Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

The fundamental yellowness of sunlight is not Rayleigh scattering, but the sun's natural black body spectrum. See my reply to the sibling comment.


There is another catch. Sun's surface is about 6000K. A light with such color temperature would be considered bluish by most people if they looked directly at a lamp with such a spectrum. Rayleigh scattering lowers it to 5600-5800K at noon time, but still most humans would call a moderately bright lamp of this color "bluish".

The eye has a built-in white balance correction, and it moves the white point towards longer waves as the brightness lowers. This is why a single 5600K lamp in a room makes bluish light, while 10 of the same lamps make it lit by bright white. Same, a single 2500K lamp in a room makes a calming sort-of-white light. but 10 such lamps make a unmistakably yellow light.

The sunlight outside at a cloudless summer noon is very bright (one usually even wants to wear sunglasses), so the sun looks white or yellowish, especially in contrast to the blue sky.




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: