Took this recently on a day when there were quite a few thunderstorms around. Nothing close enough to hit us, but I could see a number of impressive looking clouds forming such as this one. Initially I was going for a B&W with this; but while I was playing around in PS, I tried changing the mode of the channel mixer layer to overlay and immediately liked the result. Seemed to give the image an IR feel as well as made the cloud look more ominous. Any C&C are welcome!
Olympus SP-550 UZ
f8.0 @ 1/800, ISO 100
Manual mode, pattern metering
Processed in PS CS2; curves adjustment, channel mixer, shadow/highlight, some noise reduction, and added a vignette