Am I making sense?

Hello! This may be an impossible thing to do or someone may have already asked this (but I can't find the thread), but is there a way to have the snow or rain effect run behind the contents of a web page? I'm making a little page that has a window image and I'd like to make it look like it's snowing or raining outside (effect behind the window image). Is this possible? Am I making sense? I really love the scripts (because I don't know how to do them) and would like to know. Thank you in advance! :o:o