SURFACE CRYSTALS
|
|
Surface Hoar |
Firnspeigel |
Near-Surface Faceted Crystals (Radiation Recrystallized) |
Sun Crust |
Wind Crust |
|
Conditions |
Warm days, Cold nights, No wind |
Cold, clear conditions, air temperature < 0oC |
New snow, warm days, cold nights (south facing) |
Ta > 0oC |
Fresh snow, high winds |
|
Crystal Type |
Feathers at snow surface 1-10 cm |
Thin ice crust with air gap above snowpack |
Faceted snow grains similar to depth hoar |
Ice lens |
Densely well-bonded layer |
|
Process |
Snowpack cools below dew point; Deposition from vapor to solid phase |
Incoming solar radiation absorbed by snow, melt, meltwater freezes. Penetration of light through frozen layer, melting snow underneath. |
- Strong diurnal temperature - Develops strong VPG - Faceting similar to depth hoar |
Melt / Refreeze |
Increase in density and sintering |
|
Depth of formation |
1 - 10 cm |
2 - 5 cm |
2 - 20 cm |
0 - 5 cm |
0 - 10 m |
|
Avy Potential |
Running layer |
Glisse extreme, red-lining the fun meter |
Running layer |
Running layer |
Slab / Running layer |