The first discrete ammonia ice cloud positively identified on Jupiter is shown in this image taken by NASA's Galileo spacecraft. Ammonia ice (light blue) is shown in clouds to the northwest (upper left) of the Great Red Spot (large red spot in middle of figure). This unusual cloud, inside the turbulent wake region near the Great Red Spot, is produced by powerful updrafts of ammonia-laden air from deep within Jupiter's atmosphere. These updrafts are generated by the turbulence induced in Jupiter's massive westward-moving air currents by the nearby Great Red Spot.
This false-color image was composed from several near-infrared color images obtained by the Galileo's near-infrared mapping spectrometer on June 26, 1996. Reddish-orange areas show high-level clouds, yellow areas depict mid-level clouds, and green areas depict lower-level clouds. Darker areas are cloud-free regions. Light blue depicts regions of middle-to-high-altitude-level ammonia ice clouds. The Great Red Spot, which has existed for at least 300 years, is the oldest and largest weather system in our solar system. It measures over 20,000 kilometers wide (over 12,400 miles), which is about twice as wide as Earth.
NASA/JPL
from Planetary Photojournal