I have written many times about replacing unattractive or boring skies, and these two pictures are good examples of that. I just returned from a photo tour of the American Southwest, and on several occasions the sky was white or very light without artistry in the clouds. Such was the case when my group visited White Pocket near Page, Arizona. I replaced the sky with storm cloud photos from my files because the lighting from a thick cloud cover is appropriate for the kind of diffused light on the landscape we saw at White Pocket. The results are quite dramatic. I transformed the original images, which were fairy boring, into visually compelling nature shots.
Never underestimate the power of a background to make or break a picture.