Duplicate Background and set blending mode to Multiply.
Dupe this layer again 4, 5, or 6 times depending on how strong
you want the mountain.
Group or merge all these multiply layers and apply a black mask.
Paint back the mountain.
Curves and Selective Adjustment layers to add some contrast and
fine tune color.
Another Selective Color Adj. Layer > target white > change sky to blue.
Add a gradient to eliminate the blue from white areas except the sky.
Cloud brushes on sky.
Paint With Light (PWL).
USM at 15, 30, 0 will add some zing.
For even further enhancement, switch to LAB mode and make the colors really pop with
the A and B channels in a Curves Adj. Layer.