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relative humidity[′rel·əd·iv hyü′mid·əd·ē]
The (dimensionless) ratio of the actual vapor pressure of the air to the saturation vapor pressure. Abbreviated RH.
The ratio of the amount of water vapor in air to the maximum amount of water that the same volume of air can hold at the same temperature, expressed as a percentage.
The ratio of the weight of water vapor actually in humid air to the maximum possible weight of the water vapor that the air could contain at the same temperature; usually expressed as a percentage.
The ratio of the amount of water vapor in the air to the amount the air can hold at that temperature. This ratio is always expressed as a percentage.