在线英语听力室

VOA慢速英语2013 Tornado Season Returns

时间:2013-06-07 09:16:57

搜索关注在线英语听力室公众号:tingroom,领取免费英语资料大礼包。

(单词翻译)

 

Tornado1 Season Returns

From VOA Learning2 English, this is Science In The News. I'm Faith Lapidus.

And I'm Bob Doughty3. This week, we explore the science of tornadoes4. Weather experts say tornadoes are the most violent of all atmospheric5 storms. They strike in many parts of the world, including the United States.

Tornado season has begun in the United States.

A series of violent storms moved through north-central Texas in the middle of May. Some storms struck the small community of Granby, south of the Dallas-Fort Worth area. At least six people were killed. The tornadoes flattened7 or caused heavy damage to many homes.

Less than a week later, a large tornado caused major damage in the neighboring state of Oklahoma. The three kilometer wide tornado destroyed homes, businesses and two schools in Moore, just outside Oklahoma City. Officials say the storm left more than 20 people dead, and injured more than 200 others.

In May 1999, another deadly tornado hit Moore. It was one of more than 70 tornadoes reported in Oklahoma and Kansas in just 21 hours.

A tornado is a violently turning tube of air suspended8 from a thick cloud. It extends10 from a thunderstorm in the sky down to the ground. The shape is like a funnel11: wide at the top, narrower at the bottom.

Tornadoes form when winds blowing in different directions meet in the clouds and begin to turn in circles. Warm air rising from below causes the wind tube to reach toward12 the ground. Because of their circular13 movement, these windstorms are also known as twisters.

The most severe tornadoes can reach wind speeds of 320 kilometers an hour or more. The resulting paths of damage can be up to three kilometers wide, while the smallest widths14 are less than 10 meters. In some cases, the paths of damage can extend9 more than 480 kilometers.

With a tornado, bigger does not necessarily15 mean stronger. Large tornadoes can be weak. And some of the smallest tornadoes can be the most damaging. But no matter what the size, tornado winds are the strongest on Earth. Tornadoes can carry trees, cars and homes from one place to another. They can also destroy anything in their path.

Tornadoes have been observed on every continent except Antarctica. But experts say they are most commonly seen in the United States. On average, more than 1,000 are reported nationwide each year.

The National Oceanic and Atmospheric Administration16 keeps records of tornado sightings. It says tornadoes kill 70 people and injure 1,500 others nationwide in an average year.

Tornadoes are observed most often in the center of the United States, where the land is mostly flat. The area where the most violent tornadoes usually happen is known as “Tornado Alley17.” This area extends from Texas to South Dakota between the Rocky Mountains and the Appalachians.

Tornadoes can happen any time of the year. But most happen from late winter to the middle of summer. In some areas, there is a second high season in autumn.

Tornado seasons are the result of wind and weather patterns. During spring, warm air moves north and mixes with cold air remaining from winter. In autumn, the opposite happens. Cold weather moves south and combines with the last of the warm air from summer.

Tornadoes can strike with little or no warning. Most injuries happen when flying objects hit people. Experts say the best place to be is in an underground shelter, or a small, windowless room in the lowest part of a building.

People driving during a tornado are advised to find low ground and lay flat, facedown, with their hands covering their head. People in the path of a tornado often just have minutes to make life-or-death decisions.

The deadliest American tornado on record was the Tri-State Tornado of March 18, 1925. It tore across Missouri, Illinois and Indiana. Six hundred ninety-five people were killed.

Between March and May of 2011, there were 1,159 confirmed tornadoes across the United States. Scientists say that is the most on record for any three-month period. The most active month was April 2011, when 758 tornadoes were confirmed. That is the most ever for any month.

That April, the country broke a 37 year old record for the largest tornado outbreak. A “tornado outbreak” is commonly defined18 as six or more tornadoes produced by the same weather system within a day.

Scientists say the 199 tornadoes on April 27, 2011, were the most for any single day. They say the storms killed 316 people – the most ever in modern records for a 24 hour period.

No two tornadoes look exactly the same. And no two tornadoes act the same way.

Even a weak tornado requires the right combination19 of wind, temperature, pressure and humidity20. Weather experts can identify these conditions. And, when they observe them, they can advise people that tornadoes might develop. But they are not able to tell exactly where or when a tornado will hit. Tornado warnings still depend in large part on human observations.

Usually a community will receive a warning at least a few minutes before a tornado strikes. But each year there are some surprises where tornadoes develop when they are least expected.

The tornado reporting system involves watches and warnings. A tornado watch means tornadoes are possible in the area. A tornado warning means that a tornado has been seen. People are told to take shelter immediately.

Yet tornadoes can be difficult to see. Sometimes only the objects they are carrying through the air can be seen. Some night-time tornadoes have been observed because of lightning strikes nearby. But tornadoes at night are usually impossible to see.

Tornadoes that form over water are called waterspouts. But tornadoes cover a much smaller area than hurricanes, which form over oceans.

Tornadoes can be measured using wind speed information from Doppler radar21 systems. Tornadoes usually travel in a northeasterly direction, but they have been known to move in any direction. The average forward speed is about 50 kilometers an hour. But they can have a forward speed of up to 115 kilometers an hour. Or they may not move in any direction.

In the United States, the force of a tornado is judged by the damage to structures. Scientists inspect the damage before they estimate22 the severity of a tornado. They measure tornadoes on the Enhanced23 Fujita, or EF, scale.

Ted6 Fujita was a weather expert who developed a system to rate tornados24 in the 1970s. The EF scale involves wind estimates25 based on levels of damage to 28 different kinds of structures and other objects. Tornadoes that cause only light damage are called an EF-zero. Those with the highest winds that destroy well-built homes and throw vehicles great distances are called an EF-five.

Some people make a sport out of watching and following tornadoes. They are called tornado chasers or storm chasers. Their work can be seen in the extreme weather videos that are popular on television and the Internet.

Some chasers do it just because it is their idea of fun. Others do it to help document storms and warn the public. Still others are part of weather research teams.

A few years ago, an international team of scientists completed a tornado research project called VORTEX2. More than 100 researchers traveled throughout America’s Great Plains in 2009 and 2010. They used weather measurement26 instruments to collect scientific information about the life of a tornado. The goal of the project was to examine in detail how tornadoes are formed and the kinds of damage they cause.

A film about the VORTEX2 project was released27 in 2011. The film includes never before seen images of tornadoes.

The National Weather Service says the United States gets more severe weather than any other country. For one thing, the United States is also bigger than many countries. It also has many different kinds of conditions that create many different kinds of weather.

There are seacoasts and deserts, flatlands and mountains. The West Coast is along the Pacific Ocean, which is relatively28 calm. The East Coast is along the Atlantic Ocean, which is known for its hurricanes. These strike mainly the southeastern states.

This Science in the News was written by George Grow. June Simms was our producer. I'm Faith Lapidus

And I'm Bob Doughty. Join us again next week for more news about science on the Voice of America.


分享到:


点击收听单词发音收听单词发音  

1 tornado inowl     
n.飓风,龙卷风
参考例句:
  • A tornado whirled into the town last week.龙卷风上周袭击了这座城市。
  • The approaching tornado struck awe in our hearts.正在逼近的龙卷风使我们惊恐万分。
2 learning wpSzFe     
n.学问,学识,学习;动词learn的现在分词
参考例句:
  • When you are learning to ride a bicycle,you often fall off.初学骑自行车时,常会从车上掉下来。
  • Learning languages isn't just a matter of remembering words.学习语言不仅仅是记些单词的事。
3 doughty Jk5zg     
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。
4 tornadoes d428421c5237427db20a5bcb22937389     
n.龙卷风,旋风( tornado的名词复数 )
参考例句:
  • Tornadoes, severe earthquakes, and plagues create wide spread havoc. 龙卷风、大地震和瘟疫成普遍的毁坏。 来自互联网
  • Meteorologists are at odds over the working of tornadoes. 气象学者对龙卷风的运动方式看法不一。 来自互联网
5 atmospheric 6eayR     
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。
6 ted 9gazhs     
vt.翻晒,撒,撒开
参考例句:
  • The invaders gut ted the village.侵略者把村中财物洗劫一空。
  • She often teds the corn when it's sunny.天好的时候她就翻晒玉米。
7 flattened 1d5d9fedd9ab44a19d9f30a0b81f79a8     
[医](水)平扁的,弄平的
参考例句:
  • She flattened her nose and lips against the window. 她把鼻子和嘴唇紧贴着窗户。
  • I flattened myself against the wall to let them pass. 我身体紧靠着墙让他们通过。
8 suspended AhzzWs     
a.被暂时搁置的
参考例句:
  • A lamp was suspended from the ceiling. 一盏吊灯悬在天花板上。
  • The British government has now suspended humanitarian aid to the area. 英国政府现已暂停对这一地区的人道主义援助。
9 extend ZmixQ     
v.伸开;展开,伸展;扩大;加大
参考例句:
  • Can you extend your visit for a few days more?你能把你的访问再延长几天吗?
  • The examinations extend over two weeks.考试持续两个星期。
10 extends ae635f08107a69569e636835f24e6f6f     
v.(空间、时间等)延伸,延续( extend的第三人称单数 );伸展;给予;延长
参考例句:
  • This country extends its power and influence into neighbouring countries. 这个国家将其势力与影响扩大至邻国。 来自《简明英汉词典》
  • His domain extends for 20 miles in every direction. 方圆20英里之内都是他的地产。 来自《简明英汉词典》
11 funnel xhgx4     
n.漏斗;烟囱;v.汇集
参考例句:
  • He poured the petrol into the car through a funnel.他用一个漏斗把汽油灌入汽车。
  • I like the ship with a yellow funnel.我喜欢那条有黄烟囱的船。
12 toward on6we     
prep.对于,关于,接近,将近,向,朝
参考例句:
  • Suddenly I saw a tall figure approaching toward the policeman.突然间我看到一个高大的身影朝警察靠近。
  • Upon seeing her,I smiled and ran toward her. 看到她我笑了,并跑了过去。
13 circular MnHy4     
adj.圆(形)的,环形的;循环的;n.传单,通报
参考例句:
  • The bright boy altered it to a circular form.这个聪明的男孩把它改成了圆形。
  • The lamp stands on a circular base.这盏台灯是装在圆形底座上的。
14 widths 2ff2ccc5fa778194995f7a8efea73e36     
n.宽度( width的名词复数 );阔度;某一宽度的材料
参考例句:
  • These pianos are of different widths. 这些钢琴的宽度是不一样的。 来自《现代汉英综合大词典》
  • The carpet is available in various widths. 地毯现货尺寸齐全。 来自辞典例句
15 necessarily iGQxo     
adv.必要地,必需地;必定地,必然地
参考例句:
  • More work does not necessarily call for more men.增加工作量不一定就要增添人员。
  • A voter must necessarily be no younger than eighteen.选民必须在18岁以上。
16 administration mJLyZ     
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。
17 alley Cx2zK     
n.小巷,胡同;小径,小路
参考例句:
  • We live in the same alley.我们住在同一条小巷里。
  • The blind alley ended in a brick wall.这条死胡同的尽头是砖墙。
18 defined GuQzxW     
adj 定义的; 清晰的
参考例句:
  • These categories are not well defined. 这些类别划分得不太明确。
  • The powers of a judge are defined by law. 法官的权限是由法律规定的。
19 combination dWUyT     
n.组合,合并,联合;
参考例句:
  • He carried on the business in combination with his friends.他与朋友们合伙做生意。
  • The materials can be used singly or in combination.这些材料可以单独使用也可以混合用。
20 humidity tcNxW     
n.湿度,潮湿,湿气
参考例句:
  • The house is not comfortable tonight ,because of the high humidity.由于湿度高,今晚屋子里不舒服。
  • It's difficult to work because of the humidity.由于空气潮湿,工作很困难。
21 radar kTUxx     
n.雷达,无线电探测器
参考例句:
  • They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
  • Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。
22 estimate Ti4zb     
n.估计,估量;评价,看法;vt.估计,估量
参考例句:
  • We estimate the cost to be five thousand dollars.我们估计费用为5000美元。
  • The lowest estimate would put the worth of the jewel at $200.按最低的评估这块宝石也值200美元。
23 enhanced 0t0zm7     
a.加强的
参考例句:
  • Peak updraft strength is slightly enhanced with hodograph curvature. 山顶上升气流强度随速矢端迹曲率加大而稍有加强。
  • The black wimple enhanced the whiteness of her skin. 黑色的包头巾使她的皮肤显得更加白皙。
24 tornados 64f19dd0af7a26fe4bcdede94053f93c     
n.龙卷风,旋风( tornado的名词复数 )
参考例句:
  • And the national weather service reports several tornados touch down. 国家气象中心报告预测龙卷风将来袭。 来自互联网
  • They had stock footage of lightning, tornados, and hurricanes. 他们存有关于闪电、龙卷风和飓风的电影胶片。 来自互联网
25 estimates d72749910e71e75279b310239e18f36f     
估计
参考例句:
  • Unofficial estimates put the figure at over two million. 非官方的估计数字为200万以上。
  • We got estimates from three different contractors before accepting the lowest. 我们得到3个承包商的报价后,接受了最低的报价。 来自《简明英汉词典》
26 measurement xC6xu     
n.测量,衡量;(量得的)尺寸,大小
参考例句:
  • I can find the size of something by means of measurement.我可以用测量法求得某物的体积。
  • He has made an accurate measurement of my garden.他准确地丈量了我的花园。
27 released 23690fd759f17135ec9879b56ff2600c     
v.释放( release的过去式和过去分词 );放开;发布;发行
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • With hindsight it is easy to say they should not have released him. 事后才说他们本不应该释放他,这倒容易。
28 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。

本文本内容来源于互联网抓取和网友提交,仅供参考,部分栏目没有内容,如果您有更合适的内容,欢迎 点击提交 分享给大家。