Fixing to dive into Skyrim and put the game behind me. Thought I'd tackle this issue next. Using ENB series v0.292 and an ENB preset called Natural Lighting and Atmospherics.
When facing the sun, the ground surface as a whole exhibits an adaptation-like brightness inconsistency that is fairly subtle. (It is not in fact adaptation, since it happens instantly, even with adaptation disabled outright.) Sometimes the effect is not subtle at all, as shown here:
https://youtu.be/q4RZk0FIYS4I can get this to happen consistently when facing generally towards the sun. As the camera tilts towards the sky, a mysterious shadow crawls out from below the field of view and positions itself about 20 feet away. As the camera tilts back, the shadow retreats. Disabling every effect I can think of doesn't resolve this issue, but disabling the ENB of course does.
Hoping someone knows what's responsible for this.