Which term is the ratio of the amount of water vapor in air at a specific temperature?

Which term is the ratio of the amount of water vapor in air at a specific temperature?

• A. Relative Humidity (RH)
• B. Humidity
• C. Dew Point
• D. Vapor Pressure

Answer: (A)

Relative humidity is the ratio of the actual amount of water vapor in the air to the maximum amount the air can hold at that specific temperature, expressed as a percent. This measure shows how close the air is to saturation at that temperature, which is exactly what the question describes. Other terms don’t fit as precisely. Humidity is a broad, often vague term for water vapor in air. Absolute or specific humidity refers to the amount of water vapor per volume or per mass of air, not a ratio at a specific temperature. Dew point is the temperature at which air becomes saturated and water begins to condense, not a ratio. Vapor pressure is the pressure contribution of water vapor in the air, not a ratio to the maximum possible at that temperature. Relative humidity specifically captures that ratio at the given temperature.

Relative humidity is the ratio of the actual amount of water vapor in the air to the maximum amount the air can hold at that specific temperature, expressed as a percent. This measure shows how close the air is to saturation at that temperature, which is exactly what the question describes.

Other terms don’t fit as precisely. Humidity is a broad, often vague term for water vapor in air. Absolute or specific humidity refers to the amount of water vapor per volume or per mass of air, not a ratio at a specific temperature. Dew point is the temperature at which air becomes saturated and water begins to condense, not a ratio. Vapor pressure is the pressure contribution of water vapor in the air, not a ratio to the maximum possible at that temperature. Relative humidity specifically captures that ratio at the given temperature.