Dear Andrew
It appears to me that the inability of window glass to pass UV and IR is a
"reflection phenomenon" rather than an "absorption phenomenon.".
Note that different coloured glasses absorb different light frequency
ranges. For example "Red Glass" absorbs all the light in the visible
spectrum EXCEPT for the frequencies in what our eyes tell us is "red light."
Red glass is thus opaque to blue and green light.
Now, here is where the fun hits the fan: If red glass is transparent to red
light, what happens to the blue and green fractions of the incident
spectrum? Clearly, if the glass was reflective of the blue and green
fractions, then when we viewed the glass surface from the "Incoming light
side", the glass would appear to be blue-green, but when viewed from the
Outgoing light side", it would appear red. "Red Glass" is thus transparent
to Red light, absorptive of blue and green light, and reflective of UV and
Infra red light.
Why are healthy leaves green? Very simple!!.... the Leaves are very good
absorbers of Red and Blue spectral fractions, and very good reflectors of
the Green spectral fraction. :-)
One thing that puzzles me is that when I went to school, in the "Olden
Days", there were three "Primary Colors"... Red, Yellow, and Blue.Now the
three primary colors are Red, Green, and Blue. I this progress, or what?? I
don't think so!! How do I make Yellow if I only have Red, Green and Blue
crayons? ;-)
Best wishes,
Kevin
----- Original Message -----
From: <[email protected]>
To: "Discussion of biomass cooking stoves" <[email protected]>
Sent: Friday, March 09, 2012 4:28 AM
Subject: Re: [Stoves] radiant heat capture, total heat measurement
On Fri, 9 Mar 2012 03:35:06 +0000, Crispin Pemberton-Pigott wrote:
Because glass is a pretty good absorber of IR it is also a pretty good
emitter.
Surely glass absorbs the higher energy spectrum we can't see in the UV
band ( which is why you won't get a tan beside a close window) and
passes visible light and higher frequency infra red from hot bodies,
like the sun, but absorbs the lower energy infra red from cooler
bodies like earth and our bodies. This is the "greenhouse" effect,
other substances act similarly but we'd best not go there.
AJH
_______________________________________________
Stoves mailing list
to Send a Message to the list, use the email address
[email protected]
to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
for more Biomass Cooking Stoves, News and Information see our web site:
http://www.bioenergylists.org/
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.1913 / Virus Database: 2114/4858 - Release Date: 03/08/12
_______________________________________________
Stoves mailing list
to Send a Message to the list, use the email address
[email protected]
to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
for more Biomass Cooking Stoves, News and Information see our web site:
http://www.bioenergylists.org/
