Which type of cloud is described as looking like heaps of cotton balls?

Cumulus clouds are characterized by their fluffy, white appearance and are often compared to heaps of cotton balls. These clouds typically have a distinct, rounded shape with a flat base and can develop into larger cloud formations as they rise in the atmosphere. Their development is generally associated with convective currents, which are the result of warm air rising and cooling, leading to the condensation of water vapor. Cumulus clouds can vary in size and can indicate fair weather, though they may also build into larger cumulonimbus clouds, which can produce thunderstorms.

In contrast, stratus clouds present a more uniform gray layer that covers the sky, resembling a blanket, and typically signal overcast conditions. Cirrus clouds are high, thin, wispy clouds that often indicate fair weather but do not have the fluffy, cotton-like appearance of cumulus clouds. Nimbus clouds, often referred to in the context of rain-bearing clouds, usually describe types of cloud formations that contain precipitation, such as nimbostratus or cumulonimbus. These clouds do not share the characteristic shape of cumulus clouds and are often darker and denser.