Explanation on how to start making clouds here.
The start of the tool allows to setup a number of copies, that are copied along the X axis, and to set up a min and max size. The size determines the endpoint and midpoint scale of the copied sphere and the radius in which they scatter. This results in always having a nice curvy cloud. The Show result button is for previewing the settings in a faster way, this button appears in several spots of the tool to be able to look at different stages of the cloud isolating certain calculations and increasing editing speed.
Next there’s the stacking tabs. This primary stack scatters clouds onto the previously determined shape (which is first converted to metaballs to avoid invisible inside spheres). The radius varies randomly between the given points, the amount per area increases the number of spheres that are scattered in this specific stack. The merge node on the right of the network is solely for the preview to also show the input of the scatter.
Next all stacks are applied, with ever decreasing radii and ever increasing amounts the cloud takes its final shape. Then the post-scale comes into play. The foreach loop at the end of the network scales every sphere individually from its own center point to the post-sphere scale.
Note that previewing nodes are painted out of the network to avoid confusion.
Because all scattered spheres are put with their center on the surface of the input geometry, they will never float loose and creases in the cloud volume are not very deep. By scaling afterwards, less densely scattered areas will have bigger gaps and this will create a more puffy cloud with more pieces hanging loose around the edges.