大氣污染控制工程-Lecture5-2MeteorologyforairpollutioncontrolEngineers

Prof.JiakuanYangHuazhongUniversityofScienceandTechnologyAirPollutionControlEngineeringQuestionsfortheLastLecture1.Whichtwometeorologicalfactorshavegreateffectonairpollutiontransportation?2.Whichtwofactors(orparameters)affectverticalmotionintheatmosphere?3.Whichtwoparameterscandescribethetemperaturechangeoftheairparcelandthesurroundingatmospherewhentheairparcelriseup?ImportantmeteorologyelementsonairpollutionwindspeedanddirectionatmosphericstabilityFactorsthataffectverticalmotionRH(RelativeHumidity)P(Pressure)temperaturedensityOthertwofactorsthataffectverticalmotionRH=humiditysaturationhumidityTheratioofthewatercontentoftheairM≈29－0.253RHρ=PM/TRRHMρRH(RelativeHumidity)aOthertwofactorsthataffectverticalmotionVerticaldistanceP(Pressure)Pρa=－ρgdPdzDryadiabaticlapserate()isusedtodescribethetemperaturedecreaseofanairparcelwhentheairparcelrise.Standardlapserate()isusedtodescribethetemperaturedecreaseofsurroundingair(oratmosphere)whentheheightincrease.10℃/kmActuallapserate()Lecture5Meteorologyforairpollution

controlEngineersⅠRelationshipbetweenmeteorologyandairpollutionⅡEffectsofhorizontalatmosphericmotiononatmosphericstabilityⅢEffectsofverticalatmosphericmotiononatmosphericstabilityⅣMixingHeight(混合高度)andFumigation(薰煙擴散)Standardlapserate(標準直減率)Sunlightistransparentthroughtheatmosphere,sothegroundabsorbsthelargestamountofheat.Commonlythegroundtemperatureisthehighest.Thefartherawaytheground,thelowertemperature.Standardlapserate()(4)Standardlapserate()ZT1km23.4°C30°C23.4°CInthedaytime,thenearertheground,thehighertemperatureoftheatmosphere.Actuallapserate()(5)AtmosphericstabilityHowdochangesofthetemperaturesaffecttheatmosphericstability?QuestionsAtmosphericstabilityT(℃)Z(m)SurroundingairPollutedairparcel0(5)AtmosphericstabilityT(℃)Z(m)0Changeofthepollutedairparcelisthesame.10℃/kmHowever,thetemperaturedistributionofthethesurroundingairwillchangefromtimetotime,andfromoneplacetoanotherplace.(a)unstableZ0ZTT0T1’Z1T1Whenairparcelrises,T1’>T1

airparcelwillriseupperandupper.Whenairparcelfalls,T2’<T2

airparcelwillriseupperandupper.T2T2’0(b)neutralTZ

a=00(c)stableTZa0(d)verystableTZtemperatureinversiona0

TemperatureinversionZZTT300m300m10°C21°C(a)Dawn(b)Dawn+2hVerticaltemperaturedistributionmodelatthevarioustime.00

TemperatureinversionZZTT300m1800m27°C(c)Dawn+4h(d)MidafternoonVerticaltemperaturedistributionmodelatthevarioustime.00平流逆溫暖空氣平流到冷地面上而下部降溫而形成暖空氣團高溫低溫鋒面逆溫冷、暖氣團相遇冷暖間逆溫

暖氣上爬，形成鋒面ⅣMixingHeight(混合高度)Airpollutantsreleasedatgroundlevelwillbemixedalmostuniformlyuptothemixingheight,butnotaboveit.Thusthemixingheightsetstheupperlimittodispersionofatmosphericpollutants.TZ0ⅣFumigation(薰煙擴散)

P113,Figure5.15summaryUnstable,andhighwindspeedleadtolowestground-levelpollutantconcentrations.Stableatmosphere(lowactuallapseratesorinversions)andlowwindspeedleadtohighestground–levelpollutantconcentrations.ThisLectureandtheNextLectureThisLecture:Chapter5Page83~101Page111~115TheNextLecture:Chapter6Page119~146Homework5.8(Page116)Whicharefourwaystoproduceatemperatureinversion?(Page111)DISCUSSIONTopicsaboutAirpollution:IntroducingyourselfInteresti