The Story behind the Bowen Ratio

Abstract

Ira Sprague Bowen (1898?1973) was a prominent astrophysicist during the twentieth century. In his impressive oeuvre of work over the 50-year span (1920?70), there appears a lone contribution to the geophysical sciences on the subject of evaporation and conduction from water surfaces. This theoretical development led to an expression for the ratio of heat conduction to evaporative flux at the air-water interface, labeled the Bowen ratio by Harald Sverdrup in the early 1940s. The circumstances that led to this contribution are examined with attention to the character of education and research at the California Institute of Technology during the 1920s. Bowen was unaware of the important precedent work in meteorology and fluid dynamics that is also reviewed.