The Shadow Rule – you make more Vitamin D when you are taller than your shadow – 1992
Grassroots Health Oct 2015 email
“ A general rule of thumb?
When you are taller than your shadow, your body is able to make vitamin D ”
Atmospheric sun protection factor on clear days: its observed dependence on solar zenith angle and its relevance to the shadow rule for sun protection 1992
The shadow rule: a simple method for sun protection. 1998
“Thus, when a person's shadow is shorter than the person is tall, the intensity of UVR from the sun is more likely to cause sunburn.”
Actually: Generate about 1/2 as much vitamin D when shadow is as long as you are tall
Example of how much Vitamin D can be generated at 23 degrees latitude in the summer
Shaded areas are when the shadow is longer than the person
Lots of good Vitamin D in the morning - before it gets too hot
from: Sun-induced production of vitamin D3 throughout 1 year in tropical and subtropical regions: relationship with latitude, cloudiness, UV-B exposure and solar zenith angle - 2021- Which is behind a paywall - https://doi.org/10.1007/s43630-021-00015-z
Similar latitudes for which the sun is directly overhead: Sao Paulo, Florida Keys, Hong Kong, Mumbai
See also VitaminDWiki
No – 10 minutes per day of sun-UVB is NOT enough
Optimize vitamin D from the sun
5 Amazing Properties of Sunlight You've Never Heard About
Overview Suntan, melanoma and vitamin D
Morning sun?
Boost Your Winter Mood and Productivity with vitamin D or morning light
Health benefits of the sun - more than just at noon
The Healing Sun –1999 book highlights at VitaminDWiki
Sunbathe for Tubercoulous only 6-9 AM – not in middle of the day – pg , 119
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