This is a fascinating question asked by children and adults alike. What are those fluffy, white things up in the sky? How do they possibly come into existence?
Answering these questions is not as easy as asking them, but a simple definition can clear up the basics for you.
Clouds, as many people probably know, are condensed forms of water and ice. Whatever a cloud’s shape, size, or height, maybe, it had to have been formed in pretty much the same manner. So what is this process we talk about that yields rain clouds and storm clouds and the like? Let’s take a look.
The Formation
Air is very prone to expansion. When it expands and rises, this rising air sometimes cools down to a point where the water molecules start to “clump together.” This occurs so fast; they cannot be torn apart by thermal/heat energy.
The water vapor molecules are, of course, invisible. When a large number of them are combined, however, they become visible as big fluffy clouds. So clouds are only water, in the form of vapor. The vapor molecules are slightly more closely packed, less than liquid but much more than an ideal gas.
Types
There are various types of clouds. Some are denser or larger than others, some are shaped differently, and many have different colors. The colors depend on the sizes of various water droplets that make up a cloud.
The majority of the sunlight typically passes right through larger water droplets. It is the opposite, however, for small droplets. These scatter and reflect a lot of light. Thus, often, you will see that certain parts of a cloud are much brighter than the others.
For example, some clouds we call storm clouds to tend to be grayish or even black in color!
The sizes and shapes of clouds usually depend on the volume and formation of the air expanding and rising to form new clouds. The weather, of course, is a significant factor in deciding this. Thus, it is common to see smaller clouds in certain climates, while others yield larger, darker ones.