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Old 26-08-2004, 08:43 PM
Alfred Falk
 
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Salty Thumb wrote in
news:rNeXc.1129$Cc.449@trnddc07:

does anybody know if there is a word or measurement that describes
that efficiency at which a substance traps longer waved solar
radiation?

For example glass is pretty good at trapping heat, so that may be
rated at 100 "Scovillage" units or possibly it could be described as
having a "Maxwell" rating of .5 celsius per second per cubic meter.
Polycarbonate also used for green/glass houses may have a similar
values while brick or other opaque materials would be close to zero.
What would the real term for Scovillage or Maxwell be?


I would be surprised if there were such a term because the greenhouse
effect is not a property of the material alone. The obvious (to me, at
least) variables a
1) The spectrum of the incoming radiation. For an incandescent
source such as the sun this is mostly determined by the source
temperature. (The "surface" of the sun is about 6000 K) But
atmospheric absorption figures in this as well.
2) The spectrum of outgoing radiation. This is mostly determined
by the temperature reached by surfaces inside the greenhouse.
3) The transmission coefficient of the glass at every wavelength.

Also, it is not meaningful to talk about the greenhouse effect with
opaque materials as there is no radiation passing through. (Unless you
want to talk about x-rays and gamma rays.)

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