MadSci Network: Physics
Query:

Subject: What are the relative intensities of sunlight at different times of the day

Date: Sun Aug 3 19:38:12 2008
Posted by david
Grade level: nonaligned School: university of the madly inquisitive
City: tulsa State/Province: ok Country: usa
Area of science: Physics
ID: 1217817492.Ph
Message:

Note at http://www.newton.dep.anl.gov/askasci/env99/env006.htm and
http://www.opt.pacificu.edu/ce/catalog/15719-GO/UVCitek.html
talking about the intensity of uv thru the day but for a long time I have
wondered why flourescent objects seem to glow brightly while every thing else
dims and grays at sunset. Please note figure 19.
http://www.opt.pacificu.edu/ce/catalog/15719-GO/Fig%2019.jpg
What is the relative intensity of uv to vis and ir at sunset? Could it have to
do with the refraction of the blue end of the spectrum or a reflection off the
air or probably the effect of the visible color plus that of the generated light
as the object flouresces. whatever, it seems neat to see flowers, a childs
wading pool or the stripes on my riding mower or other objects glow so brightly
as everything else grays and fades.
Where can i get a chart showing a  spectrum and intensity graph of light in the
if to high uv for an area say central us on a summer clear day. With the white
over cast look of the area this time of year i assume a lot of uv could be
reflecting down off of the air as the sun gets low on the horizon as you can't
seem to block the uv effect on flourescing objects with a shadow. Thanks from a
very curious inquiring mind.
Doc



Re: What are the relative intensities of sunlight at different times of the day

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