What type of fog occurs when the ground cools rapidly and the air temperature reaches its dew point?

The type of fog that occurs when the ground cools rapidly, causing the air temperature to reach its dew point, is known as radiation fog. This phenomenon typically happens on clear nights when heat from the ground escapes into the atmosphere, resulting in a quick drop in temperature. When the air near the ground cools sufficiently, it can no longer hold the moisture it contains, leading to condensation and the formation of fog.

Radiation fog is often found in valleys and low-lying areas because these regions tend to cool more quickly than higher elevations. The key aspect of radiation fog is that it forms due to the cooling of the ground and the subsequent cooling of the air directly above it. Understanding this process highlights the conditions necessary for radiation fog to form, differentiating it from other types of fog, which have different causes related to moisture content and temperature interactions.