What type of air is likely to contribute to fog formation?

Humid air is likely to contribute to fog formation because fog is essentially a cloud that forms at or near the ground when the air becomes saturated with moisture. When the humidity in the air is high, it means there is a significant amount of water vapor present, which increases the likelihood of reaching the dew point. When the temperature of the humid air drops to the dew point, condensation occurs, leading to the formation of tiny water droplets suspended in the air, resulting in fog.

In contrast, arid air, dry air, and cold air do not provide the necessary conditions for fog development. Arid and dry air lack sufficient moisture levels, which means there is not enough water vapor to condense and form fog. While cold air can lead to fog in specific situations (such as when it comes into contact with warmer, moist air), on its own, it is not a definitive factor in fog formation without the presence of high humidity. Therefore, humid air plays a crucial role in creating the right conditions for fog to form.