Return of the elongated mysterious cloud on Mars (1800 km!)
Did you know that Earth isn't the only planet in the solar system to have clouds?
Interesting, huh? Even on the Red Planet, there are clouds.
Astronomers are aware of this, and they found a strange cloud, long about 1800 km, that
acts weirdly. Every few years in spring or summer, this curious cloud returns, before
disappearing once again. Its pretty unique behaviour really intrigued
astronomers all over the world, that was trying to explain the formation of that cloud and
its following disappearing. But now we seem to have an answer.
Ladies and gentlemen, fasten your seatbelts because we are going to talk about the resolution
to one of the strangest mysteries of the Mars planet!
With a human mission to Mars somewhere on the horizon,
the planet is being scrutinized more than ever before. Currently, 8 orbiters are operating
on the planet and some surface missions. As of February 2021, there are two operational
rovers on the surface of Mars, the Curiosity and Perseverance rovers, both operated by the United States of America space
agency NASA. A third rover, part of the Tianwen-1 mission, is currently attached to its orbiter and is
planned to land in May 2021. All of this just to say that if a cloud with
a trail of about 1800 km suddenly emerges, it's pretty easy for us to spot her.
In fact, in 2018, a camera onboard the Mars Express mission caught sight of a strangely long
and wispy cloud, billowing across the surface of the red planet.
From a distance, the 1,800-kilometer trail of fog almost resembled a plume of smoke – but
it wasn't! - and it seemed to be emerging from the top of a long-dead volcano. A unique
scenario! Looking back at other archived images, researchers
soon realized this actually had been happening for a while. Every few years in spring or
summer, this curious cloud would return, before disappearing once again. The fleeting plume
was caught on camera in 2009, 2012, 2015, 2018, and again in 2020.
A newly published study has now detailed the reasons behind why this long cloud keeps coming
and going on Mars. To do this, researchers compared high-resolution observations of the
2018 plume to other archived observations, some of which stretch back all the way to
the 1970s. Here's the cloud's story. Each year, around
the start of spring or summer in the southern Martian hemisphere, the Arsia Mons Elongated
Cloud begins to take shape. The southern solstice is when the Sun is in its southernmost position
in the sky. Since a Martian year is about twice as long as an Earth year—687 days
compared to 365—the seasons last about twice as long. This cloud grows each morning during
the season, for about three hours. Then, it disappears. We want to say it again: this
cloud grows and disappears, daily! The massive extinct volcano that is home to
the cloud is Arsia Mons, a 20 km high (12.4 miles) landmark on Mars’ surface. But what's
the difference between Mars clouds and Earth clouds? On Earth, clouds are made from water
whereas, on other planets, they could be made from a different substance such as Methane
such as on Saturn. Earth clouds are created when the water at
the ground/sea level is heated and evaporates into the upper atmosphere. When the water
reaches a certain height depending on environmental conditions at the time will group with other
water to form clouds. When the pressure dips, the clouds begin to break up in the form of
precipitation (rain/sleet/snow/hailstorms) and fall to Earth. The fallen water drops
will eventually go back up into the atmosphere to form new clouds.
Mars, instead, is too cold for liquid water, so the cloud is made of water ice. Though
it looks like it could be a plume from the volcano, it’s not. All of Mars’ volcanic
activity ceased a long time ago. Talking about our beautiful and mysterious
Martian cloud, at dawn, dense air from the base of the Arsia Mons volcano begins to climb
up the western slope. As temperatures drop, this wind expands and the moisture within
it condenses around particles of dust, creating what here on Earth we call an orographic
cloud.
Do you know what's an “Orographic cloud”?
“Before we get to know what an Orographic cloud is, please be sure to like or dislike
the video so that we can continue to improve and make these videos better for you the viewer.
Plus, be sure to subscribe to the channel by clicking the bell so that you don't miss
ANY of our weekly videos."
Orographic clouds develop in response to the forced lifting of air by the earth's topography
(mountains for example). Air passing over a mountain oscillates up
and down as it moves downstream. If the airlifts upward and cools through expansion as it rises
to its saturation temperature during this process, the water vapour within condenses
and becomes visible as a cloud. Upon reaching the mountain top, the air is
heavier than the environment and will sink down the other side, warming as it descends.
Once the air returns to its original height, it has the same buoyancy as the surrounding
air. However, the air does not stop immediately because it still has momentum carrying it
downward. With continued descent, the air becomes warmer than the surroundings and begins
to accelerate back upward towards its original height. It is during the upper-most ascent
phase of this cycle that clouds develop. In regions where the air is descending, skies
are clear. The lifting of moist air can result in the
generation of clouds, while lifting drier air may not produce any clouds at all. The
oscillations continue as the air moves further downstream from the mountains but are eventually
dampened out by mixing and friction. Each morning, over the course of several months
of observations, researchers watched this process of growth and disappearing repeat
itself. At about 45 kilometres altitude, the air begins to expand, and for the following
2.5 hours or so, the cloud is pulled westward on the wind, as fast as 600 kilometres per
hour (380 mph), before finally detaching from the volcano.
At its largest, the plume can reach 1,800 kilometres in length (more than 1,100 miles)
and 150 kilometres in width (nearly 100 miles). By noon, when the Sun is at its apex, the
cloud will have completely evaporated. In this case both the pressure from underneath
as well as the temperature need to be very specific for these clouds to form and to stay
in this cloud form for several hours, but once the temperature changes (or once all
this moist air disappears) the cloud dissipates as well.
All of this happens pretty much every single day in springtime and summertime and then
when the seasons change all this stops happening, until the next spring.
What’s interesting here is how fast all this happens. In fact, this happens in about
10 hours, which means that this cloud expands at very high speeds, up to about 600 kilometres
per hour. It is the speed of a flying aeroplane! So in some sense, there are still a lot of
different questions about this cloud and what exactly happens here. The other major question
is why this particular mountain? And why this particular location? What makes this volcano
so unique and so specific, and why doesn’t this happen around other similar volcanoes
in this area? If we look at the model of mars for example you can kind of see that there
are actually four major volcanoes here but it’s only this one, very close to the equator,
that seems to have these effects. Also, not a single orographic cloud on earth - even
the ones around Everest - are as long, move as fast or have such ridiculous dynamics!
They don’t change that fast. So whatever is happening here is actually
an extreme of the solar system!
Ice clouds are not exactly unusual on Mars, but the clouds above Arsia Mons continue to
form in summer when most others disappear. Much of the time, this specific volcano has
a cloud sitting on top of it when others around it don't – but only under some conditions
does it spread out in a long streak. (Each year, at the start of winter, this cloud can also
form a spiral.) So if this long plume is happening daily for
some time each year, why do we only have sporadic observations of it?
Researchers say it's because many of the cameras orbiting Mars are only occasionally flying
over this region in the morning, and observations are usually planned, which means we are often
taking shots of this cloud simply by chance. Luckily, an old camera still onboard the Mars
Express mission – the Visual Monitoring Camera (VMC) which has the power of a 2003
webcam – has one perk newer technology doesn't. While other cameras on orbiters try to zoom
in and get as much detail as possible, VMC is different. It’s been described as a webcam
in space, and its wide-angle helps it see things like the cloud.
Although the camera has a low spatial resolution, it has a wide field of view – essential
to see the big picture at different local times of day – and is wonderful for tracking
a feature's evolution over both a long period and in small time step.
As a result, we could study the whole cloud across numerous life cycles.
The study represents the first detailed exploration of the Arsia Mons cloud, and while scientists
say it holds similar properties to orographic clouds on Earth, its size is enormous and
its dynamics quite vivid in comparison to what we see on our own planet.
"Understanding this cloud gives us the exciting opportunity to try to replicate the cloud's
formation with models – models that will improve our knowledge of climatic systems
on both Mars and Earth," says astronomer Agustin Sánchez-Lavega, from the University
of the Basque Country. Now that we know when the cloud occurs, it
also allows us to direct other, stronger cameras in orbit to the right place at the right time,
providing us with a closer glimpse. It may not be too long until the next pics!
Before ending this video we want to recall that Earth and Mars are not the only two planets
to have clouds! All the other planets except Mercury and
probably Pluto (that's if you class Pluto as still being a planet) have clouds. Mercury
doesn't have an atmosphere so clouds can't form.
At one time, it was believed that Venus was as hospitable to life as Earth is. Venus had
water and may even have had life on it but something catastrophic occurred and no known
life exists. The clouds on Venus are highly acidic and trap the environment keeping it
warm and poisonous to any life. There is a theory that there might be microbial life
in the upper clouds but nothing too advanced. Also, all the gas giants have clouds in their
upper atmosphere. The clouds on Saturn and Jupiter are composed of tiny ice crystals
of frozen ammonia, ammonium hydrosulfide, and water. The outer gas planet (Uranus and Neptune)
clouds consist of methane! How strange is the universe we live in!
"This video ends here! Thanks for watching everyone! Did you enjoy this video? Let us
know in the comment below! See you next time on the channel!