The weird long cloud on Mars is finally revealing some of its secrets is an article by Chelsea Gohd from space.com referencing ESA's Mars Express news. The Arisa Mons Elongated Cloud (AMEC) is basically an orographic cloud the lee of the volcano Arsia Mons which is approximately 20km high. The cloud is located in 46km height and 600km/h winds create a tail which is about 1000km long and about 150km wide. The cloud head grows before sunrise, then the tail quickly grows westwards, and the cloud evaporates before afternoon. Furthermore, ESA writes in its infographics:

A curious elongated cloud on Mars has been observed over 100 times by five different missions since 1976. Mars Express has provided new insights into its daily cycle.

I italized the issue I am after: Although I follow closely what happens in the field of extraterrestrial atmospheres, I have never heard about that cloud before Mars Express. Maybe somebody could point me to earlier publications on the matter which rely on other space crafts? Are there other, similar clouds on Mars?


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    $\begingroup$ There are definitely similar clouds on Mars, I've seen them in Elysium in some MARCI images I've processed. But, I suspect you would need to go to Viking to get the AMEC images simply because NASA orbiters since the late 1990s have focused on afternoon imaging of the surface, so you'd never see the AMEC with them. Hence, MEx and MOM are the ones to really provide modern data on this. $\endgroup$ – Stuart Robbins Mar 15 at 19:03

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