In uk.sci.weather on Wed, 1 Oct 2003 at 08:37:01, Mike Tullett wrote :

But is the above exposure, or that inside the screen, more typical of
what garden plants will experience?

Very much the former, as plant tops can "see" the sky whereas that in the
screen cannot. A similar process occurs at the top of a forest canopy and
at the tops of clouds at night, thus leading them to become less stable at
that height.

If the lower temperature is more typical of what plants experience, and
will be damaged by, then surely gardeners might be mislead into leaving
their delicate plants unprotected, when they should be covering them up?
--
Paul Hyett, Cheltenham, England