I'm having trouble understanding why a clear sky is important. Surfaces radiate based on their temperature and emissivity only, right? So why would it matter what the surface is emitting toward?
Perhaps what I'm missing is that clouds emit some radiative heat back to the surface, whereas a clear sky emits very little, so the net heat loss from the surface under a cloudy sky would be lower.
Perhaps what I'm missing is that clouds emit some radiative heat back to the surface, whereas a clear sky emits very little, so the net heat loss from the surface under a cloudy sky would be lower.