Mariner Observations of the Mars North Polar Hood

Abstract

Mariner 9 photographs showing variations in the behavior of the Mars atmosphere over 21 consecutive days during northern winter are displayed. The photographs show the north polar cloud hood to be highly variable from day to day, with variations suggestive of development, motion, and decay of baroclinic waves. Lee wave clouds apparently composed primarily of water ice, convective cloud lines inferred to consist of CO₂ ice, and dust clouds all occur frequently in the active region between latitudes 40 and 60N. The wave clouds show that persistent surface westerlies and strong westerly shear occur in this region.