Scientists fine tune the cause of the super-rotation of Venus’ atmosphere
Scientists using data collected from the Japanese Venus orbiter Akatsuki have now refined their theories on the atmospheric processes that cause that atmosphere to rotate sixty times faster than the planet.
This super-rotation increases with altitude, taking only four Earth days to circulate around the entire planet towards the top of the cloud cover. The fast-moving atmosphere transports heat from the planet’s dayside to nightside, reducing the temperature differences between the two hemispheres.
What they found was that at equatorial latitudes the heat transfer is generated by what they call “atmospheric tidal waves”, generated by the dayside solar heat. At high latitudes the transfer is instead caused by atmospheric turbulence.
From what I can gather, they are calling these tidal waves because the Sun’s heat causes the atmosphere to expand upward on the day side, much as the Moon’s gravity pulls the ocean upward on Earth. It then is quickly drawn to the colder night side, driven I think in one direction because of the planet’s slow rotation.
As always, we must recognize the uncertainties. The data here is somewhat limited because there have been so few atmospheric orbiters so far sent to study Venus. While several future missions are under study in the U.S. and Russia, only India appears to have one targeted for launch, though the date has been pushed back from 2020 to 2023.
Scientists using data collected from the Japanese Venus orbiter Akatsuki have now refined their theories on the atmospheric processes that cause that atmosphere to rotate sixty times faster than the planet.
This super-rotation increases with altitude, taking only four Earth days to circulate around the entire planet towards the top of the cloud cover. The fast-moving atmosphere transports heat from the planet’s dayside to nightside, reducing the temperature differences between the two hemispheres.
What they found was that at equatorial latitudes the heat transfer is generated by what they call “atmospheric tidal waves”, generated by the dayside solar heat. At high latitudes the transfer is instead caused by atmospheric turbulence.
From what I can gather, they are calling these tidal waves because the Sun’s heat causes the atmosphere to expand upward on the day side, much as the Moon’s gravity pulls the ocean upward on Earth. It then is quickly drawn to the colder night side, driven I think in one direction because of the planet’s slow rotation.
As always, we must recognize the uncertainties. The data here is somewhat limited because there have been so few atmospheric orbiters so far sent to study Venus. While several future missions are under study in the U.S. and Russia, only India appears to have one targeted for launch, though the date has been pushed back from 2020 to 2023.