Composition of Jovian Atmosphere
Atmosphere of giant Jupiter is also giant. Atmosphere of Jupiter or Jovian atmosphere spans over 5000 km in altitude and no wonder it is the largest planetary atmosphere in our solar system. It is primarily composed of molecular hydrogen and helium. It also has methane, ammonia, ethane and water. As a result of temperatures and pressures well exceeding those of the critical points for hydrogen and helium and making them supercritical fluids, there exists no sharp boundary between gas and liquid so no clear boundary exists between the atmosphere and liquid interior part of Jupiter. In other words, Jupiter lacks any surface between its atmosphere and interior parts in opposition to what we have in planets like Earth or Mars. With no surface, the base of Jovian atmosphere is usually considered to be the level with atmospheric pressure of 100 kPa (1.0 bar). The lowest layer of Jovian atmosphere, its troposphere, contains an intricate system of clouds and hazes comprising layers of ammonia, ammonium hydrosulfide and water. The visible upper ammonia clouds are organized in a dozen zonal bands parallel to the equator. The bands alternating in color are divided into belts and zones where zones, lighter and colder than belts, match ascending gas opposed to descending gas in belts. Ammonia ice is believed to cause the lighter color of zones but the cause of darker color of belts is unsure.