lecture_4 - LECTURE 4: ACCUMULATION AND ABLATION CONVERSION...

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LECTURE 4: ACCUMULATION AND ABLATION CONVERSION OF SNOW TO GLACIER ICE Steps in transformation process Snow flake crystals (0.07-0.35) Belong to rhombohedral division of hexagonal system. Their shape is temperature dependent Névé or firn (0.4-0.8) compaction (packing) vapor pressure field and vapor transfer sintering Glacier ice (0.85-0.90) opening between grains sealed -> little permeability recrystalization & solid flow achieved -> eliminates many air bubbles interlocking crystals <1 to 20 cm diameter orientation fabrics Time required for conversion of snow to ice Antarctica and Greenland 100's to 1,000's of years
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60 to 160 m transition depth compaction/recrytalization/compression dependent on accumulation rate Alaskan example 2 to 5 years 13 m transition depth melting/refreezing dominant dependent on summer temperature CONCLUSION: A glacier is a body of ice, originating on land. Ground ice and sea ice are not glaciers; ice shelves and
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lecture_4 - LECTURE 4: ACCUMULATION AND ABLATION CONVERSION...

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