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
84
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.
Look at the four squares [■] that show where the following sentence could be inserted in the passage. For next week’s weather, the new model may yield a slightly different prediction. Where could the sentence best be added? Click on a square [■] to insert the sentence in the passage.
选项
A、Square A.
B、Square B.
C、Square C.
D、Square D.
答案
B
解析
Chronological order is a transitional device that connects the insert sentence in sequence within the text. "... tomorrow" should precede "next week" and "next month" should follow "next week."
转载请注明原文地址:https://kaotiyun.com/show/EJyO777K
0
托福(TOEFL)
相关试题推荐
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage1?Inboxes5-13onyouranswersheet,writeT
Completeeachsentencewiththecorrectending,A-H,below.Writethecorrectletter,A-H,inboxes36-40onyouranswersheet.
Completethesentencesbelow.ChooseNOMORETHANTWOWORDSfromthepassageforeachanswer.Writeyouranswersinboxes10-13
Lookatthefollowingstatements(Questions19-23)andthelistofscientistsbelow.Matcheachstatementwiththecorrectscien
Lookatthefollowingpeople(Questions20-23)andthelistofideasbelow.Matcheachpersonwiththecorrectidea,A-E.Write
Choosethecorrectletter,A,B,CorD.Writethecorrectletterinboxes33-37onyouranswersheet.Manyscientistsdislike
AccidentalScientistsAAparadoxliesclosetotheheartofscientificdiscovery.Ifyouknowjustwhatyouarelookingfor,fi
Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReadingPassage1below.AverybriefhistoryoftimeTh
HowdesertsareformedA.Adesertreferstoabarrensectionofland,mainlyinaridandsemi-aridareas,wherethereisal
Completethesummarybelow.WriteNOMORETHANTWOWORDSforeachanswer.Afterhighschoolsomepeopletravel,finda(a
随机试题
氢硫酸、亚硫酸和硫酸都是酸,因此彼此不发生反应。()
在Word2003中,要选定整个文档,应先将光标移到文档左侧的选定栏,然后______。
不可以作注射剂溶剂的是
患儿,5岁。症见发热烦躁,咳嗽喘促,气急鼻煽,呼吸困难,喉间痰鸣,面赤口渴,大便干燥,小便黄少,舌红,苔黄,脉滑数。其证候是( )。
钢绞线应力松弛性能试验,当初始负荷为公称最大力的80%时,1000h后的应力松弛率应不大于()。
教育费附加的计费基础是( )。
甲公司2×17年有关资料如下:资料(一)(1)2×17年3月1日,甲公司购入乙公司全部股权,支付价款1200万元。购入该股权之前,甲公司的管理层已经做出决议,一旦购入乙公司,将在一年内将其出售给丙公司,乙公司当前状况下即可立即出售。预计甲公司还将为出售
在激励理论中,()不考虑人的内在心态,而是注重行为及其结果。
(2021年浙江)关于化学元素,下列说法不正确的是()。
若有函数声明voidfun(floatarray[],int*ptr);以下叙述正确的是
最新回复
(
0
)