Multiple views of Venus’ clouds
Science & Exploration

Tracking alien turbulences with Venus Express

03/04/2007 1669 views 1 likes
ESA / Science & Exploration / Space Science / Venus Express

New images and data from ESA’s mission to Venus provide new insights into the turbulent and noxious atmosphere of Earth’s sister planet. What causes violent winds and turbulences? Is the surface topography playing a role in the complex global dynamics of the atmosphere? Venus Express is on the case.

Venus’ atmosphere represents a true puzzle for scientists. Winds are so powerful and fast that they circumnavigate the planet in only four Earth days – the atmospheric ‘super-rotation’ – while the planet itself is very slow in comparison, taking 243 Earth days to perform one full rotation around its axis.

At the poles things get really complicated with huge double-eyed vortices providing a truly dramatic view. In addition, a layer of dense clouds covers the whole planet as a thick curtain, preventing observers using conventional optical means from seeing what lies beneath.

Clouds over Alpha Regio on Venus
Clouds over Alpha Regio on Venus

Venus Express is on the contrary capable of looking through the atmosphere at different depths, by probing it at different infrared wavelengths. The Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board is continuing its systematic investigation of Venus’ atmospheric layers to solve the riddle of the causes for such turbulent and stormy atmosphere.

The images presented with this article focus on Venusian atmospheric turbulences and cloud features, whose shape and size vary with planetary latitudes. At the equator, clouds are irregular and assume a peculiar ‘bubble’-shape. At mid latitudes they are more regular and streaky, running almost parallel to the direction of the super rotation with speed reaching more than 400 kilometres per hour. Going higher up in latitude, in the polar region, the clouds end up in entering a vortex shape.

Cloud structures in Venus atmosphere
Cloud structures in Venus atmosphere

With its multi-wavelength eyes, VIRTIS can observe the atmosphere and the cloud layers not only at different depths, but also both in the day- and night-side of the planet – a characteristic that allows an overall assessment of the ‘environmental’ causes that can be at the origin of such an atmospheric complexity.

At the equator, the extremely violent winds of the super-rotation are in constant ‘battle’ with other kinds of local turbulences, or ‘regional’ winds, creating very complex cloud structures.

Close-up on cloud structures on Venus
Close-up on cloud structures on Venus

One type of regional wind is due to the strong flux of radiation from the Sun reaching the atmosphere of the planet on the day-side. This flux heats up the atmosphere creating convective cells, where masses of warm air move upwards and generate local turbulence and winds.

On the night-side there is obviously no flux from the Sun, but the clouds’ shape and the wind dynamics are somehow similar to that we see on the day-side. So, scientists are currently trying to understand if there is any mechanism other than ‘convection’ responsible for the equatorial turbulences, both on the day- and night-side of Venus.

Turbulences in Venus’s atmosphere
Turbulences in Venus’s atmosphere

For instance, VIRTIS imaged clouds over Alpha Regio, an area close to the equator. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 kilometres high. There might be a connection between the surface topography and the local atmospheric turbulence which is observed in this area. This and other hypotheses are being investigated by the Venus Express science teams using data from several instruments.

Actually, the Venusian topography may play an important role also in the global atmospheric dynamics. Understanding this surface-atmosphere connection is one of the major objectives of Venus Express - something to be verified in the whole course of the mission.

For more information

Giuseppe Piccioni, VIRTIS co-Principal Investigator, IASF-INAF, Rome, Italy
Email: giuseppe.piccioni @ iasf-roma.inaf.it

Pierre Drossart, VIRTIS co-Principal Investigator, Observatoire de Paris, France
Email: pierre.drossart @ obspm.fr

Håkan Svedhem, ESA Venus Express Project Scientist
Email: hakan.svedhem @ esa.int

Related Links

Temperature maps of Venus’ surface
Science & Exploration

Hot stuff on Venus! Venus Express sees right down to the he…

14/12/2006 3151 views 4 likes
Open item
'Thin' cloud layer close to Venus' South pole
Science & Exploration

Happy birthday, Venus Express!

09/11/2006 1481 views 0 likes
Open item
Radiation from below the Venusian cloud deck
Science & Exploration

Complex meteorology at Venus

13/10/2006 1998 views 4 likes
Open item
Global dynamics of Venus northern hemisphere
Science & Exploration

Flying over the cloudy world – science updates from Venus E…

12/07/2006 5784 views 5 likes
Open item
Double vortex at Venus South pole
Science & Exploration

Double vortex at Venus South Pole unveiled!

27/06/2006 11189 views 7 likes
Open item
Artist's impression of Venus Express
Science & Exploration

Venus Express has reached final orbit

09/05/2006 2725 views 2 likes
Open item
Dark Vortex over South Pole of Venus
Science & Exploration

Unexpected detail in first-ever Venus south pole images

13/04/2006 4062 views 0 likes
Open item
Artist's view of Venus Express main engine firing in space
Science & Exploration

Venus within ESA probe reach

31/03/2006 1311 views 0 likes
Open item
Artist's impression of Venus Express' trajectory
Science & Exploration

And now… straight to Venus!

03/03/2006 859 views 1 likes
Open item
Artist's view of Venus Express main engine firing in space
Enabling & Support

Successful Venus Express main engine test

17/02/2006 1600 views 1 likes
Open item
First light for Venus Express camera
Science & Exploration

First light for the Venus Monitoring Camera

30/11/2005 990 views 0 likes
Open item
Ground Segment Manager Manfred Warhaut: end of LEOP
Agency

Venus Express performs flawlessly, LEOP complete

11/11/2005 1207 views 2 likes
Open item
Artist's impression of  Venus Express spacecraft
Agency

Venus Express mission operations update

10/11/2005 1301 views 3 likes
Open item
Soyuz-Fregat carrying Venus Express lifts off
Science & Exploration

Venus Express en route to probe the planet's hidden mysteri…

09/11/2005 1601 views 0 likes
Open item
Polar vortices at Venus and Saturn compared
Science & Exploration

Saturn joins Venus in the vortex club

24/11/2006 2513 views 1 likes
Open item