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specific humidity

noun
  1. the ratio of the mass of water vapor in air to the total mass of the mixture of air and water vapor.
Compare mixing ratio, absolute humidity, dew point, relative humidity.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for specific humidity

specific humidity

noun
  1. the mass of water vapour in a sample of moist air divided by the mass of the sample
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012