Use the channel to add a blue sky to the spring White location picture

It's quicker to change the sky with the passage. Just select the appropriate channel and copy, in the copy channel to the dark and high light contrast increase, the need to retain the part of the direct black, and then the channel into a constituency, the selection of the election to be the need to retain the part. After you copy the picture, add the desired sky material at the bottom. Original

Final effect