Re: IR & Water, a higher perspective

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 24 Mar 00 at 8:08, Joshua_Putnam wrote:

> This makes me think that much of this debate has been
> people talking past each other, since there are two very
> different questions really being asked: how well does
> infrared reflect from the surface of the water, and how
> quickly does the water absorb infrared that does penetrate
> the surface?  From looking at the satellite photos, I would
> say that IR is less prone to reflect back from the water
> surface, leaving deep water looking black, but that IR does
> penetrate water reasonably well, since solar IR can reflect
> back from significant depths well enough to show the sunken
> ships.

Water is one of the best absorbers for deep-IR, especially thermal 
radiation....I believe optical watercoolers are even used in 
high-power laser applications, where heat isn't wanted.

And this extreme goes hand in hand with the fact that longer 
wavelengths are progressively absorbed by water....the longer, the 
more absorption.

Side-note: from physics class I vaguely remember that ice is one of 
the lowest reflectors of light, including thermal radiation, much
less than water....reflection factor of nearly 0.0.
I think absorption vs transmission were also quite different for 
visible vs thermal, not sure (visible transmitting, thermal absorbing)



--                 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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