lecture 8 urban heat shields

lecture 8 urban heat shields - Pollution over the city...

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1 Urban Heat Islands Urbanized regions typically maintain higher surface temperatures than surrounding areas Intensity of the heat island varies spatially with highest temperatures usually located in the city core Heat island magnitude varies with city population Reasons for the Urban Heat Island Urban surfaces (metal, asphalt, concrete, stone) absorb more radiation than rural surfaces – higher temperatures during day and evening Irregular geometric shape in a city leads to more multiple reflections and absorption of radiation and lower wind speeds – less removal of warm air through convection Use of fossil fuels causes additional heating Sealed surfaces prevent water absorption – less evaporative cooling
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Unformatted text preview: Pollution over the city redirection of outgoing long wave radiation Effect of buildings on solar radiation receipt The Urban Environment 2 Urban Heat Island: Maximum and minimum temperatures in urban areas are higher than in nearby rural settings The Urban Heat Island Characteristics of Urban Climate Less insolation (up to 30% less UV radiation, up to 15% less sunshine duration) More clouds (up to 10% more clouds, up to 100% more fog) More precipitation (up to 15% more precipitation) Higher temperatures (up to 3 C (5.4 F) higher average temperatures, up to 10% less heating degree-days) The Heat Island of Washington, D.C. Average minimum winter temperatures (C) (Dec Feb)...
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This note was uploaded on 04/25/2008 for the course GEOG 121 taught by Professor Long during the Spring '08 term at Wisc Oshkosh.

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lecture 8 urban heat shields - Pollution over the city...

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