Some are high in the sky. Others so low that they almost touch the ground. Some days there are no clouds. Clouds look quite substantial as we see them from the ground but they are composed of loosely spaced water droplets and are actually not very solid at all. They form when the composition and movement of an air mass creates the right conditions.
Clouds form when moist air cools.
We see these tiny droplets as clouds. If they are very close to the ground we see them as fog. These droplets are not big enough to fall as rain. The highest clouds are typically about 17,000 to 50,000 feet above the ground. These are the cirrus clouds which are composed of ice crystals and appear as white, silky filaments, patches or bands.