New cloud morphologies discovered on the Venus's night during Akatsuki

TL;DR

This study analyzes Venus's night cloud images from 2016-2018, revealing diverse morphologies including wave patterns, vortices, and previously unseen dark features, enhancing understanding of Venus's atmospheric dynamics.

Contribution

It reports the discovery of new cloud features on Venus's night side, expanding knowledge of its atmospheric phenomena using recent high-resolution imaging.

Findings

Identification of dark spots and streaks at mid-latitudes.

Observation of fully-developed vortices.

Detection of previously unseen dark features.

Abstract

During the years 2016 to 2018, the instruments Akatsuki/IR2 (JAXA) and IRTF/SpeX (NASA) acquired a large set of images at 1.74, 2.26 and 2.32 {\mu}m to study the nightside mid-to-lower clouds (48-60 km) of Venus. Here we summarize the rich variety of cloud morphologies apparent in these images: from frequent wave packets and billows caused by shear instabilities, to features reported decades ago like the circum-equatorial belts, bright blotches and equatorial troughs, and previously unseen features like dark spots, sharp dark streaks at mid latitudes and fully-developed vortices.