4 thoughts on “Useful knowledge for a day in the sun

  1. Wait a moment… The amount of sunlight is the same in spring and summer and the same in autumn and winter. Temperature is not the same thing as sunlight.


  2. From what I can gather, they factored temperature in because of the average amount of clothing people wear. More exposed skin means less time in the sun needed.


  3. @Joseph,

    the solar energy striking the square inch of earth (or skin) varies over the year.

    The variance is small but measurable; it relates to the angle-of-incidence of the sunlight. (The angle is much better in summertime than wintertime, due to the Sun's apparent movement towards the North sky in the summertime.)

    However, I suspect the variance in recommended times is split between this answer and BS's. Both factors are in play.

    On another front, my hometown (Metro Detroit) is at 42.3 N latitude. Is that far enough from the line to be worrisome? Maybe some more detailed research is in order.


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