The mixture of warm and air and water vapor keeps rising until it is high above the land. The higher it rises, the cooler the air around it becomes. Soon the mixture of water vapor and air reaches the upper atmosphere. The upper atmosphere is cooler than the air near the surface of the earth. It is filled with tiny particles.
Particles are tiny bits of things such as dust, salt, and volcanic ash.
When the water vapor and air mixture cools in the upper atmosphere, it hits the tiny particles that are there. When this happens, the water condenses, or changes back into water droplets. Water droplets are tiny drops of water. When millions of water droplets group together they are called a cloud.