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Local Winds High level clouds
Clouds - Physical Geography
892    Dibyendu Banerjee & Sudipta Banerjee    31/05/2021


Clouds are formed due to the rising of warm air. As solar radiation heats the ground, the air immediately above it becomes warm and lighter, and the flow of air pushes this warm air upward. This upward moving warm air contains water vapours, originated by evaporation of the water-bodies on the surface of the Earth by the heat of the Sun. However, as these water vapours move up, they become cooler and denser. In this process of cooling and getting dense, soon a time comes when the air cannot hold any more moisture, in other words, the air becomes saturated. As it rises more, its temperature drops further, and the air contracts and becomes unable to hold the moisture anymore and releases some of it. The moistures thus released cling to dust particles and become condensed into tiny droplets of water. The air floats these condensed droplets up above, and millions of these particles make up a cloud. In other words, the clouds are composed of billions of tiny water droplets or ice crystals, which are extremely small, averaging about 0.01millimetre.


Clouds are often found on the windward side of a mountain because the air blowing over the hills and mountains is forced up, which can lead to the formation of clouds that can cover the top of some of the mountains permanently. On the contrary, the air that blows down the slopes of a mountain sinks, and as its temperature rises, its capacity to hold the vapor increases, resulting in evaporation before the formation of a cloud. Consequently, it is often clear and drier on the lee side of a mountain.


Although the clouds generally appear uniformly grey or even black, they can also appear colourful. As clouds are composed of billions of tiny droplets, they act as reflective glass beads and are excellent reflectors. Consequently, clouds may appear in a variety of colours like reddish pink, pink, orange, or yellow around the time of sunrise or sunset.

Clouds act as a shield against the scorching rays of the raging sun, and thus bring relief during the hot summer days and help to regulate the Earth's temperature. They also bring rain to give new life to the thirsty souls and the dead soil and thus help the farmers to produce crops. Clouds can be beautiful and visually attractive, although they can also appear menacing, suggesting a violent turn in the weather.


There are different types of clouds and their types depend mainly on the height at which the water vapour in the air condenses. Hence, clouds are quite reliable indicators of weather conditions. They are named according to their shape and their height in the sky. The clouds are basically formed through the vertical of air above the condensation level. However, they may also form in contact with the ground surface and such clouds are known as fog, ice fog, or mist. Classification of the clouds was devised by an English man, Luke Howard, in the early 19th-century, who used Latin words to classify them. The types of clouds can be divided into three levels, high level, mid level and low level clouds, as they form in three basic patterns.

Local Winds High level clouds
Author Details
Dibyendu Banerjee & Sudipta Banerjee
Article by Dibyendu Banerjee, an Ex-student of Scottish Church College, Kolkata. Authored several novels in Bengali and translated into Bengali novels/short stories of eminent writers of the world. Regularly contributes articles to different web sites on different subjects. Edited by Sudipta Banerjee, educated at Loreto House, Kolkata. Completed her B.A [Hons] in Geography and M.A from Presidency College, Kolkata, B.Ed from the Institution of Education for Women, Hasting House, Kolkata. Taught for 38 years, as Middle School Mistress at Victoria Boys’ School, Kuseong and as Asstt Teacher in Geography at Multipurpose Govt Girls’ School, Kolkata.
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