Planet Four Talk

Two sets of fans

  • ElisabethB by ElisabethB

    I see two different sets of fans here.
    Two (or three) big brown fans and a number of faint darker and smaller fans almost perpendicular to the big ones

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  • wassock by wassock moderator

    If you look at a wider angle it looks like there are three sets of fans white, brown, and black

    enter image description here

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  • ElisabethB by ElisabethB

    Even better ! 😃
    Tx

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  • JellyMonster by JellyMonster

    I think there are only two, white and black. The brown looks to me that it is the red planets surface.

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  • p.titchin by p.titchin

    I've always taken this appearance as the underlying surface showing through

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  • mschwamb by mschwamb scientist, translator

    An interesting image. Also strikingly beautiful as well with the white and dark fans.

    Cheers,
    ~Meg

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  • CJ-DPI by CJ-DPI scientist

    This is a nice example of all the different sorts of activity we see in the spring! At first we get dark fans, then those particles start to sink into the ice and we get low contrast, sometimes grayish fans. At a very specific time - and we are hoping to sort this out with your help - the conditions are just right for bright fans to form. It is CO2 released from the vent, that condenses into frost and gets deposited on the surface. Just like dust particles the frost particles get blown downwind into the fan-shape.

    Candy

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  • wassock by wassock moderator in response to CJ-DPI's comment.

    Candy at risk of being pedantic can you clarify what you mean by "frost"?

    I would classify frost as a solid which is formed by deposition direct from the gas phase onto a surface. At home we'd be talking about the surface of grass blades, on Mars maybe the particles making up the fans. When solid co2 is formed as the gas exits a vent deposition will be into a solid suspended in the gas around each individual particle. These particles will then fall to Mars as "snow". This gives two mechanisms for providing a fresh covering of CO2 each of which will likely have different properties. True frost will form comparitively slowly and is morelikely to be crystalline whereas snow will from rapidly giving something more like a powder. If that holds then each will have different reflective patterns. And where they form may be different' something like frost only forms on an existing particulate fan but snow will go wherever the wind takes it.

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  • Portyankina by Portyankina scientist

    Hi!

    I think, Candy rather meant snow in her comment, but we often use frost for both snow and real frost - some fresh ice crystals either condensed in the atmosphere and settled down or directly condensed onto the ground...

    Anya

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

    Anyway, kinda figured that but my feeling is that it should be important to maintain the distinction as the 2 processes will produce ice with different properties and are fundamentally different processes which already have fixed meanings in peoples minds - frost just appears, as if by magic, on the ground and snow drops out of the sky. So if you say that the highlights on a fan are fresh frost I've already made an assumption about how it got there.

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  • Kitharode by Kitharode moderator

    Wassock makes a very good point there. I too had assumed that frost and snow were very different to each other.

    Thanks to all for keeping in touch.

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