Table 1 Metrics of humidity in the atmosphere. Definitions from Shuttleworth (2012)
From: Humidity Measurements
Metric | Description | Units |
|---|---|---|
Absolute humidity | Mass of water vapor per volume of moist air | g cm−3 |
Mixing ratio | Ratio between the mass of water vapor to the mass of dry air in the moist air sample, expressed in terms of densities | – |
Specific humidity | Ratio of the mass of water vapor to the mass of moist air | – |
Saturation specific humidity | Ratio of the mass of water vapor to the mass of moist air in saturated air given temperature and pressure | – |
Relative humidity | Ratio of the specific humidity of the air to the saturation specific humidity at air temperature | – |
Dew point temperature | The temperature to which air must be cooled at constant pressure for it to saturate | °C |
Wet bulb temperature | The temperature to which air is cooled by evaporating water into it at constant pressure until it is saturated | °C |
Vapor pressure | The contribution of water vapor to air pressure | kPa |
Saturated vapor pressure | The vapor pressure of saturated air; a function of temperature | kPa |
Vapor pressure deficit | Difference between saturation vapor pressure at air temperature and the vapor pressure of the air | kPa |