Frequently, the cloud itself cannot be seen because of the rain or snow that is falling from it. Other clouds are mainly water droplets. A cirrostratus cloud is a thin sheet of cloud. It often causes a halo to appear around the sun or moon. This halo is a good way to recognize a cirrostratus cloud.
Cirrocumulus clouds look like many small tufts of cotton hanging high in the sky.
These clouds are rare. Cumulus clouds are heaped-up piles of clouds. They can look like small cotton balls, or they can grow into the most spectacular of all clouds, the cumulonimbus . Its top, which contains ice crystals, spreads out in the shape of an anvil. This kind of cloud is often called a thunderhead because it frequently produces thunder .