h a l f b a k e r yOn the one hand, true. On the other hand, bollocks.
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Prevent snow avalanches by beaming microwaves of an optimal wavelength at suspected, unstable snow. The energy and wavelength of the beam are chosen so that:
(a) It is absorbed by the snow well enough to melt the surface of the crystals so they will cling together when the beam is removed, then
rapidly refreeze into a solid mass.
(b) Enough will be absorbed by the rock and soil just beneath it so that a thin zone of molten snow is formed which will freeze, creating a solid bond when the beam is removed.
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I believe that each foot of snow would absorb the same percentage of however much energy reached it. So if the first foot absorbed half of the energy, then the second foot would absorb half of the remainder and so on...
The exact amount absorbed per foot would depend partly on the wavelength used. If a wavelength could be found that had the ideal absorbtion rate by the snow while being much more easily absorbed by the soil beneath, then it should warm the snow just enough to fuse the crystals together and also melt enough near the soil's surface to form a strong bond between the snow and soil when they refreeze. |
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My understanding of avalanches is that they occur due to a boundary layer between two different layers of snow rather than from the ground itself. Perhaps if this could "homogenize" the snow layers that would be enough rather than melt it then refreeze it together. |
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Not sure if this idea would work or not. |
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Won't ice crystals just refract or reflect microwaves? |
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AusCan531,
That would be better, but I don't know how one could limit its effect to a boundary, so the only alternative is to affect all of it.
2 fries shy of a happy meal,
Word on the web suggests that ice doesn't absorb the wavelength from microwave ovens very well, so maybe infrared or some other wavelength would be needed. |
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Just a minor point, but I hope you have a large supply of disposable beam operators. Since the thin molten layer at the base might be great once it re-freezes, but when it's actually molten, you are going to trigger the avalanches instead of preventing them. |
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Also, just out of curiousity, have you checked the energy consumption for doing this on every mountain in the world? |
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MechE,
The idea is not to completely melt even a single ice crystal, but just a surface layer. Van der Waals forces should then hold them all together well enough until they can freeze into a solid mass.
And also, these operations would always be done cautiously from the greatest practical distances. |
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There are many different varieties of snow, with crystal sizes and shapes of all sizes (old-style cross-country skiers had to know them). A wave that affected one kind of snow and not another MIGHT be possible. But you probably would have to send somebody up the mountain to dig through the snow to see what was present at the boundary layer. |
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As for the problem of causing the avalanche while melting the snow, I'd use a tight beam instead of irradiating the entire slope all to once. You'd need a pattern, and controls, and more time, but you'd use less energy per second. |
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If you can partially melt & re-freeze big slabs of the surface snow, those slabs tend to surf down the front of the avalanche and become very destructive. |
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If you can partially melt & refreeze the snow down at the basal layer, thus developing the big crystals - the macro-scale density isn't changing, therefore melting smaller crystals and getting larger globs of water frozen together also means there will be larger air spaces. This weakens the overall structure of the base of the snow, and is one of the common triggers of avalanche. |
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Perhaps you could fly over the snowfield, and shine very hot very short laser pulses down onto the snow. Each pulse would melt a very slender tubular cavity down to the ground through the snow. This cavity would, because it is so thin, almost instantly refreeze. If you did a whole series they would be like nails or pins holding the proto-avalanche in position. |
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[Alvin], just out of curiousity, and with no slight intended:
do you get much snow where you live? |
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I'm convinced this would work, in the same way I'm convinced that we could prevent snow with microwaves. On the other hand the moment we abandon the tremendous effort to turn massive snowbanks into ice we may suffer some unintended consequences, specifically, huge and horrible avalanches. |
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// I'd use a tight beam // |
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A maser can deliver that sort of functionality, but the power demands are enormous. |
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Snow has a density of about 0.1; therefore each cubic metre of snow has a mass of about 100 kg. Now, the specific enthalpy of fusion of water is 333.55 kJ/kg at 0 °C - and your snow is in all probability going to be colder than that. |
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To melt your 100kg of ice will require 33 MJ of energy. Let's say you're prepared to wait one minute; so your power delivery needs to be 550 kW for the area under treatment. |
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For a patch of snowfield 100m x 100m, That's 5.5 GW of power, so you're looking at substantial nuclear plant, otherwise the Anti-Carbon lobby will come and beat you to death with their pamphlets (printed on recycled paper with organic ink). |
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We recommend that you site the reactor building in an area not prone to avalanches ... |
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baconbrain,
The idea of melting vertical columns of snow in a pattern would dramatically improve the method.
pocmloc,
Your idea sounds much like baconbrain's --- a very good one.
Alterother,
//... do you get much snow where you live?//
No, not enough for an avalanche anyway. |
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You could do [pocmloc]'s idea of melting pillars into the snow another two ways. Fire lightning bolts into the snow to make fulgurites, or shoot really fast meteors through the snow ... no, they'd hit the underlying rock and blow craters. |
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My idea above wasn't to melt pillars, it was only to melt parts of the snow at a time, but gradually get to it all, making a uniform coverage. The columns credit goes to [pocmloc]. |
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I was just asking because, while we don't get many or very
large avalanches here, we get a helluva lot of snow, and
folks from warmer climates often don't realize how many
different kinds if snow there can be and the complexity of
the winter climates; avalanches are very complicated
things. |
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Here in Canada we have slednecks to go up and bring the avvies down for us. |
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Avalanches in the Northeast US are more of a curiosity
than a hazard, because our mountains are a different
general shape. There are a few bluffs around my area that
spawn betting pools every winter, though, so those of us
involved with outdoor safety and rescue have gone through
the basic avalanche training. |
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