Using LR you have the choice of doing global edits that affect the entire image, or you can just do local edits, that only affect part of the image.
A good tool for doing local edits is the Adjustment Brush tool.
A tool I often use is the Gradient tool.
With LR 5 open, if you press the keyboard F1 key it will take you to Adobe Community Help for Lightroom and you can take advantage of the many tutorials you'll find there.
I did an very quick edit of your original using the Adjustment brush separately on the sky and on the land.
Here are the Adjustment Brush settings I used on the sky:
Temperature -50, Tint 0, Exposure =25, Contrast +60, Highlights 0, Shadows +70, Clarity +90, Saturation +10, Sharpness +25, noise Reduction -75, Moire reduction 0, Defring 0.
Here are the Adjustment Brush settings I used on the land:
Temperature/Tint 0, Exposure +1.75, Contrast +75, Highlights 0, Shadows +40, Clarity +30, Saturation 0, Sharpness +20, noise Reduction 0, Moire reduction 0, Defring 0.