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What happens to ice as the temperature falls further and further?

  1. Jun 5, 2013 #1
    Are there changes in the appearance and characteristics of ice as the temperature continues to fall? Say at -30 C, -60 C, etc? Does it remain slippery? Is there a point where it breaks up?
     
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  3. Jun 5, 2013 #2

    SteamKing

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    Ice is slippery only because applying pressure temporarily causes the surface to re-liquefy.

    AFAIK, there is no great change in appearance of ice as temperature drops.
     
  4. Jun 5, 2013 #3
    At atmospheric pressure, there are three forms of ice that may appear as temperature is lowered:

    http://www.lsbu.ac.uk/water/phase.html

    Ice 1h -> Ice 1c -> Ice 11

    Exactly what happens depends on how the process is carried out.

    At very high pressures, many forms of ice can appear on the cooling curve. The above site is a great resource that will tell you all you need to know about water and ice.
     
  5. Jun 5, 2013 #4

    D H

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    That's an old meme that is simply wrong. It's in lots of textbooks, it's taught in schools, but it's wrong. The temperature at which the water/ice transition occurs does drop with increased pressure, but this effect is very small. The amount by which the heaviest of ice skaters putting all of their weight on one blade reduces the melting point is tiny.

    There are two main lines of thought about why ice is slippery. One is friction. The friction of a blade sliding over unmelted ice causes the ice to melt. That's not the leading idea, however.

    The dominant view is that ice is slippery because of boundary layer effects. The surface of ice has a thin boundary layer that acts a whole lot like liquid water. Pressure is not needed, nor is friction. This boundary layer is always there. It's observable with electron microscopes. The thickness of this boundary layer varies with temperature. It's but a molecule thick at very cold temperatures (~ -150 C). The layer is considerable thicker at temperatures near freezing. We can skate on ice because we're not skating on ice. We're instead sliding on a thin layer of water-like ice that is always present.
     
  6. Jun 6, 2013 #5
    But it has to do with pressure I guess even speaking about the layers , because imagine a heavy iron block that is mounted on four needles would you be able to move it on ice ? No because the weight would put so much pressure on such a tiny area that the needles would have a huge grip.
    Now make those needles or whatever with a slightly bigger surface contact area and slowsly you reach a point were you can just slide on ice.

    I guess it still has to do with the force you put upon a given area to see if something slides on a surface of ice or not.
     
  7. Jun 6, 2013 #6
    A heavy iron block on needles would not slide because the needles would probably penetrate the surface of the ice, and the resulting ice shelf would prevent the block’s movement. But this would be an easily seen effect, whereas friction usually refers to microscopic effects. If the “needles” were wide enough to not cause penetration of the surface, the block would likely easily slide around.
     
  8. Jun 6, 2013 #7
    That has nothing to do with the slipperiness of ice. All that shows is you can dig into the ice and get a grip on it because its not impermeable.
     
  9. Jun 6, 2013 #8
    You are correct to say that it is wrong, you are incorrect to state that 'it is taught in schools'
    What is taught in schools is that pressure has an effect on the melting point but this is very small.
    If you are going to make general statements about what is 'taught in schools' then you should back them up some how.
    I am one of those people who teach things in schools.
     
  10. Jun 6, 2013 #9

    D H

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  11. Jun 6, 2013 #10

    berkeman

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    Very interesting, I did not know that! Thanks D H.
     
  12. Jun 8, 2013 #11
    Which is one of the reasons why we can actually skate on ice.
    The sharp knife edge of the skate will penetrate the several molecule thick layer of liquid water to obtain a grip on the solid ice. With a dull skate blade, the person will not have as much control over his/her movements as the blade will slip and slide more over the surface. Figure skaters and hockey players ( and anyone else for that matter putting on a pair of skates ) necessarily keep their skates sharpened. At competition level, sharpening is done during a game or between events.
     
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