What conditions typically lead to the formation of radiation fog?

The formation of radiation fog is most commonly associated with clear nights and calm winds. During the night, the earth's surface loses heat through radiation, which cools down rapidly. When the air near the ground cools to the dew point, moisture in the air condenses into tiny water droplets, forming fog.

Clear skies allow for maximum radiational cooling, as clouds would otherwise trap some heat. Calm winds are also crucial because they prevent the mixing of warmer air from above with the cooler, moist air near the ground. This stillness allows the temperature to drop sufficiently enough for the dew point to be reached, where fog can form.

Other conditions mentioned, such as rainy weather with strong winds, would typically not favor the development of radiation fog, as rain often raises humidity levels and wind disrupts the calm conditions necessary for significant cooling. High humidity and foggy days don't provide the specific conditions for the formation of radiation fog; they describe different fog types possibly caused by moisture but don’t involve the cooling mechanism essential for radiation fog formation. Cold water currents relate more to marine weather phenomena and do not directly cause radiation fog.