Summary
Highlights
Clouds are not made of gas, but rather a large mass of tiny liquid water droplets or ice crystals.
The process begins with the sun warming the ground, causing the air and water vapor within it to rise and cool.
As water vapor cools, it condenses and sticks to tiny particles in the air, called condensation nuclei (such as salt and dust), which provide a surface for condensation.
When enough vapor condenses around these nuclei, a cloud droplet is formed. These droplets are incredibly small, with 100 million in a cubic meter of air.
Despite their small size, a cumulus cloud can weigh as much as 500 tonnes, equivalent to about 100 elephants.
Individual water droplets are tiny and spread out, allowing clouds to stay afloat. When droplets combine and become too large and heavy, they fall as rain.