Fog

Step 6: Duplicate the Layer

Press Ctrl+J or open the Layer menu and select Duplicate Layer to create a duplicate of the layer.

Step 7: Select the Eraser tool

Select the Eraser tool from the toolbar. The Eraser settings should appear on the option bar where you can adjust the settings of the tool. Use a large brush size with a soft edge such as the one set in the image below.

Step 8: Erase the foreground

First, make sure that you have the layer mask of the top layer selected. Erase the foreground area so that the fog appears stronger in the distance.

Step 9: Duplicate the layer

Create a duplicate of the top layer by pressing Ctrl+J or opening the Layer menu and selecting Duplicate Layer. Change the opacity of this layer to 75%.

Step 10: Erase the foreground and middleground

Again, make sure that you have the layer mask of the top layer selected. Erase the foreground and background area so that the distance looks thick with fog.

Step 11: Add a Levels adjustment layer

In the layers pallet, click on the new adjustment layer icon and select Levels.

Step 12: Adjust the fog intensity

The Levels tool should appear. This tool will let us adjust the thickness of the fog. To do this, drag the middle input slider towards the right to decrease the fog or towards the left to increase the fog. Click OK when you're done.