Giant Planet Lightning in Nonideal Gases

Abstract Lightning has been directly observed or inferred on all giant planets, generally accepted to be occurring in their water clouds. However, much as Earth both cloud–cloud and cloud–ground lightning, this does not mean flashes occur a narrow altitude range: Jupiter, the Galileo spacecraft detected lightning apparently below cloud base, explicable due precipitation, Juno SRU small far above it, at pressures of only 1–2 bars. We use computationally light 1D entraining plume model, incorporating particle growth noninductive charging, which predicts wide range Jovian provides freezing point depressions caused by ammonia, modify it van der Waals equation state instead an ideal gas, well integrating evaporation rain; allows modeling planets colder than where clouds greater pressures. For Saturn, uppermost is predicted 3–4 bars; unlike ammonia required match Cassini observations. Uranus Neptune, depending convective structures, very high rates are possible deep clouds; while deeper Jupiter likely peak around 100 Voyager 2's radio observations Uranian Neptunian sferics may thus either attenuation type, shallow future resolve dichotomy.