I see what you see but I'm not sure whether it's a real effect or just an artifact of the photography. There must be some adjustment of exposure to have both th

I see what you see but I'm not sure whether it's a real effect or just an artifact of the photography. There must be some adjustment of exposure to have both the daytime and the nighttime well exposed, so it may just be the changing exposure that makes the brightness of the horizon non-monotonic.