relative humidity 

https://doi.org/10.1351/goldbook.R05267
The ratio, often expressed as a percentage, of the partial pressure of water in the atmosphere at some observed temperature, to the saturation vapour pressure of pure water at this temperature.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2210 [Terms] [Paper]
Citation: 'relative humidity' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.R05267 RIS BibTex EndNote
Div. VIPDFTextXMLJSON
Last revised: February 24, 2014