Planet Four Talk

Predawn Warming

  • wassock by wassock moderator

    Drying the glasses behind the bar (as I do a lot at the mo') gives one pause for reflection. So was musing on why it seems to be the case that there are already fans/blotches in situ when the sun get's high enough to take a picture, and thus they are forming before the sun shines upon them.

    So, seeing as how the ice is apparently very clear, would that mean that when the sun is below the horizon at a given spot but above it at the edge of the ice sheet the the sun would shine along the inside of the sheet potentially heating bits up at a distance where sunrise hasn't happened yet. I'm kinda visualising some sort of pancake fibre optic effect with the light somehow bouncing around within the ice layer.
    Just a thought, which may already be counted as part of the process, have to go, couple of cappuccinos to make. Back proper come September.

    Posted

  • mschwamb by mschwamb scientist, translator in response to wassock's comment.

    Hi Wassock,

    A great question. Here's some of my thoughts to spur discussion.

    Something like that might be happening with the spider channels. As you might have seen, there are fans that seen to originate over spider channels (though not all fans are associated with spiders channels), so it might be reflection of the side's or heating on the sides of the channel that let that area warm up more and enable the geysers to form.

    Also even if some of the earliest images of the South Pole there are sometimes fans according to what the PI of Planet Four, Candy Hansen has said during some discussions, so I think something like is happening the higher areas are receiving light where the lower elevation areas aren't.

    Cheers,

    ~Meg

    Posted

  • wassock by wassock moderator

    Thing is that if that were the case (elevation/light on the sides) then the boulders on the ridges in Inca City should be stiff with fans

    Posted

  • mschwamb by mschwamb scientist, translator in response to wassock's comment.

    It might be something with intensity, so how much light you get in a small area, since spider channels are small, but I'm not sure. I asked someone on the team who knows more about spiders and this process to reply if they get a chance.

    Cheers,

    ~Meg

    Posted

  • Portyankina by Portyankina scientist

    Hi!

    It is indeed like that! "pancake fibre optic effect" 😃

    The sun is grazing the horizon - this is what the sun does in polar areas in the beginning of spring: stays just about at the horizon height for quite some time. This gives the little bumps and holes a lot of solar energy on their sides comparing to all other surfaces. So, if the temperatures reach CO2 sublimation values, it will create lots of stress in the ice sheet, just because of the differences between shadowed and sunlit parts. I did a calculation for little trenches (like the spider arms ), and the stress comes out to be enough to break the ice (given that CO2 ice is not harder than water ice). But we do not know all the details yet, like correct elevations on the surface, top surface heat capacity or even its albedo - is there some water ice in it?, etc.. And this means the timing of the whole thing might not fit.

    For the IC boulders: they are even more complicated case, as they are on slopes. SO, we are thinking right now that they might not get enough thickness of ice during deposition time to at all contain any pressure that would be enough for eruption/outgassing. But I did not do such calculations yet.

    Anya

    Posted

  • pete-j by pete-j

    Fascinating discussion! I am sure models could include the many variables to take this into account; as mentioned above: elevation angle, ice composition mix (pure CO2 or not -- which should affect the sublimation rate) and the albedo.

    Pete J.

    Posted

  • mschwamb by mschwamb scientist, translator in response to pete-j's comment.

    Hi Pete,

    That definitely is something that might be possible in the future when we've got some catalogs from combining the collective markings. The data set you're creating is the first of its kind of these images.

    Cheers,

    ~Meg

    Posted