Cumulonimbus clouds produce rain, hail and other attributes of thunderstorms. These clouds begin as cumulus clouds that achieve vertical growth. Tornadoes are also a product of cumulonimbus clouds.
Cumulonimbus clouds have a layered effect, which is indicative of the cloud growth. The reach of the cloud extends from 1000 feet above the surface to more than 40,000 feet. Water vapor and updrafts within a cumulus cloud create the larger cumulonimbus as part of the thunderstorm cycle. Sometimes the anvil-shaped top of the cloud is visible before the lower part of the clouds, which appears as a wall. These clouds also produce winter storms, such as blizzards.