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
"Weather and Chaotic Systems" Scientists today have a very good understanding of the physical laws and mathematical equatio
"Weather and Chaotic Systems" Scientists today have a very good understanding of the physical laws and mathematical equatio
admin
2012-01-14
68
问题
"Weather and Chaotic Systems"
Scientists today have a very good understanding of the physical laws and mathematical equations that govern the behavior and motion of atoms in the air, oceans, and land. Why, then, do we have so much trouble predicting the weather? For a long time, most scientists
assumed
that the difficulty of weather prediction would go away once we had enough weather stations to collect data from around the world and sufficiently powerful computers to deal with all the data. However, we now know that weather is
fundamentally
unpredictable on time scales longer than a few weeks. To understand why, we must look at the nature of scientific prediction.
→ Suppose you want to predict the location of a car on a road 1 minute from now. You need two basic pieces of information: where the car is now, and how fast it is moving. If the car is now passing Smith Road and heading north at 1 mile per minute, it will be 1 mile north of Smith Road in 1 minute.
Now, suppose you want to predict the weather. Again, you need two basic types of information: (1) the current weather and (2) how weather changes from one moment to the next. You could attempt to predict the weather by creating a "model world." For example, you could overlay a globe of the Earth with graph paper and then specify the current temperature, pressure, cloud cover, and wind within each square. These are your starting points, or initial conditions. Next, you could input all the initial conditions into a computer, along with a set of equations (physical laws) that describe the processes that can change weather from one moment to the next.
→ Suppose the initial conditions represent the weather around the Earth at this very moment and you run your computer model to predict the weather for the next month in New York City. The model might tell you that tomorrow will be warm and sunny, with cooling during the next week and a major storm passing through a month from now. Now suppose you run the model again but make one minor change in the initial conditions—say, a small change in the wind speed somewhere over Brazil.A For tomorrow’s weather, this slightly different initial condition will not change the weather prediction for New York City.B But for next month’s weather, the two predictions may not agree at all! C
The disagreement between the two predictions arises because the laws governing weather can cause very tiny changes in initial conditions to be greatly magnified over time.D This extreme sensitivity to initial conditions is sometimes called the butterfly effect: If initial conditions change by as much as the flap of a butterfly’s wings, the resulting prediction may be very different.
→ The butterfly effect is a hallmark of chaotic systems. Simple systems are described by linear equations
in which
, for example, increasing a cause produces a proportional increase in an effect. In contrast, chaotic systems are described by nonlinear equations, which allow for subtler and more intricate interactions. For example, the economy is nonlinear because a rise in interest rates does not automatically produce a corresponding change in consumer spending. Weather is nonlinear because a change in the wind speed in one location does not automatically produce a corresponding change in another location. Many (but not all) nonlinear systems exhibit chaotic behavior.
→ Despite their name, chaotic systems are not completely random. In fact, many chaotic systems have a kind of underlying order that explains the general
features
of their behavior even while details at any particular moment remain unpredictable. In a sense, many chaotic systems are "predictably unpredictable." Our understanding of chaotic systems is increasing at a tremendous rate, but much remains to be learned about them.
The word features in the passage is closest in meaning to
选项
A、problems
B、exceptions
C、characteristics
D、benefits
答案
C
解析
In this passage, characteristics is a synonym for "features." Context comes from the contrast with "details" later in the sentence.
转载请注明原文地址:https://kaotiyun.com/show/IJyO777K
0
托福(TOEFL)
相关试题推荐
Lookatthefollowingstatements(Questions19-23)andthelistofscientistsbelow.Matcheachstatementwiththecorrectscien
ChooseTWOletters,A-E.Writethecorrectlettersinboxes7and8onyouranswersheet.WhichTWOpositivefunctionsaboutMin
AccidentalScientistsAAparadoxliesclosetotheheartofscientificdiscovery.Ifyouknowjustwhatyouarelookingfor,fi
AccidentalScientistsAAparadoxliesclosetotheheartofscientificdiscovery.Ifyouknowjustwhatyouarelookingfor,fi
AccordingtoMrSingh,onwhichthingdomanypeoplemakesuperficialobservations?AccordingtoMrSingh,whatareyoungIndia
Thievesoftentargetstudents’homesbecausestudents______.tencomputergames
Thingsthatseemexcitingandfascinatingcanlaterseem______accordingtoAliandJatinder.WhatdoesAlisayKatarinashoul
Thelecturersaysthatanessayislike______toaspecificquestion.Useinterviewstogatherinformation.
Accordingtothepassage,anorganismwithouthardbodypartsItcanbeinferredthatfloodplains,deltas,andstreamchannel
NarratorListentoaconversationbetweenastudentandaacademicadviser.Nowgetreadytoanswerthequestions.Youmayusey
随机试题
顾客满意度调查的主要环节是?
引起熊胆解痉作用的化学成分是()。
月经周期长短不规则,经期长短不一,出血量不定,甚至大量出血,停经期查宫颈黏液呈羊齿状结晶。应诊断为()
背景某工程公司中标承包一城市道路施工项目,道路总长15km,其中包括一段燃气管线的敷设。工程建设工期很紧,为抓紧时间,该公司很快组成项目经理部,项目部进行了临建。项目部拿到设计院提供的设计施工图决定立即开始施工,监理工程师尚未到场。开工后项目部组
下列属于瓜茄类蔬菜的是()。
对非领导成员公务员的定期考核采取()方式。
2011年1—9月,全国造船完工5101万载重吨,同比增长18.3%,9月份当月完工786万载重吨,环比增长67.2%,新承接船舶订单规模2902万载重吨,同比下降42.8%,手持船舶订单规模16886万载重吨,同比下降13.8%,比2010年底下降14.
Windows98中,一旦用户打开了一个应用程序窗口,系统就会自动______。
Isawanadforadevicethatallowsyourdogtotalktoyou.BowLingual,aJapaneseinvention,enteredtheAmericanmarketac
StudiesoftheWeddellsealinthelaboratoryhavedescribedthephysiologicalmechanismsthatallowthesealtocopewiththee
最新回复
(
0
)