Sunset scene in Grimsby city, Lincolnshire county, England. A single cloud can contain billions of kilograms of water, but not all clouds produce rain.

Red, down-like cumulus clouds above a row of trees. They are located at an altitude of about 2,000 m and signal an approaching storm.

The Golden Gate Bridge in San Francisco, USA seems to float above a sea of low-level clouds. These clouds, which usually form at altitudes below 2,000 m, always carry rain or ice. If clouds touch the ground they are called dew.

The clouds look like dozens of plates stacked on top of each other above the top of Mount Rainier, Washington state, USA. They are created when high-level winds move over rough terrain.

The beautiful sunset scene in Tassajara, California, USA is enhanced by soaring clouds. However, the highest clouds often produce rain, thunder, lightning, hail and wind. Therefore, they can ruin the beautiful scenery at any time.

Cumulonimbus clouds are often columnar or mushroom shaped. They are the highest type of clouds, usually forming at altitudes of 15,000 m or more. The tops of these clouds often expand because they encounter winds aloft.

Cumulonimbus clouds over the city of Mitchellton, Saskatchewan province, Canada.

Brightly colored clouds and calm water create a beautiful sunset for boaters on the Winisk River in Ontario, Canada.

Clouds above Crate Lake in Oregon, USA. Usually clouds are white because they reflect sunlight.

White clouds look like curls of cotton above the Kalahari Desert in South Africa. Most clouds are created by the upward movement of air.

A photo taken by the Galileo spacecraft shows the extent of cloud cover above Antarctica.