I adjusted the contrast and saturation of the picture. Then I have created the basic effect of Cumulous formations raising up from the normal height of the clouds. Compact clouds are used to create towers and hills of clouds rising up by airflows. You need to realize that all of the clouds create shadows behind and underneath them, so you'll need to sketch that in.
I have added more contrast and saturation again. The basic mass of clouds starts to look like what I had in mind.
It's time to give the scenery depth and space feeling. I have concentrated on the clouds in the distance and added some breaches in the basic level of clouds. Airflows create not just towers and hills, but also some breaches and abysses. I have painted them by using a rich blue colour, so that it could look like there's an ocean under the clouds. I have lowered the opacity of the layer with details in the back. It's because I wanted to simulate this misty atmospheric effect (haze), which usually appears looking over vast distances.
I have added some more detail to the clouds in the front, without this they would look like they would be closer- and I did not want this. I want the observer to have the feeling that he or she is very high above the huge mass of clouds.
To polish off my work I have tuned up the saturation of the cloud-shadows in the front and gave them slight tone of yellow-green colour. Thanks to that, they do not look so monochromatic.
When I showed the finished picture to my girlfriend, she was able to tell me a very unbiased opinion. When you work on something long enough, you sometimes become blind to some of the errors that may lie within it. Having a person who hasn't been staring at the work as long as I have and telling me that it looks good must mean that my work on the background is definitely finished. The clouds look really spectacular and the viewer has the feeling of flight above the vast space. That's exactly what I was aiming for in this picture, and it only took me about 2 - 3 hours.
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