Which type of fog is related to a small temperature dew point spread and high relative humidity?

Radiation fog occurs when the ground loses heat through radiation, typically during clear, calm nights. As the temperature drops, it can reach the dew point, resulting in condensation and forming fog. This type of fog is characterized by a small temperature-dew point spread, which means the air is nearly saturated with moisture, leading to high relative humidity conditions. The formation process relies heavily on cooling, and the presence of high humidity is crucial for radiation fog development.

In contrast, steam fog forms when cold air moves over warm water, causing moisture to evaporate and condense when it encounters the cooler air above. Frontal fog is associated with the lifting of warm, moist air over cold fronts, leading to cloud formation rather than a straightforward temperature-dew point relationship. Ice fog occurs in extremely cold temperatures, where water vapor can deposit directly as ice crystals, requiring specific conditions that are not tied to relative humidity in the same way as radiation fog.