What type of fog forms at night when the land surface cools the air above it to below the dew point?

Radiation fog is the phenomenon that occurs when the land surface cools rapidly at night, causing the air directly above it to cool below the dew point. This process typically happens on clear nights where there is minimal cloud cover allowing for efficient cooling. As the ground loses heat, the air in contact with the surface cools as well, leading to condensation of moisture in the air and forming fog.

This type of fog is most commonly seen in valleys and low-lying areas where cold air can accumulate. The formation relies heavily on the cooling of the ground and the consequent drop in air temperature at the surface. In contrast, advection fog develops when warm, moist air moves over a cooler surface, leading to cooling of that air and condensation. High-inversion fog is associated with temperature inversions, where warmer air traps cooler air underneath, and upslope fog forms as moist air rises and cools along a slope or terrain.

Understanding the distinct characteristics that lead to the formation of different types of fog is crucial in meteorological studies and practical aviation applications.