Mysterious elongated cloud spotted near the equator on Mars

The Mars Express mission of the European Space Agency has been observing since September 13 a white cloud lying in the atmosphere of the Red Planet. This dramatic drama is located 20 km above the Arsia Mons volcano, near the equator of the planet and is about 1500 km long.

Despite the cloud hovering over the volcano, researchers suggest that it is not related to volcanic activity. It is probably a cloud of water ice driven by the influence of the leeward slope of the volcano.

The Mars Express Visual Surveillance Camera (VMC) has captured this cloud hundreds of times over the last few weeks. The cloud extends towards the west of Arsia Mons – one of the three volcanoes that make up Tharsis Montes.

the @esamarswebcam on our #March The Express mission observed an elongated cloud hovering near the Arsia Mons volcano. Without connection with volcanic activity, this cloud of water ice is driven by the influence of the slope on the airflow.
Learn more: https://t.co/QQ0hnbTbTC pic.twitter.com/oRSCaxdHnT– ESA (@esa) October 28, 2018

During a Martian year, several clouds form on the great Martian volcanoes. Most of them begin to disappear as the planet enters its winter solstice in the northern hemisphere. However, a recurrent water ice cloud, like that observed in the study, forms along the southwestern flank of the Arsia Mons volcano. Mars Express and many previous missions also reported the appearance of a cloud-type characteristic feature on this volcano in 2009, 2012, and 2015.

It is difficult to understand the precise conditions that give rise to such clouds. However, researchers have found that this atmospheric feature that covers a large region of the Arsia Mons volcano changes structure throughout the day.

"The appearance of the cloud varies throughout the Martian day, its length increasing during the leeward morning of the volcano, almost parallel to the equator, and reaching such an impressive size that could make it visible even by telescopes on Earth, "said ESA in a statement. .

The formation of water ice clouds is influenced by the amount of dust present in the atmosphere. ESA's Mars Express spacecraft got images of a cloud after the big Martian dust storm that swept the entire planet in June and July. The unprecedented catalog of images taken by Mars Express could provide important information about the effects of dust on cloud development and its variability throughout the year.