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Why does snow melt slower on ski runs than off-run snow?


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Anyone know what resorts do to keep the snow on the runs less likely to melt than surrounding non-resort snow? Do they put loads of chemicals on there or something? Kind of interested to know.

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I'm not sure but I was under the impression that they regularly put chemicals on the snow to keep it's condition as long as possible. Interesting question though, looking forward to some enlightenment on this from other people.

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It's just more densely compacted by all the traffic over it, and thus maintains a lower temperature for longer.

 

If you're a slob who doesn't clear snow from in front of your house, electing instead to step in the postman's footprints heading to your door, then those footprints will get compacted and remain there till spring when all the rest of the snow has melted. Don't ask me how I know that though.

 

No chemicals required.

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It could be the puff jacket symptom.

 

A puff jacket keeps you warm cause it lets air fill the channels that your natural body heat proceeds to warm up.

 

Same can be said for the unpacked snow I would guess. Full of air, sun heats the pack up, this in turn heats the air pockets up melting the snow.

 

With the packed snow, seeing what they do to that my guess is that they indvertenly, or advertenly, "burp" the runs, like you would a baby, every night preventing this from happening.

 

But, hey, what would I know, I am a humanities grad. wink.gif

 

[This message has been edited by mogski (edited 07 March 2002).]

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mogski, you obviously haven't burped a baby before. People, never run over a tot in a groomer or on a snowboard to get the gas out of it. You may do it a permanent injury.

 

Damn humanities grads, I dunno...

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[amateur science from politics graduate}

 

Could be a flawed assumption. Does gelende snow melt any slower? For starters, if you're going to build a resort, common sense dictates that you'd build it where there's lots of snow. Due to the nature of snow falls and other factors such as sheltering/winds etc., this can mean one side of the mountain and not another.

 

A good few resorts (inc. pow mecca Niseko) have large snowmachines to help them build up a base or in some cases just to stay in business. This of course means that there's even more "snow" on the runs. Presumably, the groomers can also push the snow around to help the coverage early/late season.

 

Gelende are also higher than the surrounding villages/towns. I think 1000m of altitude equates to a temperature drop of 6 degrees Centigrade, so if it's colder higher up, the snow's going to stick around longer than it does lower down.

 

As for skied on and unskied (yes!) snow at a similar location, I would have thought that the friction from the skis/board would warm up the snow, resulting in it melting faster. According to the blurb, the top of the range Burton boards (BMC, Dragon) use such friction to heat up and melt indium particles included in the base to make the boards faster. Whether there's anything in this is another thing altogether. rolleyes.gif

 

[/amateur science from politics graduate}

 

On the chemicals front, I think the cost of chemicals for a large resort would be prohibitive for all the courses. However, on a vid I saw guys at Mt Hood throwing handfulls of something on a half-pipe in what looked like summer. Anybody know what it is?

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yep, that stuff they were throwing on the

halfpipe was sodium nitrate (fertilizer).

Like many salts, it increases the

melting/freezing temp of the snow/water.

 

just don't get a facefull.

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Friction? I think I'll stick with the packing theory NoFakie.

 

Think about it - compared to the heat of the afternoon sun glaring down on a piste, the 'heat' generated by the friction of a board passing over a fraction of the slope - it's neglible. The heat caused by the friction of a board would only affect the very top layer of snow and would not lead to any significant melting of the total pack. That's why riders of the hi-tech Dragon boards don't leave a wet trail behind them like a slug - if Burton's blurb has any truth to it, it's a question of microns rather than even milimeters.

 

Friction is not part of the equation, but the combined weight of people and snowcats surely is. BTW, I've never seen groomers going and getting snow from elsewhere, have you?

 

More dubious theorizing, this time from an English grad.

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I think you've pretty much said it, Ocean11.

The rear implement on the grooming vehicle called the tiller acts much like an agricultural implement of the same name. The difference is that the grooming vehicle effect is to impart kinetic energy into the snow pack. The tilled snow first heats up as friction and pressure are imparted, then the idividual snow crystals sinter together and re-freeze. The desired result is a compact, durable corduroy surface every mountain manager and every powderfreak loves to hate. Because it is a denser snowpack than the natural, it doesn't melt or allow rain to percolate through and melt it as easily. Another factor on many Japanese slopes is that the snow is machine produced. These snow crystals are much more compact and spherical than their natural counterparts and so they create a more dense pack.

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Just when I was begining to enjoy all this back yard snow tech professional analysis frown.gif

 

[This message has been edited by mogski (edited 08 March 2002).]

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Essentially no chemicals. Fertilizing salts may be used but usually only on pipes and inruns etc. to harden them up. Blackcomb also salts the Horstmann glacier for racing camps etc. in the summer. It would be too costly and harmful to apply salts on large ski runs. An exception to this is the non-harmful bacteria(derived from vegetables) called Snomax that some North American/Euro and a very few Japanese resorts add to their snowmaking water supply. These harmless bacteria particles form a nuclei around which water can more efficiently freeze to create...yup, snow. Most natural snowflakes start out in the atmosphere in a similar manner, water bonds to any available atmospheric nuclei such as dust particles or pollution. Hey, maybe thats why ol' Nihon gets such major snow dumps.

 

P.S. Sorry Mogski.

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