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
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that peri
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that peri
admin
2014-12-26
33
问题
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that periodically develops along the Pacific coast of South America—has excited researchers. Jacob Bjerknes pointed out over 20 years ago how winds might create either abnormally warm or abnormally cold water in the eastern equatorial Pacific. Nonetheless, until the development of the models no one could explain why conditions should regularly shift from one to the other, as happens in the periodic oscillations between appearances of the warm EI Nino and the cold so-called anti-El Nino. The answer, at least if the current model that links the behavior of the ocean to that of the atmosphere is correct, is to be found in the ocean.
It has long been known that during an El Nino, two conditions exist: unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and winds blow from the west into the warmer air rising over the warm water in the east. These winds tend to create a feedback mechanism by driving the warmer surface water into a "pile" that blocks the normal upwelling of deeper, cold water in the east and further warms the eastern water, thus strengthening the wind still more. The contribution of the model is to show that the winds of an El Nino, which raise sea level in the cast, simultaneously send a signal to the west lowering sea level. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level, mat moves westward parallel to the equator at 25 to 85 kilometers per day. Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as, the Philippines and Indonesia.
When the waves meet the western boundary, they are reflected, and the model predicts that Rossby waves will be broken into numerous coastal Kelvin waves carrying the same negative sea-level signal. These eventually shoot toward the equator, and then head eastward along the equator propelled by the rotation of the Earth at a speed of about 250 kilometers per day. When enough Kelvin waves of sufficient amplitude arrive from the western Pacific, their negative sea-level signal overcomes the feedback mechanism tending to raise the sea level, and they begin to drive the system into the opposite cold mode. This produces a gradual shift in winds, one that will eventually send positive sea-level Rossby waves westward, waves that will eventually return as cold cycle-ending positive Kelvin waves, beginning another warming cycle.
Which of the following best describes the organization of the first paragraph?
选项
A、A model is described and its value assessed.
B、A result is reported and its importance explained.
C、A phenomenon is noted and its significance debated.
D、A hypothesis is introduced and contrary evidence presented.
答案
B
解析
推断题。根据第一段的整体结构The recent,apparently Successfulprediction...has excited researchers...Nonetheless.until the development of themodels no one could explain why…分析.该段首先介绍了数学模式对厄尔尼诺现象的发生进行了成功的预测,这次预测鼓舞了研究人员。而这些数学模式发展出来之前.没有人能够解释为什么这些状况发生期间出现周期性的变化。由这些分析可推知该段的逻辑顺序是先报道了一个结果,然后解释了它的重要性,和B选项表达一致。
转载请注明原文地址:https://kaotiyun.com/show/16h7777K
0
大学英语六级
相关试题推荐
Thepurposeofaletterofapplicationistohelpyouto"sell"yourself.Itshouldstateclearlythejobyouwant,andshouldt
Thepurposeofaletterofapplicationistohelpyouto"sell"yourself.Itshouldstateclearlythejobyouwant,andshouldt
Lastweek,speakersataprograminWashingtondiscussedusingnanotechnology(纳米技术)toimprovehealthcareindevelopingcountrie
AnewstudysaysancientsnowontopofMountKilimanjaroinTanzaniacouldbegoneinabout20years.Hugelayersoficeformed
AnewstudysaysancientsnowontopofMountKilimanjaroinTanzaniacouldbegoneinabout20years.Hugelayersoficeformed
AnewstudysaysancientsnowontopofMountKilimanjaroinTanzaniacouldbegoneinabout20years.Hugelayersoficeformed
A、Reviewsomemoviestheyhaveseenbefore.B、Watchnewfilmsreleasedrecently.C、Writeareviewonamovietheyhaveseenbefo
AteamofGermanscientistshastakenpicturesofanancientfishthatwasthoughttohavediedoutlongago.Thepicturesmayp
AteamofGermanscientistshastakenpicturesofanancientfishthatwasthoughttohavediedoutlongago.Thepicturesmayp
随机试题
请用上“茶叶”“创业”“劣质”“下雨”“悉心”这五个词编一个故事。
房间隔缺损特征性的改变是
某沥青混合料车辙试验结果如下表所示,请回答以下问题。关于沥青混合料车辙试验结果,下列说法正确的有()。
职业健康安全与环境管理体系(),体系文件写到的要做到,做到的要有有效记录。
根据《支付结算办法》的规定,付款人承兑商业汇票,必须满足所附有的条件。()
下列关于房产供给的叙述错误的是()
(),就是执法必严,使应负刑事责任的犯罪分子不能逃避法律的制裁,特别是对于那些严重的刑事犯罪分子必须严厉打击。
甲、乙、丙共谋抢劫一杂货店,在去踩点的途中,遇到他们的朋友丁,于是邀丁一起干。丁拒绝,甲说不干就算了,现在陪我们一起去看看。在察看该路边店时,丁告诫甲、乙、丙:店在路边,进去时行动要快,路边有公用电话,要防止报警,还随手扯断了电话线,尔后四人离去。当晚,甲
简述可撤销的民事法律行为与无效民事行为的区别。
AgingposesaseriouschallengetoOECD(OrganizationofEconomicCo-operationandDevelopment)countries,inparticular,howto
最新回复
(
0
)