Strange phenomenon on the surface of Mars

Mysterious 900 MILE long 'plume' cloud spotted on the surface of Mars near a giant volcano

• Huge cloud is now over 900 miles (1500km) long and began forming near the 20 km-high Arsia Mons volcano
• Scientists believe the vast cloud is not caused by volcanic activity, but is a water ice cloud
• Believed the vast dust storm earlier this year on Mars may be behind its huge size

Since 13 September 2018, the Visual Monitoring Camera (VMC) on board ESA's Mars Express has been observing the of a curious cloud formation. The cloud can be seen in this VMC image taken 10 October as the white, elongated feature extending 1500 km westward of the volcano. The huge cloud is now over 900 miles (1500km) long, and began forming near the 20 km-high Arsia Mons volcano, close to the planet’s equator.

Daily Mail,

30 October, 2018

Scientists are closely tracking a mysterious giant 'plume' cloud on the surface of Mars.

The huge cloud is now over 900 miles (1500km) long, and began forming near the 20 km-high Arsia Mons volcano, close to the planet’s equator.

However, scientists believe the vast cloud is not caused by volcanic activity.

Instead, it is a water ice cloud 'driven by the influence of the volcano’s leeward slope on the air flow' – something that scientists call an orographic or lee cloud – and a regular phenomenon in this region.

'The cloud’s appearance varies throughout the martian day, growing in length during local morning downwind of the volcano, almost parallel to the equator, and reaching such an impressive size that could make it visible even to telescopes on Earth,' the European Space Agency said.

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Left, The water ice cloud, which arises as the volcano slope interacts with the air flow, can be seen as the white, elongated feature in the lower left part of the image, extending westward of the volcano and casting a shadow on the surface. The image was taken on 17 September 2018, from an altitude of 11 000 km. North is up. Right, The cloud began forming near the 20 km-high Arsia Mons volcano, close to the planet’s equator. a comparison, the cone-shaped volcano has a diameter of about 250 km; a view of the region with labels is provided here.

ESA’s Mars Express has been observing the evolution of the storm since 13 September.

The formation of water ice clouds is sensitive to the amount of dust present in the atmosphere, ESA said.

These images, obtained after the major dust storm that engulfed the entire planet in June and July, will provide important information on the effect of dust on the cloud development and on its variability throughout the year.

The High Resolution Stereo Camera on board ESA’s Mars Express snapped a view of a curious cloud formation that appears regularly in the vicinity of the Arsia Mons volcano. This water ice cloud, which arises as the volcano slope interacts with the air flow, can be seen as the long white feature extending to the lower right of the volcano. The cloud, which measures 915 km in this view, also casts a shadow on the surface. This image was taken on 21 September 2018 from an altitude of about 6930 km. North is up.

Mars just experienced its northern hemisphere winter solstice on 16 October. 

In the months leading up to the solstice, most cloud activity disappears over big volcanoes like Arsia Mons; its summit is covered with clouds throughout the rest of the martian year.

However, a seasonally recurrent water ice cloud, like the one shown in this image, is known to form along the southwest flank of this volcano - it was previously observed by Mars Express and other missions in 2009, 2012 and 2015. 

THE MARTIAN MEGASTORM KILLING OPPORTUNITY: WHAT DO WE KNOW?

The Martian dust storm that has blotted out the sun above Opportunity has continued to intensify.

The storm has been growing since the end of May, and by mid-June had already covered 14-million square miles (35-million square kilometers) of Mars' surface, or a quarter of the planet.

Now, the experts say it’s grown to be a planet-circling dust event – though they don’t quite know what’s driving it.

This series of images shows simulated views of a darkening Martian sky blotting out the Sun from NASA's Opportunity rover's point of view, with the right side simulating Opportunity's current view in the global dust storm (June 2018). The left starts with a blindingly bright mid-afternoon sky, with the sun appearing bigger because of brightness. The right shows the Sun so obscured by dust it looks like a pinprick. Each frame corresponds to a tau value, or measure of opacity: 1, 3, 5, 7, 9, 11.

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This graphic compares atmospheric opacity in different Mars years from the point of view of NASA’s Opportunity rover. The green spike in 2018 (Mars Year 34) shows how quickly the global dust storm building at Mars blotted out the sky. A previous dust storm in 2007 (red, Mars Year 28) was slower to build

When the orbiter team saw the storm nearing Opportunity, they notified the rover's team to begin preparing contingency plans.

In a matter of days, the storm had ballooned. 

It now spans more than 7 million square miles (18 million square kilometers) -- an area greater than North America -- and includes Opportunity's current location at Perseverance Valley. 

More importantly, the swirling dust has raised the atmospheric opacity, or 'tau,' in the valley.

This is comparable to an extremely smoggy day that blots out sunlight. The rover uses solar panels to provide power and to recharge its batteries.

Opportunity's power levels had dropped significantly by Wednesday, June 6, requiring the rover to shift to minimal operations.

On June 12, NASA confirmed the rover had fallen silent.