Which type of cloud is associated with thunderstorms?

Cumulonimbus clouds are the type associated with thunderstorms due to their vertical development and ability to reach great heights in the atmosphere. These clouds are towering and often have a characteristic anvil-shaped top that signifies intense upward motion of air, which is critical for thunderstorm formation. Within a cumulonimbus cloud, strong convection occurs, allowing for the development of rain, lightning, and severe weather conditions. The dense, moist air rises rapidly, leading to the formation of precipitation and the potential for severe characteristics such as hail and tornadoes.

The other cloud types listed do not have the same attributes that lead to thunderstorms. Cumulus clouds are generally puffy and indicate fair weather. Stratus clouds form in layer and usually bring overcast skies and light precipitation but are not associated with the severe weather conditions of thunderstorms. Cumulostratus clouds, which combine features of both cumulus and stratus, can produce light precipitation but are not the primary clouds associated with thunderstorms.