out come of this
>Open any image that you want to apply the rain to. I'm using the one shown below. Create a new layer, and fill it with Black. Press filter > noise > add noise and use the following settings.
Amount: 60
Gaussian
Monochromatic
>Now create three more layers and do the same thing that you did in the previous step except for the amount increase it by one for each layer.
>Next you have to apply a motion blur. Do this by going to filter>blur>motion blur and use these settings:
Angle: 80
Distance: 30
>Now do that to all the layers that have the noise on them.
>Now click on every level with the noise on them and change their blending mode to screen and change their opacity to 50%.
>The final step for photoshop is to click on the button to transfer the image to imageready.
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>OK now that your in imageready you are gonna make the rain fall.
>Now on the animation bar make three new frames.
>In the animation panel, create 3 more frames, leaving you with a total of four. On frame 1, leave only layer 1 visible. On frame 2, leave only layer 2 visible, etc.
>Now click the play button on the animation panel to see if you did it right and if you did good job.
i wrote this up a long ass time ago for planetrenders.net