Which statement best describes relative humidity?

Which statement best describes relative humidity?

• A. The percentage of water vapor a certain volume of air contains relative to the maximum amount it can hold if saturated.
• B. The amount of water in liquid form per cubic meter.
• C. The temperature at which air becomes saturated.
• D. The ratio of water vapor to atmospheric pressure.

Answer: (A)

Relative humidity measures how much water vapor is in the air compared with how much it could hold at the current temperature. It’s the current amount of moisture expressed as a percentage of the maximum possible amount the air can contain if it were saturated. Because warmer air can hold more moisture, the same amount of water vapor results in different RH values as temperature changes. For example, air at 25°C can contain more water vapor than air at 15°C; if both have the same actual vapor, the cooler air will have a higher relative humidity. The other descriptions refer to either the total amount of water vapor (absolute humidity), the temperature at which air becomes saturated (dew point), or a pressure ratio not specific to saturation, so they don’t define relative humidity.

Relative humidity measures how much water vapor is in the air compared with how much it could hold at the current temperature. It’s the current amount of moisture expressed as a percentage of the maximum possible amount the air can contain if it were saturated. Because warmer air can hold more moisture, the same amount of water vapor results in different RH values as temperature changes. For example, air at 25°C can contain more water vapor than air at 15°C; if both have the same actual vapor, the cooler air will have a higher relative humidity. The other descriptions refer to either the total amount of water vapor (absolute humidity), the temperature at which air becomes saturated (dew point), or a pressure ratio not specific to saturation, so they don’t define relative humidity.