What describes the concentration of water vapor in the air?

The concentration of water vapor in the air is best described by absolute humidity. Absolute humidity refers specifically to the actual amount of water vapor present in a given volume of air, typically expressed in grams of water per cubic meter of air. This measurement provides a direct indication of the moisture present, regardless of temperature.

Relative humidity, while related, represents the amount of water vapor in the air as a percentage of the maximum amount the air can hold at a specific temperature. This measurement is affected by temperature changes, which means that it is not a direct measure of vapor concentration.

Saturation vapor pressure is a measure of the pressure exerted by water vapor in the air when it is saturated, and it varies with temperature. Cloud cover refers to the fraction of the sky covered by clouds and does not relate directly to the concentration of water vapor.

Understanding these distinctions is key to grasping how moisture is represented in meteorology and atmospheric science, emphasizing that absolute humidity provides the clearest picture of water vapor concentration in the atmosphere.