Poster: A snowHead
|
I photographed this unusual snow surface at Vallorcine today. The facets were large up to an inch or more. They were soft to ski on. Are they-
true "faces planes" or surface hoar?
What are the implications when another layer of snow falls on top of this?
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
jbob, If you haven't already, watch the avalanche video here (or follow the snowheads thread )- this av. was caused by surface hoar, which looks like your pics, and forms a very dangerous, unstable layer when new snow falls on it.
A few phrases from the vid... "formed on cold, clear, calm nights" ...."essentially frozen dew"...."big feathery crystals"..."one of the most deadly weak layers"....
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
I have seen the fern like crystals, but these were different, they were square, and very big.
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
Looks very similar around schladming at the moment maybe 10 - 20 cm of these crystals, very nice to ski on, but worrying for the next dump of snow that lands on it.
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
Lets hope it warms up before the next snowfalls, so the facetting breaks down....or it rains
Otherwise could be a long term unstable layer buried.
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
Faceted snow is formed in the snow pack and caused by temperature gradients, the photograph shows a surface hoar which is something different. Buried that will become a depth hoar. Faceting will tend to occur where the temperature gradient in the snow pack exceeds 1'c per 10cm.
Faceting probably accounts for the majority of avalanche incidents I'd guess but davidof may have some real data. While depth hoar will probably run a close second.
|
|
|
|
|
|