How to create REALISTIC SKY in
photoshop?

STEP I : Start a new document any size you want.

Create a new layer, and fill it with a Linear gradient of dark blue to lighter blue.

Darker blue: #395D9E
Lighter blue: #6A9BC9

STEP II : Create a new layer.

- Press D to reset your color pallete

- Go to Filter->Render->Clouds.

- Then Filter->Render->Difference Clouds.

- Press CTRL+F twice.
- Set the clouds layer blending mode to: Screen

STEP III :Go to image->Adjustments->Levels.
And set the input values to: 20, 1.00, and 120

STEP IV :Duplicate the cloud layer (Press CTRL+J). Then go to Filter->Stylize->Extrude:

select block in type & enter 2 pixels , 15 depth, level-based and check on solid front faces..

STEP V : Reduce to Opacity of the original cloud layer to 70%, and the extrude layer to 50%

Now select the extruded cloud layer and apply a gaussian blur with 5.0 px setting. (Filter->Blur-Gaussian Blur)

download this .PSD file