Martian atmospheric vertical structure has been observed in situ with three landers (the Viking Landers and the Mars Pathfinder) during their descents, with the Mini-TES instruments on board the Mars Exploration Rovers and by several orbiters by means of, e.g., infrared sounders, stellar and solar occultation as well as radio wave propagation. The structure exhibits diurnal, seasonal and spatial variations, wave phenomena and aerosol (ices and dust) layers.