Date:

Atmospheric tidal waves maintain Venus’ super-rotation

Images from the Akatsuki spacecraft unveil what keeps Venus’s atmosphere rotating much faster than the planet itself.

An international research team led by Takeshi Horinouchi of Hokkaido University has revealed that this ‘super-rotation’ is maintained near the equator by atmospheric tidal waves formed from solar heating on the planet’s dayside and cooling on its nightside. Closer to the poles, however, atmospheric turbulence and other kinds of waves have a more pronounced effect. The study was published online in Science on April 23.

- Advertisement -

Venus rotates very slowly, taking 243 Earth days to rotate once around its axis. Despite this very slow rotation, Venus’ atmosphere rotates westward 60 times faster than its planetary rotation. 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. “Since the super-rotation was discovered in the 1960s, however, the mechanism behind its forming and maintenance has been a long-standing mystery,” says Horinouchi.

Horinouchi and his colleagues from the Institute of Space and Astronautical Science (ISAS, JAXA) and other institutes developed a new, highly precise method to track clouds and derive wind velocities from images provided by ultraviolet and infrared cameras on the Akatsuki spacecraft, which began its orbit of Venus in December 2015. This allowed them to estimate the contributions of atmospheric waves and turbulence to the super-rotation.

The group first noticed that atmospheric temperature differences between low and high latitudes are as small as it cannot be explained without a circulation across latitudes. “Since such circulation should alter the wind distribution and weaken the super-rotation peak, it also implies there is another mechanism which reinforces and maintains the observed wind distribution,” Horinouchi explained. Further analyses revealed that the maintenance is sustained by the thermal tide — an atmospheric wave excited by the solar heating contrast between the dayside and the nightside — which provides the acceleration at low latitudes. Earlier studies proposed that atmospheric turbulence and the waves other than the thermal tide may provide the acceleration. However, the current study showed that they work oppositely to weakly decelerate the super-rotation at low latitude, even though they play an important role at mid- to high latitudes.

Their findings uncovered the factors that maintain the super-rotation while suggesting a dual circulation system that effectively transports heat across the globe: the meridional circulation that slowly transports heat towards the poles and the super-rotation that rapidly transports heat towards the planet’s nightside.

- Advertisement -

“Our study could help better understand atmospheric systems on tidally-locked exo-planets whose one side always facing the central stars, which is similar to Venus having a very long solar day,” Horinouchi added.

HOKKAIDO UNIVERSITY

Header Image – Venus – Computer Simulated Global View Centered at 90 Degrees East Longitude (NASA/JPL). Credit : NASA/JPL

- Advertisement -
spot_img
Mark Milligan
Mark Milligan
Mark Milligan is multi-award-winning journalist and the Managing Editor at HeritageDaily. His background is in archaeology and computer science, having written over 7,500 articles across several online publications. Mark is a member of the Association of British Science Writers (ABSW), the World Federation of Science Journalists, and in 2023 was the recipient of the British Citizen Award for Education, the BCA Medal of Honour, and the UK Prime Minister's Points of Light Award.
spot_img

Mobile Application

spot_img

Related Articles

Archaeologists search crash site of WWII B-17 for lost pilot

Archaeologists from Cotswold Archaeology are excavating the crash site of a WWII B-17 Flying Fortress in an English woodland.

Roman Era tomb found guarded by carved bull heads

Archaeologists excavating at the ancient Tharsa necropolis have uncovered a Roman Era tomb guarded by two carved bull heads.

Revolutionary war barracks discovered at Colonial Williamsburg

Archaeologists excavating at Colonial Williamsburg have discovered a barracks for soldiers of the Continental Army during the American War of Independence.

Pleistocene hunter-gatherers settled in Cyprus thousands of years earlier than previously thought

Archaeologists have found that Pleistocene hunter-gatherers settled in Cyprus thousands of years earlier than previously thought.

Groundbreaking study reveals new insights into chosen locations of pyramids’ sites

A groundbreaking study, published in the journal Communications Earth & Environment, has revealed why the largest concentration of pyramids in Egypt were built along a narrow desert strip.

Soldiers’ graffiti depicting hangings found on door at Dover Castle

Conservation of a Georgian door at Dover Castle has revealed etchings depicting hangings and graffiti from time of French Revolution.

Archaeologists find Roman villa with ornate indoor plunge pool

Archaeologists from the National Institute of Cultural Heritage have uncovered a Roman villa with an indoor plunge pool during excavations at the port city of Durrës, Albania.

Archaeologists excavate medieval timber hall

Archaeologists from the University of York have returned to Skipsea in East Yorkshire, England, to excavate the remains of a medieval timber hall.