In 2018, a camera aboard the Mars Express mission captured the sight of a strange, long, clever cloud, swirling over the surface of the red planet.
From a distance, the 1,500-kilometer (930-mile) mist path was almost like a haze, and it appeared to emerge from the top of a long-dead volcano.
Looking back at archive images, researchers realized that this had been happening for a while. Every few years in the spring or summer, this strange cloud would return, before leaving again. The fleet plug was captured on camera in 2009, 2012, 2015, 2018, and again in 2020.
A newly published study has now explained the reasons behind why this long infertile cloud continues to come and go on Mars. To do this, researchers compared the high-resolution ideas of the 2018 plug-in to other archival ideas, some of which stretch back all the way to the 1970s.
This is the story of the cloud. Every year, around the beginning of spring or summer in the southern Martian hemisphere, the Arsia Mons Elongated Cloud begins to take shape.
At daybreak, dense air from the base of the Arsia Mons volcano begins to climb up the western slope. As the temperature drops, this wind expands and the moisture in it circulates around particles of dust, creating what we have here on Earth called an orographic cloud.
Each morning, over several months of observations, researchers observed this process repeating itself. At an altitude of 45 kilometers, the air begins to expand, and for the 2.5 hours or so, the cloud is dragged westward to the wind, as fast as 600 kilometers per hour (380 mph). , before parting with the last volcano.
At maximum, the plug can reach 1,800 kilometers (more than 1,100 miles) and 150 kilometers (nearly 100 miles) wide. By noon, when the sun is at apex, the cloud will have completely grown.
Clouds of ice are not just uncommon on Mars, but the clouds above Arsia Mons still form in the summer when most of the rest disappears. Of course, much of the time, there is a cloud in this particular volcano when others are not around – but only in some cases does it spread out in a long climb. (Every year, at the beginning of winter, this cloud can be a spiral.)
Profile of Arsia Mons Elongated Cloud. (ESA)
So if this long plug is happening every day for an extended period of time every year, why do we only have temporary ideas about it?
Researchers say this is because many of the cameras orbiting Mars just fly over this area in the morning, and observation is usually planned, which means that we often take pictures of this cloud just by chance.
Fortunately, an old camera still on board the Mars Express mission has one newer technology – the Visual Camera Camera (VMC) which has 2003 webcam power.
“Ged [the camera] with low spatial resolution, it has a wide range of view – essential to see the big picture at different local times of the day – and is wonderful for monitoring the evolution of a feature over both a long time and in a small step time, “explains astronaut Jorge Hernández Bernal of the University of the Basque Country in Bilbao, Spain.
“As a result, we were able to study the entire cloud over several life cycles.”
The study represents the first detailed study of the Arsia Mons cloud, and although scientists claim that there are orographic cloud-like features on Earth, its size is enormous and its dynamics are quite dynamic by comparison. to what we see on our own planet.
“Understanding this cloud provides us with an exciting opportunity to try to reproduce the shape of the clouds with models – models that will improve our knowledge of climate systems on both Mars and Earth,” said the astronaut Agustin Sánchez-Lavega, also from the University of the Basque Country.
Now that we know when the cloud is happening, it allows us to direct other, stronger cameras in orbit to the right place at the right time, giving us a closer look. It may not be too long until the next pictures.
The study was published in the Journal of Geophysical Research.