I have looked at many Mars photos, but don't see many with a visible feature of what looks like fog. So, here is one for example from Rover Curiosity sol day 1221.
http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/01221/opgs/edr/ncam/NRB_505890214EDR_D0520948TRAV00409M_.JPG
(click on pic to expand)
(http://s16.postimg.org/n3jd37rzp/Mars_Curiosity_Sol_day_1221_Screen_Shot_2016_02.jpg)
The problem is that it's to know if what we are looking at is fog or dust, as we are only seeing something getting between the camera and the far away crater rim.
I think only different wavelengths (and that's why they use them) could tell us if it's one or the other.
This is also one of the techniques used for blurring out the artificial structures on or near the horizon! :o
Quote from: ArMaP on February 09, 2016, 12:26:26 PM
The problem is that it's to know if what we are looking at is fog or dust, as we are only seeing something getting between the camera and the far away crater rim.
I think only different wavelengths (and that's why they use them) could tell us if it's one or the other.
I think the sun is a good indicator in this picture , just like it was in all the others :D
more atmosphere to scatter through = that massive Bloom we see regularly
funbox
Quote from: funbox on February 10, 2016, 01:36:28 PM
I think the sun is a good indicator in this picture , just like it was in all the others :D
more atmosphere to scatter through = that massive Bloom we see regularly
How does that help understand if this is for or dust? ???
Quote from: ArMaP on February 10, 2016, 01:50:38 PM
How does that help understand if this is for or dust? ???
the time it appears ArMaP, I doubt ive seen many sunrises where it hasn't appeared, does dust usually have properties that are explicit to morning time >?
I say there's more evidence of it being water, just via the time it appears
funbox
Fog on Mars
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Fog_Viking_02.gif)
Courtesy © 1998 by Calvin J. Hamilton
Image taken by the Viking spacecraft. Fog often appears in low-lying areas. It typically occurs in the southern hemisphere especially in the Argyre and Hellas basins. It forms frequently in craters. Occasionally, it occurs in higher regions such as Sinus Sabaeus and Solis Planum. (Click image for larger view)
Chasma Australe Fog
MGS MOC Release No. MOC2-528, 29 October 2003
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Fog_MSSS_M0904025_02.gif)
Courtesy NASA/JPL/Malin Space Science Systems
Fog is a common occurrence in some areas of the retreating south polar seasonal frost cap. Fogs are commonly banked-up against steep slopes or found inside defrosting craters. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captured mid-afternoon fog banked against the layered walls of Chasma Australe, a trough in the south polar region of Mars. The frost-covered layers of Chasma Australe can be seen on the right side of this image, the billowy fog is to the left. Sunlight illuminates this scene from the upper left. The fog, probably composed of water ice crystals, casts shadows on the chasm wall. This picture is located near 83.5°S, 257.9°W, and covers an area 3 km (1.9 mi) wide.
Image Source: Malin Space Systems 2003/10/29 M09 04025
Dust Plume
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Dust_Plume_Viking_02.gif)
Courtesy © 1998 by Calvin J. Hamilton
Image taken by the Viking spacecraft. This is an example of a dust plume in the Solis Planum region. This image was taken during the springtime for this region. Plumes are found primarily in the southern hemisphere, in highlands such as Syrtis Major and in elevated regions such as Tharsis. (Click image for larger view)
Martian Weather by Bluebird
http://www.thelivingmoon.com/43ancients/02files/Mars_Blue_Bird_Weather.html
Dust storm on Mars compared to one on Earth
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/mars_and_earth_storms.jpg)
More Clouds on Mars
Lee Wave Cloud
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Leewave_Viking_02.gif)
Courtesy © 1998 by Calvin J. Hamilton
Image taken by the Viking spacecraft. This is a good example of a lee wave associated with an impact crater. Note the wave periodicity in the clouds.
Lee Wave Cloud
Crater with Wavy Fog
MGS MOC Release No. MOC2-424, 17 July 2003
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Leewave_MSSS_02.jpg)
Courtesy NASA/JPL/Malin Space Science Systems
Craters near the edge of the retreating south polar seasonal frost cap often have fog in them, this time of year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image was acquired just a few days ago on July 13, 2003. It shows a crater, 36 km (22 mi) across, that is enveloped in fog. This picture was taken as a context frame for a high resolution view that was intended to show dunes on the floor of the crater. That high resolution view was frustrated by thick fog that hid the dunes from view. This wide angle context frame shows that winds from the lower right (southeast) were blowing over the crater, causing the fog to bunch up in a wavy, rippled pattern. Winds streaming off the polar cap toward the north create a variety of patterns in the fogs formed by water ice or vapor as the seasonal cap retreats during southern spring. This picture is located at 66.4°S, 208.6°W, sunlight illuminates the scene from the upper left (northwest).
Image Source: Malin Space Systems 2003/07/17 R07-00964
Wave Clouds
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Wave_Cloud_Viking.gif)
Courtesy © 1998 by Calvin J. Hamilton
Image taken by the Viking spacecraft. Wave clouds usually occur at the lee of a large obstacle. They are often found at the edge of the polar cap, and in the Tharsis and Lunae Planum regions of Mars.
Quote from: ArMaP on February 09, 2016, 12:26:26 PM
The problem is that it's to know if what we are looking at is fog or dust, as we are only seeing something getting between the camera and the far away crater rim.
Well you can always give it to us in REAL COLOR :P
Like this one
(http://www.thelivingmoon.com/46ats_members/ArMaP/04images/3ef83413c675.gif)
ArMaP's Collection
(Edited by Pegasus)
Green Fog GREEN FOG(http://www.thelivingmoon.com/43ancients/04images/Mars4/Seminole_L257atc-A677R1/Fog_003_ArMaP.png)
http://www.thelivingmoon.com/43ancients/02files/Mars_Images_58_Green_Fog.html
NASA's version
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Seminole_L257atc-A677R1/Fog_001.png)
Image credit: NASA/JPL/Cornell
The Image above is clipped from the original full size (60 MB) image with no adjustment in size color or contrast. Just over the hill you can see a greenish fog on the valley floor. This image according to NASA is in true color. The source files are linked above in the article. The fog was first spotted by Exhuberant1's brother and brought to Pegasus. He also sent a copy to Mike Singh for his opinion. [see below]
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Seminole_L257atc-A677R1/Fog_002.png)
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Spirit_Sol_229/space_skeleton_150.jpg)
Mike Singh's Collection
(Edited by Pegasus)
Green Fog (http://www.thelivingmoon.com/43ancients/04images/Mars4/Seminole_L257atc-A677R1/6122c476f98445540bde80e32e99f7f7.jpg)
Dust Devils on Mars
(http://apod.nasa.gov/apod/image/0504/dustdevil5_spirit_big.gif)
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/dustdevil_mgs.jpg)
A Dust Devil on Mars
Credit: Malin Space Science Systems, MGS, JPL, NASA (Click image for larger view)
Explanation: Does the surface of Mars change? When inspecting yearly images of the Martian surface taken by the robot spacecraft Mars Global Surveyor currently orbiting Mars, sometimes new dark trails are visible. Although originally a mystery, the culprit is now usually known to be a dust devil, a huge swirling gas-cloud with similarities to a terrestrial tornado. Pictured above, a recent image has not only captured a new dark trail but the actual dust devil itself climbing a crater wall. Dust devils are created when Martian air is heated by a warm surface and begins to spin as it rises. Dust devils can stretch 8 kilometers high but usually last only a few minutes.
Sourse: NASA Astronomy Picture of the Day
Martian Dust Devils in Action
Spirit Rover
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/spirit_sol587nav.gif)
Spirit Sol 587
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/spirit_sol632nav.gif)
Spirit Sol 632
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/spirit_sol640nav.gif)
Spirit Sol 640
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/spirit_sol568nav.gif)
Spirit Sol 640
Quote from: funbox on February 10, 2016, 01:58:25 PM
the time it appears ArMaP, I doubt ive seen many sunrises where it hasn't appeared, does dust usually have properties that are explicit to morning time >?
The time? What time was it on that location when the photo was taken?
QuoteI say there's more evidence of it being water, just via the time it appears
Dust can appear in the air regardless of the time of day.
I assume the red thing is a mistake in color?
(http://s15.postimg.org/71zpmhpgr/mars_red_thing.jpg)
(http://[url=http://postimage.org/%5D%5Bimg%20width=640%20height=480%5Dhttp://s15.postimg.org/71zpmhpgr/mars_red_thing.jpg)[/url]
image hosting 30 mb (http://postimage.org/)[/img]
Quote from: zorgon on February 10, 2016, 08:00:10 PM
Well you can always give it to us in REAL COLOR :P
Like this one
(http://www.thelivingmoon.com/46ats_members/ArMaP/04images/3ef83413c675.gif)
ArMaP's Collection
(Edited by Pegasus)
Green Fog
GREEN FOG
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Seminole_L257atc-A677R1/Fog_003_ArMaP.png)
http://www.thelivingmoon.com/43ancients/02files/Mars_Images_58_Green_Fog.html
I have posted my opinion about that "green fog" several times, but here's once more, to avoid misunderstandings: when a dust devil (or something else) appears only on the image from the (in this case) green channel it will look green.
Quote from: ArMaP on February 10, 2016, 10:14:18 PM
I have posted my opinion about that "green fog" several times, but here's once more, to avoid misunderstandings: when a dust devil (or something else) appears only on the image from the (in this case) green channel it will look green.
Okay so the 'fog' is there but only recorded on the 'green' channel so the fog looks green because only green light reflects
The point is the 'fog' is there to be recorded on that green channel so we can see it as green fog
Dust however being mostly iron oxide red dust on mars SHOULD appear brownish red not GREEN
:P
Well, here is an article that provide some corroboration about the for-certain-reality of some types of fog on Mars. This information was published in 2011, however, it is "new" to me and maybe also to some others here. It does add a bit to what we are discussing in this thread.
Martian-Fog Study Finds Thick Haze, "Diamond Dust"
National Geographic News
By Brian Handwerk, for National Geographic News
PUBLISHED APRIL 6, 2011
Scientists probed the Martian fog using NASA's Phoenix Mars Lander. The craft touched down on Mars in May 2008—during the planet's late northern summer—and collected data for about five months before succumbing to frigid winter conditions.
Pictures from Phoenix revealed, for example, that there's water ice in the shallow Martian soil, but scientists aren't yet sure whether that ice is a relic of ancient times or is formed by ongoing processes.
During four nights near the middle of the Phoenix mission, scientists aimed a green laser beam affixed to the lander into the Martian skies and used a pair of cameras to record the result.
The new analysis of this data shows that Martian fog contains about 1.7 milligrams of water ice per cubic meter. Most of the fog is made of particles a little smaller than a thousandth of an inch wide, with an occasional larger particle settling out and falling toward the surface.
"If you went outside on a dusty or foggy night with a laser pointer and pointed it straight up, you'd see what we saw on Mars," said study co-author Mark Lemmon, a planetary scientist at Texas A&M University.
"You'd see the green beam and points of light every once in a while as a particle drifted through that beam."
More:http://news.nationalgeographic.com/news/2011/04/110404-nasa-mars-fog-water-cycle-phoenix-space-science/
(http://s10.postimg.org/l4wicsmqh/Screen_Shot_2016_02_10_at_5_00_04_PM.jpg)
Wispy Clouds Passing Overhead
Opportunity Rover Sol 950
(http://mars.nasa.gov/mer/gallery/all/1/n/950/1N212516144EDN76ACP1585L0M1.JPG)
Wispy Afternoon Clouds
Rover Opportunity Sol 956
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/Clouds_PIA09170.gif)
More Clouds on Mars
Mars Pathfinder Sol 16
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/82453_full.jpg)
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/82454_full.jpg)
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Weather/82381_full.jpg)
Here is a color-enhanced video of moving clouds passing over NASA's Mars Lander. See http://phoenixonmars.wordpress.com for more on the Mars landing.
http://www.youtube.com/watch?v=AbTCewNErzQ
https://www.youtube.com/watch?v=AbTCewNErzQ
Quote from: zorgon on February 10, 2016, 10:40:16 PM
The point is the 'fog' is there to be recorded on that green channel so we can see it as green fog
It's there, being "fog" is some people's interpretation.
My interpretation is that it's a dust devil.
QuoteDust however being mostly iron oxide red dust on mars SHOULD appear brownish red not GREEN
I hope you are joking, because if you aren't that is one of the most ignorant things you have said. :(
(https://assets.goodstatic.com/s3/magazine/assets/545696/original/Mars.jpg=s1200x1200)
http://www.youtube.com/watch?v=Rg5wrZZ9Gr4
https://www.youtube.com/watch?v=Rg5wrZZ9Gr4
Quote from: ArMaP on February 10, 2016, 11:33:23 PM
It's there, being "fog" is some people's interpretation.
My interpretation is that it's a dust devil.
Nasa disagrees with your interpretation :P
(http://www.thelivingmoon.com/43ancients/04images/Mars4/Life/303609main_satreya_vid_01_1280_03.jpg)
QuoteI hope you are joking, because if you aren't that is one of the most ignorant things you have said. :(
NASA has been pushing the 'Dust is Red' line for decades :P
(http://www.spaceanswers.com/wp-content/uploads/2012/06/Mars-red-surface.jpg)
QuoteThe red colour we see in images of Mars is the result of iron rusting. Rocks and soil on the surface of Mars contained a dust composed mostly of iron and small amounts of other elements such as chlorine and sulhpur. The rocks and soil were eroded by wind and the dust was blown across the surface by ancient volcanoes. Recent evidence points to the very fine dust also being spread across the planet by water, backed up by the presence of channels and ducts across the surface of Mars.
The iron within the dust reacted with oxygen, producing a red rust colour, while the sky appears red as storms carried the dust into the atmosphere. This dusty surface, which is between a few millimetres and two metres deep, sits above hardened lava composed mostly of basalt. The concentration of iron in this basalt is much higher than that on Earth, contributing to the red appearance of Mars.
As to your "Dust Devil" interpretation... NASA disagrees THIS is what a dust devil looks like on Mars :P
(http://mars.nasa.gov/images/21_The_Serpent_Dust_Devil_on_Mars_PIA15116.jpg)
Perhaps YOUR interpretations are not correct :D
Quote from: zorgon on February 10, 2016, 11:41:10 PM
Nasa disagrees with your interpretation :P
OK, point to where NASA says that instead of posting a useless image.
QuoteAs to your "Dust Devil" interpretation... NASA disagrees THIS is what a dust devil looks like on Mars :P
My interpretations may be wrong, but, apparently, you haven't learned a thing about digital photography in all these years, and that's disappointing.
This is how the green channel of the red dust photo you posted looks.
(http://www.thelivingmoon.com/gallery/albums/userpics/10002/Green2.jpg)
The photos from Opportunity and Spirit are all greyscale, so to create colour images we have to use one image for each chanel (red, green and blue).
To try to reproduce the situation I took three photos of my kitchen above the microwave oven (so I could use it to place the camera and not move the camera); the first photo had only the wall, the second had my hand on the hall, the third only the wall again.
I used the red channel of the first photo, the green channel of the second photo and the blue channel of the third photo to create the image below.
(http://www.thelivingmoon.com/gallery/albums/userpics/10002/Silly_Z.jpg)
As you can see, the parts that appeared in all channels have the normal colours (although the photos turned out too dark, but I don't want to waste more time with this now), but the part that appears only in one channel appears ghostly and with strange colours.
In fact, it happened something I didn't think about (but that's obvious, if we think about it): my hand looks magenta when over a brighter background, green when over a darker background.
That happens for the same reason the red dust photo you posted has a green channel, unless the colours is pure red, green or blue it will always appear on more than one channel (if it's pure magenta, yellow or cyan it appears in only two channels), if there's even an hint of (in this case) green in the image, the green channel will have the corresponding image, and the less green it has the darker the green channel. Obviously, the opposite happens, the greener the image the brighter the green channel will look.
Quote from: ArMaP on February 10, 2016, 08:15:03 PM
The time? What time was it on that location when the photo was taken?
Dust can appear in the air regardless of the time of day.
*takes a huge lungful of air a dives in*
it might explain why were getting so many pictures of morning sunrise, someone at Nasa's also interested in the regular bloom.
I don't see how you see it as so unfathomable, given that there's already plenty of observations and pictures of it already.
didn't we discuss fog recently on the oddities thread ?
fogbox
Quote from: ArMaP on February 11, 2016, 12:42:42 AM
OK, point to where NASA says that instead of posting a useless image.
In the text below the 'useless image'
"producing a red rust colour,
while the sky appears red as storms carried the dust into the atmosphere."
Quote from: funbox on February 11, 2016, 03:15:34 AM
it might explain why were getting so many pictures of morning sunrise, someone at Nasa's also interested in the regular bloom.
Why are you assuming this is morning sunrise instead of looking at the time the photo was taken?
QuoteI don't see how you see it as so unfathomable, given that there's already plenty of observations and pictures of it already.
I don't, I just try not to assume things are one thing and disregard all other possibilities.
Quotedidn't we discuss fog recently on the oddities thread ?
Yes, but does that mean that dust doesn't exist?
Quote from: ArMaP on February 11, 2016, 10:10:15 AM
I don't, I just try not to assume things are one thing and disregard all other possibilities.
The problem with that method is that you NEVER come to a conclusion :P
Quote from: zorgon on February 11, 2016, 07:30:07 AM
In the text below the 'useless image'
"producing a red rust colour, while the sky appears red as storms carried the dust into the atmosphere."
As you said "Nasa disagrees with your interpretation" as an answer to my "My interpretation is that it's a dust devil.", I was expecting a reference to dustdevils, not to the colour of the dust in the air.
Quote from: zorgon on February 11, 2016, 10:24:15 AM
The problem with that method is that you NEVER come to a conclusion :P
I prefer to take time until I have enough data, and only then come to a possible conclusion instead of jumping to conclusions and waste time going in the wrong direction.
QuoteWhy are you assuming this is morning sunrise instead of looking at the time the photo was taken?
look at all the other pictures, never mind this one , the sun scattering is most apparent at sunrise, or are they just for fun :D
QuoteI don't, I just try not to assume things are one thing and disregard all other possibilities
and that's good , but if you was to go with what we can see visually from the pictures , is that mostly high noon shot , don't have the same scattering of light , and background objects tend to be a little more visible
what mechanism if its dust, clears it up .. the wind ?
funbox
Quote from: funbox on February 11, 2016, 11:44:23 PM
look at all the other pictures, never mind this one , the sun scattering is most apparent at sunrise, or are they just for fun :D
What other pictures? The ones from the same sol or any other picture?
And that's one thing I avoid doing, as it brings more variables to the equation and makes it harder to solve, not easier. If we want to solve a problem, one usual method is to break it into smaller, easier problems; finding more problems as if they are solutions is faking a solution and doesn't bring us closer to the real answer.
Quotewhat mechanism if its dust, clears it up .. the wind ?
Yes, and maybe humidity, if enough, but I doubt it.
PS: in the case of the photo we are talking about, if you look at this page (http://curiosityrover.com/imgpoint.php?name=NRB_505890214EDR_D0520948TRAV00409M_) you can see that the camera was pointing almost directly to west. The time the photo was taken (Mars time) was 01:34:09 P.M.
That's a strange sunrise. ::)
PPS: if you look at the "fog" you can see the it appears to have a more or less constant density regardless of the place in front (or on) the crater rim; if this was fog I would expect it to remain closer to more specific areas instead of homogeneously distributed along the crater rim.
QuoteWhat other pictures? The ones from the same sol or any other picture?
take any pic of any of the last 1000+ sols where the sun was photographed in the morning
QuoteAnd that's one thing I avoid doing, as it brings more variables to the equation and makes it harder to solve, not easier. If we want to solve a problem, one usual method is to break it into smaller, easier problems; finding more problems as if they are solutions is faking a solution and doesn't bring us closer to the real answer.
can you explain this in terms related to the current discussion?
QuoteYes, and maybe humidity, if enough, but I doubt it.
temperature inversion . the bodies of air trapped in the crator that vary in temperature would form a layer , trapping Water in a temperature suitable for forming Fog/water vapour
Quote
PS: in the case of the photo we are talking about, if you look at this page you can see that the camera was pointing almost directly to west. The time the photo was taken (Mars time) was 01:34:09 P.M.
so your saying the Fog had a late rise .. plausible , just as here on earth, some days Fog can linger
funbox
Quote from: funbox on February 12, 2016, 12:40:53 PM
take any pic of any of the last 1000+ sols where the sun was photographed in the morning
OK, that explains it.
Quotecan you explain this in terms related to the current discussion?
We are talking about a specific photo, you talked about "other pictures" without specifying what you meant (as usual), that's why I said that. If you had said "other pictures where the sun was photographed in the morning" my answer would have been different.
Quotetemperature inversion . the bodies of air trapped in the crator that vary in temperature would form a layer , trapping Water in a temperature suitable for forming Fog/water vapour
So, are you talking about a hypothetical colder air layer moving over the warmer air inside the crater and creating a fog layer?
Quoteso your saying the Fog had a late rise .. plausible , just as here on earth, some days Fog can linger
No, I'm saying it's not fog.
QuoteSo, are you talking about a hypothetical colder air layer moving over the warmer air inside the crater and creating a fog layer?
indeed , otherwise how could you get dust devils if opposite bodies of air didn't interact
why is it not Fog ?
funbox
Quote from: funbox on February 12, 2016, 10:38:49 PM
indeed , otherwise how could you get dust devils if opposite bodies of air didn't interact
Now I'm confused, again.
Were you talking about dust devils or fog? Fog is created by differences in temperature between two layers of the atmosphere, dust devils are a much smaller phenomena that can happen just because there's wind blowing in the right direction.
Quotewhy is it not Fog ?
I already said, it doesn't look like fog, it looks too uniform, dust in the air looks like that.
Quote from: ArMaP on February 12, 2016, 11:04:50 PM
Now I'm confused, again.
Were you talking about dust devils or fog? Fog is created by differences in temperature between two layers of the atmosphere, dust devils are a much smaller phenomena that can happen just because there's wind blowing in the right direction.
please explain this further please :D
in the right direction ? ..
*dark and distant chuckling can be heard far far down deep*
funbox
On my street there's a building slightly recessed from the others, and if the wind blows from East to West it creates small dust devils in front of that building.
Dust devils are only a result of wind.
Quote from: ArMaP on February 13, 2016, 12:13:53 AM
On my street there's a building slightly recessed from the others, and if the wind blows from East to West it creates small dust devils in front of that building.
Dust devils are only a result of wind.
no links to a Nasa type explanation ? surprising ,
hows the fever? you feeling better yet ?
funbox
Quote from: ArMaP on February 13, 2016, 12:13:53 AM
On my street there's a building slightly recessed from the others, and if the wind blows from East to West it creates small dust devils in front of that building.
Dust devils are only a result of wind.
hmm ,a simple wiki for you :D, given your not 100% :D
https://en.wikipedia.org/wiki/Dust_devil
QuoteDust devils form when hot air near the surface rises quickly through a small pocket of cooler, low-pressure air above it. If conditions are just right, the air may begin to rotate. As the air rapidly rises, the column of hot air is stretched vertically, thereby moving mass closer to the axis of rotation, which causes intensification of the spinning effect by conservation of angular momentum. The secondary flow in the dust devil causes other hot air to speed horizontally inward to the bottom of the newly forming vortex. As more hot air rushes in toward the developing vortex to replace the air that is rising, the spinning effect becomes further intensified and self-sustaining. A dust devil, fully formed, is a funnel-like chimney through which hot air moves, both upwards and in a circle. As the hot air rises, it cools, loses its buoyancy and eventually ceases to rise. As it rises, it displaces air which descends outside the core of the vortex. This cool air returning acts as a balance against the spinning hot-air outer wall and keeps the system stable.[5]
The spinning effect, along with surface friction, usually will produce a forward momentum. The dust devil is able to sustain itself longer by moving over nearby sources of hot surface air.
As available extreme hot air near the surface is channeled up the dust devil, eventually surrounding cooler air will be sucked in. Once this occurs, the effect is dramatic, and the dust devil dissipates in seconds. Usually this occurs when the dust devil is not moving fast enough (depletion) or begins to enter a terrain where the surface temperatures are cooler, causing unbalance.[6]
funbox
Quote from: funbox on February 13, 2016, 12:18:54 AM
no links to a Nasa type explanation ? surprising ,
No, I preferred a personal observation. :)
Quotehows the fever? you feeling better yet ?
Almost gone, thanks. :)
Quote from: funbox on February 13, 2016, 01:14:53 PM
If conditions are just right, the air may begin to rotate.
I suppose that's the part I talked about, the direction of the wind and the shape of the area that create those "right conditions" to make it rotate. :)
Quote from: ArMaP on February 13, 2016, 03:47:04 PM
I suppose that's the part I talked about, the direction of the wind and the shape of the area that create those "right conditions" to make it rotate. :)
indeed but even that "Wind" is the interaction of varying density's/ temperatures of bodies of air.
just like water, temperature, separation and sometimes violent interactions takes place ,add to that a fluctuating solar heater that cycles in cycles , well..
care to add a few more variable for the soup ? :D
funbox
Quote from: funbox on February 13, 2016, 03:59:30 PM
care to add a few more variable for the soup ? :D
The type of ground, some types are better at conserving the temperature than others, so they will not get cold after sunset as fast and, at sunrise, they are already warmer. :)
Quote from: ArMaP on February 13, 2016, 12:13:53 AM
On my street there's a building slightly recessed from the others, and if the wind blows from East to West it creates small dust devils in front of that building.
No those are wind tunnel vortexes not 'dust devils' Yes they will stir up the dust because they are wind :P
QuoteDust devils are only a result of wind.
I am surprised that you say ONLY because in this case you are incorrect A Dust Devil is formed by rising heat... that is why they are so common out here in the deserts
Oh I see funbox just posted the description :P
Quote from: zorgon on February 13, 2016, 11:58:11 PM
I am surprised that you say ONLY because in this case you are incorrect A Dust Devil is formed by rising heat... that is why they are so common out here in the deserts
Well, the hotter air rising is still wind, only vertical. :P
Quote from: ArMaP on February 14, 2016, 12:41:06 AM
Well, the hotter air rising is still wind, only vertical. :P
hot air ArMaP ? .., what about the cooloer air.. no vortex without that :D
but this is all additional to the temperature inversions that may or may not be causing fog
you cannot deny though that early morning have a certain haze about them :D
funbox
Quote from: funbox on February 14, 2016, 01:34:13 PM
hot air ArMaP ? .., what about the cooloer air.. no vortex without that :D
Hotter air implies hotter than something else, and that something else is, obviously, cooler air. :)
Quotebut this is all additional to the temperature inversions that may or may not be causing fog
you cannot deny though that early morning have a certain haze about them :D
The problem is in ignoring that the haze remains throughout the day, until sunset (we don't have night photos to show if the haze is still there).
Yes, there's haze in the morning, but the haze remains for the whole day, and the next, and the next, and is consistent with dust in the air.
Yes, we have photos of what appears to be fog, but not on Gale crater, unless I miss those.
QuoteThe problem is in ignoring that the haze remains throughout the day, until sunset (we don't have night photos to show if the haze is still there).
do you have accumulated evidence to say that for certain ? ide like to see a full day sequence to know that for certain. you say theres no night photos *Dark chuckling* , but then there isn't a set of photos that show a full day cycle. unless you have seen such a set?
funbox
I saw a full day sequence from (I think) the NavCams some months ago, but I don't remember if it showed a wide area or just an area close to the rover, I have to look for it.
For now, the closest I can get to that is this:
Taken at 11:53 AM (Mars local time)
(http://mars.jpl.nasa.gov/msl-raw-images/msss/01246/mcam/1246ML0058150000504017E01_DXXX.jpg)(http://mars.jpl.nasa.gov/msl-raw-images/msss/01246/mcam/1246MR0058150000603637E01_DXXX.jpg)
Taken at 04:53 PM (Mars local time)
(http://mars.jpl.nasa.gov/msl-raw-images/msss/01246/mcam/1246ML0058220000504024E01_DXXX.jpg)
(http://mars.jpl.nasa.gov/msl-raw-images/msss/01246/mcam/1246MR0058220000603650E01_DXXX.jpg)
PS: a correction regarding night photos, we do have night photos, but they are either from the sky (showing stars or Mars natural satellites) or from MAHLI, usually showing a small area of the ground illuminated by the camera's LEDs.
did you white balance the pictures beforehand?
there's no point in relying on Rawjpg's there's no color truth in them until true white is identified
but asides the obvious colour nonsense , ill wait until ive seen the full set .. do you remember if they kept the same framed shot for all the sequences?
funbox
Quote from: funbox on February 14, 2016, 03:13:55 PM
did you white balance the pictures beforehand?
No, if you look at the source you can see they are on NASA's site.
Quotethere's no point in relying on Rawjpg's there's no color truth in them until true white is identified
You can always wait for the radiometrically corrected versions posted on the PDS.
Quotebut asides the obvious colour nonsense , ill wait until ive seen the full set .. do you remember if they kept the same framed shot for all the sequences?
From what I remember it was always the same scene.