Re: Gasoline thrown in the campfire and burning 3-D images!

[P3D George Gioumousis <georggms@xxxxxxxxxx>]

P3D Gabriel Jacob wrote
> 
> RBT mounts were made white on the side that faces the light so that it can
> reflect the radiant heat. Now why is the other side black? It seems (and
> I am only guessing here) whatever little energy is absorbed from the white
> side can be more efficiently emitted if it is black! Since the temperature
> difference between the white side and black side is greater on the white
> side, the black part will radiate instead of absorb.
> 
Good guess. Back in my younger days, when I was in graduate school studying
non-equilibrium phenomena, I read a book (purely theoretical in those 
days) on the design of space craft. The recipe was to make the thing
a sphere, with one side black and the other side silver. Too hot: face
the silver side to the sun and the black side emits to the stars. Too
cold: face the black side to the sun so it could soak up the heat while 
the silver side emits very little to the stars.

Related Phenomena:

1. Frost forms when the air temperature is above freezing.

2. The best rooftop solar collectors are made of a material which
is black at visual wavelengths and a reflector at 10 microns, which 
is the peak of the black body curve for something near the boiling
point of water.

-- 
                           stereo                stereo
George Gioumousis           /---\        |       /---\ 
                             o o         |       o o  
georggms@xxxxxxxxxx           |          |         |   
(415) 494-6276              \===/        |       \===/ 
                           stereo                stereo


------------------------------