Solar direct horizontal illuminance for ZE = 15 cmag:



Height of Sun evening / 1 degree: +6 (centre, refracted), 0 (upper rim, refracted), -6, -12, -15, -18:


Height of Sun morning / 1 degree: +6 (centre, refracted), 0 (upper rim, refracted), -6, -12, -15, -18:


Lunar height and faintess, no atmosphere, no horizon: