http://thebest3d.com/pdpro/tutorials/animswap/index.html

In a nutshell, the displacement map DWA was created byvertically
flipping an animation containing snowfall. Lots of snowfall, to the
point where you don't see or recognize a few distinct snow flakes.
Instead, it's a whole 'wall' of particles moving like through rush
hour. Large flakes, lots of them. And not too much contrast either
unless you want it crazy distorted.

I also used an alpha channel with progressive transition (linear alpha
fader) so the amount of distortion is stronger up high and down low.
As a result and side effect, when the camera moves sideways fast and
you see the edge of the sand dune go from high to low along the slope,
you see a ghost image, like double-vision. Not intended, but actually
a neat effect when you want to convey the looks and feels of
fata-morganas and you're about to collapse from this desert heat.

Welcome to Death Valley ;-) this works well also for inside a nuclear reactor when hot water rises just as it's going 'Chernobyl'

-Philip

Attached Link: http://thebest3d.com/pdpro/tutorials/animswap/camel-and-desert.swf

http://thebest3d.com/pdpro/tutorials/animswap/camel-and-desert.swf

Also has step7 adding lens flares, and step 8 on cropping the video and resizing/resampling to usable size for compression codecs when saving to AVI