Which description best defines cumuliform clouds?

Cumuliform clouds are characterized by their lumpy, billowy appearance, which resembles the shape of cotton balls or popcorn. They typically have a well-defined base and exhibit a vertical development, often leading to the formation of towering structures. This distinct visual characteristic is due to the upward movement of warm, moist air which cools and condenses to form these cloud types.

The description highlights the key features of cumuliform clouds, such as their structural base and the generally puffy shape. This is particularly relevant as cumuliform clouds can evolve into more complex formations, such as cumulonimbus clouds, which are associated with thunderstorms.

In contrast, other types of clouds have different characteristics; for example, clouds that appear as uniform horizontal layers belong to the stratus category, while thin, wispy clouds would be classified as cirrus clouds. Clouds associated with precipitation are typically more varied and can include several types, not limited to cumuliform. Therefore, the defining traits of cumuliform clouds align closely with the selected option.