Clouds are made of water. In general, they consist of water droplets or ice crystals. As the droplets and crystals grow sufficiently heavy, they fall down as rain. Fog is a cloud that reaches the earth’s surface. The clouds are created when moist air rises it cools and condenses into very small droplets or ice crystals.
Clouds cool the planet by reflecting solar radiation back into space. On the other hand they have a warming effect in the winter also prevents the heat escaping from the Earth’s surface.
In addition to the regulation of the temperature, the clouds are vital for plants and animals, as they carry water from the rivers and the wetter regions to drier regions. If there were no clouds, it would not rain water and many plants die from drought. Then there would be no food for the animals.
In deserted lands it is usually not raining. They are dead spots, in which only species that can survive are those, that specialize in surviving such hostile environments.