In a message dated 2/16/99 6:20:49 PM Central Standard Time, bbrown@conemsco.com writes:
>
> > Carbon dioxide, the major constituent of the
> > atmosphere, is incapable of producing the postulated runaway
> > on its own. It would require an additional component to "close" the
> > critical 25 % transparency window that permits reradiation back into
space
> > at thermal wavelengths. Water vapor, the primary candidate, is
> > conspicuously absent.
>
> Why are we talking about 'candidates'? Anyone with a telescope can see
that
> Venus' atmosphere is in fact opaque to visible light. The last I heard,
the
> composition of Venus' atmosphere had been measured to a pretty high degree
> of accuracy. Plug those numbers into a greenhouse simulation, and you get
a
> good agreement with the observed surface temperature value. So what
problem
> are we trying to explain?
My understanding of the greenhouse effect is that the atmosphere acts like a
diode. A one way valve. Radiation (visible light) is able to pass thru
(incoming) and heats up the surface...which then radiates heat (outgoing) but
which is unable to leave due to the atmosphere being opaque to infared
wavelengths.
So given that....how is Venus suffering from "runaway greenhouse"? Given an
opaque atmosphere how is it getting ANY heat?
Just wundering...
EvMick