Snow composition

[2knees]

So i'm still trying to figure yesterday's conditions out in my head. 80 degrees on sat, temps overnight dont get below 40 ish at the lowest, a little rain, yet a frozen tundra. Can someone explain to me how the heck that happens? a little crunchy, i could understand but sheets of ice and frozen coral? that you'd expect if it went down to 20 degrees or so, but that didnt happen.

only thing i can think is that the wind was howling like crazy, which it was, and it dried out all the moisture, but even that doesnt explain the relatively hard freeze that happened.

 

[bvibert]

Someone mentioned yesterday that it was because the ground is still frozen, so the cold soaks up from the ground and re-freezes everything. Sounds reasonable to me.

 

[severine]

Thermal insulation from the snow? And like Brian said, since the ground is still frozen, that would help. Sort of like throwing ice in a cooler.

 

[bobbutts]

a small layer of cold air forms above the snow
if it's windy the air will mix and have a uniform temp, if it's calm it doesn't mix so the cold pockets persist

picture a chest freezer, and you leave it open for awhile, it will still be cold, the warm air doesn't penetrate going down and the cold air doesn't rise.. now take a fan and blow all in the thing, not so cold anymore

 

[skiadikt]

yeah the snow sets up because of thermal cooling from the base snow/ice. guess we had the same thing at k on sunday. was about 55 at the base and despite the clouds & fog we were sure the snow would have been nice & soft like it was saturday. wrong ... ice & frozen coral. problem was no sun. throw in the lack of visibility and it wasn't much fun. once we got just a little sun things softened. interestingly when we went to bear to ski ol in the early afternoon, sun was shining (as it was when we dropped off a car at 8am), felt 10 degrees warmer and the snow was perfection.

 

[GrilledSteezeSandwich]

I've experienced harder packed snow when it's 70 degrees than 45 degrees...when it's really warm the slush at the surface melts so fast leaving behind the hardpacked manmade base form months back which is almost a glacier in that it's so thick and old..just because it's uber warm does not mean the snow will be uber soft..

 

[Rambo]

I think most of what snow base is left is mostly all machine made. Machine made snow is like 12 times more dense and has much less oxygen than natural snow and is much more melt resistant. Machine made snow in the warm spring tends to change into 16 different classifications such as, loose granular, corn, frozen crud... etc. When machine made snow metamorphosizes into crud it seems to slow down the melting process.

 

[mondeo]

Only explanation I can think of is that the evaporation of water/sublimation of the snow drops the temperature of the snowpack below freezing. That and water drainage without new melting makes it less slushy. Other than that, the entire snowpack/ground combination at this point has to be 32 degrees.