteorologist, presented a paper called
"On the Modification of Clouds", a system in which clouds should be classified. This system is still used to this day and divides clouds into two categories, layered and convective, which indicates at what altitude they can be found and the processes that form them.

Layered cloud - these have a flattened appearance and not much vertical height.

Convective cloud - are clouds produced by pockets of warm air thermals rising directly from the surface below.

Each cloud belongs to a family (genus): high, medium, low and vertical. Within each family there are species for clouds which distinguishes their appearances and varieties.Clouds are measured at their base height rather than from the top of the cloud.

Cloud chart from jmmcdgll at Flickr Creative Commons

Fair Weather Cumulus Clouds by Nicholas T at Flickr Creative Commons

Cumulus Clouds
At an altitude of about 2000 - 6000 feet, the Cumulus are one of the most common with flat bases and fluffy cotton wool cauliflower like tops that grow vertically. Cumulus are formed by a convection of air pushing a thermal of hot air upwards, as it rises it cools, expands and the water vapour condenses into tiny cloud droplets. If these clouds don't have too much vertical growth, fair weather is ahead. However, these benign looking clouds can develop into the more ominous Congestus Cumulus, which can then grow on into the awesome Cumulonimbus.

Cumulonimbus by toxickore at Flikr

Cumulonimbus Cloud - the King of Clouds
This gigantic cloud is responsible for most types of extreme weather, such as thunder storms, heavy rain, hail, snow and tornados. These dense clouds can tower up to 10 miles in height, when a cumulonimbus reaches the troposphere the high winds flatten the top which creates an anvil shape. These clouds can been seen in groups or alone and are most common in tropical or temperate regions. Cumulonimbus can hold up to half a million tons of water. They can grow to form a Supercell Cloud which has the potential to be the most severe of thunderstorms - the photo below is of a Supercell, very scary!

Cloud to Ground Lightning from a Central Nebraska Supercell Buy at AllPosters.com

Stratocumulus
These grey lumpy clouds look like flattened cumulus and they appear in either horizontal layers of patches, rows or masses. They can produce limited drizzle and a little light rain, and can cover the whole sky for many hundreds of miles. These clouds are responsible for bringing a winter gloom that hangs around for days.

Nicholas T at Flickr

Nimbostratus - the Rain Cloud
Covering the whole sky in a grey blanket, nimbostratus most commonly produce persistent moderate to heavy rain or snow. If you want to find out about how rain happens, visit my page "Rain! Glorious Rain!" to learn more.

Stratus Cloud - the Drizzly Cloud.
When a large air mass cools at the same time, this creates a stratus Cloud. These clouds are a featureless grey mass, horizontal and the lowest forming. Stratus are fog or mist at ground level, the highest it can reach is 6,500 feet when it becomes a "cloudy day".

Low Clouds over a Rain Forest at Twilight. Buy at Allposters.com

Altostratus Cloud by de:Benutzer:LivingShadow at Wikimedia

Altostratus - the boring cloud
When the Stratus clouds rise about 6500 feet it becomes the Altostratus. This flat mass belongs to the middle level of clouds, the thicker the cloud becomes the greyer it gets.
Altocumulus
If there is a humid morning, you may see these grayish, puffy clouds which often precede a thunder storm. They can look like parrallel bands or rolling masses.

Altocumulus Cloud by Tea, two sugars at Flickr

Cirrocumulus
When you see these pretty puffy clouds sailing high, fair weather is forecast for tomorrow. These are seen in rows and form patterns like popcorn, cirrocumulus can also form a pattern termed "mackerel sky" due to the fish scale effect they produce. Cirrostratus can mean rain or snow within the next day.

Cirrocumulus by globevisions at Flickr

Cirrus Clouds
These are the highest clouds at 16,500 to 45,000 feet and are composed of tiny ice particles. They make wonderful wispy shapes due to the 100 - 150 mph fluctuating winds at that height. Cirrus mean fair weather ahead and are nicknamed "mare's tails".

Cirrus Clouds against a Deep Blue Evening Sky. Buy at Allposters.com

Contrails
Contrails are artificial clouds made from ice particles produced from the aerosals from aircraft exhaust. They are produced in very cold temperatures at -40 degrees and at high altitudes of 26,000 feet. This picture is the contrail from a missile launch.

Contrails of a Missile Launch at Sunset. Buy at Allposters.com

Asperatus Undulatus Cloud by Agathman at Wikimedia Commons

Undulatus Asperatus Cloud
This surreal looking cloud is a new discovery, the first since 1951! This has been put forward for official classification by the founder of the Cloud Appreciation Society, Gavin Pretor-Pinney. It looks scary, but these clouds generally follow after a storm rather than become one. The wave affect comes from turbulent differing air masses pushing cloud into shapes like rough waves on the sea. I have been lucky enough to see one of these, read more about this special cloud here: A Guide to the Undulatus Asperatus

Morning Glory Cloud
This is a roll cloud which can reach 1000 km long and 1-2km high, this rare cloud is found in North Australia in the Gulf Carpentaria. The Morning Glory is accompanied by short squalls of wind, the air at the front of the roll pushes up, with the air at the rear of the cloud sinks. Because of this "cloud surfers", glider pilots can ride these clouds like waves.

Morning Glory Cloud by Mick Petroff at Wikimedia commons

The UFO Cloud
This is an Altocumulus Lenticularis, a rare lens-shaped cloud that forms when moist air flows over mountains. Read more about this majestic cloud here: Clouds That Look Like UFOs: Altocumulus Lenticularis Cloud

Lenticular Cloud by Rootmeansquare at Wikimedia commons

The Nacreous Cloud
This cloud occurs in the polar regions during winter at a very high altitude of 15,000 to 25,000 metres. They form at low temperatures and although beautiful they contribute to the destruction of the ozone layer. These clouds convert benign chlorine in the atmosphere into a destructive form and also by removing the nitrogen compounds that help prevent the chlorine becoming reactive. These clouds are becoming more common in the polar regions, particularly the Artic. Read more about this cloud formation here: A Guide to Rare Nacreous Clouds.

Polar stratospheric cloud over Asker, Norway by Mathiasm at Wikimedia

Mammatus Clouds
Mammatus comes from the Latin, meaning "mammary" because of their bosomy shape! Mammatus clouds look like portents of scary weather, but they are actually harmless. Mammatus form of often on the underside of an anvil cumulonimbus cloud, after the storm has passed. The ice crystals at the top of the anvil start to sink as they become heavier than the surrounding air. The base of a cloud is flat because all moisture evaporates at that level, but the ice crystals they are still too large to melt, so they sink further - and this creates the mammatus pockets.

Clouds Like Cotton Balls (Mammatus cloud) by eviltomthai, on Flickr

White sheep, white sheep,
On a blue hill,
When the wind stops,
You all stand still.
When the wind blows,
You walk away slow.
White sheep, white sheep,
Where do you go?

Heavy hearts, like heavy clouds in the sky, are best relieved by the letting of a little water.
Christopher Morley

I am the daughter of Earth and Water,
And the nursling of the Sky;
I pass through the pores of the ocean and shores;
I change, but I cannot die.
For after the rain when with never a stain
The pavilion of Heaven is bare,
And the winds and sunbeams with their convex gleams
Build up the blue dome of air,
I silently laugh at my own cenotaph,
And out of the caverns of rain,
Like a child from the womb, like a ghost from the tomb,
I arise and unbuild it again.
(taken from the last verse)

It is better to have your head in the clouds, and know where you are... than to breathe the clearer atmosphere below them, and think that you are in paradise.
Henry David Thoreau