-----Original Message-----
From: William Beaty
Subject: Re: The blueness of water
A fifth question: doesn't the color of dissolved minerals override the
H2O absorbtion and scattering spectrum? I suspect that a lake filled with
distilled water would look different than any existing lake. When dealing
with a slab of transparent material many meters thick, even the tiniest
impurity provides a very obvious coloration.
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A sufficiently high concentration of colored particles or plant matter
suspended in water will certainly give water the color of the particles or
plants.
But typical bodies of water are blue because water is a selective absorber -
the particles, air bubbles, reflectivity of the sea floor, etc. mainly
affect the path length of incident light in the water that determines how
much of the red/green light gets absorbed. Swimming pools are nice examples.
Note that the color of the water in a swimming pool greatly depends on the
darkness of the pool bottom. (Swimming pools are not blue because the
bottoms or sides are painted blue - in general, the sides/bottom are white
or grey).
Larry Woolf; General Atomics; 3550 General Atomics Court, San Diego, CA
92121; Phone:858-526-8575; FAX:858-526-8568; http://www.sci-ed-ga.org