The dewpoint is the temperature at which air becomes saturated and can hold no more water.

• A. The temperature at which dew forms
• B. The temperature at which air becomes saturated and can hold no more water
• C. The humidity level at 100 percent
• D. The temperature at which water vapor condenses

Answer: (B)

The dewpoint is the temperature to which air must be cooled for it to become saturated with water vapor. At that temperature the air can hold no more moisture, so relative humidity reaches 100 percent and any further cooling leads to condensation. This definition links moisture content directly to a cooling temperature, which is exactly what the statement expresses. Understand that dew forms on surfaces when air is cooled to the dewpoint, so the dewpoint isn’t simply “the temperature at which dew forms” in the air itself. Relative humidity being 100 percent describes how full the air is with vapor, not the temperature needed to reach saturation. Condensation happens as the air reaches or goes below the dewpoint, but the dewpoint itself is the threshold temperature for saturation, not the condensation event itself.