The message
from Dave Fawthrop contains these words:

I would believe -40C to -50C the IR thermometer might not *see* the clouds,
but something else far higher.

If anyone remembers Daedalus and Dreadco in the back of New Scientist
many moons ago, the author suggests using reflectors to radiate heat
into the blackness of space, since at night it's a nice low temperature
- perfect for the cold end of a heat engine using solar stored from the
previous day as the hot end.
Not an entirely stupid idea.

--
Skipweasel
Pay no attention to that man behind the curtain.