A recurring mystery cloud on Mars that has long since baffled scientists around the world finally has an explanation. Appearing over the Arsia Mons volcano in the southern hemisphere of Mars, the long plume-like mystery cloud on Mars had been in observations for a long time – since as early as the 1970s. Now, after capturing its repeated reappearance in 2018 and 2020, scientists have an explanation for what may be causing this unusual cloud stretch. A lot of this explanation owes itself to a tiny Visual Monitoring Camera (VMC) aboard the Mars Express mission that orbits the planet – a camera that barely has the resolution of a decades-old webcam, but still offers a wide field of view. The latter, as it so happened, has proved crucial in unlocking this intriguing mystery cloud on Mars.
As reported by Science Alert, the study of the mystery cloud on Mars found that the origin of this plume began at the onset of Martian spring or summer. During this period, at dawn each day, dense, cold air from the base of the Arsia Mons volcano started rising upward from its western slope. With dropping temperatures, the air starts collecting dust along with its moisture, which then condenses to form what is known as an orographic cloud on Earth. Once this stretch of air reaches an altitude of about 45km, it is then confronted by fast winds of up to 600kmph, and is then detached from the volcano and moves westward.
At its most expansive stretch, this mystery cloud on Mars can reach a length of almost 1,800km – longer than the distance between Delhi and Mumbai. At its widest, it grows up to 150km. Subsequent to reaching this elongated cloud state, the plume disappears due to evaporation, when the Sun reaches its peak on the region. The plume, as the study reports, can also form during the winter months on Mars, during which the nature of winds on the planet (owing partially due to the lack of an Earth-like atmosphere) can cause it to form a large spiral as well.
Researchers who observed the cloud found that it is actually a regular occurrence on the planet, and it is only our sporadic cameras and the lack of uniform, regular observations that led us to believe that it is irregular in nature. Given this revelation of the mystery cloud on Mars, it will be interesting to see if more such clouds exist on the planet, which can give mankind further dough to study the constituents of the Martian atmosphere, and understand the behaviour of winds on the planet in closer detail. This can then add to the possibility of mankind setting up a residential colony on the planet at some point of time in future.