From: Billy Brown (bbrown@conemsco.com)
Date: Wed Feb 17 1999 - 08:02:28 MST
EvMick@aol.com wrote:
> 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?
The models get pretty complex on this, but the basic idea is that Venus'
atmosphere is not 100% opaque. Visible light coming in from space tends to
penetrate much deeper than IR light trying to make it back into space. This
gives you a greenhouse effect, because it is easier for energy to get in
than to get out. Most of the energy would be deposited in the middle layers
of the atmosphere rather than at the surface, so you have a lot of complex
modeling to do to figure out things like the surface temperature.
When last I checked (about 3 years ago) we still didn't have a complete
model of the Venusian atmosphere, but the partial ones were showing a decent
level of agreement with our observations. There are probably thing going
one here that we haven't caught on to yet, but the basic concept of massive
greenhouse warming looks sound.
Billy Brown, MCSE+I
bbrown@conemsco.com
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