The Galileo lightning data confirm that convection is occurring there. No lightning was seen coming from the anticyclones. That's what we see in the Voyager movies, and the Galileo lightning data bear it out. Whether the precipitation is rain or snow is uncertain, says Ingersoll. Models of terrestrial lightning suggest that to build up electrical charge, both liquid water and ice have to be present.
Rain requires a relatively wet Jupiter, and that's a controversial subject.
Water is hard to detect from the outside because it is hidden below the ammonia clouds. And the Galileo probe hit a dry spot where we didn't expect much water. Fortunately the Galileo imaging system caught glimpses of a cloud so deep it has to be water, according to findings to be reported at the conference by Dr. Don Banfield of Cornell University and an imaging team affiliate. Banfield showed images of the water cloud near the convective centers in the cyclonic regions. These results appear in the September issue of Icarus, the International Journal of Solar System Studies.