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Vitamin D vs angle of the sun

see wikipage: http://www.vitamindwiki.com/tiki-index.php?page_id=3152

90 degrees60 degrees20 degrees
no shadowshadow almost as long
as person
very long shadow
Max vitamin D50% of vitamin D zero vitamin D

About 10X less vitamin D from the sun if stand instead of lie down in bathing suit

  • Person standing has about 3X less skin exposed to the air
    due to to wearing short sleeves instead of bathing suit
  • Person standing has about 3X less light falling on the exposed skin (for US latitudes in summer)

Based on

  1. person in short sleeves has 1/3 as much skin exposed as a person in a bathing suit
  2. No – 10 minutes per day of sun-UVB is NOT enough
    Holick: difference between standing and lying down 3.5X at 30 latitude, 2X at high latitude
  3. the following two charts from: UV creates Vitamin D
    Horizontal (lie down): 80 degrees 90%, 60 degrees 50%, 40 degrees 20%, 20 degrees 0%
    Vertical (standing):   80 degrees 110%, 60 degrees 75%, 40 degrees 30%, 20 degrees 0%

Image Image

But, The Shadow Rule – you make more Vitamin D when you are taller than your shadow – 1992
shows lots of vitamin D can be generated in the morning at 23 degrees latitude


See also web

  • Health effects of sun exposure WikiPedia
    At high noon, ultraviolet radiation reaching ground level is 95% UVA and 5% UVB
    . . before 10am and after 2pm this percentage changes over time to 99% UVA and 1% UVB.

short URL for this page = http://is.gd/angleofsun