Mon Prof Augmenté
Snow Layers and Cup Crystals
Inside snow, some layers are warmer than others. That difference slowly changes star-shaped crystals into loose, cup-shaped grains that can let a hard slab slide.
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Age 13: open this week
Browse Age 13
In the picture
- Dense white slab at the top of the snow cutaway.
- A cup-shaped faceted grain in the magnified inset.
- A star-shaped crystal in the lower snow layer.
- The dark ground at the bottom of the cutaway.
Examples
- A hard crust on a ski slope can slide when a weak cup-crystal layer lies under it.
- Sugar-like snow on a sidewalk can collapse under your boots.
Key takeaways
- Temperature differences inside snow can change crystal shapes.
- Cup-shaped grains are loose and weak, so a slab above them may slide.
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Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
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