Great expectaions dating
But notice that the convective heat loss by the greenhouse roof (200 W/m2, inferred as a residual) is only 8 W/m2 less than if the greenhouse was not there (208 W/m2).In contrast, the extra IR energy “input” (actually, reduced IR “loss”) is twelve times as large (100 W/m2) as the reduction in the convective loss (8 W/m2).
Was contracted by national city mortgage, mi to inspect, winterize and secure my residence.While working on a new website devoted to answering greenhouse questions, I decided to examine this issue.What piqued my interest was a couple quick back-of-the-envelope calculations that (1) for a glass covered greenhouse, the downward infrared (IR) emission from the roof should be about 100 W/m2 more than from a clear sky (a pane of glass is high emissivity, and opaque to broadband infrared), and (2) the realization that a greenhouse generates its own convection from the roof because the glass heats up, so convective air currents inside have their heat conducted (albeit inefficiently) through the glass, then the warm glass of the roof causes its own convection.UPDATE: It appears the debate was brought up in the literature by R. In any event, his paper was refuted by Edwin Berry (Comments on “The Greenhouse Effect”, J. Meteorology, 1974) who showed several problems with Lee’s analysis.So, I guess I’m left wondering…where did the oft-cited claim that a greenhouse does not operate through a greenhouse effect come from?Two days after, i called the mortgage company and they gave me the code to the lock box to get in.
Upon entry i noticed my brand new leather furniture was stolen. Well, they said they will try to get my furniture back.
Add to this the fact that greenhouses are usually vented, which means they lose heat convectively anyway that by-passes the greenhouse structure.
So, the question is: Does a greenhouse work more from infrared heating (the “greenhouse effect”), or more from the inhibition of convective heat loss?
Now, with a greenhouse in place, we assume the average temperature of the interior rises, and that the glass roof reaches a temperature intermediate between the inside and outside air temperatures: What really changes a lot is the downwelling IR, increasing from the sky value of 350 W/m2 to 450 W/m2, an increase of 100 W/m2.
Convective heat generated (but temporarily “trapped”) within the greenhouse increases substantially, from 208 without the roof to 275 with the roof, for an increase of 67, which further heats the air, which in turn is helping to heat up the roof.
One of the oft-cited objections to the term “greenhouse effect” is that it is a misnomer, that a real greenhouse (you know, the kind you grow plants in) doesn’t work by inhibiting infrared energy loss.