I have a photo that I would like to post process to add a rain effect. Can anybody explain how I would go about adding the effect or suggest a good tutorial?
Ideally I would be able to use my existing software (Photoshop Elements 8).
A good place to start: http://www.pxleyes.com/tutorials/photoshop/category/rain/
There is a tutorial for this effect here. It is for PS but you can still achieve the same look in PS. Here are the basic steps below:
Now you have rain!
On another note you can find decent rain (or snow) brushes for Photoshop (CS X or Elements). Here is one set I have used and a Google search turns up many results.