Pole Approximations: a quick look at the slope

Just finished reading a book on avalanches, Snow Sense,
and one point that was made a few times is, measure the slope!

So, I went out this past week and did so.

For those of you without your inclinometer (or those too lazy to dig it out)
I have come up with some approximations via some basic Trigonometry.

You can use your poles to measure the slope,
keeping 1 pole straight up, and the other horizontal (this makes them perpendicular).
Now then, where does the horizontal one meet the straight one???
(note: poles should not be plunged into the snow!)

This is the question that determines the slope.

Here are the answers:
If the horizontal one meets the straight one right on top, then it's 45 degrees.
Makes sense, right? It's a 1:1:root2 right triangle, or 45:45:90.

Here's how it breaks down, approximately:
1/1 ==> 45 degrees
3/4 ==> 37 degrees
2/3 ==> 33.5 degrees
1/2 ==> 26.5 degrees
less than that, get on the lift already!

And this deserves to be here.

Quote:

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Originally Posted by upallnight

Good info for rough approximations.

Note: For those who find themselves on some steeper terrain, you can also use this method for slopes > 45 degrees.

If the vertical pole intersects the horizontal pole at approximately...
...the 3/4-point of the horizontal pole ==> 53 degrees
...the 2/3-point of the horizontal pole ==> 56.5 degrees
...the mid-point of the horizontal pole ==> 63.5 degrees (yikes!)

It's pretty easy to get the vertical pole plumb (just dangle the pole by its strap); getting the horizontal pole level is tougher.

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Just thought I'd share that, because it was bugging me.

It might be a good idea to mark your poles at those designations,
because the eye can lie. Nothing some duct tape can't handle.

As for keeping the poles straight up/vertical, and horizontal/flat, bring a level (torpedo).;)

I use this method once in awhile. It gives a good, quick approx for route finding on the way up.

The ski pole method is a "passable" method for getting your slope angle for where your standing. Which means your already standing on the "trapdoor" of the potental avalanche slope. Its better to use your inclinometer to measure a slope from a nice safe location, before you go out on to the slope. The other thing about using the ski pole method is that your only getting a very short meassurment sample of the slope.

I highly recommend practicing with your inclinometer even during the summer, so that you can "train your eyes," to recognize avalanche slope angles. Go out an measure your house roof for a start.:wink:

Cheers,
Halsted Morris
CAIC

Quote:

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Originally Posted by TeleAl

Here's how it breaks down, approximately:
1/1 ==> 45 degrees
3/4 ==> 37 degrees
2/3 ==> 33.5 degrees
1/2 ==> 26.5 degrees
less than that, get on the lift already!

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Good info for rough approximations.

Note: For those who find themselves on some steeper terrain, you can also use this method for slopes > 45 degrees.

If the vertical pole intersects the horizontal pole at approximately...
...the 3/4-point of the horizontal pole ==> 53 degrees
...the 2/3-point of the horizontal pole ==> 56.5 degrees
...the mid-point of the horizontal pole ==> 63.5 degrees (yikes!)

It's pretty easy to get the vertical pole plumb (just dangle the pole by its strap); getting the horizontal pole level is tougher.

Quote:

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Originally Posted by Hacksaw

I highly recommend practicing with your inclinometer even during the summer, so that you can "train your eyes," to recognize avalanche slope angles.
Cheers,
Halsted Morris
CAIC

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Exactly why I was doing this with my poles, to train my eyes.

Quote:

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Originally Posted by upallnight

...the mid-point of the horizontal pole ==> 63.5 degrees (yikes!)

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Does snow stick to slopes that steep?

Quote:

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Originally Posted by TeleAl

Does snow stick to slopes that steep?

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Sometimes - on rare occassions

http://www.leelau.net/2006/Chiefpasc...ascallSkin.jpg

Central couloir in this picture is 65 degrees apparently. Coast mountain snow is very sticky and has high water content. I know Andrew McLeans "Chuting Gallery" describes some 60+ degree slopes

Quote:

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Originally Posted by TeleAl

Does snow stick to slopes that steep?

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Ah....maritime snowpacks....yum! Steep mountains (AK ranges; Coastal range) + snow that actually bonds to anything... Mmmm mmmm mmmm.

Witness: The fingers @ Squaw and how fast they can go from being "cliffs" to skiable in 1 storm.

I've never been on anything great than about 61/62 (and that was for a short stretch), but I know folks who have been on up to 65-67...and I think I remember reading that Jeremy Jones made a few turns (yeah, we're talking skiing/riding not hucking) on 70-degree terrain. For anything over 60, the snow and everything else has to be just perfect.

60 felt like an elevator shaft to me...couldn't even fathom going another 5 degrees, much less 10 -- without my crampons and ax and fingernails.

Coincidentally, I am just now watching TGR's RE:Evolution of sports...and they just talked about how they are flying around Haines, AK looking for lines as steep as 65 degree.

Oh...they also showed a brief clip of someone talking and it lookd like they had a completely broken Rossi Squad.

They're all wearing AvaLungs.

Al, great advice in here.

I duct-taped up a pole last night and it was fun and quick to use on the Rond and Cold du Plan today.

Avy considerations aside, I was getting tired lately of having discussions like this:

Skier 1: Dude that slope was like 45 degrees.
Skier 2: Now way man it was like 50 at least!
Skier 3: Bolluks. No more than 40!

And practically speaking, when the book says "45 degrees" this will really help decide what that really means, I think.

Good tip too about the 45 degree+ thing with the second pole.