Question Ground "cooling"??

Discussion in 'Alpine & Snow' started by AJS, May 1, 2016.

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  1. AJS

    AJS One of Us

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    Hi all,

    I know this has no doubt been covered somewhere already* but to me I always thought "ground cooling" pre-season snows made sense. Thanks to all the excellent weather chat on here I now know that's not correct however my partner is not so sure and in trying to explain that a pre-season snow would not "cool the ground" I looked for the scientific evidence/explanation online I came up blank. Would anyone mind sharing their thoughts? Would really love to get a better understanding.

    Cheers!

    *I haven't been able to find a discussion about this using the mobile page however if it has been discussed and someone could point me in the right direction I'd be happy to delete this thread
     
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  2. benchives

    benchives Part of the Furniture Ski Pass: Gold

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    Popcorn worthy term along with bumper season
     
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  3. Majikthise

    Majikthise Sage Moderator Ski Pass: Gold

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    Number of issues..
    Snow actually insulates the ground,
    water is also a good conductor of heat
    Wet soil has greater thermal conductivity than dry soil... So the best ground cooler is probably a deep fall of cold dry snow on dry ground.
    But..we mostly don't have bare earth, we have grass and shrubbery which trap air.. So flattening that has advantages.. Heavy wet snow will do that better than dry snow..
    However #2 it really all depends on the follow up..and some argument can be made for the benefits of rain saturating but not eroding an early snow pack.
    However #3
    It all depends....
     
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  4. benchives

    benchives Part of the Furniture Ski Pass: Gold

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    Ha

    It's a feel good vibey term

    Way of saying snows coming but without monitoring the direction of crow flight paths in the Thredbo valley

    Also takes the edge off when it's rains and you are expecting snow, so hence its overuse
     
  5. DidSurfNowSki

    DidSurfNowSki One of them Ski Pass: Gold

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    It's mostly this.

    The soil and rocks in our ski fields are mostly dark and absorb the Aussie heat really well. The best ground cooler is 2m of snow.
     
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  6. Kletterer

    Kletterer Thredbo Doughnut Tragic Moderator Ski Pass: Gold

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    Frost is what you are looking for pre snowfall
     
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  7. telecrag

    telecrag Old n' Crusty Ski Pass: Gold

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    I like pre snow snow, followed by snow!

    If ground cooling was a big thing, run some refrigeration under the groomer runs! Extend the season!
     
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  8. ladycamper

    ladycamper One of Us

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    At times in the autumn I've seen small puddles among high alpine grasslands that are frozen on top for morning or much of the day.
     
  9. Kletterer

    Kletterer Thredbo Doughnut Tragic Moderator Ski Pass: Gold

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    Done plenty of summer/ autumn seasons working at Hotham and Falls Ck. There is no formula for best lead up scenario. You never know what to expect and the best you can hope for is what telecrag mentioned above.
     
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  10. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    This plus biotic activity in a lot of Alpine soils keeps the ground warm under snow.
     
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  11. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    This. As @Majikthise said, rain and snow don't do much to cool the ground. A series of heavy frosts with low day time temps will freeze the ground solid for up to 10cm in Aus. If snow falls while the ground is frozen by frost it can stay frozen all winter.
     
  12. cin

    cin Old n' Crusty Ski Pass: Gold

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    Correct me if I'm wrong, but cold weather at this time of the year is beneficial mainly for cooling the dams that provide the water for snow making. And a day of snow is nowhere near as good as a week or two of nice cool temps.
     
  13. bengarden

    bengarden One of Us Ski Pass: Silver

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    What you want is consistent cold temps i.e. not what we see lots of in OZ. As Cin says above consistent cold temps for weeks is better than a quick front that comes through which dumps snow before temps bounce back above freezing. It's way too warm in OZ at present for any ground cooling to really take effect although the temp is forecast to get below freezing tonight @ Perisher ( its 2 degrees at 6pm presently )
     
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  14. Astro66

    Astro66 Still looking for a park in Thredbo Ski Pass: Gold

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    I've read where structures are built on permafrost. Good ventilation keeps the ground frozen so structures don't subside.

    Also moisture and wind creates an evaporative effect.
     
  15. Normo

    Normo Mostly Harmless Ski Pass: Gold

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    THIS is "Ground Cooling"...............:)

     
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  16. currawong

    currawong Old but not so Crusty Ski Pass: Gold

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    Ground cooling or not, it was good to see some snow falling at Falls today. Mostly it was sago but there were some big flakes.
     
  17. benchives

    benchives Part of the Furniture Ski Pass: Gold

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    Last winter was a good example of a long consistent cold period iirc
     
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  18. DidSurfNowSki

    DidSurfNowSki One of them Ski Pass: Gold

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    Did you borrow Astro's skis ? They look a little yellow and smallish.
     
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  19. Normo

    Normo Mostly Harmless Ski Pass: Gold

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    They were hiries. A bit like me....bigger in the backside! :D
     
  20. Donza

    Donza Pool Room

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    Nah this is incorrect..
    But.. I'm on my phone.
    Ground will never freeze solid. It has too much thermal mass.
    Best thing to lower the temp of the ground by a massive .3 degrees is cloudy weather
     
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  21. Astro66

    Astro66 Still looking for a park in Thredbo Ski Pass: Gold

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    Stay on topic. I have girly black skis now. :p
     
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  22. Egbert

    Egbert One of Us

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    Won't do much for Perisher though.
     
  23. Marty_McSly

    Marty_McSly Staying the **** at home. Ski Pass: Gold

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    Looks flat :D
     
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  24. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Can you define ground and solid? Without more info my personal observations when measuring soil temperature during my Honours near Perisher, discussion with the only scientists who work in alpine ecology in Australia, the literature review I did and the well documented solifluction in the Australian Alps is really hard to reconcile with your assertion.
     
  25. TomGroggon

    TomGroggon One of Us

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    The best ground cooler is snowmaking it will power up in a few weeks
     
  26. DidSurfNowSki

    DidSurfNowSki One of them Ski Pass: Gold

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    Post-doctorate thesis fully peer reviewed and published for all to see else it didn't happen :p
     
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  27. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Fund me and I'll do it!
     
  28. Vermillion

    Vermillion Pool Room Ski Pass: Gold

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    If you've ever tried to make snow over different surfaces you'll notice that making it over straw grass get the best 'stick' and the most snow build up from a 0 base. Plenty of times i've made snow on 10-15cms tall grass with a concrete path next to it, and i'll have snow sticking and accumulating on the grass hours before it starts on the concrete. This is the same with gravel and bare earth too, grass wins out all the time with its ability to cool down overnight.

    It takes an enormous amount of cold to cool down a solid earth layer, just like a concrete slab. In AUS it's not often you have days and days of negative temps to get that layer frozen. I've found, if you can get shade on to a slope, you significantly increase the coolness of that slope. That's one of the reasons why the south side of hills gets snow to stick earlier than the northside (in most cases). The best conditions i've found are the shade, plus cool days with a frost overnight, and if you can get an overcast day or 2 then that's a bonus.

    IMO in AUS because we dont really have the conditions to create a permafrost layer, I reckon a couple of days of the above-mentioned conditions are generally as good as you're going to get for a base-builder, so that's what i'd be looking for.
     
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  29. Vermillion

    Vermillion Pool Room Ski Pass: Gold

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    Typical academic with their hands out looking for a cash-grab :p
     
  30. climberman

    climberman CloudRide1000 Legend Ski Pass: Gold

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    C'mon, I came close!
     
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  31. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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  32. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Where were you making snow?
     
  33. Snow Blowey

    Snow Blowey Old n' Crusty Ski Pass: Gold

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    Can confirm i have encountered frozen solid soil in the aussie mountains. Trying to dig out a marooned 4wd at the time.
     
  34. Ubiquitous Steve

    Ubiquitous Steve A Local Ski Pass: Gold

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    note...... gale warning out for Vic Alps for Tues damaging winds gusting to 110km/hour...

    should be a bit of a windchill factor for sure.....o_O
     
  35. sbm

    sbm One of Us

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    I remember reading an avalanche bulletin for Colorado in the US, where they got a big dump on top of bare ground early in the season. The snow has an insulating effect, and they were predicting that the heat in the ground trapped under the snow, combined with the cold air temperatures behind the storm front, would lead to a very strong temperature gradient across the snow, and lead to a rapidly forming depth hoar layer (hoar frost that forms next to the ground underneath the snow, an infamous, invisible and deadly avalanche problem).

    I believe the ground does hold some heat, but cold clear nights would probably cool it faster than wet snow, by allowing it to radiate away.

    (Interestingly, snow is such an efficient radiator of heat, that it will refreeze better on clear and cloudless spring night with above-freezing temperatures, then on a cloudy night with freezing temperatures!)
     
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  36. DidSurfNowSki

    DidSurfNowSki One of them Ski Pass: Gold

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    Another interesting fact about water is that it is its most dense at 4C, ie above freezing. This means that icebergs float rather than sink. Most solids are generally heavier than a substance's liquid form. Life on this planet would be very, very different if the bottom of our oceans were covered in ice.
     
  37. telecrag

    telecrag Old n' Crusty Ski Pass: Gold

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    The real trick with ground cooling, is to get it deep enough to freeze the earth's core, only then can we really begin to accumulate snow. I suggest injecting liquid nitrogen into any mine shaft deeper than open cut, but fill those too just in case, and all the oil rigs can wack it down the drill.

    Go winter!
     
  38. Marty_McSly

    Marty_McSly Staying the **** at home. Ski Pass: Gold

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    Sounds like fracking to me.
    :out:
     
  39. iagreewithhim

    iagreewithhim One of Us Ski Pass: Silver

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    Life wouldn't exist on our planet. Ice would form at the surface of the ocean (near the poles) and then sink to the bottom, where it would never thaw. Every year the amount of ice would increase until every ocean was frozen solid, except perhaps for a little skin of liquid water on the surface near the equator in summer. Life on Earth depends on liquid water. Without it, life would never have evolved.

    More importantly, if water didn't expand when it froze, you couldn't ski on it!