Tuesday, 24 March 2026
Lee Waves on Mars
Lee waves are atmospheric gravity waves that form when stable air flows over significant topographic obstacles like mountains, volcanoes, or large crater rims. As the wind is forced upward by the terrain, it undergoes adiabatic cooling, causing water vapor or carbon dioxide to condense into visible, ripple-like clouds on the downwind (lee) side. They often appear as "cloud trains" or straight, parallel lines perpendicular to the wind direction.
Some can form "ship-wake" patterns or extend over 1,000 km downwind from large craters. Horizontal wavelengths typically range from 15 km to 50 km, though some massive volcanic structures, such as Arsia Mons, have reached 60 km. These waves are most common during Mars' northern fall and winter, when high near-surface stability and strong wind shear from the winter mid-latitude jet stream create ideal conditions for their formation.
Depending on the temperature and altitude (typically between 10 km and 55 km), these clouds can be composed of water ice crystals or CO2 ice. Recent high-cadence images from the Emirates Mars Mission (EMM) have even shown lee waves rapidly evolving into dust storm features within a single morning.
){kind=logo}
