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Cool Cloud Formations!
What are clouds?
What clouds are made of? How are clouds made? What are the different types of cloud formation? These questions are often asked by kids as they become curious about the world around them, and it can be hard to explain!
This is a simple guide to help adults and children understand the different types of cloud, how they form and how each type of cloud affects our weather.
Clouds may often hide the sun but there are so many wonderful shapes and sizes, from the night shining cloud, to the all powerful supercell! How many of these weird clouds have you seen?
I hope you will enjoy this basic guide to clouds and find the cloud photos here as fascinating as I do!
The 4 major cloud types
In a nutshell, the 4 major cloud types are:
Nephology - the physics of clouds
How clouds are made
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.
Make a cloud in a bottle!
Vertical cloud formations
Identifying Cumulus, Cumulonimbus and Supercell 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 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 tornadoes. These dense clouds can tower up to 14 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!
Low cloud types - What clouds make it rain?
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.
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 horizontal grey mass and the lowest forming. Fog and mist are Stratus clouds at ground level, but the highest can reach is is 6,500 feet when it becomes a "cloudy day".
Middle cloud formations - clouds that hide the sun
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 grayer it gets. It is a very dull looking cloud, but always looks lovely during a sunset as you can see from the image on the right.
If there is a humid morning, you may see these grayish, puffy clouds which often precede a thunderstorm. They can look like parallel bands or rolling masses.
High level cloud types - clouds formed from ice crystals
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 "a mackerel sky" due to the fish scale effect they produce! Cirrostratus can mean rain or snow within the next day.
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".
Contrails are artificial clouds made from ice particles produced from the aerosols from aircraft exhaust. They are produced in very cold temperatures at -40 degrees and at high altitudes of 26,000 feet.
Contrail from a space shuttle launch
Weird cloud formations....have you seen any of these rare clouds?
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.
Watch people cloud surfing roll clouds!
These absolutely beautiful and ethereal clouds are seen on the very edges of the world's atmosphere, in the mesosphere. Noctilucent clouds look like thin spidery blue veins against the twilight sky, glowing electric silver and blue - hence their nickname "night shining clouds". So what are Noctilucent Clouds? Some scientists believe that they are a sign of global warming, others believe that it could be space dust in the higher reaches of the mesosphere catching the rays of the sun.
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 air masses pushing cloud into shapes like rough waves on the sea.
The Lenticular cloud
This is an Altocumulus Lenticularis, a rare lens-shaped cloud that forms when moist air flows over mountains. Some people believe that aliens hide in these clouds or that Lenticular clouds are actually flying saucers!
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 Nacreous clouds 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 Arctic.
Mammatus comes from the Latin, meaning "mammary" because of their bosomy shape! Mammatus clouds look like they are bringing apocalyptic 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.
Daffodils by William Wordsworth
Great websites about clouds and weather
- Clouds - Met Office
Find out more about clouds
- The Cloud Appreciation Soceity
The official society for all cloud lovers! This is the number one place to look if you want to see stunning photos and submit your own, learn more about clouds and chat with like minded cloud appreciators!
- The Royal Meteorological Society
The Royal Meteorological Society is the Learned and Professional Society for anyone whose profession or interests are connected with weather.
- NASA Earth Observatory : Home
The Earth Observatory's mission is to share with the public the images, stories, and discoveries about climate and the environment that emerge from NASA research, including its satellite missions, in-the-field research, and climate models.
- World Meteorological Homepage | WMO
Weather from all over the globe!