专业英语温室效应

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Unit Four:The Greenhouse Effect,第四课 温室效应,New words:,Triple 三倍于 quadruple 四倍于,National Academy of Science 国家科学院,Impact 影响 effect,Feedback 反响 annual 每年的,Seasonal 每季的,Expand 扩展 extend spread,Antarctic 南极洲 Greenland 格陵兰,Flood 洪水泛滥 Bangladesh 孟加拉,Bay of Bengal 孟加拉湾(BOB),Timely 定时的，准时的,Zone 区域 region,Infrared radiation 红外辐射,Climatic feedback 气候反响,Snow cover 雪盖,Et al.等等人 etc.等等物,4,5,6,7,辐射,物体以电磁波或粒子流形式向四周传递或交换能量的方式。,电磁波谱,辐射的根本学问,辐射是太阳能传输到地球的唯一途径,大气窗,:,713,大气中的辐射传输过程,大气对短波的影响,吸取,散射,反射,吸取,逆辐射,大气对长波的影响,ppm:part per million,P1:,Man is reversing millions of years of natural evolution by putting into the atmosphere carbon that had been sequestered over the ages as fossil fuels.,Atmospheric concentrations of CO2,are likely to,double,and possibly triple,by 2100.,Because no historical precedent exists,reasonable,expectations,about future climate must be based on scientific evidence,not geological records.After evaluating the available evidence,the National Academy of Sciences concluded,that a doubling of atmospheric concentrations of CO2 would warm the earths average temperature 1.5-4.5,.,P2:,The greenhouse effect of the atmosphere has never been doubted.,More of the suns radiation is visible light,which passes through the atmosphere largely,undeterred,.,When the radiation strikes the earth,it warms the surface,which then radiates the heat as infrared radiation.However,atmospheric CO,2,water vapor,and some other gases absorb the infrared radiation rather than allow it to pass undeterredly through the atmosphere to space.,Because the atmosphere traps the heat and warms the earth in a manner somewhat analogous to the glass panels of a greenhouse,this phenomenon is generally,known as,the“greenhouse effect”.Without this effect,the earth would be 33(60)colder that it is currently.,P3:The extent to which CO,2,absorbs heat has been known for almost a century,Scientists show that doubling of atmospheric CO,2,would raise the average temperature1.2 if nothing else in the earths climatic system changed.However,many parts of the climate will change,amplifying,the direct impact of CO,2,.Because these changes are not completely understood,the total warming is difficult to estimate.The current uncertainty,surrounding the impact of CO,2,on average temperature,is centered around these climatic“feedback”,not the direct warming from CO,2,.,P4,：,The most important feedback will result from the warmer atmospheres ability to retain moisture.Because water vapor also absorbs infrared radiation,additional heating will result.Hanson er al.estimate that double CO,2,would increase the atmospheres water vapor content 30%,heating the earth and additional 1.4,.,P5:Another important positive feedback concerns the,impact,of snow and ice cover,on,the earths albedo,the extent to which it reflects sunlight.Ice and snow reflect most of the suns radiation,while water and soil absorb it.An increase in surface temperatures would melt snow on land and floating ice and,thereby,allow the earth to absorb energy that would otherwise be reflected back into space.Hanson et al.estimate an additional warming of 0.4 from the albedo effect.,P6:A feedback that is less understood is the impact of a global warming on clouds,which also reflect sunlight into space.The effects of clouds on the earths albedo depend on their heights and other properties,as well as the extent of cloud cover.Thus,the impact of a global warming on clouds is somewhat uncertain.Nevertheless,with somewhat less confidence,Hanson et al.estimate a 2%reduction in cloud cover and a resulting warming of 0.5,.They also estimate that increase in cloud height would result in an additional warming of 0.5,for a total impact of 1.0,from clouds.,P7,：,Although the increase in the average temperature of the earth is a convenient shorthand description of CO2 induced climate change,it masks important regional implications.Most searchers agree that polar temperature would increase two to,three times,the earths average increase.The worlds climate depends largely on circulation patterns by which the atmosphere and the oceans transport heat from warm to cold regions.,P7,：,As a result,any significant change in the difference between equatorial and polar temperatures could dramatically affect climatic patterns.A particularly important effect of these changes will be shifts in annual and seasonal precipitation and evaporation,with some areas gaining and other losing.Furthermore,because hurricanes require an