SSAO (shader)

S.S.A.O.[1] is a real time shading filter that approximates ambient occlusion. As the EDL shader, this is a faster alternative to normal-based shading.

SSAO in action on a blank cloud

Note: SSAO requires a contiguous depth map. Therefore if your cloud is too sparse at the current viewing zoom, you must increase the point size (so as to fill the holes).