South-polar features on Venus similar to those near the north pole.
Piccioni, G ; Drossart, P ; Sanchez-Lavega, A ; et al. ; - ASI Sponsor
Nov - 2007
DOI: 10.1038/nature06209
ISSN : 1476-4687 ;
journal : Nature

Issue : 7170
type: Article Journal

Abstract
Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright dipole feature surrounded by a cold collar at its north pole. The polar dipole is a double-eye feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.

keywords : VENUS EXPRESS