Arsia Mons on Mars is one of the highest volcanoes in the solar system – more than twice Mount Everest – and it is the theater of a very peculiar weather phenomenon. Every morning during the spring, a long and wide cloud of water ice is seen rising from the top of the extinct volcano. And now scientists have finally unlocked his secrets.
The cloud, published in the Journal of Geophysical Research, is estimated to be 1,800 kilometers long and 150 kilometers long. Observations have shown that the cloud itself is orographic and forms due to the volcano.
With its 20 kilometers (63,360 feet) altitude, Arsia Mons plays a major role in local weather. Even a planet as dry as Mars has some moisture in the air. It is staged along the sides of the volcanoes and combined in higher and cooler heights in a cloud.
This phenomenon occurs every morning every few months. Just before sunrise, the cloud will begin to form about 600 kilometers (375 miles) per hour westward and expand at an altitude of 45 kilometers (27 miles). As it reaches its maximum length, it becomes loose and floats westwards where it evaporates before noon.
“Although orographic clouds are regularly observed on Earth, they do not reach such great lengths and do not exhibit such vivid dynamics,” co-author Agustin Sánchez-Lavega of the University of the Basque Country said in a statement. “Understanding this cloud offers us the exciting opportunity to try to replicate cloud formation with models – models that will improve our knowledge of climate systems on both Mars and Earth.”
Sánchez-Lavega is the Scientific Head of Visual Monitoring Camera, or VMC, one of the instruments on board the Mars Space of the European Space Agency. The instrument, nicknamed “the webcam”, is a wide-field low-resolution camera originally used to confirm the separation between Mars Express and the Beagle 2 Lander in 2003 and then use it for public outreach.
“However, the VMC has recently been reclassified as a camera for science,” added lead author Jorge Hernández Bernal, also from the University of the Basque Country. “Although it has a low spatial resolution, it has a wide field of view – essential to see the whole picture at different local times of the day – and it is wonderful to see the evolution of a function over a long period of time and in small to follow time steps. . As a result, we were able to study the entire cloud through different life cycles. ”
VMC, along with other instruments of Mars Express and missions of NASA and the Indian Space Research Organization, could now characterize how this cloud forms, changes and disappears.