How Do Clouds Form?

Although clouds might look like they are made of gas, they are actually a large mass of tiny drops of liquid water or ice crystals. The cloud formation process usually begins when the heat from the sun warms the ground. This causes the air at the ground level to rise, and the water vapor within it to cool. When cooled, the water vapor collides with and sticks to tiny particles floating in the air. These are known as condensation nuclei, containing aerosols such as salt and dust. As the vapor rises and cools, these nuclei provide the surface for the vapor to condense onto. When enough vapor condenses around the nuclei, a cloud droplet is formed. These droplets are so small that a cubic meter of air contains 100 million of them. However, combine to make a cumulus cloud, they can weigh as much as 500 tonnes (). That's roughly 100 elephants. The individual water droplets are so tiny and spread out that they stay afloat as a cloud. Sometimes these water droplets combined to become larger drops or crystals. And if they become large enough and too heavy, they will gradually fall from the sky as rain.