Planet Four Talk

Cross shaped

  • ElisabethB by ElisabethB

    And some more of these 'any way the wind blows' ones ! 😉

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  • wassock by wassock moderator

    Now I'm seeing stars. Nice one

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  • ElisabethB by ElisabethB

    Merry Christmas ! 😉

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  • Kitharode by Kitharode moderator in response to ElisabethB's comment.

    You're certainly helping me build my 'Wind Direction Indicators' collection. Cheers. 😉

    I'm betting that even a first approximation map of the wind on Mars is going to be really interesting. There's bound to be a surprise or two and I see some really interesting questions being raised. Can't wait.

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  • ElisabethB by ElisabethB

    These ones are really interesting !
    Good luck with the collection !
    Here's to finding lots more ! 😃

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  • Kitharode by Kitharode moderator

    So the question arises; Does the wind change direction instantly to form fans in different directions, or do the vents stop venting and begin again later when the the wind has changed? Single 'straight' fans seem easy enough, single 'wide' fans suggest a single venting in a slowly changing wind(ish). But distinct multi-directional fans seem to me to be a special case.

    I'm trying to pull together some data in support of a 'working hypothesis' that vents (in some areas) open and close because of changes in temperature during day and night. It seems plausible at least that as the sun rises and sets so the temperature will vary, but I'm aware that plausible is not the same as possible or probable.

    But that's the beauty of citizen science methinks. Chuck it in the mix and see what drops out. One never knows .. * 😛 *

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  • Kitharode by Kitharode moderator

    Talking of stars - Pleiades ?? http://planetfour.org/subjects/standard/50e748c65e2ed211dc004a5d.jpg

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  • wassock by wassock moderator

    My interest in these in the apparent consistency of the relative sizes of the individual fans in each group. You could zoom the small ones to get a match with a bigger one. If the wind speed for each event is constant for each vent the n the relative size of the eruption at each vent must stay the same for each eruption. So the big one ALWAYS ejects twice as much as the one half its size

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  • Kitharode by Kitharode moderator

    By relative sizes, and zooming small into large, are you saying that the ratio of length-width appears to be the same in each fan from the same vent? If so, I follow your thinking and it is indeed interesting.

    Different, but related I think, I've noticed lately that densely packed fan fields have small fans, with bigger/longer fans being more widely spaced. In some ways this is an obvious statement, but it makes me wonder about the minimum size required to create a pocket of co2 gas which can vent, as well as how it is that so many fans can form all at once.

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  • wassock by wassock moderator

    No that's not quite it Kith. Most of the fans are the same shape Ishmael, they are like little clones of oneanother. The size of each fan is related to how much is vented and the wind speed at the time. Because,for and individual ray the wind must be the same for all the vents, the different size fans are down to the rate of production at each fan. If the relative proportions of the different fans are the same for every vent the already must be a common feature governing how much comes out of each. One way of doing that would be to have them all drawing from the same gas reservoir.

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  • wassock by wassock moderator

    A packed field of by fans would be just a big blotch as they all would overlap. Smallest size? I've seen a few tiny but perfectly formed ones

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  • Kitharode by Kitharode moderator

    Yes, clones of each other. Now I see what you're saying. Same 'shape', same directions, but different sizes. Same wind speed for each event is a safe assumption I think, therefore your 'different amounts' idea rings true.

    When you say "all drawing from the same gas reservoir" do you mean each vent draws from its own reservoir for its multiple fans, or are you suggesting that all the vents are drawing from one huge reservoir? I'm assuming the former.

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  • wassock by wassock moderator

    Simplest way is that the whole of the underneath is connected so that each vent gets a share of all the gas available according to basicly how big its hole is. Course you then need a mechanism to start and stop. Alterntly if each vent calls upon a fixed area of ice and there's a simple relation ship between amount of sun and area it shines on vs amount of gas produced then that would work to.

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  • Kitharode by Kitharode moderator

    Indeed. So what can be found to add weight to one or the other of these scenarios? I'm not sure.

    Do you see any value in the idea that day and night temperature changes could act as the stop/start mechanism?

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  • wassock by wassock moderator

    Think the idea that there's an eruption every day, or rather a slow oozing maybe, is easier to deal with rather than something which requires all those holes to seal and burst repeatedly. Once the loose dust is exhausted further emmisions whould be just gas - hence fans of frost/snow

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  • wassock by wassock moderator in response to Kitharode's comment.

    Do you have a clear picture of how day and night work at the poles. I'm working on the same principle as for our poles - in winter it's dark all the time in summer the sun's up all the time and a gradual transition between the 2 - how long is day/night at the mid point?

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  • ElisabethB by ElisabethB

    http://talk.planetfour.org/#/subjects/APF000148r
    multidirectional fans

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  • Kitharode by Kitharode moderator

    Wassock. You have it right. With the axial tilt of Mars being just about the same as Earth you can take polar night/day to work the same on both planets. Very roughly (complicated by the high eccentricity of Mars' orbit) there are two 'days' on Mars for each day on Earth, so other than that the onset of permanent day/night works the same.

    I'll bring this up with my astrofriends tonight if I get chance just to make sure I'm not missing anything significant. Diurnal variation of temperature is one of six possible scenarios mentioned in the literature for venting in one particular region at least (paper III in your email). I believe it has a part to play, but having said that I can't then understand why we don't get 'spiders by latitude', which I would have liked to see but apparently does not happen.

    ElizabethB. Good image. If you can make time, could you explain your procedure for inserting an image in a discussion. Here would be good. http://talk.planetfour.org/#/boards/BPF0000004/discussions/DPF0000d19 Many Thanks.

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  • ElisabethB by ElisabethB

    Here's how I did it :

    I'm using Chrome. So, I right click on the image and select "copy image url" and then I use the image icon (6th one from the left) and just past the image url. You can then insert some text (a name or so) and voila ! Hope this helps !

    And I posted this in the thread you mentioned

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  • Kitharode by Kitharode moderator

    ElizabethB. Many thanks for that. Still doesn't work, but appreciate your input. 😉

    Wassock. This is worth a look at for 'sun paths'; http://notesfromnoosphere.blogspot.co.uk/2012/05/simple-geometry-of-sun-paths.html

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