A Physical Bound on the Bowen Ratio

Abstract

Forbidding supersaturation above an evaporating water (or sublimating ice) surface fixes an upper bound on ?, the Bowen ratio; a similar bound holds for evaporation from unsaturated surfaces. The bound arises from the nonlinearity of the temperature dependence of saturated water vapor density. The resulting inequalities are compared with other estimates of ? and related quantities. The case of supersaturation, with fog formation, lies outside the scope of this study.