Joined: 07 Dec 2004 Posts: 2435 Location: Whistler, BC
Posted: Fri Jan 07, 2005 11:24 pm Post subject: Role of Static Charges in Windslab and Cornice Development
I recall reading on more than one occasion that static electrical charges are involved in attracting snow grains to snow grains during wind transport events that lead to windslab and cornice development. Unfortunately, I haven't been able to put my finger on any reliable sources to back this assertion.
Still, there is something going on that allows large fetches to be largely snow free in dry climates and yet fully formed cornices can be found on ridge tops. Anyone have some reasonable links or text references for this phenomena?
I can't answer your question, or point to any links that can, but Cesare posted to a thread before the crash that discussed wind tranport.. I've been watching wind transport remotely through Tundra Cam and wishing that the previous wind transport thread was still around. I don't recall any discussion of charge, but discussion of grain size and the amount of transport that happens very close to the snow surface.
I'm guessing that the subject line alone will bring out the deep-thinking snow science folks and you will get an answer, or at least a lot of good discussion.
Joined: 06 Dec 2004 Posts: 13193 Location: People's Republic
Posted: Sun Jan 09, 2005 2:48 am Post subject:
Thanks for the vote of confidence, Jenny. Unfortunately, I too must confess ignorance. My background in wind transport would seem to predate this research and I have not been up on recent developments for quite some years.
I had always thought that it was normal bonding that caused saltating (bouncing and rolling) crystals to become attached to the end of the horizontal surface at the break atop a ridge. As these begin to cantilever, gravity goes to work, deforming the layer until it reaches a vertical plane. Subsequent cantilevering and deformation will cause earlier layers to be pushed farther so that they curl back towards the wind direction. If you dig a trench through a cornice and spray the wall with food coloring, you can see these layer orientations quite clearly.
I did not know of any role of static charges in this. But it does sound plausible in that the length of the cantilever can be surprising. _________________ that sounds like a sure-fire way to get bitch-slapped by devil's club -- dschane
I found a study posted on [url=http://www.avalanche.org/~moonstone/issw%2094'/measurements%20of%20the%20electric%20field%20gradient%20in%20a%20blizzard.htm]www.avalanche.org[/url] that ties in what I recall from the before-the-crash thread and the disccusion of electrostatic charge. What I recall Cesare discussing was the high amount of snow that is transported within 10cm of the snow surface. The paper (from ISSW '94, by Schmidt & Dent) discusses testing done to measure charge within that same area and a finding that the charge was locally higher and "...can affect saltation trajectories by as much as 24%..."
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
All of the comments above are owned by the
poster, telemarktips.com is not responsible in any way for the
content. The views expressed by the posters are not necessarily
those of Tt.com, its management or owners. Ski safe, be happy,
rip it up, smile on your brother and sister!