What is the state of the air when fog or dew has formed as the temperature drops?

When fog or dew forms as the temperature drops, the state of the air is best described as saturated. This occurs when the air's temperature cools to the dew point, leading to the condensation of water vapor. At this point, the air can no longer hold all of its moisture in vapor form, resulting in the formation of tiny water droplets that create fog or dew.

Saturation indicates that the air is at 100% relative humidity, meaning it is fully loaded with moisture. This phenomenon reflects the fundamental principles of thermodynamics and meteorology, where temperature changes directly impact the capacity of air to hold moisture. Thus, fog is an indication that the air has reached its limits concerning moisture content, highlighting the relationship between temperature and humidity in atmospheric conditions.