NASA’s Juno orbiter has detected ‘wave trains’ — massive structures of moving air that appear like waves — in the atmosphere of Jupiter.
Three waves can be seen in this image, which is an excerpt of a JunoCam image taken on February 2, 2017, during Juno’s fourth flyby of Jupiter. The region imaged in this picture is part of the visibly dark band just north of Jupiter’s equator known as the North Equatorial Belt. Most of this belt is characterized by downwelling motions, but during the fourth flyby it had several bright areas of upwelling clouds. One of those upwelling clouds appears to be accompanied by dark regions, which are most likely shadows. The shadow associated with the center of the three waves is about 25 miles (40 km) long; from the angle of illumination, researchers deduced that the shadowed part of the wave must be around 4 miles (7 km) above the main cloud deck, with the peak of the wave probably close to 6 miles (10 km) above the main cloud deck. Image credit: NASA / JPL-Caltech / SwRI / MSSS / JunoCam.
Wave trains are towering atmospheric structures that trail one after the other as they roam Jupiter.
They were first detected by NASA’s Voyager missions during their flybys of the giant planet in 1979.
“Juno’s imager called the JunoCam has counted more distinct wave trains than any other spacecraft mission since Voyager,” said Juno team member Dr. Glenn Orton, of NASA’s Jet Propulsion Laboratory.
“The trains, which consist of as few as two waves and as many as several dozen, can have a distance between crests as small as about 40 miles (65 km) and as large as about 760 miles (1,200 km).”
“The shadow of the wave structure in one image allowed us to estimate the height of one wave to be about 6 miles (10 km) high.”
Most of the waves are seen in elongated wave trains, spread out in an east-west direction, with wave crests that are perpendicular to the orientation of the train.
Other fronts in similar wave trains tilt significantly with respect to the orientation of the wave train, and still other wave trains follow slanted or meandering paths.
“The waves can appear close to other Jovian atmospheric features, near vortices or along flow lines, and others exhibit no relationship with anything nearby,” Dr. Orton noted.
“Some wave trains appear as if they are converging, and others appear to be overlapping, possibly at two different atmospheric levels.”
“In one case, wave fronts appear to be radiating outward from the center of a cyclone.”
“Although analysis is ongoing, most waves are expected to be atmospheric gravity waves — up-and-down ripples that form in the atmosphere above something that disturbs air flow, such as a thunderstorm updraft, disruptions of flow around other features, or from some other disturbance that JunoCam does not detect.”
