Tuesday’s Arsia Mons is one of the highest volcanoes in the solar system – more than twice the height of Everest – and is the scene of a very strange weather event. Every morning during spring, long and wide clouds of water ice seen rising from the top of the extinct volcano. Now, scientists have finally unlocked its secrets. Published in the Journal of Geophysical Research, the cloud estimated to cover 1,800 kilometers (1,120 miles) and 150 kilometers (93 miles). Observations have shown that the cloud itself is aromatic, due to the volcano.
With an altitude of 20 kilometers (63,360 feet), Arsia Mons plays a huge role in the local climate. Even dry planets like Mars have some moisture in the air. It formed by condensing the edge of the volcano to a higher and cooler altitude. This happens every morning for several months. Just before sunrise, the cloud will expand and expand westward at an altitude of about 600 kilometers (27 miles) per hour, about 45 kilometers (375 miles) west. After it reaches its maximum length it is detached and floats to the west where it evaporates before noon. Co-author Agustin Sánchez-Lavega, of the University of the Basque Country, said in a statement, “Although aerographic clouds are commonly seen on Earth, they do not reach such great lengths or show such clear dynamics.”
“Understanding this cloud gives us an interesting opportunity to try to replicate the structure of our clouds with models – models that will improve our knowledge of the climate of both Mars and Earth.” The Sánchez-Lavega is a science-led instrument on the Visual Monitoring Camera, or VMC, one of the passengers on the European Space Agency’s Mars Express. The device, nicknamed “Webcam”, is a wide-range low-race camera that used in 2003 to ensure the separation between the Mars Express and the Beagle 2 Lander, and later to publicize. “However, recently, VMC was reclassified as a camera for science,” added Jorge Hernandez Bernal, a leading author from the Basque Country University.
“Although it has a small spatial resolution, it has a wide field – it is necessary to look at the big picture at different local times of the day – and it is wonderful to look for the evolution of a feature in both long time and short time.” VMC, along with other instruments of the Express on Tuesday and missions from NASA and the Indian Space Research Organization, has now been able to identify how the cloud changed shape and disappeared.