Thanks for all the answers.  I think I may have worded the question wrong.  I would like to make  clouds that my airplane can fly down through.  Basically the angle would be looking down from above the airplane and the camera would follow the airplane down through the clouds to clearer skys below?  This is there is a way to do this with out having to place a zillion volumetric clouds by hand.

Also in the terrain editor, is there a way to clip a terrain so that you when I am using grayscale maps that I don't always have a flat ground square surrounding my grayscale map.  I'm not sure if I am explaining it very well.  In Bryce, in the terrain editor, we can have a slider bar the allows us to define what levels of the terrain are shown.  Any brycers out there that can explain this a bit better for me?