What the??
I'm using blue fog...
Anyway, thanks for all your tips, I'll try to implement they but, today, I was improving my terrain a bit, and them I entered in the "View Entire Terrain" mode. But something strange happened. When I set the camera (like the one in my last WIP) the castle, the nearby trees and some rocks disappeared!!! I don't know why, but only these doodads disappeared, the others don't, and this only happens in that camera angle and in the View Entire Terrain mode... Strange, and I can't proced with my terrain now, as whitout the mode, the Yggdrasill and the clouds are covered by the fog...
Here's a screenshot, and I'm not joking!