Voyager 2 images of the southern hemisphere of Uranus indicate that submicrometersize haze particles and particles of a methane condensation cloud produce faint patterns in the atmosphere. The alignment of the cloud bands is similar to that of bands on Jupiter and Saturn, but the zonal winds are nearly opposite. At mid-latitudes (-70 degrees to -27 degrees ), where winds were measured, the atmosphere rotates faster than the magnetic field; however, the rotation rate of the atmosphere decreases toward the equator, so that the two probably corotate at about -20 degrees . Voyager images confirm the extremely low albedo of the ring particles. High phase angle images reveal on the order of 10(2) new ringlike features of very low optical depth and relatively high dust abundance interspersed within the main rings, as well as a broad, diffuse, low optical depth ring just inside the main rings system. Nine of the newly discovered small satellites (40 to 165 kilometers in diameter) orbit between the rings and Miranda; the tenth is within the ring system. Two of these small objects may gravitationally confine the e ring. Oberon and Umbriel have heavily cratered surfaces resembling the ancient cratered highlands of Earth's moon, although Umbriel is almost completely covered with uniform dark material, which perhaps indicates some ongoing process. Titania and Ariel show crater populations different from those on Oberon and Umbriel; these were probably generated by collisions with debris confined to their orbits. Titania and Ariel also show many extensional fault systems; Ariel shows strong evidence for the presence of extrusive material. About halfof Miranda's surface is relatively bland, old, cratered terrain. The remainder comprises three large regions of younger terrain, each rectangular to ovoid in plan, that display complex sets of parallel and intersecting scarps and ridges as well as numerous outcrops of bright and dark materials, perhaps suggesting some exotic composition.
Voyager 2 images provide a basis for detailed study of the morphology and circulation of Saturn's northern mid‐latitudes. Both Saturn's large‐scale cloud bands and the distribution of its local cloud features have a characteristic zonal organization. The region between 30°N and 45°N contains two oppositely directed jets in close proximity, with many bright, active features in the westward jet, and an unusual ribbon‐like wave feature encircling the planet in the eastward jet. Several of the smaller features within the westward jet do not remain at fixed latitudes and interact with each other. One group of v‐shaped features is found to have periods of high activity correlated with the passage of a cyclonic bright spot. The ribbon wave was Fourier analyzed to determine its spectral composition. The greatest power is near wave number 9, with significant additional peaks appearing at planetary wave numbers 19, 25–27, 35–38, and 47–51. The phase velocity increases with wave number but is not well described by a Rossby‐Haurwitz dispersion relation. The curvature of the mean wind profile obtained from cloud tracking indicates that the westward jet exceeds the standard barotropic instability condition, while the eastward jet marginally exceeds the deep‐circulation instability condition of Ingersoll and Pollard (1982). The rms eddy velocities on Saturn are less than half as large as those observed on Jupiter.
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