step 1 of 5
i have used the black to greenish gradient.

step 2 of 5
Do tranform the final image and take copies to have short clouds shapes.
Smudge tool will help you to adjust the edges.

step 3 of 5
I used black as i wanted to create a silhoutte effect.
Make copies of the images and place it separately as u desire.

step 4 of 5
and as usual make several copies to have it placed elsewhere
its jus to Fill up the place and also to create a lively environment

step 5 of 5
Draw a semicircle and tails to it with the pen tool and reduce the opacity to have it merge to the shape.
now add the ray escaping out of the clouds to create a clean and gloomy atmosphere.
Can also say it a finishing touch, so u get the final image.

Final result

