We all know clouds as the puffy white masses in the air or the dark gray clouds that bring us rain, but have you ever wondered what they are made of? To answer this question we first need to look at the water cycle.
The water cycle
In basic terms the water cycle is the continuous movement of water on Earth and how water changes states (solid, liquid or gas) on the Earth. The first third of the water cycle is when surface water evaporates into the atmosphere. It then condenses (which forms clouds) and falls back to the earth in the form of rain or snow. This rain and snow eventually makes its way to large bodies of water, such as lakes and oceans, where the process begins again.
What are clouds made of?
By following the water cycle we can see the clouds are made of water vapor. However, water vapor is invisible and it is the condensation process that makes clouds visible. The upper reaches of the atmosphere much cooler than the surface of the earth and when the water vapor cools it changes from gas to liquid. These tiny droplets of liquid are so light that they can stay suspended in the air, sometimes with the help of small dust particles. Light is reflected and refracted from these water droplets and this is how clouds become visible. Rain or snow occurs when the water droplets become too heavy to remain in the air.