Private Pilot Private Exam

What does the term "dewpoint" refer to?

1. The temperature of the air

2. The temperature at which condensation occurs

3. The temperature at which air must be cooled to become saturated

4. The temperature of the ground at night

The correct answer is: The temperature at which air must be cooled to become saturated

The term "dewpoint" specifically refers to the temperature at which air must be cooled to become saturated with moisture. When air cools to its dew point, it can no longer hold all the moisture it contains, leading to condensation. This is the point at which water vapor in the air begins to condense into liquid water, forming dew, fog, or clouds. Understanding the dew point is crucial for pilots, as it provides insight into humidity levels and potential weather phenomena. For instance, a high dew point indicates a greater amount of moisture in the air, which can affect visibility and cloud formation. Conversely, a low dew point generally suggests drier air, which can lead to clearer skies. In relation to the other choices, while the temperature of the air and the temperature of the ground at night can influence weather conditions, they do not directly define what dewpoint means. Additionally, the temperature at which condensation occurs is closely related but not the precise definition; the dew point specifically denotes the temperature needed for saturation, which triggers condensation.