How does fog typically occur?

Fog typically occurs when the temperature near the ground reaches its dew point. This cooling process results in moisture in the air condensing into tiny water droplets that create the fog. When warm, moist air comes into contact with cooler surfaces or air, it can cool down to the point where it can no longer hold all of its moisture, leading to condensation. This is particularly common during the early morning or late evening when temperatures drop.

Other options relate to conditions or phenomena that can influence weather but don’t directly explain the process by which fog forms. For example, high humidity levels can contribute to the potential for fog, but it’s the cooling of the air to its dew point that actually results in fog formation. Similarly, while pollutants can influence air quality and visibility, fog is primarily a result of temperature and moisture conditions. Therefore, the key concept is understanding that it's the relationship between temperature, moisture, and dew point that directly leads to the formation of fog.