Creating a fantasy photo montage with various resources in photoshop.
* Duplicate sky image layer. Apply Color Balance settings. Add yellow and red colors. Image >Adjustments > Color Balance.
* You may apply Photo Filter (yellow, orange color with 25% Opacity). Image >Adjustments > Photo Filter.
* Add Layer Mask to duplicated layer. Fill it with black-and-white linear gradient.
* You should get something like that: