5
$\begingroup$

I'm not well-versed in physics, so I hope you'll forgive me if this question is significantly off the mark.

I'm interested in the predominant frequencies of light over the course of one day. My understanding is that as the sun rises and falls, the atmosphere absorbs differing amounts of light, and that is responsible for the changing colour of the daylight, for example becoming more red as the sun sets.

I guess that there is some curve from (all but) absolute darkness, through to broadband white light during the middle of the day, back to darkness again over the course of twenty-four hours?

If so, is it possible to approximate the makeup of the light at a given point during the day? And if so, how? I appreciate that there are probably significant complicating factors, so any rough approximation would be fine.

Again, I'm coming from a layman position here, so I apologise if I've drastically misunderstood something.

Improve this question
$\endgroup$
4
  • 1
    $\begingroup$ Just to check: Are you only interested in visible light? Also: When you say "predominant" you're referring to the total intensity accumulated during 24 hours right? Furthermore, it will depend on your latitude and day of the year. $\endgroup$
    – cinico
    Commented Nov 27, 2013 at 18:03
  • $\begingroup$ @cinico: I'm particularly interested in visible light, but my question is kind of exploratory so any information would be appreciated. What I meant by predominant is that at a particular point in time, what is the makeup of the light in terms of what frequencies are present; so for example in the morning and evening I'd expect a bias towards the red end of the visible spectrum, and a wider set of frequencies (i.e. a whiter light) towards the middle of the day. $\endgroup$
    – kfb
    Commented Nov 27, 2013 at 22:05
  • $\begingroup$ @kfb I think cincio is trying to imply that when you get to IR pretty much everything on the planet will be glowing $\endgroup$
    – jk.
    Commented Nov 28, 2013 at 14:40
  • $\begingroup$ @jk. Ah, I see. In that case, I think sticking with visible light makes sense for what I'm currently thinking of. $\endgroup$
    – kfb
    Commented Nov 29, 2013 at 10:48

1 Answer 1

Reset to default
1
$\begingroup$

I found a good paper that can help you. However, due to copyright issues I cannot put the spectra here.

Try to get this article:

"The Distribution of Energy in the Visible Spectrum of Daylight". A. H. TAYLOR and G. P. KERR. J. Opt. Soc. Am. 31 no. 1, pp. 3-8 (1941) . Also available here (pdf).

Improve this answer
$\endgroup$
1
  • $\begingroup$ 1941 copyright... is it still considered to be under copyright? Do the copyright law corruptions created for one Mickey Mouse corporation (Disney) by their wholly owned subsidiary (the US Congress) also apply to scientific papers? $\endgroup$
    – Phil Perry
    Commented Jun 23, 2014 at 17:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.