Re: Greenhouse Misconception

[Rick Tarara <rbtarara@SPRYNET.COM>]

Anything I know about this I've learned from this list as I too was a
believer in greenhouses work by the greenhouse effect.  However, the
convincing evidence (for me) is that if one makes a greenhouse using a glass
or plastic that IS transparent to infrared, it works just about as well as
one with glass.  Promote convection in a greenhouse or car and the
temperatures will be much lower.  The GH effect IS present in a traditional
greenhouse but the amount of convection is much more critical to the
temperatures achieved.

Rick

----- Original Message -----
From: paul o johnson <pojhome@FLASH.NET>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Tuesday, July 27, 1999 11:35 AM
Subject: Re: Greenhouse Misconception


> Rick Tarara wrote:
>
> > My take on some of these:
> >
> > > 2) The misconception is that absorption by the glass in greenhouses is
> > > the main factor
> > >      responsible for higher temperatures inside.
> > > I always thought it was. What, then, is the main factor?
> >
> > Convection, or lack thereof is apparently the major factor although I
still
> > use the greenhouse (with an appropriate disclaimer) when trying to
explain
> > the global greenhouse effect.
>
> I don't follow you, Rick. I can see where the absence of convection would
keep
> warmer air in the greenhouse (or in the lower atmosphere) but how does
such
> absence cause that air to be warmer in the first place? Isn't that due to
solar
> radiation into the enclosed space being greater than the air's radiation
out?
> poj