#gravity wave

Nature Denatured and Found Again by Michael Pisaro

Let’s start small; Nature Denatured and Found Again is a document of five summers well spent. In the summer of 2011 Michael Pisaro, an American composer, educator, and musician associated with the Wandelweiser composers collective, traveled to Neufelden, Austria to join artist Joachim Eckl at a former storehouse called Die Station (The Station). It is situated near the Grosse Mühl, a small river that empties into the Danube. Decorated with items culled from movie sets and an old Hilton hotel, it houses some of Eckl’s work and provides living and studio space for visiting artists, who mix with each other and townspeople in encounters intended to realize Joseph Beuys’ concept of “social sculpture” (in a nutshell, the idea that people gathering together can collectively change society through art).

From Astronomy Picture of the Day; March 6, 2018:

Colorful Airglow Bands Surround Milky Way Xiaohan Wang

Strange Structure Spotted On Venus

Venus is already very weird planet. After greenhouse effect, extreme temperatures, and pressures, dense clouds with crazy rotation speed, now the scientist noticed something new. The strange and unknown structure has been spotted on Venus stretching for 10,000 kilometers in the clouds of its atmosphere. To be even stranger this structure resist the sulfuric clouds, regardless they are spinning faster than the planet itself.  Scientists now try to explain it and they have some interesting assumptions.

The atmosphere of Venus is composed primarily of carbon dioxide with sulfuric acid clouds that spins faster that the planet. It is the hottest object after Sun in our Solar System.

Gravity Waves Lighting Up Venus Atmosphere

Last December the camera of Japan’s Akatsuki spacecraft first time spotted anomalies in the upper atmosphere. Scientists from Rikkyo University in Tokyo published their findings in Nature. They captured the area in infrared images and measured that pockets stretching for 10,000 kilometers above the mountainous region of Venus. There has been a lot of speculations about this. However, the best guess is that it’s some sort of gravity wave.

Images taken over four days from Akatsuki showed the wave staying in roughly the same place. ©Planet-C

Gravity waves are not gravitational waves. A gravity wave is a wave propagated on a liquid surface or in a fluid through the effects of gravity. So, it is a common thing on rocky planets. Earth example of such waves is the one above The Andes in Patagonia.

What is strange about this Venus gravity wave is that scientist didn’t expect that these waves could forms so high in the atmosphere. Yet, only a massive gravity wave can resist the rotation speed of acid clouds. And the fact that the structure is formed above the Venus mountains proves it even more.

Illustration of surface winds on Venus being pushed up by a mountain, causing tension in the upper atmosphere that slows the high-altitude winds. Credit: ESA

The research team claims that study clearly shows the evidence of the existence of stationary gravity waves. Further, the research reveals that such stationary gravity waves can have a very large scale. This one on Venus is perhaps the greatest ever observed in the Solar System.

Clearing

Low clouds over the ocean are important for regulating the Earth’s climate as they reflect a lot of solar energy back into space. The dynamics of these clouds are important to understand the planet’s weather and also to understand the shallow ecosystems in the ocean. This video shows something funny happening to these clouds in the southern ocean off the west coast of Africa – they’re literally knocked out of existence by a wave.

Scientists led by a group at NC State collected a number of satellite views of these clouds off the African coast and found that there’s a particular season and time of day where the clouds are just knocked away. The clouds are hit by a gravity wave – a wave in the atmosphere where Gravity is the restoring force (note that this is different from a gravitational wave: https://tmblr.co/Zyv2Js21a6wKe).

Heating during the day over Africa during one specific time of year triggers this gravity wave. The wave migrates as part of a chain heading out to the ocean, and in the process it hits these clouds. Sometimes, gravity waves can lead to the formation of clouds – a wave that pushes air upwards will trigger cloud formation as the air cools. Other times, gravity waves can trigger ripples in the sky, where clouds form in lines as air alternates up and down. At this spot, particularly during the month of May, the wave comes in at just the right altitude and with the right movement to hit these clouds and actually push the air downwards where the clouds vanish.

The scientists who identified this cloud erosion suggest that a series of dropsondes, sensors dropped from planes that are commonly used to measure air conditions in hurricanes, could be targeted at one of these wave fronts to see how much the air is moving and how exactly it triggers cloud collapse. Kinda neat to watch!

-JBB