Actually, it has nothing to do with 'believing' in Carrara - it's that I simply know the toolset.

Man, for me, cumulus clouds have been the holy grail in Carrara.

I was working on them during the creation of this thread last year. That technic works ok for dark types of clouds/smoke but I wasn't satisfied with it for white cloud results. The files are available on my site in the Dark Arts section for download if you want to pick up where I left off.

Instead, I'll typically use billboards with photos in a scene because it's faster. If I really need a cloud scene where clouds are the 'hero', I pop over to Vue. Vue 9 especially has really made cloud creation fast and rendering easy - and even Vue doesn't do great Cumulus. You can get outstanding results in Carrara but it usually takes about 4 times as long. Professionally, I don't have that kind of time on assignments so I go with what I know works.

Fluid/particle solvers are perfect for this because it's a 'reaction' to movement and volume and not a geometry or quasi volumetric construction. Scroll to the smoke samples here (Fluid sovlers are also used for fire) or check out this VFX artist's samples here. In the materials, it's easy to turn the black smoke to white. 

I'm not saying it can't be done in Carrara; I just haven't had the time to try all of the tricks I have in mind to pull it off! :D

Mark