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Tornadoes
龍卷風(fēng)
A tornado is a violently turning tube of air suspended from a thick cloud.
龍卷風(fēng)是由雷暴云層伸展至地面的漏斗狀云柱的強(qiáng)風(fēng)渦旋。
It extends from a thunderstorm in the sky down to the ground.
兩股空氣強(qiáng)烈相對流運(yùn)動(dòng)，相互摩擦形成空氣漩渦，空氣繞龍卷風(fēng)的軸快速旋轉(zhuǎn)，
The shape is like a funnel:
其形狀就像漏斗:
wide at the top, narrower at the bottom.
頂部寬，底部細(xì)長，
Tornadoes form when winds blowing in different directions meet in the clouds and begin to turn in circles.
四面八方的氣流被吸入漩渦的底部，并隨即變?yōu)槔@軸心向上的渦流。
Warm air rising from below causes the wind tube to reach toward the ground.
來自下面熱空氣上升使風(fēng)管朝向地面。
Because of their circular movement,these windstorms are also known as twisters.
由于自身的圓周運(yùn)動(dòng),這些風(fēng)暴也被稱為龍卷風(fēng)。
The most severe tornadoes can reach wind speeds of 320 kilometers an hour or more.
其最高速度達(dá)到每小時(shí)320千米。
Weather experts can identify the conditions to form a tornado.
氣象專家可以辨別出龍卷風(fēng)形成的條件具備與否，
And when they observe them,they can advise people that tornadoes might develop.
一旦觀測到這些情況，他們會(huì)向當(dāng)?shù)鼐用癜l(fā)出警報(bào)。
But they are not able to tell exactly where or when a tornado will hit.
但是，他們卻無法精確地推算出龍卷風(fēng)會(huì)在什么時(shí)候襲擊哪一個(gè)地方。
Tornado warnings still depend in large part on human observations.
龍卷風(fēng)警告仍然在很大程度上依靠著人類的觀察。
