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If you see this growing on the top of the snowpack, beware of the next big dump. It is a very weak layer that can cause Avalanches. This photo is from a hand railing. On the snow the crystal growths look more feathery and have more of a snowflake shape.
I saw a very nice example of "surface hoar" in the freezer at the local grocery store.
who says it never gets cold in the Sierra
nice pic. it certainly does stick around for a while. rain, sun and wind before the next dump are good ways to get rid of it. though, you still have to track the layer to see what aspects and elevations it has survived.
I'll play. This was after an exceptionally cold week north of whistler.
Frank - that's a wonderful picture. Such a clean fracture line and such a big cohesive block to slide on the line.
Sorry Lee - pit.
The layer was so good and the sun right we had to back dig it for the shot.
Wolf creek.
Frank....that looks crazy dangerous....you long did it take for things to settle?
Tom,Quote:
Originally Posted by FrankZappa
As a snow nerd I have always loved that photo. But, its a scary photo. It is the perfect example photo of Ian McCammon's 5 Lemons (a field method of identifying structual weakness in the snowpack). The lemons are:
1) A weak layer within 1 meter of the snow surface.
2) A weak layer thickness of less than 10 cm thinkness.
3) A hand hardness difference of greater than one step.
4) There is a difference in snow grain size of 1 mm or greater, between snow layers.
5) There are persistent snow gain types (depth hoar, near surface faceted crystals, buried surface hoar and mixed forms) present in the weak layer.
I see 4 out of 5 lemons (if I could do the hand hardness test, I'll bet there are 5 lemons present) in the photo.
Buried surface hoar has been know to last upwards of 6 weeks in the snowpack....
Cheers,
Halsted
Good stuff
Frank-
That's a phenomenal photo. Nice work.
Awesome pic and information - thanks!
clean and scary.Quote:
Originally Posted by FrankZappa
For fucks sake Frank, that photo just sent a well nasty chill down my spine. Just off for a bourbon now to settle my nerves again. :cool:
But nice example of a classic layer, they are not always that easy to spot.
probably had something to do with this yesterday:Quote:
Originally Posted by jwolter7
http://www.tdg.ch/files/imagecache/4...iablerets1.jpg
f2f - that's terrific stuff. Microscope in the field? Or if in a lab under cold conditions?
i only have a link to the image so i have no info about the conditions. similar pictures indicate that images at that resolution are taken with a low-temparature scanning electron microscope, so i would imagine they were not taken in the field. wikipedia's page on "snow" has a link to a similar, though not as pretty, picture with somewhat of an explanation.Quote:
Originally Posted by LeeLau
edit: found it, linked to from wikipedia: http://emu.arsusda.gov/snowsite/default.html
the graupel pic is here: http://emu.arsusda.gov/snowsite/rimegraupel/rg.html
http://upload.wikimedia.org/wikipedi...n_series-3.jpg
wow! more pictures please, these are great!
^^^^^
It's like a CNC machine carved out that stellar snow flake. Amazing photo.
great pics