Free-standing clouds in Bryce have never worked to me – until recently. I discovered a glaring fact when watching the shadows cast by the clouds on a wheat field in the Caledon district. The cloud didn’t look particularly big but the shadow must have been at least a kilometre across. I realised that a cloud is a big thing.
My clouds in Bryce were simply too small so the cloud material (set to Fuzzy Shade mode) just lacked the minute detail and scale that a normal fluffy cloud would have. I normally create clouds with squashed spheres and apply a simple cloud material to it – volumetric clouds just kill the rendering time, and the dreaded intersection artefacts when two volumetric objects intersect (the image thumbnail enlarges to show what I mean), make the exercise more frustrating than rewarding. This time I cranked up the size and made the cloud colossal (in comparison to the terrain) and it actually started to work. My advice to you – think big!