When air temperature is lowered while moisture content remains constant, what happens to relative humidity?

When air temperature is lowered while the moisture content remains constant, the relative humidity increases. Relative humidity is defined as the ratio of the current amount of water vapor in the air to the maximum amount of water vapor that air can hold at a given temperature, expressed as a percentage.

As the temperature drops, the air's capacity to hold water vapor decreases. Since the amount of moisture in the air does not change, but the air's capacity to hold that moisture decreases with lower temperatures, the relative humidity must rise. This can be understood by recognizing that at lower temperatures, the same amount of moisture represents a higher percentage of the air's total saturation point. Consequently, the air becomes more saturated, leading to higher relative humidity levels.

In this context, it’s clear why the other responses don't align with the principles of humidity and temperature relationships.