Lecture 6 Energy Exchange & Winter

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Unformatted text preview: C (27°F to 14°F). Firn up Close (x80) Permafrost – Where & What? Factors Affec?ng Permafrost Depth l༆  Ul?mate driver is the air temperature and its length below freezing – Frost Degree Days (Ambient temp below zero x # days) l༆  Specific heat capacity of the ground composi?on, par?cularly the percentage of water present l༆  Whether that water is yet frozen l༆  Thermal conduc?vity of the mixture – how quickly will the heat be carried away l༆  Source of energy under the ground – natural warming – needs to be less… l༆  Solar gain from above l༆  hgp://www.urecon.com/applica?ons/municipal_freeze.html l༆  The number of days below freezing point x the actual temperature l༆  FDD = #days x ΔT Permafrost So to Check a Story…. l༆  Frozen water main in Banff was 14’ deep l༆  9,000 FDD (Fahrenheit) or 5,000 FDD (Celsius) l༆  Assume a 5 month winter, FDD = #days x ΔT...
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This document was uploaded on 01/17/2014.

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