Bloodsong, start with a really weird sky or you're not going to see huge differences. Alternately, load a really wierd color map. The functions affect (1) the shape of the tranparency on the layers, so one cloudy one will look much like another but griddy ones look different (2) the distribution of colors from the color map, so a plain color map won't produce noticeable changes even with a strange function. Also try deleting extra cloud layers and see what you can do with just one. mary