Coldest cloud top on record, page-5

The reflection or as you say "re-emitted back into space" of energy is a big contributor
to temperature variation.

People who live in desert areas are well aware of the freezing mornings and
very hot afternoons.

The clear skies allow the heat to be lost to space.

However when there is cloud, temperatures are moderated
and less heat is lost overnight.

Clouds are the greenhouse.
On a clear night CO2 is irrelevant.