Mountains may cause huge waves in Venusian clouds

by Kate S. Zalzal
Wednesday, April 19, 2017

A huge stationary wave observed over Venus may result from mountain topography. Credit: Planet-C project/Japan Aerospace Exploration Agency (JAXA).

An enormous, stationary, bow-shaped feature has been detected in the cloud-tops of Venus' thick, sulfuric acid-rich atmosphere. The structure, stretching more than 10,000 kilometers, remains fixed over Venus' surface despite atmospheric winds that whip around the planet at 100 meters per second.

Japanese scientists studying the feature, which was observed in infrared and ultraviolet images obtained in 2015 by the Japanese orbiter Akatsuki, reported in Nature Geoscience that the feature is likely a gravity wave, generated in the lower atmosphere as winds passed over mountains.

The study provides the “first direct evidence of dynamical coupling between the lower atmosphere and the middle or high atmosphere of Venus,” says co-author Makoto Taguchi, an astronomer at Rikkyo University in Tokyo. This large wave is one of many bow-shaped structures observed on Venus recently, he says. “The thermal structure at the cloud-tops may provide a way to infer the wind condition in the lower atmosphere … which we cannot see with conventional wavelengths.” This may help scientists better understand the super-rotation of Venus' atmosphere.

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