王瑩

What are tornadoes？

什么是龍卷風(fēng)？

Tornadoes， also called twisters， are vertical funnels of rapidlyspinning air.

龍卷風(fēng)也叫旋風(fēng)，是垂直的漏斗狀高速旋轉(zhuǎn)的氣流。

Tornadoes form when warm， humid air mix with cold， dryair. Tornadoes are born in thunderstorms and often come with hail.

龍卷風(fēng)形成于溫暖、潮濕的空氣與寒冷、干燥的空氣對(duì)流時(shí)，是云層中雷暴的產(chǎn)物，同時(shí)常常伴有冰雹天氣。

Where and when？

什么時(shí)候，在哪里？

These dangerous storms occur around the world， but theUnited States is a place with the most， with about 1000 tornadoesevery year.

這樣危險(xiǎn)的風(fēng)暴在全世界范圍內(nèi)都會(huì)出現(xiàn)，但美國(guó)是龍卷風(fēng)的高發(fā)地，每年約出現(xiàn)1000 次。

Tornadoes can occur at any time of year， but they are morecommon from early spring to summer. Although they can format any time of the day or night， most tornadoes form in the lateafternoon.

龍卷風(fēng)在一年中的任何時(shí)候都有可能形成，但最常出現(xiàn)的時(shí)間段是早春到夏季之間。盡管在一天之中，白天和夜里都有可能出現(xiàn)龍卷風(fēng)，但大多數(shù)的龍卷風(fēng)形成于傍晚時(shí)分。

Duration and Speed

持續(xù)時(shí)間和時(shí)速

When a tornado hits the ground， it may live for as little as afew seconds or as long as three hours. The average twister is about200 meters wide and moves about 48 km/h. Most dont travelmore than 10 km before stopping.

當(dāng)龍卷風(fēng)擊中地面時(shí)，它可能會(huì)持續(xù)幾秒鐘，也可能會(huì)長(zhǎng)達(dá)3 個(gè)小時(shí)。龍卷風(fēng)平均寬度約200 米，移動(dòng)速度約48 千米/ 小時(shí)。大多數(shù)龍卷風(fēng)的移動(dòng)距離不會(huì)超過(guò)10 千米。

Dangerous！

危險(xiǎn)！

Very strong winds break homes and businesses. Winds canalso destroy bridges and trains， send cars and trucks flying， pulltrees into the sky， and take all the water out the rivers.

強(qiáng)風(fēng)會(huì)摧毀房屋和商鋪。風(fēng)還可能會(huì)摧毀橋梁和火車，讓汽車和卡車飛起來(lái)，把樹(shù)拉向天空，把河里的水都帶走。

Strong winds sometimes kill or hurt people by pushing themto the ground or throwing them into the sky. But most peopleget hurt by flying debris from broken houses—parts of the roof，broken glass， doors， pieces of metal.

強(qiáng)風(fēng)有時(shí)會(huì)將人推倒在地或拋向天空，從而導(dǎo)致人受傷或死亡。但大多數(shù)人在龍卷風(fēng)中受傷的原因都是被破碎房屋的碎片——破碎的屋頂、碎玻璃、門和金屬碎片弄傷。

I. Yes or No？

1. Tornadoes are also called twisters. （ ）

2. There are about 10，000 tornadoes in the United States every

year. （ ）

3. Most tornadoes can travel more than 10 km before stopping.（ ）

4. Tornadoes are more common from early spring to summer.（ ）

5. Most tornadoes form in the late afternoon. （ ）

II. Fill in the blanks.

1. Tornadoes are vertical funnels of _______.

2. Tornadoes form when _______ air mix with _______ air.

3. The average twister is about _______ wide and moves about_______.

III. Answer the question.

Why are tornadoes dangerous？

Keys to Tornadoes

I. 1. Yes 2. No 3. No 4. Yes 5. Yes

II. 1. rapidly spinning air 2. warm， humid; cold， dry 3. 200 meters; 48 km/h

III. Because tornadoes are strong winds， so they can break homes and hurt people.