iandol on wed 13 sep 00
Point No. One. A Black Body is a hypothetical construct invented for the =
purpose of making comparisons about radiation emissions and absorptions. =
It is considered to absorb all radiation which falls upon it. No =
reflections at all.
Point No. Two. Black Body Radiation is the radiation of all frequencies =
that would be emitted by a black body.
See Stefans Law.
Air is transparent to visible light. However, heating it changes its =
density. Change in density of a transparent substance alters the pathway =
of light through that medium. So what is seen, the shimmers, in a kiln, =
be it electric or gas or wood or oil, are the effects of density =
changes, sort of mirage. Not only that, when some hydrocarbons decompose =
due to heat, the carbon remains in the atmosphere for a period of time =
before it oxidises. So that gives a darkening cloudy effect.
Yes, all elements can absorb energy and radiate it. But not always at =
the same wavelength. Which is why many elements radiate strong colours =
eg Sodium yellow, Strontium red and so on. Incandescent air I have seen =
is always blue, brilliant electric blue. Nothing black about a stroke of =
lightening.
Last word. I use a torch to look at my cones. They reflect the light and =
look lighter than their background. The molten glaze behind the cones =
also reflects light as well. Brilliant reflection. Air in between does =
not seem to mask what I see.
Ivor Lewis
=20
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