Last Tuesday I posted on image manipulation after I'd photographed a weather front coming across the country. Various comments indicated a divergence of views on the results and Adrian offered to give a lesson in the techniques involved in achieving various results. He subsequently posted a tutorial and the results on his blog Seeing to Pictures.
The original image he used was
and the final result was:
Adrian made the point "I have exaggerated the editing but for folk to see a difference I have to".