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Re: The blueness of water



Bernard Cleyet wrote:

a bit difficult to obtain meter sized optical glass --

one could check out fused quartz tubing or cane tho.

The loss in really good glass is less than 0.05 dB per meter
according to figure 2 in
http://irfibers.rutgers.edu/pdf_files/ir_fiber_review.pdf

Anything you can notice by looking at a 1 meter sample is !!not!!
relevant to a discussion of the amount of intrinsic scattering.
You're seeing impurities and junk effects, not the intrinsic
physics.

I also suspect that most of the anecdotes about swimming
pools are similarly off-target, because of high levels of
impurities.

Most people have never seen a large sample of really pure water.
I still claim that pure water is not nearly as blue as most
people think, and not blue enough to explain the blueness of
mountain lakes.

I support my claim with observations of the ultra-pure water
in neutrino detectors, such as
http://www.nobel.se/physics/educational/poster/1995/underground.jpg
http://www.mindspring.com/~divegeek/erie.htm

Yes, there is a bluish cast to those pictures, but the far-away
objects are not noticeably bluer than the foreground objects.
Also note the extremely clear and sharp view of the distant
objects.