A Primer on Jupiter’s Clouds »

Justin Cowart:

The most obvious features of Jupiter are its bands of light and dark clouds. These are bordered by jet streams blowing east and west. The light areas are called zones. The air inside zones is circulating anti-cyclonically, making them a broad area of higher air pressure. The increased pressure supports the formation of high-altitude clouds of white ammonia ice, which mostly obscure the deeper, more colorful clouds. The dark areas are called belts, and inside these the air circulates cyclonically. In the belts, the ammonia ice clouds aren’t thick enough to obscure the view, allowing us to see a deeper cloud deck of ammonium sulfide and ammonium hydrosulfide, as well as a rich brew of organic compounds. These chemicals could be giving the belts their brownish color.