What type of clouds are categorized as big rain clouds?

Nimbus clouds are recognized as the type of clouds that produce significant precipitation, such as rain. The term "nimbus" itself is derived from the Latin word for rain, underscoring the association with precipitation. Nimbus clouds are often dark and thick, indicating a large volume of water vapor, which condenses to form raindrops.

They can exist in various forms but are most frequently associated with nimbostratus clouds, which are expansive and cover large areas, resulting in steady, continuous rainfall. Initialized from cumulus clouds during development, they play a crucial role in the weather system by delivering substantial rain, as opposed to lighter precipitation associated with other cloud types.

Cumulus clouds, while they can produce rain, are typically puffy and indicate fair weather unless they have developed into more mature storm clouds, such as cumulonimbus. Stratus clouds are usually associated with overcast conditions and light drizzle, while cirrus clouds are high-altitude clouds that signify fair weather and do not produce precipitation. This reinforces why the designation of nimbo as a distinguishing factor for rain clouds is essential.