In terms of physical characteristics, how are cumulus clouds typically described?

Cumulus clouds are typically described as white and billowy due to their distinct, puffy structure that resembles cotton balls. This characteristic appearance is a result of their formation processes, which occur when warm, moist air rises and cools, leading to condensation of water vapor into visible clouds. The white coloration is largely due to the sunlight reflecting off the water droplets within the cloud.

The billowy nature of cumulus clouds indicates not only their vertical development but also the ongoing convection processes driving their formation. These clouds are often associated with fair weather, though larger, towering cumulus clouds can indicate developing thunderstorms. This description stands in contrast to the other options, which do not accurately capture the typical appearance of cumulus clouds.