This morning air temperature was -2 Celsius, Freezing Fog was reported by the broadcast media, car windshields had a frozen film that may have been frozen dew, and other (non-glass) car surfaces has large drops that were frozen and other areas with what looked like hoarfrost.

How could the water have "frozen" solid without first crystallizing, given the air temperature was only -2? I was under the impression that for homogenous nucleation, the temperature would need to fall in the range of -20 C or colder. Could Radiation Cooling remove so much heat that the water drops experienced a -20 C ambient condition?