The clouds in this shot where painted in Photoshop. I created 5 different layers; clouds, lightning white, lightning glow, clouds hi-lighted from lightning, clouds glowing internally from lightning. I used an animated mask in After Effects to reveal the different layers. The normal cloud layer was treated with the Mirage plugin from Puffin's Image Lounge, and copied 3 times with a lighten only compositing method, then mesh warped. This technique brought the clouds alive.