Neither versions (8km or 16km) carry foggy horizons (I like it foggy-less). It's just my own personal choice. My rationale is that in real life, there is a minimal amount of smog in the middle of the ocean, so foggy horizons don't look correct... Also, I think it just looks nicer when it is clear.
However, feel free to add foggy horizons yourself.
But in all versions, I believe a fog-like effect does show up at dusk and dawn.