Bill gave a thoughtful reply to my rhetorical questions regarding the
greenhouse effect. And answered in about the same manner as I would've
answered my on questions (with the possible exception of the last paragraph
:-)
Let me expand the discussion by giving my short version of the Greenhouse
effect (I invite comment, criticism and discussion; in particular does this
match most people's idea of what the "Greenhouse effect" is:
I view it as involving two aspects.
An enclosed container that has two properties (both of which are essential
for the greenhouse effect).
i) The container is transparent to incoming light at the predominate
wavelengths of the ultimate source of energy (typically our sun, at the
visible wavelength's).
ii) opacity at the wavelengths of light radiated at a specifice temperature
as given by the Stefan-Boltzmann law.
This means that one of the channels available for getting rid of energy
(i.e. through radiation) are not available to our container; therefore the
equilibrium temperature in the container is higher than what would be the
case if all three channels of energy output were available (conduction,
convection and radiation).
It has been pointed out that actually a gardener's greenhouse, also removes
the convection channel as well (and this fact predominates over the removal
of the radiation channel; by how much is part of my question).
I have two thoughts regarding this.
a) The greenhouse effect involves (i) and (ii) above; both the input and
output; and therefore I think since (i) is certainly present (and essential)
that the greenhouse effect has a lot to do with why it is warm inside the
glass structure.
b) perhaps the "greenhouse effect" should refer to (i) and the removal of
both the convective and radiative channels for energy loss. Then there
would be no arguement over why the inside of the glass structure is warm
(answer the greenhouse effect). Also, we could make the same reply for why
the temperature of the surface of Venus is so high (compared to
Stefan-boltzmann prediction). Again greenhouse effect; I'll note that for
planets gravity is the reason the convective channel is not present (at
least to any significant degree).