Take a conventional landscape view and expose for the sky, take another image exposed for the landscape. Process the two images normally, copy the lighter image onto the darker image and erase the over exposed sky to show the darker sky underneath.
Using CS6, I opened both files side by side, and as I hadn’t actually copied a sky from one image to another, this was all new to me. Luckily I’d bought a magazine that showed me the steps I needed to do as I’m very much still learning Photoshop as I usually just use it for basic enhancement.
Exposed for sky
Exposed for foreground
Now using Photoshop (in my case as this is my chosen software), take this image or any other photograph with a sky. Then choose a different sky from an existing or new photograph.
I selected the sky from the previous exercise and copied the canal image onto it. Using different tools such as the expand and then feather, it helped to reduce/avoid any harsh edges. As the sky was quite dark already I didn’t want to do any further processing to this so I flattened the layers and then saved the image. For a first attempt I’m quite pleased by it as the original image was ruined by such a white sky and where you can’t easily revisit a location, it’s nice that it can be rectified. My only personal caveat would be that any work continued to look realistic and that I didn’t produce anything that couldn’t be seen on another different weather day.
Image with new sky