To understand the origin of the bands and spots, the most interesting areas to observe turned out to be the borders that separate the bands. The photographs taken by the Pioneer and Voyager probes showed that these confines are convoluted and wrinkled into vortexes, like torrents of water along the shores. As we already know, Jupiter has a very high speed of rotation, that approaches 40 000 kilometers per hour at the equator. Evidently, this rotation generates atmospheric circulation, which consists of large extensive "corridors" parallel to the equator. The Great Red Spot is part of this circulation and is something very similar to what on Earth we might call a hurricane. A hurricane, however, that has continued without interruption, at least from that day in 1665 in which it was seen for the first time. Considering the bands and the Great Red Spot, it was still not clear why there were alternating lighter and darker bands. Today, thanks to the data collected by the probes, we can answer this question. One of the discoveries made by the Pioneer probes during their approach to the planet was that, in addition to hydrogen and helium, Jupiter's clouds also contain a certain amount of ammonia. Ammonia freezes at a temperature of -77 degrees Celsius. The temperature of the upper surface of the clouds is around -120 degrees: enough for the ammonia in that layer to stabilize into ice crystals, with strong solar light reflecting power. This is why the layers containing the crystals appear to be almost white. But why do the adjacent layers have such a different and darker color? The answer was again provided by the Pioneer probes: they indicated that the upper surface of the Great Red Spot appears at an altitude of 240 kilometers lower than the upper surface of the clouds. The internal temperature of Jupiter increases gradually from the exterior to the interior: at the center it reaches 30 000 degrees. The difference in altitude between the Great Red Spot and that which surrounds it makes its internal temperature higher, at least enough to transform the ammonia ice crystals into droplets, which do not reflect as much light. Thus, the surface of Jupiter's clouds is not all at the same height: the top of the lighter bands is higher than the top of the darker bands.
To understand the origin of the bands and spots, the most interesting areas to observe turned out to be the borders that separate the bands. The photographs taken by the Pioneer and Voyager probes showed that these confines are convoluted and wrinkled into vortexes, like torrents of water along the shores. As we already know, Jupiter has a very high speed of rotation, that approaches 40 000 kilometers per hour at the equator. Evidently, this rotation generates atmospheric circulation, which consists of large extensive "corridors" parallel to the equator. The Great Red Spot is part of this circulation and is something very similar to what on Earth we might call a hurricane. A hurricane, however, that has continued without interruption, at least from that day in 1665 in which it was seen for the first time. Considering the bands and the Great Red Spot, it was still not clear why there were alternating lighter and darker bands. Today, thanks to the data collected by the probes, we can answer this question. One of the discoveries made by the Pioneer probes during their approach to the planet was that, in addition to hydrogen and helium, Jupiter's clouds also contain a certain amount of ammonia. Ammonia freezes at a temperature of -77 degrees Celsius. The temperature of the upper surface of the clouds is around -120 degrees: enough for the ammonia in that layer to stabilize into ice crystals, with strong solar light reflecting power. This is why the layers containing the crystals appear to be almost white. But why do the adjacent layers have such a different and darker color? The answer was again provided by the Pioneer probes: they indicated that the upper surface of the Great Red Spot appears at an altitude of 240 kilometers lower than the upper surface of the clouds. The internal temperature of Jupiter increases gradually from the exterior to the interior: at the center it reaches 30 000 degrees. The difference in altitude between the Great Red Spot and that which surrounds it makes its internal temperature higher, at least enough to transform the ammonia ice crystals into droplets, which do not reflect as much light. Thus, the surface of Jupiter's clouds is not all at the same height: the top of the lighter bands is higher than the top of the darker bands.
