I went back to West Virginia again this week. While I was dissapointed with a high pressure system and mostly clear skies (again!), on this day the clouds formed by rising air cooling over the mountains stuck around until sunset (usually they burn off about an hour before). I used a relatively quick exposure for the ground, and a 240 second exposure (ISO 100, f/22) for the sky. Ambient pink light directly behind me lit the foreground rocks up a slight pink, as well as burning in the color onto the tops of the mountains that were higher in elevation than the one I was on.