In uk.d-i-y, David wrote:

I'm not too sure about your radiative/convective loss assessment though.

Given that the top of the pot is pretty much sealed it doesn't matter if you
get any air down at the bottom of the pot, by whatever means

Ah, sorry, there's another unstated assumption of mine - that the pot has
a Hole in the middle of the "base" (base when used as pot, top when used
as light cover) - 'cuz all the pottery pots I've seen have this kind of a
drainage hole in them. Thuz, the conditions are right for a useful
convective flow from the bottom of the pot to the top, if air can get
in at the bottom. If there's no such 'ole, then of course there isn't
going to be nearly the same air flow, and a higher proportion of the
(smaller) losses will be by radiation (assert): though you're right that a
fair bit of the losses even from an "unholed" pot will be from convection
currents around the outer surface of the pot.

(Have we worked this one to death yet? ;-)

Stefek