If you couldn’t guess, it’s the Golden Gate Bridge solidly encased in what I can only assume is a Vonnegutian Fog-9.
Since 3-D objects have 2-D shadows, 4-D objects would have 3-D shadows, no? Or perhaps this fog is a 4-D version of the bridge viewed through past, present and future. Can’t quite tell as this is making my head hurt – someone get me a chronodimensionologist.
Reminds me of this Sutro fog shot on Wikipedia:
Or this fog-sunset combo by craigiest: