As the temperature of the air reaches the dew point, ____________.

When the temperature of the air reaches the dew point, the air becomes saturated with moisture. At this point, the relative humidity reaches 100%, which is the condition necessary for condensation to occur. This process can lead to the formation of various types of moisture in the atmosphere, including fog. Fog specifically forms when air near the ground cools to its dew point, creating visible water droplets suspended in the air.

The relationship between temperature, dew point, and humidity is crucial in understanding meteorological phenomena. As the air temperature drops to the dew point, it can't hold all the moisture it did at the higher temperature, leading to condensation and the potential for fog. This is especially common in calm, clear nights when the ground cools rapidly, and the air near the surface drops to its dew point.

While precipitation can occur after the dew point is reached, it typically requires additional processes, such as upward motion and cloud formation, which may not happen immediately. Additionally, humidity levels do not decrease but rather reach their maximum potential at saturation. The air does not become dry, as reaching the dew point indicates that the air is holding a significant amount of moisture. Thus, the formation of fog is a direct consequence of air reaching the dew point.