Every once in a while Cape Town's setting sun treats us to the most beautifully brilliant-orange hue. I believe this has to do with the frequency of red and orange light being far lower than the other visible light in the spectrum. On days when a lot of dust has been scattered into the atmosphere the light with a higher frequency is easily blocked by the dust particles, allowing mostly the low-frequency orange and red light to reach us.

But, that said, I guess it's best not to think about the physics of light and to just enjoy the beauty of it. :)  In case you missed my previous post, I'll be publishing a few photos of the sun setting on (what I suspect may have been) the last reasonably warm day until summer arrives at the end of the year. See the first photo in the series here.