A is for Angle

~ Sunday 17th December 2017

A is for Angle, which most people agree is the single most important factor in identifying Avalanche terrain. But what Angle are we talking about? "Steep"! But not Jérémy Heitz "steep", not "Steep" the classic ski film, not the notorious "steep bit" off the 4-man chairlift - this is a particular "steep", defined in EAWS terminology as terrain over 30 degrees. De La Sole were wrong, 30 is the magic number (or maybe they were talking about something else?)

Simply put, most avalanches occur on terrain over about 30 degrees, so it makes sense to learn how to identify this Angle so we can do something about it. As well as some compasses, there are several gadgets on the market which accurately measure slope angle, and there's also an App for that - download a free inclinometer for your smartphone. However, I don't like gadgets and prefer to use stuff I always have with me when skiing - like ski sticks.

The technically-minded favour the right-angle triangle system, and use bits of tape on their ski sticks to measure slopes. With 1 vertical stick and one horizontal you can measure angles as long as you remembered your "O" level SOHCAHTOA and stuck the tape in the right place. It works with telescopic sticks too, as long as they're both the same length - you only put tape on the handle section or they won't telescope...

Now I started studying BSc Engineering but ended up with a French BA, so I prefer the simpler Equilateral Triangle system. You need 2 sticks the same length, and no tape - so it also works with borrowed or hired sticks.

Make a print directly in the fall line...this is one side of the triangle.

Plant one stick vertically in the bottom end of the print - hold the stick loosely by the handle and let it hang vertically, then plant it in the snow

Keep that stick vertical, put the other stick in the top end of the print and see if it joins the other. If it does, it's a 30 degree slope!

If it doesn't reach, it's less than 30. If it overlaps, it's more than 30.

Now, don't try this in committing terrain! Practise on small, safe slopes to get the hang of it and then train yourself to spot 30 degree slopes before you commit to them. Stop. Think. You are entering Avalanche Terrain. Is it safe? There's more to it than just Angle, but this is a crucial first step...

B is for...?

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