< p >中午,阳光是来自近你正上方,穿过~ 2英里(4公里)相当稠密大气层到达你(大气压力在2英里大约海平面气压的一半)。在日落(或日出),因为阳光是旅游主要是平行于表面,它穿过浓密的大气长得多的时间。当穿越浓密的大气层受到更多的< a href = " https://en.wikipedia.org/wiki/Diffuse_sky_radiation " rel = " noreferrer " > < / >,这降低了观测到的光的强度。< / p > < p >,或者认为是一种不同的方式,看日落和日出时,你看不到太阳作为一个定义良好的点。这是朦胧的,太阳附近的天空也放出大量的光。额外的光的光从一束否则直接分散。如果都集中到一个点,这将是光明的/更痛苦看(虽然不像正午的阳光明亮,摇摇欲坠的统计和光吸收的原因)。< / p > < p > < a href = " https://i.stack.imgur.com/J9DY4.jpg " rel = " noreferrer " > < img src = " https://i.stack.imgur.com/J9DY4.jpg " alt = " Creative Commons的日落…由……马里奥·安东尼奥?" > < / > < / p > < p >使用一个< a href = " https://dizzib.github。io/earth/curve-calc/" rel="noreferrer">Earth Curvature Calculator, sunlight at the horizon travels through ~120 miles of 'dense' atmosphere (ie has an altitude <2 miles). That will fall off rather quickly the higher above the horizon the sun is. (dense atmosphere in this refers partly to just thicker air; but also to particulates/dust in the air, haze, mist, fog, etc)