Stationary Bow-Shaped Gravity Wave at Venus Cloud Tops
Discovery of a massive, planet-spanning stationary gravity wave in Venus's atmosphere by Akatsuki, anchored over Aphrodite Terra.
The Giant Stationary Gravity Wave
Japan’s Akatsuki orbiter captured one of the solar system’s largest atmospheric features in December 2015: a bow-shaped stationary gravity wave stretching ~10,000 km north-south at Venus’s cloud tops (~65-70 km altitude).
Mechanism: Orographic Gravity Wave
The wave anchored over Aphrodite Terra, a continent-sized highland. Lower-atmosphere winds flowing over topography disturb denser air below, generating buoyancy oscillations that propagate upward as gravity waves.
On Venus, these waves manifest as bright, bow-shaped temperature anomalies in infrared (warmer/drier air) and UV images.
“Over several days of observation, the bow-shaped structure remained relatively fixed in position above the highland on the slowly rotating surface, despite the background atmospheric super rotation.”
— Fukuhara et al. (2017)
“This is a striking discovery, since we have seen features extending horizontally for thousands of kilometres that are not super-rotating but are stationary, or fixed to the highlands of the slowly-rotating solid planet.”
— Professor Masato Nakamura (Akatsuki Project Scientist)
Primary Source: 2017 Discovery
Akatsuki’s Longwave Infrared Camera (LIR) and Ultraviolet Imager (UVI) first spotted the feature shortly after orbital insertion.
The wave disappeared by mid-January 2016, suggesting variable lower-atmosphere conditions.
Follow-up Observations and Quotes
Subsequent Akatsuki monitoring revealed similar bow waves recur, often in afternoons/evenings over low-latitude highlands.
“We suppose that highlands are a key to generating the stationary gravity waves, because most of the bows—and we have found more than 15 bows so far—have appeared above the highlands at their centers.”
— Makoto Taguchi (Rikkyo University)
“It further shows that such stationary gravity waves can have a very large scale—perhaps the greatest ever observed in the solar system.”
— Akatsuki team (2017)
Later studies confirmed topographic and local-time dependence, with waves potentially decelerating superrotation via momentum deposition.
Implications for Atmospheric Dynamics and Missions
These waves highlight strong coupling between Venus’s surface topography and upper atmosphere, challenging models of uniform superrotation. They may transport energy/momentum vertically, influencing global circulation.
For buoyant missions operating at cloud levels (50-70 km), such stationary features offer predictable wind patterns for station-keeping—exploitable “gravity wave surfing” zones over highlands.
Source Data:
- Akatsuki LIR (10 μm thermal emission) and UVI images
- Numerical simulations of orographic wave propagation
- Venus topography from Magellan radar mapping