Sequence of infrared images of the lower clouds on Venus, showing a consistent pattern of planetary-scale cloud discontinuity. This type of giant atmospheric wave has never been seen before on other planets in our solar system. Image by Javier Peralta / JAXA-Planet-C-team / Astrophysics and Space Sciences.
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Scientists have announced something new and unexpected: a giant atmospheric “wave” as a disturbance in the lower atmosphere of Venus. It is different from anything else seen in the solar system. The researchers said it had been moving above the planet’s surface for almost 35 years (50 km) for almost 35 years. It went completely undetected so far.
The amazing discovery is reported in a new peer-reviewed study, published May 27, 2020, in Geophysical research letters.
Venus is the planet next to the sun from Earth. It is completely covered by thick clouds. These clouds are so close that we cannot see beneath them to see the surface of Venus. For this reason, the lower atmosphere and surface of Venus have remained largely mysterious. We know that the clouds of Venus are mostly carbon dioxide, with droplets of sulfuric acid. Strong wind patterns were previously observed in the atmosphere of Venus in ultraviolet and infrared light.
The new atmospheric feature – a giant wall of acid clouds – differs from previous observations in part because it is the first enormous atmospheric wave found at the lower cloud level in the atmosphere of Venus, at altitudes between 29.5 and 35 miles (47.5 and 56.5 km). This wall of clouds is massive, extending up to 7,500 miles (7,500 km) over the equator of Venus, from 30 degrees north to 40 degrees south.
According to the researchers, it orbits the planet in five days, at about 204 miles per hour (328 km / h). It has been doing so since at least 1983.
The Japanese space agency JAXA’s Venus orbiter Akatsuki made the discovery. The phenomenon looked like an atmospheric wave, only much larger than what is typically seen. It was discovered by Akatsuki when the spacecraft obtained detailed infrared images of the night side of Venus, and studied the middle and lower layers of the planet’s atmosphere.
Animation shows the lower clouds of Venus (about 30 miles / 50 km above the surface) in infrared light. Light clouds are more transparent to thermal radiation emitted from the ground than dark clouds. Image by Javier Peralta / JAXA-Planet C-team / Astrophysics and Space Sciences.
Pedro Machado – from the Institute of Astrophysics and Space Sciences, part of the University of Lisbon in Portugal – said in a statement:
If this happened on Earth, it would be a frontal surface on the planet’s scale, and that’s incredible. During the follow-up campaign, we went back to images I made in the infrared in 2012 with the Galileo National Telescope in the Canary Islands, and we found exactly the same disturbance.
The Institute of Astrophysics and Space Sciences has conducted a long-running research program to study the winds of Venus. It also contributed subsequent observations with NASA’s Infrared Telescope Facility in Hawaii, coordinated with Akatsuki’s new observations.
Enormous cloud patterns were previously observed in the atmosphere of Venus, such as the Y-wave, a dark Y-shaped structure found in the upper atmosphere that occupies almost the entire planetary disk. It is only seen as observed in ultraviolet light. There is also a 6,200 kilometer long (10,000 km long) arcuate stationary wave, also in the upper cloud layers, thought to be caused by the enormous mountain mountains of the planet.
Meanwhile, in visible light, the dense atmosphere of Venus looks very bright.
Example of undulations behind the atmospheric discontinuity on the night side of Venus on April 15, 2016. Image by Javier Peralta / JAXA-Planet C-team / Astrophysics and Space Sciences.
Pattern of cloudburst seen in infrared images taken by the Japanese space agency JAXA Akatsuki Venus orbiter in 2016. Image via Javier Peralta / JAXA-Planet C-team / Astrophysics and Space Sciences.
Finding this phenomenon in the lower atmosphere is interesting, not only because it was not previously noticed, but also because this region in the atmosphere of Venus is thought to be responsible for the healing glass fiber effect of the planet. This effect causes the heat of the sun at the surface of Venus. It maintains the surface at a temperature of 869 degrees Fahrenheit (465 degrees Celsius), hot enough to melt lead. The dynamics of Venus’ atmosphere are generally not yet well understood, so planetary scales such as this would allow scientists to better understand how the planet’s surface and atmosphere interact.
Javier Peralta, who led the new study, said:
Since the disturbance can not be observed in the ultraviolet images sensing the top of the clouds at an altitude of about 43-mile (70 km), confirming the wavelength is critical. We would finally have found a wave that transports momentum and energy from the deep atmosphere and disappears before we reach the top of the clouds. It would therefore present momentum at the level where we observe the fastest winds of the so-called atmospheric superrotation of Venus, whose mechanisms have been a mystery for a long time.
Ultraviolet image of the Y-wave in the upper atmosphere of Venus, from the Pioneer Venus Orbiter on February 26, 1979. Image via NASA / Astronomy Now.
The arc-shaped atmospheric wave in the upper atmosphere of Venus, as seen by Akatsuki in 2015. It is thought to be caused by Venus’ massive mountain ranges. Image via JAXA / Science Alert.
Illustration of Akatsuki artists around Venus. Image via ISAS / JAXA.
This newly discovered cloud front on Venus is essentially meteorological. Basically we are talking here about the weather on Venus. The feature seems to be unique; it has never been seen before on other planets in the solar system. It is therefore difficult to know what is happening, even though the researchers invented computer simulations to try to mimic the cloud function. The mechanisms that can create such a gigantic and long-lasting atmospheric wave are not yet known.
One possibility is that this atmospheric disturbance may be a physical manifestation of a kind of Kelvin wave, a class of atmospheric gravitational waves that share some important common features with this disturbance. Kelvin waves can maintain their shape over long periods, and propagate in this case in the same direction as Venus’ super-rotating winds. Kelvin waves can also interact with other types of atmospheric waves, such as Rossby waves, which occur naturally as a result of the planet’s rotation. Like Kelvin waves, they can be seen in both atmospheres and oceans. On Venus, they may transfer energy from the super-rotation of the atmosphere – where the atmosphere rotates faster than the planet itself – to the equator.
The researchers saw images of Venus as far back as 1983. They were able to confirm the presence of the same features seen by Akatsuki. But how did this particular – and enormous – wind formation go unnoticed for so long? According to Machado:
… we needed access to a large, growing and scattered collection of images of Venus collected over the last decades using various telescopes.
Javier Peralta, an Akatsuki mission team member leading the new study. Image via The Planetary Society.
The discovery of such a large atmospheric phenomenon on Venus, after it had not been detected for so long, came as a great surprise to scientists. The discovery will help her learn more about the complex atmosphere of the planet and how it interacts with the planet itself.
Bottom line: Researchers have discovered a gigantic atmospheric wave phenomenon in the lower atmosphere of Venus, something not otherwise seen in the solar system.
Source: A long-lived sharp disturbance on the lower clouds of Venus
Via Institute of Astrophysics and Space Sciences
Via Institute of Space and Astronautical Sciences
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