HiRISE image: Dunes in formation

Migratory birds and military aircraft — like during World War II — often fly in a V-shaped formation. The “V” formation greatly boosts the efficiency and range of flying birds, because all except the first fly in the upward motion of air — called upwash — from the wingtip vortices of the bird ahead. In this image of a dune field in a large crater near Mawrth Vallis, some of the dunes appear to be in formation…. [More at link]