image: Schematic illustration on how the super-rotation of Venus' atmosphere is maintained. In the cloud layer of Venus, a vertical and north-south circulation, called the meridional circulation, exists (white arrows) to transport heat from low latitudes to high latitudes, because sunlight is absorbed more at low latitudes. This circulation also transports the angular momentum, which corresponds to the strength of the circulating winds (yellow arrows), to decelerate the superrotation. The deceleration is compensated by the acceleration by the thermal tide, which transports angular momentum both horizontally and vertically (red arrows). Other waves and turbulence work oppositely but weakly at low latitudes (blue allows), while they play an important role at mid latitudes (pale blue arrows; to transport the angular momentum to shortcut the meridional circulation). The combination of these effects manifests a system to effectively transport heat across the globe by the combination of the slow poleward heat transport by the meridional circulation and the fast heat transport to the night-side by the meridional circulation. Such a dual circulation system might present on tidally locked exo-planets to reduce temperature differences over them. This material relates to a paper that appeared in the 24 April issue of Science, published by AAAS. The paper, by T. Horinouchi at Hokkaido University in Sapporo, Japan, and colleagues was titled, "How waves and turbulence maintain the super-rotation of Venus' atmosphere." view more
Credit: [Credit: (C)Planet-C project team]