Clouds are actually water vapors or tiny droplets of water or ice crystals so small they can float in the air. The formation of clouds follows the Water Cycle as mentioned below:
When the water on the ground warms up by the sun’s heat, it changes from a liquid into water vapors; this process is called evaporation. Due to differences in density between warm humid air (low) and dry air (high), the warm humid air rises because of its lower density. As the water vapor in humid air cools down it becomes water again, this process is called condensation. Water falls from the sky in the form of rain, snow, hail, or sleet, this process is called precipitation.
How are clouds formed?
Air contains a small percentage of water vapors from oceans, lakes, rivers etc. It is usually in the form of an invisible water vapor due to the heat of the sun. The air on the surface is warm and when the warm air laden with water vapors rises into the sky, it expands due to the decrease in atmospheric pressure and warm air cools and the cool air can no longer hold all its water vapors, so it changes into small drops of water vapors.
The water vapors condense into tiny pieces of dust called aerosols (condensation nuclei) that are floating in the air and form a tiny droplet around each aerosol. When billions of these droplets come together, they become a visible cloud. Cloud droplets are tiny, only 1/100 mm in diameter, and are thus very light and practically float freely in the air. The tiny droplets just aren’t heavy enough to fall. The droplets grow into drops by acquiring more water and becoming larger. When they reach a diameter greater than 1/10 mm they can’t stay floating in the cloud and will start to fall. This results in the precipitation, i.e., rainfall.
Types of clouds
1.Cumulonimbus Clouds are thunderstorm clouds. These clouds are associated with heavy rain, snow, hail, lightning and even tornadoes.
2. Cirrus clouds are the most common type of the high clouds. They are composed of ice and are thin, wispy white clouds blown in high winds into long streamers.
3. Cirrocumulus clouds appear as small, rounded white puffs that appear in long rows. Cirrocumulus clouds are usually seen in the winter.
4. Altostratus clouds are gray or blue-gray mid level clouds composed of ice crystals(snow) and water droplets(rain). The clouds usually cover the entire sky.
5. Altocumulus clouds are made of water droplets and appear as gray puffy masses. They usually form in groups. Altocumulus clouds also bring thunderstorms.
6. Cumulus clouds are white, puffy clouds that look like pieces of floating cotton. Cumulus clouds are often called “fair-weather clouds”. The base of each cloud is flat and the top of each cloud has rounded towers. These clouds grow upward and they can develop into giant cumulonimbus clouds, which are thunderstorm clouds.
7. Stratus clouds are uniform grayish clouds that often cover the entire sky. They resemble fog that doesn’t reach the ground. Light mist or drizzle sometimes falls out of these clouds.
8. Stratocumulus clouds Clouds are low level clouds, puffy and gray. Most form in rows with blue sky visible in between them. Rain rarely occurs with stratocumulus clouds.
Why do clouds form at different heights in the atmosphere?
The height or level at which a cloud forms depends on the temperature and pressure of the air and the amount of water content it has and the wind. For example, colder clouds are higher in the atmosphere and warmer ones closer to the earth surface. Also warmer clouds can hold more water vapor than colder clouds.
Why are clouds white?
An object looks red if it absorbs all colors of the visible spectrum except red. Similarly other colored objects appear so because they absorb all colors of the visible spectrum except the color they appear to be. Clouds are white because they reflect all colors of different wavelengths, which combine to produce white light.
Why do clouds turn gray?
If the clouds get thick enough or high enough then it does not scatter all the light, therefore appearing gray or dark. Also, if there are lots of other clouds around, their shadows can add to the gray or multicolored gray appearance.
Zia Ahmed Khan, email: khanziaahmed50@gmail.com
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