photoman022 wrote:
Back in my film days (uh oh, a geezer pontificating!) I used different colored filters to accentuate different aspects of my black and white photography. I think (it was a long time ago!) the red filter accentuated the clouds in the sky; using filters in film is a short distance from sky replacement (which I regularly do in my digital photography).
The B&W sky filters were yellow, orange, and red in order of strength. Now you can apply the effect of any of them when doing a B&W conversion. But you're still stuck with the clouds that were actually there, so if you don't like them, you can replace the sky.