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Re: BlACK or WHITE it ain't.!!

To: Don Kerr <dkveuro@pop.flash.net>, dkveuro@flash.net,
Subject: Re: BlACK or WHITE it ain't.!!
From: Aleksandr Milewski <n6mod@milewski.org>
Date: Sun, 26 Dec 1999 13:00:55 -0800
At 13:53 -0600 on 991226, Don Kerr commanded the electrons to create 
a missive titled "BlACK or WHITE it ain't.!!":

|White building when you want to warm the building at night time in the
|winter.
|Black building when you need to cool the building at night, any time.
|You with me.....?

And this is the important part. Remember that the black building will 
also have higher emissivity (sp?) than the white building. That is, 
while the black building absorbs more radiation, it also radiates 
much more effectively than the white building. Pour coffee at the 
same temperature into a white coffee cup and a black coffee cup and 
put thermometers in both; the black cup will cool the coffee faster.

At 12:57 -0500 991226, Lin, Gary wrote:
|I studied this in trying to determine which color on an amp in the trunk
|radiated heat faster, black or white, since there would be no light
|absorption but instead heat radiation.  Turns out it would make more of a
|difference of what kind of finish (brushed/anodized vs. heavy paint coated)
|was on it, paint being an insulator vs. bare metal.

But, your black anodized amplifier will shed heat faster than the 
brushed/clear anodized/white anodized amplifier. Most heat sinks are 
black anodized with good reason. In a desperate attempt to get back 
on-topic, black anodized brake parts are Good, white enameled parts 
are Bad.

|I suspect that is what Phil and Tony are experiencing between chrome/bare
|steel vs. a painted surface, the heat conductivity of the metal, since
|silver is a relatively light color.  This does not diminish the white/black
|factor.  Hope this off topic gave you some knowedge to use somewhere.

Don't confuse specular reflections with albedo. White is much more 
reflective than chrome, and chrome has really lousy emissivity. 
(Worse than white paint by a long shot) So the chrome is darker than 
you'd think, and it can't shed heat well at all.

In general, you want a white building. Think of it as free 
insulation. It keeps the heat out, it keeps the heat in. If you want 
solar heat, put in a solar heat (hot water) system, then you can turn 
it off in the summer.

(And sound (audio) is NOT electromagnetic radiation. If it were, 
speakers wouldn't need cones.)

Just my $0.02

-Zandr
---------------------------------------------------------------------
Aleksandr Milewski                                              N6MOD
n6mod@milewski.org                           http://www.milewski.org/

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