EN
The free convection of the water and air over the globe induces evaporation of standing water and the generation of wind, respectively. The ratio of the corresponding heat transfer coefficients is shown to be equal to the ratio of solar power going into evaporation/precipitation and into wind generation. The present work provides a justification for the estimate on wind power reported by M. King Hubbert and also that wind generation on a global scale is about two-order magnitudes less than the solar power responsible for rainfall. This paper resolves the existing ambiguity in the estimates of wind power over the globe.