Superimposing images using layer modes in Photoshop

The conceptual image above was created by combining two photographs in Photoshop and altering the layer mode of one of them to superimpose the clouds over the silhouette of the man. Here's how: 

The tow photographs below were stacked one over the other as layers in Photoshop with the sky image on the bottom. The top layer of the man had its mode changed to "Light". This meant that everything lighter than the sky photo was preserved while everything darker allowed the lighter parts of the image below to pass through so the sky passed through the dark silhouette of the man. 

A vibrancy adjustment layer was added to the man image only and the vibrancy and saturation were dialed to almost nothing resulting in an almost black and white image. The sky layer was enlarged and positioned to suit the composition and a curves layer added to it to brighten the sky and lower the contrast. That was it.