Night Sky Radiation

Roof cladding absorbs radiation from the sun and the attic space becomes warmer, and some of this heat is radiated at night into a clear night sky.
Because all objects radiate heat to cooler objects, night sky radiation will occur when there are no clouds in the sky, at a rate dependent upon the emittance of the roof cladding.
Radiation to the sky can cause the cladding temperature to drop as much as 5˚C below that of the surrounding air and this will produce dew when the dew point is reached, or frost if the temperature falls below zero.
Draft Clause: