Thanks for the reference and the link. I had never heard of this natural phenomenon before. My first thought on viewing the image was "Someone really knows how to mess around the PhotoShop . . ." and "this could be the root source for a hoax or a conspiracy theory." Good to know that it is something that occurs in nature!
Obviously, I did use CS6 to recover cloud detail and also to colour balance so the sky was the right colour. I had to expose for the sky which somewhat desaturated the colour, at least thats what seems to happen with A7.
I actually have a very nice Lee System 7 filter setup which would have been ideal for this - if only I had had the time to set up a tripod, mount the filters, frame it all up nicely etc etc. As it was I have about three minutes to catch this before is expanded further and began to disperse.
I would add that the small and relatively cheap Leica C-40 Summicron is a fabulous lens for the A7. No smearing as far as I can tell, very sharp stopped down and it seems to draw beautifully with the A7 sensor. Interesting match when you consider that about 40 years separates the technology!