An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

In a system of moist air, the ratio of the mass of water vapor to the total volume of the system. → humidity.

→ absolute; → humidity.

Generally, a measure of the water vapor content of the air. Popularly, it is used synonymously with → relative humidity. → absolute humidity, → dew point, → mixing ratio, → specific humidity.

Humidity, from O.Fr. humide, from L. humidus "moist, wet," variant (by influence of humus "earth") of umidus, from umere "be moist."

Nam "humidity, moisture," from Mid.Pers. nam, namb "moisture;" Av. napta- "moist," nabās-câ- "cloud," nabah- "sky;" cf. Skt. nábhas- "moisture, cloud, mist;" Gk. nephos "cloud, mass of clouds," nephele "cloud;" L. nebula "mist," nimbus "rainstorm, rain cloud;" O.H.G. nebul; Ger. Nebel "fog;" O.E. nifol "dark;" from PIE *nebh- "cloud, vapor, fog, moist, sky."

The amount of moisture in the air compared to what the air can "hold" at that temperature. It is given by the ratio of the partial pressure of water vapor in the mixture to the saturated vapor pressure of water at a specific temperature.

→ relative; → humidity.

The dimensionless ratio of the mass of water vapor to the total mass in a particular volume. → humidity

→ specific; → humidity.