While driving a boat from Rizal to Abbotts it seemed that every time I crossed a region line, the water changed. The water was set to Default in the Environment Settings and the sky was set to [TOR] MIDDAY – Salmon without change at any time. Here’s what it looked like.
Again, this happened with every region crossing I remember. Dark, light, dark, light, etc., regardless of orientation on my travels south. I’ve seen it before but never really thought about it. I’ll have to investigate more. Maybe try other viewers and certainly other Windlight settings.