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Why do Uranus's cloud bands run parallel to its equator?
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Uranus
Two views of the southern hemisphere of Uranus, produced from images obtained by Voyager 2 on Jan. 17, 1986. In colours visible to the unaided human eye, Uranus is a bland, nearly featureless sphere (left). In a colour-enhanced view processed to bring out low-contrast details, Uranus shows the banded cloud structure common to the four giant planets (right). From the polar perspective of Voyager at the time, the bands appear concentric around the planet's rotational axis, which is pointing nearly toward the Sun. Small ring-shaped features in the right image are artifacts arising from dust in the spacecraft's camera.
Uranus's cloud bands run parallel to its equator primarily because of the planet's rotation, rather than the distribution of absorbed sunlight. This phenomenon is driven by the Coriolis force, which deflects atmospheric movement as the planet spins.1
Essentially, the rotation of the planet controls these cloud patterns, creating a zonal flow similar to that seen on Jupiter and Saturn. Because of this effect, Uranus’s atmospheric circulation functions like a tipped-over version of those larger gas giants. While Uranus experiences unique seasonal changes due to its extreme axial tilt, the consistent orientation of its cloud bands demonstrates that the planet's internal rotation is the dominant factor in shaping its atmospheric structure.1