Scientists have known that giant Jupiter contains ammonia gas and had speculated that clouds of pure ammonia ice might form there. Now the Galileo spacecraft has provided picture proof.

The large red area is Jupiter's famed Great Red Spot, an intense storm more powerful than any terrestrial hurricane and over 12,400 miles (20,000 kilometers) wide, which is close to twice as wide as Earth.

The false colors are produced from images taken in the invisible near-infrared wavelength of light. 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.

"Detecting a localized ice cloud confirms the common belief that ammonia clouds do exist on Jupiter," said Kevin Baines, research scientist at NASA's Jet Propulsion Laboratory.

(Yes, the ammonia on Jupiter is like the stuff manufactured in great quantities here on Earth, primarily as an ingredient in fertilizer. In the 19th century, a weakened form of it was used in smelling salts.)

Scientists expected that the low temperatures in Jupiter's outer atmosphere would cause the ammonia gas to condense into ice, but they had not seen evidence before.

Baines said that the ammonia cloud is located in an especially turbulent area. A current flows around the Great Red Spot from east to west. Behind it, the current eddies and whirls, just as a rock in a stream creates whirlpools and whitewater behind it.

Another powerful current moving in the opposite direction may intensify the ammonia spot, researchers said. This tumultuous motion pulls up ammonia from below the cloud level. As it rises, the ammonia cools and condenses into ice, creating fresh clouds.

Because of all the roiling and boiling, the spot was named the Turbulent Wake Anomaly. The image was presented at the recent annual meeting of the American Astronomical Society's Division of Planetary Sciences meeting.

Galileo and the Cassini spacecraft will analyze the spot later this year, looking for answers to whether other substances in Jupiter's upper atmosphere might be transported from below in a similar manner.

Galileo, which has been orbiting Jupiter and its moons since 1995, has previously produced spectacular images of Jupiter's raging clouds. One 1997 shot, below, also used near-infrared to show variations in cloud height and thickness.

The dark blue area is a hole in the clouds, covered by an overlying thin haze. Scientists call the hole a hot spot, because heat from Jupiter's deep atmosphere rises up through it.

Bluish clouds are high and thin, reddish clouds are low and white clouds are high and thick. The light blue region to the left is covered by a very high haze layer. The multicolored region to the right has overlapping cloud layers of different heights.

The image covers an area about 21,100 by 6,800 miles (34,000 kilometers by 11,000 kilometers).

Both images were provided by NASA's Jet Propulsion Laboratory.