Venus wave may be Solar System's biggest

bbc.com ^ | 16 January 2017 | Paul Rincon

[BenLurkin]

The...wave is thought to form as the lower atmosphere flows over mountains on Venus' surface.

...

Just after entering orbit around Venus in 2015, the Akatsuki orbiter observed a bow-shaped feature in the upper atmosphere over several days.

Curiously, the bright structure - which stretched for 10,000km - remained stationary at the altitude of Venus' cloud tops. This is difficult to reconcile with what we know about Venus' thick upper atmosphere, in which clouds streak by at 100 metres per second (m/s).

The clouds travel much faster than the slowly rotating planet below, where a Venusian day lasts longer than it takes for the planet to orbit the Sun.

Makoto Taguchi from Rikkyo University in Tokyo, Atsushi Yamazaki from the Japan Aerospace Exploration Agency (Jaxa) and others show that the bright region was fixed over a mountainous region of the surface known as Aphrodite Terra. It was also found to be hotter than surrounding parts of the atmosphere.

The researchers propose that the phenomenon is the result of a gravity wave that is generated as the lower atmosphere passes over mountains and then propagates upwards through Venus' thick atmosphere. Gravity waves ensue when a fluid - such as a liquid, gas or plasma - is displaced from a position of equilibrium.

Dr Colin Wilson, a planetary scientist from the University of Oxford, who was not involved in the study, explained: "If you have a stream and it's flowing over a rock, you get the gravity waves propagating upwards through the water. At the surface of the stream, you will see it as changes in height.

"What's happening here is slightly different, because we're seeing it in cloud top temperatures. But the air particles are moving up and down, very much as the water particles are moving up and down."

[BenLurkin]

[noiseman]

It's the same phenomenon that sailplane pilots use to reach the stratosphere without an engine. Mountain wave has been used to reach altitudes over 50,000 feet, and is thought to extend to perhaps 90,000 feet or more. I used to fly sailplanes, and wave lift is incredibly smooth (just so long as you avoid the VERY turbulent rotor underneath). You just catch the updraft portion, adjust your speed to stay in it, and up you go on an invisible elevator. Climb rates can reach as high as 6,000 feet per minute, though in practice they're usually more in the range of about 1,000 to 3,000 fpm.

Fascinating that the same effect occurs on Venus.

[BenLurkin]

Interesting!

[Does so]

Fascinating that the same effect occurs on Venus.

'Nothing like vaporous sulfuric acid clouds wafting from sulfuric acid oceans. :-/

[noiseman]

That is one difference. Also, the tens of billions it would cost to get a glider to Venus and the quick death that would occur as it melts around the occupant.

[SunkenCiv]

Note: this topic is from 01/16/2017. Thanks BenLurkin. There's hardly been a more appropriate topic, if ya know what I mean.

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