Here’s a short video on using clouds to paint explosions or fire with Photoshop.
The main concept is to create a brush from a cloud.
You’ll need a photo of a cloud to play along, so if it’s night or there aren’t any fluffy clouds close by to photograph, grab one of these…
As always, you can reach me with questions and comments at firstname.lastname@example.org.
Here’s what you could end up with: