In this two morning photos of mount Triglav you can see the diference between good and not so good light. When there is no good light available you must work on composition and mood. If there were no clouds in the sky (second photo) photo would be ordinary.

Good light; Canon 5D mark II, Canon EF 70-200 f4 IS, at 200mm, f7.1, 1/100

Ordinary light but interensting clouds; Canon 5D mark II, Canon EF 70-200 f4 IS, at 200mm, f7.1, 1/125