Talk:Length of daytime

message: 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)
replies: text: They are available in any book about solar radiation. --Roland 22:05, 3 May 2006 (UTC)

text: 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)
replies: text:  Follow the external links. Gulliveig 09:48, 3 March 2007 (UTC)

message: 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
:: Thanks for pointing this out. It has just been corrected in the redone plot. --Roland 00:58, 21 November 2009 (UTC)
thread_title: Julian Day

message: 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)
replies: text: If you look at page 515 of the Explanatory Supplement to the Astronomical Almanac (3rd ed.) you will see it is an iterative procedure (that is, guess and check). To carry out the procedure, further algorithms are needed to calculate the position of the sun in equatorial coordinates. So trying to describe it in the article would be very involved. Jc3s5h (talk) 21:10, 30 October 2013 (UTC)
thread_title: Question

message: 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)
replies: text: 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)

text: Given the ambiguous name, the article should talk about both, or link to another article that talks about length of the solar day.  —Preceding unsigned comment added by 89.103.130.151 (talk) 10:02, 14 July 2009 (UTC)

text: I've added an extra section and link to the Tidal Acceleration article which talks about this. Robert Walker (talk) 18:57, 5 November 2010 (UTC)
thread_title: Day Length increases

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

message: Elsewhere in Dawn there is reference to astronomic dawn, nautical dawn and civil dawn.  In some countries there is also lighting-up time which in England was 30 minutes before sunrise and after sunset.  
For an example site, such as London, how would these three dawns & sun-dawn show on a graph?? Salisbury-99 (talk) 09:16, 22 September 2008 (UTC)
thread_title:  when is it daylight? graph? 

message: I live in Denver, CO, elevation 5,280 feet and during the equinox the length of day seems to be 12 hours and 10 minutes.  In Leadville, CO, elevation 10,152 feet, the length of daylight seems to be 12 hours and 20 minutes during the equinox.  Is this due to altitude/elevation causing the sun to be above the horizon relative to those locations for a longer period of time?  My guess  is that the "12 hours everywhere" rule is based on an assumption that the whole earth sits at mean sea level.  Seeing as how much of the earth is NOT at mean sea level, this general rule has some major exceptions.  Might be worth explaining this in the article. Leahcim506 (talk) 07:42, 16 April 2010 (UTC)
replies: text: See for a more complete explanation Equinox#Length of equinoctial day and night. Most important effects are the size of the Sun, the atmospheric lift, and latitude. Altitude has a very minor effect. −Woodstone (talk) 12:52, 16 April 2010 (UTC)
thread_title:  "Generally" 12 hours of Daylight on Equinox? 

message: Any chance of a math function to compute the length of a day based on latitude and time since the winter solstice?--99.110.255.113 (talk) 17:28, 19 November 2010 (UTC)
thread_title:  Mathematical function? 

message: I found the chart somewhat difficult to interpret.  
For one thing, the 12 hr contour line should be made symmetrical, although the color codes would still be different for daylight vs night.
If you added a second nocturnal 12 hr contour, then what is the space between the contours?  Should the 12 hr contour be represented by straight lines?  an "H" shape?  With perhaps an 11 hr contour being a closely associated curve.
I would also encourage adding a chart summary directly below the chart. 
Mark the Arctic/Antarctic Circle on the chart (66° 33′ N/S respectively), with associated 24 hr/0 hr contours.  Perhaps also indicate the equinoxes (sun above equator) and solstices (sun above tropic of Capricorn/Cancer).
A legend?
Brown - 23 to 24 hrs daylight, 0 to 1 hr night (see notes above, I'd adjust to actually 24/0).  White for daylight, black for night?
Orange - 18 to 23 hr daylight, 1 to 6 hr night.
Yellow - 14 to 16 hr daylight, 6 to 10 hrs night.
etc.
Keelec (talk) 19:23, 1 April 2012 (UTC)
replies: text: Yeah, I think that there are some issues with this graph. Either the label that says 1 hour is meant to be 0 hours; and the label that says 23 hours is meant to be 24 hours; or the graph should have displayed the 0 and 24 hour contours instead of the current 1 and 23 hour contours. Can someone who understands the Sunrise equation please produce a better graph? Thank-you, --123.243.217.67 (talk) 17:40, 2 August 2014 (UTC)
thread_title:  Hours of daylight vs latitude vs day of year Chart 

message: just a friendly reminder to include that...considering it was shorter at the start of this planet
Paranoid Android1208 (talk) 02:46, 30 May 2013 (UTC)
thread_title:  day length throughout history 

message: The term "length of day" is standard.  Where is it referred to as "day length" except in this article?  Vaughan Pratt (talk) 00:37, 9 December 2014 (UTC)
thread_title:  Move to "Length of day"?