Not happy with the original image, I have been playing around with it for the last couple of weeks. Not only am I much happier with it, I managed to increase the time it takes to render by about 8!!
There is a touch of post work to it. A few people have asked me how I did the circles of cloud and I will answer soon enough with a tgd example file once I get it sorted.
The orange light in the cracks is a luminescent plane. The light from the volcano is a light source.
Enjoy