Cloud Weight It might seem surprising, but the average cumulus cloud, those cotton-like clouds you see on fair weather days, ...

the cirrus, characterized by its swift motion and feathery appearance; the cumulus, composed of round heaped-up masses; and the stratus, or low ground clouds, such as rise from valleys at night.

From cirrus wisps to stratus blankets to cumulus puffs, clouds generally look lighter than air, unless there's a dark nimbus cloud dumping rain on you. With an understanding of how clouds are made ...