There are lots of ways to do this, but I doubt that a single color adjustment would ever be sufficient. If it were me, I would start out by generating separate masks for:
(1) the snow fields on the mountain;
(2) the left side of the mountain and the clouds on that side;
(3) the sky;
(4) the flying whale;
(5) the shadow areas.
Note: These initial masks can be very approximate as you are going to manually adjust them by painting black and white on them to feather the selections to blend into each other.
Then, using those masks, make a first pass at getting the colors, brightness and contrast in those three areas roughly correct. Next, manually paint on the masks to blend the areas into each other. After yo do this, you may want to go back and make a final tweak to the colors, brightness and contrast in each area.
You might want to use a color gradient for the sky.
Some people are not as mask-crazy as I am, and would be able to use fewer selections to get a good overall effect, but I find that erring on the side to too many selections is better than having too few, especially for someone without a lot of experience in PS.