However, lightning discharges within clouds are by far the most common. On Jupiter, where no solid surface exists, lightning is believed to be occurring within the water clouds. The Lightning and Radio Emission Detector searched for optical flashes and radio waves emitted by lightning discharges. No optical lightning flashes were observed in the vicinity of the Galileo Probe , but many discharges were observed at radio frequencies. Radio wave intensity suggests lightning activity is 3-10 times less common than on Earth.
Initial analysis implies that lightning on Jupiter is very different than on Earth.
The unusual form of the radio signals from the lightning indicates more work on lightning discharge physics on Jupiter is needed. Ideas of water cloud distribution, precipitation, and heat escape from Jupiter may need revision. Little evidence of organic molecules was found. The Neutral Mass Spectrometer and Helium Abundance Detector found several key elements in nearly solar proportions in Jupiter's atmosphere, providing fundamental clues to Jupiter's formation and evolution. The Helium Abundance Detector experiment very accurately measured the abundance of helium in Jupiter's atmosphere.