New Images Reveal Ever-Present Venus Vortex More Chaotic and Unpredictable

A cyclone swirls at Venus' south pole, churning the atmosphere and changing on an almost daily basis. Now, new research and images show that the South Polar Vortex is far more chaotic and unpredictable than previously thought.  

In order to properly examine this vortex, the researchers used infrared images from the VIRTIS instrument onboard the European Space Agency's Venus Express spacecraft. This instrument helped provide spectral images at different levels in Venus' atmosphere, and allowed the scientists observe the lower and upper clouds of the planet.

The vortex itself moves around the Pole, forming several different layers that are separated by about 12 miles each. Yet each of these layers are unique, changing their morphology.

Atmosphere vortices themselves are common in the atmospheres of different planets in our solar system. Yet how the behave largely depends on the planet itself. Venus, although similar in size to Earth, is drastically different from our planet in other ways. It rotates slowly on its axis--a day on Venus lasts about 243 Earth days. In addition, it spins in the opposite direction to Earth and has a vastly different atmosphere. Venus possesses a dense carbon dioxide atmosphere, causing surface pressures to be 90 times greater than those found on Earth. Because of the greenhouse gases, surface temperatures of the planet can reach up to 842 degrees Fahrenheit. And about 28 to 47 miles above the surface of Venus, sulfuric acid clouds speed at 223 mph--much faster than the planet itself rotates.

It's this atmospheric circulation that causes the permanent vortices at both poles. The researchers tracked the changes in the winds in the vortex, studying images obtained by the Venus Express Orbiter. The vortex itself has centers of rotation at two different altitude levels--26 and 38 miles above the surface. Neither of these centers are aligned and instead wander around the south pole of the planet with no established pattern. They can howl at velocities of up to 34 mph.

While scientists can certainly show that this vortex is variable enough to alter its shape in only a day, they haven't found out exactly why that's the case. Researchers hope that these findings will help future studies on the vortex and its relationship with the atmospheric rotation.

The findings are published in Nature Geoscience.