Now simply paint some mist. Don't overdo it because it wouldn't look realistic. On the photo below you can get the inspiration of how much you should paint.

Note: The trick of doing good looking photo manipulations is to do more gentle changes instead of one big. Yes, it's more time consuming but it gives you much more realistic results.

Step 7 - Increasing Contrast

In this step you'll add more drama to your picture by increasing its contrast. How? Simply add new adjustment layer Levels on the top of all layers and set the Input Levels on 0; 0,7; 200.

If you look at your image now you see that some parts of it are too dark and it doesn't look nice and some details stop being visible.

To correct that grab the Brush Tool (B). Select some soft round brush, lower its Opacity on about 40% and pick black color. Click on the layer mask of this adjustment layer and start painting over the areas where you want to make the adjustment less visible. You should end up with something similar as on the following picture.

Step 8 - Changing Light and Shadows

As I said before we want drama in your picture! Another way how you can achieve it is by adding more interesting lighting. Right now the photo manipulations looks quite flat with no difference between lights and shadows. You'll fix it in this step.

Add new empty layer on the top of all layers and name it LIGHTS&SHADOWS. Grab the Paint Bucket Tool (G) and pick mid grey color (#808080). Fill the layer with it.

Now you need to change its Blending Mode from Normal to Overlay to blend this new layer with the rest of the layers and make the picture invisible again.

Why have you done something like that? Because now you can use this layer to lighten and darken some parts of the image to make it more dimensional! Simply grab the Brush Tool (B), pick some soft round brush, lower its Opacity on 10% and start painting over the areas that should be lighter. Than use black colored brush for darkening.

Generally you should lighten those parts of mountains which are facing to the light source and darken those on the opposite side. After you're done with mountains move on clouds and ground applying the same principle as before.

On the picture below you can get the exact idea of where you should paint with black and white.

On the following picture you can compare how the photo manipulation looks before and after this step.

Step 9 - Desaturation

In this step you'll start building stronger atmosphere by slightly desaturating your photo manipulation.

Firstly add new adjustment layer Hue/Saturation on the top of all layers. Choose Reds and set the value Saturation on -30. Then choose Yellows and set the value Saturation on -80. This way you desaturate only red and yellow tones and e.g. sky still remains blue/cyan.

To create even more dramatic atmosphere you'll add some dark blue tones to the shadows of the picture. Add new adjustment layer Gradient Map on the top of all layers. In the Gradient Editor in Presets menu choose gradient named Foreground to Transparent and then choose some light cyanish color as you foreground color. Press OK.

To achieve the effect mentioned above change its Blending Mode from Normal to Multiply.

The area of the ground where light from sky hits the ground should remain lighter than the rest of the image. To achieve simply grab the Brush Tool (B), select some soft round brush, set the Opacity on about 40% and pick black color. Click on the layer mask of Gradient Map adjustment layer you've just added and paint black over the parts which should stay lighter. On the picture below these parts are highlighted with red color.