1. Joined
    06 Mar '12
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    27 Dec '13 11:184 edits
    this research explains the mystery of why new snowflakes still continually form in snow clouds long after particles that act as nucleus to seed new snowflakes, specks of dust, should have been all purged out of the atmosphere, by assuming the existence of mysterious hidden atmospheric particles that have yet to be discovered that less efficiently act as snowflake nuclei and that persist for much longer in the snow clouds as a result:

    http://phys.org/news/2013-12-frozen-north.html

    But I cannot help wonder if they have completely overlooked a much simpler credible alternative hypothesis;
    with sufficient relative humidity, the snowflakes can be seeded without any nuclei at all i.e. seeded even in air that is infinitely pure and free of contaminants.
    Why not? This hypothesis should be testable in a lab to prove or disprove it so I don't see why it wouldn't be scientific.
  2. Germany
    Joined
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    27 Dec '13 11:39
    I haven't studied this particular topic very well, but I would presume they have a good reason to think you need impurities as a catalyst for snowflake formation. Impurities are at the heart of many physical phenomena, for example pure water is a very poor conductor of electricity. Without any kind of dust particles, the nucleation of solid water phases is very slow. There is a related simple experiment that you can perform at home (but don't try this at home). Take some distilled water, and put it in the microwave. With sufficient power, you can easily heat the water far beyond 100°C, since the formation of gas bubbles in pure water is a very slow process.

    YouTube
  3. Standard memberDeepThought
    Losing the Thread
    Cosmopolis
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    27 Dec '13 14:322 edits
    Originally posted by KazetNagorra
    I haven't studied this particular topic very well, but I would presume they have a good reason to think you need impurities as a catalyst for snowflake formation. Impurities are at the heart of many physical phenomena, for example pure water is a very poor conductor of electricity. Without any kind of dust particles, the nucleation of solid water phases ...[text shortened]... gas bubbles in pure water is a very slow process.

    http://www.youtube.com/watch?v=1_OXM4mr_i0
    Freezing experiments are relatively safe, and also possible at home if your freezer can manage a sufficiently low temperature: YouTube

    I'm skeptical about "new atmospheric particles", so there'd have to be no mixing of dust-free air (from above the cloud) and no shockwaves, which I'd imagine is unlikely as snow forming clouds are pretty turbulent. My comments come with an even stronger caveat than Kazet's as I know virtually nothing about atmospheric physics.
  4. Subscribersonhouse
    Fast and Curious
    slatington, pa, usa
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    27 Dec '13 15:332 edits
    Originally posted by humy
    this research explains the mystery of why new snowflakes still continually form in snow clouds long after particles that act as nucleus to seed new snowflakes, specks of dust, should have been all purged out of the atmosphere, by assuming the existence of mysterious hidden atmospheric particles that have yet to be discovered that less efficiently act as snowfla ...[text shortened]... hould be testable in a lab to prove or disprove it so I don't see why it wouldn't be scientific.
    Why does it have to be the inclusion of nucleation particles after it starts forming? You see crystallization in some substances where the particles themselves are the nucleation agent.

    http://en.wikipedia.org/wiki/Crystallization

    Hadn't studied this phenomenon much but that wiki seems to be a good start.

    I don't see why you couldn't do an experiment in a chamber where you have pure air, say 100% N2, then introduce a small amount of dust, where you know the mass of the dust and then the subsequent buildup of snow when you inject water at the right temperature and so forth. With X amount of dust, it will get used up leaving only N2 then you can see if nucleation continues unabated.

    I wonder if you can make snow with DI water? 100% H2O might take a larger amount of dust to start precipitating crystals. Just a guess.

    Looking at Mars photos where the atmosphere is something like 1 Torr or so seems to prevent the formation of snowflakes, presumably because the absolute mass density of water in the atmosphere is so much lower. You remember the pictures of one of the rovers where they found ice crystals on the legs of the machine and the ground under it. If I remember right, they were very small crystals. I would assume there would be plenty of material for nucleation on Mars since the atmosphere is so dusty but not much crystallization can happen there.
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