This simple tutorial will show you how to create the lightning effect in a realistic yet very compact way using photoshop !.

1 - Open a new document and set its size to (800 pixles * 600 pixles) (cmd +n)

2- Set the foreground and background color to white, then using the gradient tool, make something similar to the picture below. (Try pressing x then d)
3- At last an actual use for the difference cloud filter! Apply this filter from under the filter > render menu.
4- Invert your picture. (cmd + i)
5- Bring out the levels (Image > Adjusments > Levels) and play around until you get something similar to the image below. (cmd + l)
6- Bring out the hue/saturation (Image > Adjustments > Hue/Saturation) and tweak it until you get to a color you like. Make sure the colorize option is checked.
7- Now your effect is ready.
I got the image below from the interweb, and I added the lightning layer I made over it, then blended them together using screen .
8- Add spice as you may! here is my final result.
More cool things to come
Have a good one