Clouds are one of nature's most visible wonders, and they can tell us a lot about what's going on in the atmosphere. The variety of ways clouds can form and the variable nature of the atmosphere result in an enormous variety of cloud shapes, sizes, and textures.
Many people believe that clouds are only made up of water vapor. However, this is absolutely not true. Water vapor is invisible and is always present in the air, around us. Sometimes there is more water vapor in the air than usual. In this case, the air is humid and oppressive. Other times there is less water vapor in the air than usual and we indicate that the air is drier and fresher.
Clouds appear when there is too much water vapor for the air to hold. Water vapor condenses to form tiny water droplets; that is, there is a transition from the gas phase to the liquid phase. As a result, this water makes the cloud visible. The water droplets are so small that they hang in the air.