With high performance glazing it is possible, under certain conditions, to have condensation on the outside of the glazing. The glazing radiates to the sky and on a cold, clear night that can reduce the temperature of the outside surface to below the dew point. Condensation will form similarly to the condensation on a car windshield and, once the sun comes up, the condensation will disappear.
This phenomenon is only possible when the glazing unit is high performance and little heat is being transmitted to the outer surface. It is not likely to occur on a cloudy night.
