On the largest scales , planetary climates can be described by their Rossby number ( Ro ) . Ro is in response to Gr / Re ^ { 2 } , where Gr is the Grashof number and Re is the Reynolds number .
We here simplify Gr / Re ^ { 2 } as h , where h = H / H _ { Earth } with H = gP / ( 2 \pi V _ { e } ) for a planet with surface gravity g , rotation period P and equatorial velocity V \textsubscript e. Unlike h , Ro is difficult to obtain because of a large diversity in observation .
We perform on an in-depth literature search on average ( av ) and maximum ( mx ) wind velocity for each planet in the Solar system by various observational methods and by altitude .
We explore a correlation between Ro and h expressed as a power law with index \alpha based on wind velocities of planets in the Solar system .
We obtain a correlation between Ro and h with \alpha = 0.56 ( av ) and \alpha = 0.52 ( mx ) .
Earth ’ s H = H _ { Earth } ( h = 1 ) is primarily due to lunar tidal interaction , given our relatively distant habitable zone ( HZ ) to the Sun .
Our positive correlation , therefore , suggests exoplanet-moon systems as the ‘ go-to-place ’ in our searches for potentially advanced life in exosolar system .