What does relative humidity measure?

the amount of water in cirrus clouds

the amount of water that has evaporated into the air

the amount of frozen water that has condensed from the air

the amount of water vapor in the air compared to the amount the air can hold

The answer is D.

Explanation:

Relative humidity is a measure of the amount of moisture in the air relative to the total amount of moisture the air can hold. For instance, if the relative humidity was 50%, then the air is only half saturated with moisture. Warmer air can hold more moisture than colder air.

Option (D)

Explanation:

The relative humidity refers to the quantification of water vapor prevailing in the atmosphere in relation to the normal atmospheric temperature. In simple words, it is a ratio between the total amount of water vapor existing in the air to the total amount of water vapor that can store in the air at a particular temperature. In the atmosphere, the warm air carries more moisture content compared to the cold air. The warmer air has lower relative humidity and the cooler air has higher relative humidity. It is usually expressed in terms of percentage where 0% depicts that it is dry air and 100% indicates that the air is fully moist.

Thus, the correct answer is option (D).