what method to average out alternate bands of blue then turquoise in sky

Hi, screen capture from a flight sim of a sky, and after use of levels to make the clouds a bit more bright, noticed the blue sky graduating down from darker blue to horizon had bands of blue then turquoise-blue then blue etc repeating and getting lighter, so reached for blur tool, did nothing at all, yet blurred the clouds, so added noise, all it did was blur the noise but not the banding. .

do a test, drew alternate sprays of blue and purple, overlapping , tested it, did nothing. 

Just how does one blend those alternate bands together keeping the progression from darker blue to lighter blue ?

Blur tool seems limited, it wont blue solid colours as per my test.

try it for yourself.

No tool we tried made a scrap of difference. Photoshop beaten by a sim sky with banding, eh what ?

Merlin