Not sure of exact method, but maybe this will help.
On a new layer, I chose color of sky, darken it turned up saturation a bit and changed the hue of color and painted the whole sky
Then I used the original layer and pasted that as a layer mask for the new layer and invert the layer mask.
Then you can play with curves on the mask. (I like to use the S-Curve)
On a new layer, I chose color of sky, darken it turned up saturation a bit and changed the hue of color and painted the whole sky
Then I used the original layer and pasted that as a layer mask for the new layer and invert the layer mask.
Then you can play with curves on the mask. (I like to use the S-Curve)