<p>This was taken on a sunny day. The rain was added in GIMP. Here's how:
</p><p><br></p><p>Open a photo you want to add rain to in GIMP
</p><p>Create a new image - keep the default size (the same size as your photo)
</p><p>Add noise using filter-&gt;noise, with the maximum settings
</p><p>add linear motion blur, with length about 50 pixels and angle about 90 degree 
</p><p>invert the color
</p><p>crank up the contrast until you can see the streaks clearly,
</p><p>using color to alpha, make the black transparent
</p><p>copy+paste onto your photo
</p><p>tweek opacity as desired, 
</p><p>anchor layer and save file.
</p>
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This won 2 ribbons - one in a monthly contest and one in a year long "best of" contest. My first "end-of-year" ribbon:-)
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/7780290@N05">David</a>
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/davidjoyner/14294618325/">guard tower with fake rain</a>