Fog occurs when the air temperature near the ground reaches what?

Fog forms when the air temperature near the ground reaches the dew point. The dew point is the temperature at which air becomes saturated with moisture and can no longer hold all the water vapor present. When the temperature drops to this level, the humidity in the air reaches 100%, causing water vapor to condense into tiny water droplets that remain suspended in the air, resulting in fog.

This phenomenon is crucial in understanding weather patterns and visibility conditions, especially in transportation and aviation contexts. Conditions that lead to fog typically involve calm winds and high humidity levels, both of which contribute to the temperature dropping to the dew point near the ground.