Height of base: 1,100 - 6,500 ft
Shape: Fibrous upper edges, anvil top
Latin: cumulus - heap; nimbus - rainy cloud
Precipitation: Heavy rain and thunderstorms
Cumulonimbus are heavy and dense low-level clouds, extending high into the sky in towers, plumes or mountain shaped peaks. Commonly known as thunderclouds, the base is often flat and very dark, and may only be a few hundred feet above the Earth's surface. Cumulonimbus clouds are associated with extreme weather such as heavy torrential downpours, hail storms, lightning and tornados.
If there is thunder, lightning or hail, it's a cumulonimbus cloud rather than nimbostratus.
The fluffy, cauliflower-shaped cumulus are one of the most common and distinctive types of cloud. All cumulus clouds develop because of convection.
Stratocumulus clouds consists of large, rounded masses of stratus that form groups, lines or waves.
Stratus clouds tend to be featureless, low altitude clouds that cover the sky in a blanket of white or grey.
Last updated: 7 August 2014