Relative evaporation
"Ratio of the actual rate of evaporation from land and water surfaces to the potential evaporation under the existing conditions." (United Nations Publications, 2013)
Sources
United Nations Publications. "Glossary of Shared Water Resources (English-Arabic): Technical, Socioeconomic and Legal Terminology." (2013). DOI:https://dx.doi.org/10.18356/70b462ce-en