Off Topic: average daylight

From: Stephan Szyman (
Date: Wed Jun 14 2006 - 20:01:32 EDT

  • Next message: Jeff Umbarger: "Re: Off Topic: average daylight"

    hi there, sylvie,
    great question!
    at first, I was leaning toward answering that the further one goes from the 
    tropics, the fewer minutes per year of daylight one will experience,  but 
    this proved false. in their summer each polar region stays in sunlight 24 
    hours per day during the period near solstice (and conversely, in darkness 
    during the winter.)
    if you look at an analemma (when centered on the equator) you will see that 
    it is symmetrical, and visually represents the balance we are wondering 
    about, the average amount of daylight hours for a given location on the 
    earth's surface (disregarding,  of course, topographical and other 
    obstacles! it is important to remember the earth is far from being a perfect 
    I came to the conclusion that yes, for any given location on the earth's 
    surface, the average hours of sunlight or daylight annualy would be 
    "roughly" the same.  just to be on the safe side,  I called a retired 
    physicist I know (the directory of the society's observatory;) even he 
    seemed stumped for a few minutes, but he told me that he believed my 
    analysis to be correct.
    I will forward this question to my greatest resource in these matters, the 
    seesat-L emailing-list.
    >Hey Stephan,
    >I have a question for you and I think you are probably the only person
    >that I know who can answer it.
    >Last night I was talking to a friend and we were wondering whether the
    >average amount of daylight hours that any given location on the earth
    >gets over the course of the year would be the same.
    >Any thoughts?
    >Hope all is well,
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