This video says about itself:
17 January 2017
Venus is covered in a thick atmosphere, with clouds of sulphuric acid moving westwards faster than the planet itself rotates.
But among this fast-moving atmosphere scientists have discovered a mysterious ‘sideways smile’ on its surface stretching 6,200 miles (10,000 km) across.
The stationary patch could be a giant wave caused by the gravity from mountains below, the first of its kind to be observed on the planet, according to a new study published on January 16th.
Researchers from the Rikkyo University in Tokyo studied the bow-shaped patch, after it was spotted in December 2015.
‘The most surprising feature of the bow is that it stayed at almost same geographical position despite the background atmospheric super-rotation, the uniform westward wind of which the maximum speed is 100 metres/second at the cloud-top altitudes,’ researchers say.
But exactly why the bow stayed still when the rest of Venus’ atmosphere moves so quickly continues to puzzle scientists.
From Science News:
Weird wave found in Venus’ wind-whipped atmosphere
10,000-kilometer-long stationary feature may have been the biggest of its kind in solar system
By Ashley Yeager
6:11pm, January 17, 2017
With scorching temperatures and a mind-numbingly slow rotation (one Venus day lasts 243 Earth days), Venus was already a contender for weirdest planet in the solar system. Now add a giant arc-shaped structure to its list of oddities. The mysterious 10,000-kilometer-long structure was so big that it appeared to stretch between the planet’s poles. And it didn’t budge, even as winds in the planet’s upper atmosphere whipped along at a brisk 100 meters per second.
The C-shaped structure, which lasted at least four Earth days, could be a gravity wave, a large disturbance in the flow of a fluid or air, scientists say. It may have formed on Venus when winds in the planet’s lower atmosphere slammed into a mountain range and were pushed into the upper atmosphere, where it got stuck, a team of Japanese researchers report January 16 in Nature Geoscience.
Captured in images taken by JAXA’s Akatsuki spacecraft in December 2015, the structure could be the largest stationary gravity wave ever observed in the solar system. If it did shift from the lower to upper atmosphere, there may be more going on near the surface of the planet than scientists previously thought.