Seeking advice on how to fix a problem with an image

[cbk]

Hello,

I made the mistake of not checking my sensor carefully enough before photographing. As a result there are waves of cleaning fluid on several of my images, particularly noticeable in the sky. I have not had any success trying to make it not noticeable so I am looking for ideas on how to correct this in Photoshop without replacing the sky. All advice is appreciated.

Thank you.

[Steve Gordon]

Brushing in a gaussian blur in the sky would be my 1st option.

[TonyW]

Mask to select sky only and apply Surface Blur.  You will need to experiment with radius and threshold to get the best effect and you may want/need to brush back some areas through the mask.

FWIW your image with some adjustment to accentuate problems and using the suggested workflow

[cbk]

Both ideas worked really well, thanks for helping save these images.

[PeterAit]

You could have just titled the photo "Unusual cloud formation" 

[earlybird]

What f stop did you use for this picture?