Jupiter's atmospheric chemistry. Diagram showing the Jovian atmospheric chemistry of methane (CH4), a trace constituent of Jupiter's mostly hydrogen and helium atmosphere. In the upper layers (top), charged particles (cosmic rays) and ultraviolet (UV) solar radiation drive the production of hydrocarbon radicals that reform as compounds like ethyne (C2H2). Further down (centre), lightning drives reactions with other trace compounds like ammonia (NH3) and hydrogen sulphide (H2S), producing the red, brown and yellows of the Jovian clouds. Deep down (bottom left), methane is driven up by the internal heat to react with water (H2O), producing carbon monoxide (CO) and hydrogen (H2).