Talk:Day length

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This is not too technical. There are already quite a few related entries, such as sunrise, sunset, declination, zenith, azimuth, etc.. Day length is simply the time from sunrise to sunset. --Roland 04:23, 28 April 2006 (UTC)

Do you have any references for this information? Kevin 09:44, 2 May 2006 (UTC)

They are available in any book about solar radiation. --Roland 22:05, 3 May 2006 (UTC)
What I meant was did you have any specific references/citations that you could put into the article, so that a layman could look up the information. Kevin 01:03, 4 May 2006 (UTC)
Follow the external links. Gulliveig 09:48, 3 March 2007 (UTC)

Contents

[edit] Julian Day

In the chart, the term "Julian Day" is incorrectly used to mean "day of the year". Numbering the days of the year from 1 to 365 (or 366) is a common way of reckoning dates, but it is NOT the "Julian Day." See the wikipedia entries for "Julian Day" and "ordinal date". - M 2006-07-24

[edit] Question

I have a question- where can I learn about how the length of day differs at any given latitude?

Please title and sign your comments. Although comments are no FAQ, the answer is easy to provide: for a good primer follow the external links to the formulas ;) Gulliveig 09:48, 3 March 2007 (UTC)

[edit] Day Length increases

I thought that the spin of the earth was gradually decreasing, and hence the length of day was gradually increasing. I seem to remember something like 16 hour days during the age of the dinosaurs. There is no mention of this here. Does anyone know enough about it to write it up here?

Anthony Wood

Agreed : but there should be someone better able than I. 82.163.24.100 (talk) 13:36, 19 November 2007 (UTC)
What you are talking about is the length of the solar day, which is a property of the Earth, currently about 24 hours, which is the length of time between one noon and the next. What this article is talking about is the length of time between sunrise and sunset, which varies depending on location and season. --Spoon! (talk) 08:04, 15 December 2007 (UTC)

[edit] Meaning of Day Length

There are two different types of meaning; basically the length of the daylight and the interval between midnights. They need separate treatments.

For the interval between midnights, there are I think at least three types of variation :

  • Systematic during each year - orbital geometry - Equation of Time
  • Other Short term - changes in moment of inertia - Leap Second variation
  • Long term - tidal dissipation - recession of Moon.

It may be almost sufficient to link to the corresponding pages.

82.163.24.100 (talk) 13:36, 19 November 2007 (UTC)

The latter is the length of a solar day. You can link to that. --Spoon! (talk) 08:12, 15 December 2007 (UTC)