Scientists think a huge "gravity wave" may have been launched into the atmosphere by a large mountain, like Maat Mons pictured here.
In an astonishing new discovery, scientists have spotted a gigantic wave in the upper atmosphere of Venus, a startling find because it is staying so still above the surface of the planet. While clouds in the regions are common, they typically move at 100 meters per second, whereas the cloud is basically stationary when compared to the rotation of the planet.
Researchers think the wave may have been created in the lower atmosphere and then flowed over a mountain, like Maat Mons pictures above, a huge volcano that is the second-highest mountain on Venus. This so-called “gravity wave” has nothing to do with the recently written about graviational waves, which have to do with space-time ripples.
This gravity wave is an indication that the atmospheric dynamics on Venus are much more complex than scientists realized, and there is a lot of learning yet to be done about this phenomena. The findings were made thanks to observations by Japan’s Akatsuki spacecraft, which has been orbiting Venus since 2015.
The statement notes: “The planet Venus is covered by thick clouds of sulfuric acid that move westwards because the entire upper atmosphere rotates much faster than the planet itself. At the cloud tops, about 65 km in altitude, small-scale features are predominantly carried by the background wind at speeds of approximately 100 m s−1. In contrast, planetary-scale atmospheric features have been observed to move slightly faster or slower than the background wind, a phenomenon that has been interpreted to reflect the propagation of planetary-scale waves. Here we report the detection of an interhemispheric bow-shaped structure stretching 10,000 km across at the cloud-top level of Venus in middle infrared and ultraviolet images from the Japanese orbiter Akatsuki.
“Over several days of observation, the bow-shaped structure remained relatively fixed in position above the highland on the slowly rotating surface, despite the background atmospheric super rotation. We suggest that the bow-shaped structure is the result of an atmospheric gravity wave generated in the lower atmosphere by mountain topography that then propagated upwards. Numerical simulations provide preliminary support for this interpretation, but the formation and propagation of a mountain gravity wave remain difficult to reconcile with assumed near-surface conditions on Venus. We suggest that winds in the deep atmosphere may be spatially or temporally more variable than previously thought.”