How to become a cloud expert in 5 minutes and impress your friends!
This post is a re-cap of your old geography lessons, a cloud 101! When you were too cool for school you may have professed that you found this boring….but you can drop the act now. How much do you really know about clouds?
If your knowledge is below par, relax! We have everything you need to know right here. We will start with the basics.
What Exactly Are Clouds?
A cloud is defined by Google as….a visible mass of condensed watery vapour floating in the atmosphere, typically high above the general level of the ground. They are a collection of tiny droplets of water or ice crystals, so small and light that they float.
They bring rain that is essential to life and regulate the temperature of the Earth. They can change shape and form and provide indictors to weather that is on the way.
How Do Clouds Form?
The short answer is that clouds appear as water changes from gas to liquid in the air. The process is called convection. The sun heats the ground and air directly above it. As it warms, the air becomes lighter and flows upwards, carrying water vapour (evaporation). As the air continues to rise it cools and deposits the water vapour, which ‘condenses’ and clusters together, remaining in the atmosphere.
The opposite can happen when air sinks. It can carry more water vapour, and clouds appear to dissolve as the water changes back from tiny liquid droplets into gas.
Clouds can also form over mountains where air is forced upward against the steep slope, and when two large bodies of air collide.
Clouds tend to appear white because their water droplets are large enough to scatter the light of the spectrum, which combine to produce white light. If they get thick enough, or reach a high enough altitude, where light cannot get through, the clouds appear dark and grey.
Heights of Cloud
Clouds are constantly changing and can be seen in a huge variety of forms. Luke Howard, a pharmacist from London and amateur meteorologist, wrote a book ‘The Modification of Clouds’, in 1803 which classified the clouds, this is the foundation still used today. Howard classified them using Latin words based on their appearance.
The World Meteorological Organisation (WMO) includes additional classifications to bring us 10 main types of cloud, known as genera. These genera are split between three levels – cloud low (CL), cloud medium (CM) and cloud high (CH) – according to the height of the atmosphere in which they tend to form. “Low” clouds are usually below about 6,500 feet in altitude. ”Middle” clouds are generally from about 6,500 feet to 20,000 feet, and high clouds form at around 20,000 and 40,000+ feet in altitude.
Types Of Cloud
The names for clouds are usually are combinations of the prefixes or suffixes listed below.
Stratus/Strato = flat, layered and smooth, suggesting sheets or layers
Cumulus/Cumulo = heaped up, piled and puffy
Cirrus/Cirro = High up, wispy, meaning curly or fibrous
Alto = Medium level
Nimbus/Nimbo = Rain-bearing cloud
These are detached clouds, formed of delicate, wispy, white streamers, composed of ice. They are the most common of the high clouds. They are usually an indicator of fair weather, showing particularly well the direction of approaching wind. They often appear silky smooth and can be coloured in bright reds and yellows at sunrise and sunset.
These are thin and flat, and often blanket the whole sky with a translucent skin. You can usually see the sun or moon through the veil of cirrostratus clouds, with a pretty halo effect. They tend to be a warning of a rain or snow storm that is brewing.
These are most often an indication of pleasant but cold weather, or adversely, a hurricane in tropical areas. Cirrocumulus clouds are like small round cotton wall balls, arranged in rows. Often likened to the scales on a fish they are arranged in the sky in a regular recurring pattern of ripples.
These are bluey-grey clouds that appear at mid height, formed of ice crystals and water. They tend to cover the whole sky and form as a warning of rain storms to come. The sun is usually visible through altostratus clouds, but no halo effect is seen.
These also form at mid level. They are puffy blobs off grey that hang around in groups. They are common on a hot day as an indicator of thunderstorms on the horizon. It is not unusual for altocumulus clouds to be present with other types of cloud simultaneously.
These clouds are usually grey and cover the entire sky in a mid level fog. Stratus are often accompanied by a light mist or drizzle.
These are piled up puffs of grey fluff that form in regular, honeycomb type rolls across a blue sky. They are not generally rain clouds, but can change to nimbostratus clouds.
These are heavy and wet looking grey clouds that bring continual light rain or snow. They are sometimes accompanies by low, ragged clouds, and are thick enough to hide the sun entirely.
These are the pretty white bunny tails that float across the sky in fair weather. The tops are often wispy and tall in peaks. They are quite dense and detached, in a brilliant white, except for the base which can be quite dark. Cumulus clouds grow upwards and can become giant cumulonimbus clouds.
These are the dense and heavy thunderstorm clouds, which tend to have flat tops due to high winds. They bring bad weather, heavy rain, snow, hail and lightening. These anvil shaped clouds can be associated with hurricanes.
In addition to these 10 commonly seen clouds there are others associated withe extreme weather and unusual phenomena. Mammatus clouds are low slung blobs that hang from cumulonimbus clouds in severe weather. Lenticular clouds look like flying saucers and form near mountains due to unusual wind patterns. Fog is a cloud that forms on the ground, reducing visibility to dangerous levels. Fractus clouds are raggedy, torn pieces of cloud that have broken away from larger clouds, often in high winds.
No two clouds are exactly alike, and they come in all shapes and sizes – and are frequently gazed upon by daydreamers, who can find all manner of images within the clusters of water vapour. They are fascinating to people of all ages and can be a useful tool in predicting the weather. Now that you have the facts you can go out and impress your friends with your cloud-based knowledge!
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