Abstract
Firstly identified in images from JAXA’s orbiter Akatsuki, the cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. Interpreted as a new type of Kelvin wave, this disruption is associated to dramatic changes in the clouds’ opacity and distribution of aerosols, and it may constitute a critical piece for our understanding of the thermal balance and atmospheric circulation of Venus. Here, we report its reappearance on the dayside middle clouds four years after its last detection with Akatsuki/IR1, and for the first time, we characterize its main properties using exclusively near-infrared images from amateur observations. In agreement with previous reports, the discontinuity exhibited temporal variations in its zonal speed, orientation, length, and its effect over the clouds’ albedo during the 2019/2020 eastern elongation. Finally, a comparison with simultaneous observations by Akatsuki UVI and LIR confirmed that the discontinuity is not visible on the upper clouds’ albedo or thermal emission, while zonal speeds are slower than winds at the clouds’ top and faster than at the middle clouds, evidencing that this Kelvin wave might be transporting momentum up to upper clouds.
Highlights
Venus is permanently covered by a thick stratified atmosphere
The resolution of the amateur images ranged from 187 to 663 km depending on the apparent angular size of Venus and the best resolution allowed by the diameter of the telescope [19]
We report the reappearance of the equatorial discontinuity at the dayside middle clouds of Venus [9], which is a global-scale atmospheric wave comparable with other planetary phenomena such as the Y-feature [11] and the giant stationary bow-shape wave [12]
Summary
Venus is permanently covered by a thick stratified atmosphere. Within altitudes∼48–70 km above the surface, we find clouds of sulfuric acid [1]. Top of lower latitudes, which is 60 times faster than the planetary rotation [2] This is the layer that has been observed continuously for almost a century with violet and ultraviolet (UV) filters [3,4], whose dark/bright features are caused by known (SO2 ) and unknown absorbers [1,5]. Under this layer, the middle clouds (50.5–56.5 km above the surface) are observed on the dayside at visible and near-infrared (NIR) wavelengths up to 1 μm [1,6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
