Here are a few recent oil sketches where I experimented with refracted light and rippled effects.
As I mentioned in a Wetcanvas thread, I usually begin with a classical portrait then start playing around with the palette knife, adding concentrated pigments which (hopefully) would mix optically to resemble the underlying skin tone (like Chuck Close). The vertical palette knife applications are closely spaced around the brightest highlight then alternate with blurred passages to form ripples, similar to viewing the subject through a window while it's raining.
The tricky thing is that I have to work alla prima so that I can move paint around, which can turn messy if I fiddle with it too much. But I like the voyeuristic feel and the rhythmic tension between abstraction and realism. I got the idea from videos (Matrix and Talking Heads among others) and also from contemporary artists such as:
One of the ladies in art class said they all look like they're taking a shower. I thought that was pretty funny but that's exactly what I had in mind.