SCIENCE IN THE NEWS - Severe Ocean Storms: Behind Nature's P

SCIENCE IN THE NEWS - Severe Ocean Storms: Behind Nature's Power
By Caty Weaver¹

Broadcast: Tuesday, September 27, 2005

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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Bob Doughty².

VOICE TWO:

 
Ed Rappaport, deputy³ director of the National Hurricane Center, shows the expected path of Hurricane Rita as it neared the Texas and Louisiana coast
And I'm Barbara Klein. Our subject this week is the science of severe ocean storms.

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VOICE ONE:

Violent ocean storms in the northern part of the world usually develop in late summer or autumn near the equator⁴. Scientists call them cyclones⁵ when they develop over the Indian Ocean. When they happen over the northwestern Pacific Ocean, the storms are called typhoons. And, in the eastern Pacific and the Atlantic Ocean, they are called hurricanes.

Ocean storms develop when the air temperature in one area is different from the temperature nearby. Warmer air rises, while cooler air drops. These movements create a difference in the pressure of the atmosphere.

If the pressure changes over a large area, it can cause winds to blow in a huge circle. Thick clouds form and heavy rains fall as the storm gains speed and moves over the ocean waters.

VOICE TWO:

The strongest winds happen in the area known as the eyewall. It surrounds the center, or eye, of the storm. The eye itself is calm by comparison⁶, with light winds and clear skies.

Winds in severe ocean storms can reach speeds of more than two hundred fifty kilometers an hour. Up to fifty centimeters of rain can fall. Some storms have produced more than one hundred fifty centimeters of rain. These storms also cause high waves and ocean surges⁸.

A surge⁷ is a continuous⁹ movement of water that may reach as high as six meters or more. The water smashes¹⁰ across low coastal¹¹ areas. Surges are commonly responsible for about ninety percent of all deaths from ocean storms.

VOICE ONE:

The National Hurricane Center in Miami, Florida, keeps watch on severe storms. It works¹² closely¹³ with public officials and with radio and television stations to keep people informed. Experts believe this early warning system has helped reduce the number of deaths from ocean storms in recent years.

But sometimes people cannot or will not flee the path of a storm, as Hurricane Katrina showed tragically¹⁴. The storm struck the coast of the Gulf¹⁵ of Mexico on August twenty-ninth. More than one thousand bodies have been found, most of them in Louisiana.

 
Lafitte, Louisiana, after Hurricane Rita passed through
In the past week, coastal areas of Texas and Louisiana had to prepare for Hurricane Rita. Three million people fled to higher ground. Rita caused widespread property damage, but not as much as had been feared.

The Atlantic hurricane season continues officially until November thirtieth.

VOICE TWO:

Weather scientists use computers to create models that show where a storm might go. Models combine information such as temperatures, wind speed, atmospheric¹⁶ pressure and the amount of water in the atmosphere.

Scientists collect the information with satellites, weather balloons and devices¹⁷ floating in the world's oceans. They also collect information from ships and passenger flights and from government planes. These planes fly into and around storms. The crews drop instruments on parachutes. The instruments report temperature, pressure, wind speed and other details.

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VOICE ONE:

You are listening to SCIENCE IN THE NEWS in VOA Special English.

Scientists use the Saffir-Simpson Hurricane Scale to measure the intensity¹⁸ of storms based on wind speed. The scale is divided into categories.

A category one storm has winds of about one hundred twenty to one hundred fifty kilometers an hour. It can damage trees and lightweight structures.

Wind speeds in a category two hurricane can reach close to one hundred eighty kilometers an hour. These storms are often powerful enough to break windows or blow the roof off a house.

Winds between about one hundred eighty and two hundred fifty kilometers an hour represent categories three and four.

Anything even more powerful is a category five hurricane.

VOICE TWO:

Katrina was a category four when it hit land. It struck the Gulf Coast with a wind speed of about two hundred thirty kilometers an hour. But government scientists say other forces helped make Katrina the most destructive¹⁹ hurricane ever to hit the United States.

Scientists at the National Oceanic and Atmospheric Administration²⁰ say Katrina's air pressure was very low. The lower the air pressure, the stronger the storm. And Katrina was an unusually wide storm. The edges reached from Texas to Florida.

VOICE ONE:

Katrina's most damaging power, however, came from the water it brought. The storm surge was estimated²¹ at more than six meters, and may have been as high as nine. The storm also brought heavy rainfall.

 
New Orleans after Katrina
All this water poured into Lake Pontchartrain on the north side of New Orleans. It also flooded into the Mississippi River to the south. New Orleans was built below sea level. The city is surrounded by levees made of earth and walls made of concrete. The water and wind pressure from Katrina broke through the flood dams.

The surge washed away large areas of the coastal cities of Biloxi and Gulfport, Mississippi. There was also heavy damage in Alabama.

Studies have warned for years of the risk in continued development along the Gulf Coast. Scientists have said that more hurricane barriers are needed to protect areas where people live.

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VOICE TWO:

Scientists at the Georgia Institute of Technology and the National Center for Atmospheric Research recently did a study of hurricanes. They say the number of the most powerful storms has increased by almost one hundred percent in the past thirty-five years. The researchers noted²² that ocean surface temperatures have also increased during the same period. The study appeared in Science magazine.

Peter Webster of the School of Earth and Atmospheric Sciences at Georgia Tech was one of the leaders of the research. He says the world had an average of about ten category four and five hurricanes per year in the nineteen seventies. But Professor Webster says the average has increased to eighteen per year since nineteen ninety.

VOICE ONE:

The researchers say that about thirty-five percent of all hurricanes in the past ten years were category four or five. That was up from around twenty percent in the nineteen seventies. The largest increases took place in the North Pacific and Southwest Pacific, and the North and South Indian oceans.

The increase was a little smaller in the North Atlantic. But the study says North Atlantic hurricanes have increased in total number. Also, they last longer than they did before nineteen ninety-five.

Kerry Emanuel at the Massachusetts Institute of Technology recently did a study of North Atlantic and North Pacific hurricanes. His findings²³ appeared in Nature magazine. He used a different measure of power. But he, too, found a sharp increase in the last thirty years in the intensity of hurricanes and the time they last.

VOICE TWO:

Peter Webster says it is not clear if the changes are the result of global warming caused by human activity. He says researchers need a longer record of hurricane information to see if such activity is natural over time. And the professor says they also need to understand more about the part that hurricanes play in Earth's climate.

As he describes it, hurricanes help cool the oceans and control the heat balance in the atmosphere. They evaporate²⁴ water and then spread the tropical²⁵ heat of the oceans up into the sky.

The new studies provide more evidence of a relationship between increases in ocean surface temperatures and the intensity of hurricanes. But Professor Webster says "it is not a simple relationship," and it is difficult to understand.

He says the total number of hurricanes has decreased in the past ten years. The average time they last has decreased also. Yet sea surface temperatures reportedly have increased the most of any period back to the nineteen seventies.

(MUSIC)

VOICE ONE:

SCIENCE IN THE NEWS was written by Caty Weaver. Jill Moss²⁶ was our producer. Our programs are on the Web at www.tingroom.com. I'm Bob Doughty.

VOICE TWO:

And I'm Barbara Klein. To send e-mail, write to [email protected]. Listen again next week for more news about science in Special English on the Voice of America.

1 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

2 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

3 deputy   

n.代理人，代表，副职；adj.代理的，副的

参考例句：

• John will act as a deputy for me during my absence.我离开期间，约翰将代理我的职务。
• She is the deputy headmistress of the school.她是那所学校的代理校长。

4 equator   

n.赤道，（平分球形物体的面的）圆

参考例句：

• Singapore is near the equator.新加坡位于赤道附近。
• The United States is north of the equator.美国位于赤道以北。

5 cyclones   

n.气旋( cyclone的名词复数 )；旋风；飓风；暴风

参考例句：

• The pricipal objective in designing cyclones is to create a vortex. 设计旋风除尘器的主要目的在于造成涡旋运动。 来自辞典例句
• Middle-latitude cyclones originate at the popar front. 中纬度地区的气旋发源于极锋。 来自辞典例句

6 comparison   

n.比较，对照；比拟，比喻

参考例句：

• They make a comparison of New York to a beehive.他们把纽约比作一个蜂巢。
• This dress is really cheaper by comparison.比较起来，这件衣服确实便宜。

7 surge   

n.汹涌，澎湃；vi.汹涌，强烈感到，飞涨；vt.放开，松手

参考例句：

• The surge travelled southwards along the coast.浪涛沿着海岸向南涌去。
• It failed to stimulate a surge of investment in industry.这没有能刺激工业投资的激增。

8 surges   

n.奔涌向前( surge的名词复数 )；（数量的）急剧上升；（感情等）洋溢；浪涛般汹涌奔腾v.（波涛等）汹涌( surge的第三人称单数 )；（人群等）蜂拥而出；使强烈地感到

参考例句：

• The Yellow River surges onward like ten thousand horses galloping. 黄河以万马奔腾之势滚滚向前。 来自《现代汉英综合大词典》
• The raging tide of revolution surges forward. 革命怒潮汹涌澎湃。 来自《现代汉英综合大词典》

9 continuous   

adj.继续的，连续的，持续的，延伸的

参考例句：

• She finally got in after 10 years'continuous effort.坚持不懈地努力了十年后，她终于当选了。
• We must be continuous to study.我们必须不断学习。

10 smashes   

v.打碎，捣烂( smash的第三人称单数 )；捣毁；重击；撞毁（车辆）

参考例句：

• It's the lunatic fringe of the Animal Liberation Front which smashes the windows of butchers' shops, not ordinary members like us. 是“动物解放阵线”的极端分子打碎了肉店的玻璃窗，可不是我们这样的普通成员。 来自《简明英汉词典》
• He smashes the watch in frustrrustration. 将军此刻的心情是得意与失意参半。 来自辞典例句

11 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

12 works   

n.作品，著作；工厂，活动部件，机件

参考例句：

• We expect writers to produce more and better works.我们期望作家们写出更多更好的作品。
• The novel is regarded as one of the classic works.这篇小说被公认为是最优秀的作品之一。

13 closely   

adv.紧密地；严密地，密切地

参考例句：

• We shall follow closely the development of the situation.我们将密切注意形势的发展。
• The two companies are closely tied up with each other.这两家公司之间有密切联系。

14 tragically   

adv. 悲剧地，悲惨地

参考例句：

• Their daughter was tragically killed in a road accident. 他们的女儿不幸死于车祸。
• Her father died tragically in a car crash. 她父亲在一场车祸中惨死。

15 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

16 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

17 devices   

n.设备；装置( device的名词复数 )；花招；（为实现某种目的的）计划；手段

参考例句：

• electrical labour-saving devices around the home 节省劳力的各种家用电器
• modern labour-saving devices such as washing machines and dishwashers 诸如洗衣机和洗碗机之类的现代化省力设备

18 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

19 destructive   

adj.破坏（性）的，毁灭（性）的

参考例句：

• In the end,it will be destructive of our whole society.它最终会毁灭我们整个社会。
• It is the most destructive storm in 20 years.这是20年来破坏性最大的一次风暴。

20 administration   

n.经营，管理；行政，行政机关，管理部门

参考例句：

• Who is in charge of the administration of your company?你们公司的行政工作由谁负责？
• The teachers are responsible to the school administration.教师向学校行政负责。

21 estimated   

adj．根据估计的

参考例句：

• She estimated the breadth of the lake to be 500 metres. 她估计湖面大约有500米宽。
• The man estimated for the repair of the car. 那人估算了修理汽车的费用。

22 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

23 findings   

n.发现物( finding的名词复数 )；调查（或研究）的结果；（陪审团的）裁决

参考例句：

• It behoves us to study these findings carefully. 我们理应认真研究这些发现。
• Their findings have been widely disseminated . 他们的研究成果已经广为传播。

24 evaporate   

vi.蒸发，挥发，消失；vt.使蒸发，使挥发

参考例句：

• Clearly,the star wars problem was not going to evaporate.显然，星球大战问题并没有不了了之。
• It will evaporate like a spirit.它将来总要像幽灵一样化成云烟。

25 tropical   

adj.热带的，热带的，炎热的

参考例句：

• You must grow these tropical flowers in a glasshouse.你必须把这些热带花卉种在温室里。
• This disease is widespread in tropical areas.这种疾病在热带地区蔓延很广。

26 moss   

n.苔，藓，地衣

参考例句：

• Moss grows on a rock.苔藓生在石头上。
• He was found asleep on a pillow of leaves and moss.有人看见他枕着树叶和苔藓睡着了。