Which cloud type is specifically associated with thunderstorms?

Cumulonimbus clouds are specifically associated with thunderstorms due to their vertical development and structure. These clouds are capable of producing severe weather phenomena, including heavy rain, lightning, hail, and tornadoes. Cumulonimbus clouds typically develop in an unstable atmosphere where warm, moist air rises rapidly, leading to strong updrafts and the formation of towering cloud structures that can reach high altitudes. The presence of these characteristics directly correlates with severe weather, making these clouds the primary type associated with thunderstorm activity.

In contrast, cumulus clouds are generally puffy, white clouds that may indicate fair weather rather than severe storms. Stratus clouds are low, gray clouds that often lead to overcast conditions and light mist or drizzle but lack the vertical growth needed to form thunderstorms. Altostratus clouds are mid-level clouds that can cover the sky and produce light precipitation but are not indicative of severe weather or thunderstorms. Thus, cumulonimbus stands out as the only cloud type inherently linked to thunderstorms.