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Leigh made the following interesting comment/observation concerning
greenhouses; and I confess to never having thought about it much.
I don't think I've harped on it before in this group, but how many
of you out there are teaching your students that a greenhouse gets
warm because of the greenhouse effect, the same effect that heats
planetary surfaces with atmospheres? That's a lie, of course. It
has been known since the teens that greenhouses are heated by the
supression of cooling by convection. R. W. Wood (who probably knew
that all along) proved it by making a test greenhouse out of rock
salt. Today we use polyethylene sheet for some greenhouses, the
same material that is used for infrared windows in vacuum apparatus.
I have the following question: Are not both affects happening
simultaneously and contributing to the warmth inside the greenhouse (or
car)? (It doesn't get to hot inside my car on a cloudy day, or at night, up
here in the upper midwest). So it strikes me that one should be asking
which is the predominate affect?
Joel