To determine the relative humidity of the air when dew forms, let's consider the process of dew formation.
When air temperature cools down to the dew point, the air becomes saturated with moisture. This means the air cannot hold any more water vapor, and excess moisture begins to condense into liquid water, forming dew.
At the point of saturation, the relative humidity reaches its maximum level. Relative humidity is defined as the percentage of moisture in the air compared to the maximum amount of moisture the air can hold at that temperature.
When dew forms, the air is at saturation point, meaning it is holding the maximum amount of moisture possible. Therefore, the relative humidity is:
(A) [tex]\(100\%\)[/tex]
So, the relative humidity of the air when dew forms is [tex]\(100\%\)[/tex].
