USCG Meteorology Practice Exam

Radiation fog is a phenomenon that occurs when the ground loses heat through radiation on clear nights, leading to a drop in temperature near the surface. As the air cools, it can reach its dew point, causing moisture in the air to condense into tiny water droplets, forming fog. This process typically happens under calm conditions, where the absence of wind contributes to the effective cooling of the surface.

The correct option highlights the relationship between radiation fog and temperature inversions. A temperature inversion occurs when a layer of warmer air traps cooler air near the ground, which can enhance the cooling effect and promote fog formation. This scenario is particularly conducive to forming radiation fog, as the cooler air can maintain sufficient humidity levels to support condensation.

Other conditions like heavy rain, high winds, or warm waters are generally not associated with the formation of radiation fog. Heavy rain tends to create conditions for other types of fog, such as advection fog, while high winds typically displace the cooled air, preventing the calm environment needed for radiation fog to form. Warm water can lead to different fog types, like steam fog, rather than the cool, ground-based conditions required for radiation fog.