Problem: The colors in this picture seemed so tranquil to me that I set out to create a change of atmosphere while retaining recognizable aspects of the original photo. I wanted to use only PSP tools, no third party plug-ins.
Working on a copy, I first selected (feathered) and copied the area of the cityscape, Started with a dark grey background as my first layer.
Next layer, using the push tool I pulled the dark buildings up into the sky area, and mixed the colors up, and lightly erased in areas to let the grey background mix in.
Then using the warp tool I swirled the sky area around until I achieved the look I wanted. A dark, stormy sky that was beginning to break up.
On another layer, I put my copy of the cityscape, placing it low in the picture and applied a soft focus to it to make it look like it was in fog.
Added a bit of noise and finished with a softened lightning strike.
Took appx. 1 hour.