Category: General
Posted by: admin
karma: 31 [+/-] -
[Edited for clarity with no change to content on Sept 19, 2021. This first appeared on avalanche-blog.org which has since been transferred to a new site. It has been reposted here and has a courtesy link from that new site.]

The alpha angle is the angle from the end of the runout to the top of the starting zone. For a brief definition including a diagram you can see the avalanche center glossary:

Avalanche Center -> Education Center -> Glossary -> Alpha Angle

Alpha angles (used to measure runout distance) do NOT depend on climatology. Whether a mountain range is maritime or continental (or something else) does not make much difference. Despite what may have found its way into the popular literature. What is important isn't entirely clear, but it's not climate. Every mountain range seems to offer its own behavior regarding maximum runout potentials, and each range must be analyzed separately.

» Read More

Category: General
Posted by: admin
karma: 5 [+/-] -
The promotion of this "test" as something useful in decision making in the field has bothered me for quite a while. Here is the short version of my concerns, as well as a suggestion for what to ask anyone promoting this.

[[ Note: This is being reposted on this blog in December 2014, about 7 years after it first appeared on a blog that has been discontinued. I have not followed the technical literature over this period very closely and more work has been done. However, my fundamental concerns remain. Especially for use outside a large data collection operation. (I have reservations about what I consider an over reliance on stability tests in general outside of such programs.) At the end I have added a few comments as of reposting this at the end of 2014. ]]

» Read More

Category: General
Posted by: admin
karma: 8 [+/-] -
Slabs of snow are continuous bodies, and are subject to deformation and the development of internal stresses for that reason. Loose snow without any cohesion does not form a continuous body and its behavior is that of a collection of unconnected grains. Comments in at least one public advisory show a lack of understanding of the fundamental differences.

» Read More

Category: General
Posted by: admin
karma: 18 [+/-] -
For years the figure of 1 C per 10 cm of depth has been called a "critical temperature gradient" and considered the gradient in the snowpack at which faceting of the grains begins. In a recent forum topic the original question was what is most important for faceting and of course this number was presented right away.

What is actually important is the vapor pressure gradient. Depending on the temperature the gradient may need to be much larger than this "critical value" before faceting actually begins to occur.

» Read More

Category: General
Posted by: admin
karma: 6 [+/-] -
(First posted on Avalanche-Blog.com, the original date has been kept and only a few small changes have been made.)

Summer is the time when I can try to read a few things, avalanche related and not. I usually purchase various new and archival publications to add to the library. Among my recent purchases is "Secrets of the Snow - Visual Clues to Avalanche and Ski Conditions" by Ed LaChapelle.

» Read More