首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to
admin
2011-04-26
88
问题
Water will evaporate from any wetted surface. A .significantly large fraction of the rainfall that falls on land is returned to the atmosphere in this fashion. In addition water is assimilated by root systems of growing plants and is later transpired from the leaf surfaces by a process essentially identical to evaporation. The two effects, evaporation and transpiration, cannot be individually discriminated for their effectiveness in returning rainfall to the atmosphere, but their sum contribution can be evaluated and is usually called the evapotranspiration factor. The fraction of rain falling on the United States that is returned to the atmosphere by evapotranspiration, for example, is 70 percent; for the world as a whole, approximately 62 percent. In arid countries such as Australia the fraction is larger, and in less arid areas such as the United Kingdom it is lower. Water returned to the atmosphere by evapotranspiration is unavailable to man, except in, the sense that useful plants may be grown in the place of useless ones. It cannot be trapped and redistributed for industrial or other purposes.
In regions of low rainfall, plant cover will develop to a point where all precipitation is used in evapotranspiration and none remains for stream now. Seasonal rainfalls provide a qualifier for this statement because streams will flow even in the most arid areas during periods of maximum rainfall. In general, if the potential evapotranspiration—that which would result from the maximum plant cover a region could support under ideal circumstances—should exceed the precipitation, overland stream flow ceases. Conversely, if evapotranspiration is less than precipitation, runoff is generated.
The amount by which precipitation exceeds evapotranspiration is the perennial yield of stream flow water, and this is the usable fraction of rain and snowfall. Across the entire United States the water yield amounts to 30 percent of the total rainfall, or approximately 1.77×1015 liters per year. But when we consider the distribution of water deficiencies and surpluses we find that essentially the entire eastern half of the United States, together with a small region in the Pacific northwest, enjoys water surplus, while most of the country to west of the Mississippi is water- deficient and arid.
It can be inferred from the passage that ______.
选项
A、more than 30% of total rainfall can yield stream flow in the United States
B、the water in the entire eastern haft of U. S.A. goes beyond its necessary need
C、west part of U. S. A.doesn’t have perennial yield of stream flow water
D、the yield of stream flow water is ’unevenly distributed in the United States
答案
D
解析
转载请注明原文地址:https://www.kaotiyun.com/show/zo6O777K
0
考博英语
相关试题推荐
•Readthefollowingtext.•Arethesentences16-22“right”or“wrong”?Ifthereisnotenoughinformationtoanswer“Right”
Readtheadvertisementbelowforahotdrinksmachine.Aresentences16-22"Right"or"Wrong"?Ifthereisnotenoughinformatio
DOWNTOWNAPARTMENTSImmediateoccupancyThemostfavourableprice$1,270upwardsClosetoshoppingcentres
Readtheintroductionbelowtoabusinessreferencebook.ChoosethecorrectwordtofilleachgapfromA,BorContheopposit
Readthenewspaperarticlebelowaboutapartnershipbetweenindustryandschools.Aresentences16-22belowthearticle"Ri
Readtheadvertisementbelowforahotdrinksmachine.Aresentences16-22"Right"or"Wrong"?Ifthereisnotenoughinform
Forfinancialreasons,employeestravelingtotheUSAwillflyovernighttoBaltimoreratherthanWashington.Employeesflyingt
ReadthenewspaperarticlebelowaboutJapaneseinvestment.Foreachquestion(23-28),choosethecorrectanswer.Markonelet
MEMOTo:AllStaffFrom:EuniceLaneDate:15June2009Subject:StaffTrainingProgrammeTwochoicesareavailablefortheStaf
Hisattitudetowardsocialwelfarelegislation,basedentirelyonhisperceptionofhimselfasaself-mademan,______himthes
随机试题
A.2:1B.3:1C.5:1D.6:1E.7:1竹叶石膏汤原方中麦冬与半夏的配伍比例是
与脾的病变无关的是
A解表散寒,行气宽中,解鱼蟹毒B祛风解表,消肿排脓C发汗解表,温经通脉,助阳化气D发汗解表,温中止呕,温肺止咳E祛风解表,胜湿止痛,解痉生姜的功效是()
新财公司主要从事建筑工程,某年开展了以下业务:(1)承包本市某建筑工程项目,并与建设方签订建筑工程施工总包合同,总包合同明确工程总造价为3000万元,其中200万元的建筑工程项目分包给甲建筑工程公司。年度工程项目全部完工,新财公司取得工程款3000万元,
简述进口货物单据审单的一般过程。
与图书相比,期刊的特点有()等。
在PowerPoint2003中设置自定义动画出现的开始时间。如图所示,播放时动画效果出现的顺序是()。
受教育权是儿童享有的一项基本权利.是一项合法权利。()
当掷一枚均匀硬币时,问至少应掷多少次才能保证正面出现的频率在0.4至0.6之间的概率不小于0.97试用切比雪夫不等式和中心极限定理来分别求解.(Ф(1.645)=0.95)
Traditionally,universitieshavecarriedouttwomainactivities:researchandteaching.Manyexpertswouldarguethatboththes
最新回复
(
0
)