What results in the condensation of water vapor to form dew or fog?

The formation of dew or fog occurs when the temperature of the air drops to the dew point, which is the temperature at which water vapor condenses into liquid water. When the temperature and the dew point are the same, or the temperature/dew point spread is zero, it indicates that the air is fully saturated with moisture, leading to condensation.

In this state, water vapor in the air condenses into tiny water droplets that form dew on surfaces near the ground or results in the visibility-reducing phenomenon known as fog. This situation is most common during the early morning hours or late at night when temperatures typically drop.

High humidity levels can contribute to the likelihood of condensation but do not directly indicate a specific event like dew or fog formation without the correlating temperature condition. Wind speed is not a primary factor in dew or fog formation, as calm conditions tend to allow for greater cooling and thus more effective condensation. Temperature below freezing pertains to frost formation rather than dew or fog, as it involves different conditions for condensation in the form of ice rather than liquid water.