Atmospheric storm of Venus baffles scientists

Mar 13, 2008 14:27 GMT  ·  By

Just a few days ago, ESAs Venus Express spacecraft reported the observation of a weird haze developing into the Venusian atmosphere for no apparent reason. The question about what really determined the appearance of the feature still remains, albeit the ESA has shifted its attention back to the eye of a hurricane ravaging through Earth's twin at least since 1974, when the spacecraft Mariner 10 first detected it.

The structure measuring 2,000 kilometers in diameter, located near the planet's south pole, changes shape once every few days and seems to have a twin in the opposite side of the planet, at the north pole, detected by NASA's Pioneer Venus mission that took place in 1979. After observing the strange flicker of light with the Venus Express spacecraft, ESA engineers decided to probe it by executing a thermal scan on the area with the help of an infrared camera.

The temperature of the top regions of the atmosphere in the hurricane revealed that the central core of the vortex has a higher temperature than the surrounding gas, the heating process probably being determined by a downward motion of air which enables the formation of a depression region in the upper layers. Co-Principal Investigator for the Visible and Infrared Thermal Imaging Spectrometer of Venus Express Giuseppe Piccioni says that for a better understanding of the movements of air inside the hurricane, one only has to imagine the dynamics of water flowing out of a tub while pulling the plug.

Violent change in shape

During observations in 2006, the ESA revealed that the hurricane identified its shape with that of an hourglass, almost identical to that of the structure observed in 1979 by the Pioneer Venus spacecraft. Further still, its appearance was seemingly changing in relation to the planet's orbit around the Sun, only to form a so-called 'classic' dipole right in the center of the vortex in the early days of 2007. One Earth-day later, the hurricane changed its shape drastically into a circular vortex, with tendencies of taking a oval shape.

In short, the shape of the central regions vary violently within the matter of a few hours, due to the complex structure determined by randomly flowing masses of air, regardless of the altitude. Not surprisingly, similar to the appearance of the bright haze, the phenomenon which powers the vortex remains unknown even though it was discovered some 34 years ago.

What is the cause?

"One explanation is that atmospheric gases heated by the Sun at the equator, rise and then move poleward. In the polar regions, they converge and sinks again," says Colin Wilson of the University of Oxford. From here, the Coriolis effect of the planet takes over, pushing the moving front of air sideways, behaving in a similar fashion to the vortices in the centers of hurricane here on Earth.

The study on the feature will continue, in the hope that one day scientists will be able to better understand why it experiences such a violent change in shape, and how is the hurricane really powered by the planet's dynamics.

Photo Gallery (2 Images)

Still picture of the hurricane on Venus
Animation of the eye of the hurricane
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