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龙卷风小科普

Tornadoes 101 | National Geographic

They begin life as ghosts,
最初 它们像幽灵一样
gently coursing through a solitary existence,
是一种孤独而温和的存在
but slowly, their gentility turns to rage.
但这种温和逐渐演变成了愤怒
They grow larger and larger, hurling and twisting,
它们变得越来越大 咆哮着 缠绕着
and desperately reaching down from the sky.
疯狂地自天空向地面延生
And what began as an invisible shade
开始只是无形的阴影
is turned into a monster.
后来却变成了可怕的怪物
Tornadoes are powerful spinning columns of air
龙卷风是从地面伸展至云端的
that stretch from the ground to the clouds.
猛烈旋转的空气柱
Most are relatively weak,
大多数龙卷风都比较弱
but the few that grow into large events
但也有少数演变为强龙卷风
are extremely violent and cause immense destruction.
其强大的破坏力往往造成巨大的损失
Tornadoes occur on six of the seven continents.
全球七大洲中的六个洲都发生过龙卷风
The country with the most tornadoes based on land size
从国土面积来看 最常发生龙卷风的国家
is the United Kingdom,
是英国
with an average of about 33 tornadoes reported each year
平均每年有33起龙卷风
But the country with the greatest overall number of tornadoes
但要论龙卷风数量最多
and the most intense is the United States,
强度最大 非美国莫属
with over 1,000 reported annually.
每年报道超过1000起的龙卷风
Tornadoes, no matter where they occur,
不管在哪里产生 龙卷风都可以归为两类
are classified as either supercell tornadoes,
一类是超级单体龙卷风
which form within supercells, the most powerful class of thunderstorms,
这种龙卷风产生于超级单体(一种最强烈的雷暴)
or non-supercell tornadoes which are smaller and weaker,
另一类为规模更小 强度也更弱的非超级单体龙卷风
and form within non-supercell storms.
这种龙卷风产生于非超级单体风暴
There are many theories surrounding the formation of tornadoes.
关于龙卷风的形成 有许多的理论
One key component they share
这些理论的相同之处在于
is the presence of both high and low pressure air in a given space.
都认为在某一空间中同时存在高气压和低气压
Air particles from the area of high pressure
高压区的空气微粒
move toward an area of low pressure,
向低压区域移动
a movement that creates wind.
由此产生风
Non-supercell tornadoes,
非超级单体龙卷风
such as waterspouts and landspouts,
例如水龙卷和陆龙卷
begin when cool high-pressure air
形成于冷高压空气
and warm low-pressure air are present,
和暖低压空气的相遇
particularly near ground level.
尤其是在近地面的地方相遇
As air particles move horizontally
当空气微粒从高压区
from the high pressure area to the low pressure area,
向低压区水平移动时
wind begins to pick up.
就开始刮风了
Winds blowing at different speeds
有着不同速度
and in different directions and altitudes
来自不同方向和不同高度的风
begin to blow cyclically.
开始循环地吹
In the case of non-supercell tornadoes,
直至形成垂直旋转的漩涡
they turn into an upright spinning vortex.
这就是非超级单体龙卷风
But to create supercell tornadoes,
但要想形成超级单体龙卷风
the circumstances are slightly different.
情况则略有不同
Violent supercell storms draw warm low-pressure air
猛烈的超级单体风暴将暖低压空气
up to a higher altitude,
抬升至高处
leaving behind cool high-pressure air near the ground.
而冷高压空气则留在近地面
Air particles attempting to bring
空气微粒在低压区和高压区运动
the two levels of air pressure into balance
试图使气压达到平衡
creates wind that blows vertically.
这就产生了垂直吹的风
The wind increases and starts to blow in a cyclical fashion,
风越来越大 并开始循环地吹
creating a pipe of wind that rolls along the ground.
从而形成一个沿着地面滚动的风柱
In both cases, an upward current of wind called an updraft
这两种情况中 向上的风都称之为上升气流
provides the final ingredient for creating a tornado.
这是产生龙卷风的最后一个要素
In a budding non-supercell tornado,
在刚刚产生的非超级单体龙卷风中
an updraft stretches its vertical vortex until it reaches the clouds.
上升气流将垂直涡旋伸展至云端
To create a supercell tornado,
若要形成超级单体龙卷风
an updraft lifts the rolling pipe of wind upward
则需上升气流将旋转的风柱逐渐抬起
until it stands upright.
直至垂直
Then it pulls condensation from the skies
然后 天空中的冷凝物
and into the spinning vortex.
被吸入漩涡
As soon as the vortices, supercell or non-supercell,
当超单体或非超单体旋涡
connect the ground to the clouds,
将地面和云端连接起来时
they are officially classified as tornadoes.
才真正形成龙卷风
All tornadoes are rated based on a system called
所有龙卷风都可根据
the Enhanced Fujita Scale.
改良藤田级数进行评级
The Enhanced Fujita, or EF, Scale,
改良藤田级数 也称为EF级数
classifies tornadoes from a rating of EF0 to EF5.
将龙卷风分成EF0到EF5的六个等级
The rating is based on a number of factors,
评级基于许多因素
such as the damage a tornado causes
例如龙卷风的破坏程度
and the Doppler radar estimates of its wind speeds.
和多普勒雷达所估计的风速
EF0 tornadoes are the weakest,
EF0级龙卷风最弱
with the wind speeds between 65 to 85 miles per hour.
风速在每小时65到85英里之间
EF5 tornadoes are the strongest,
EF5级龙卷风最强
with the wind speeds exceeding 200 miles per hour.
风速超过每小时200英里
One of the strongest tornadoes recorded
1999年发生在俄克拉荷马州俄克拉荷马州市的龙卷风
occurred in Oklahoma City, Oklahoma in 1999.
是有记录的最强龙卷风之一
Born from a supercell thunderstorm,
它产生于超级单体雷暴
the EF5 tornado had a wind speed of over 300 miles per hour.
增强藤田级数为EF5 风速超过300英里/小时
It resulted in 36 fatalities, injured nearly 600,
那场龙卷风造成了36人死亡 近600人受伤
and caused about $1 billion in damages.
经济损失约为10亿美元
While tornadoes cannot be prevented,
尽管龙卷风的发生无法阻止
measures are being taken to protect communities.
但人类仍然采取了一系列措施来保护家园
Meteorologists closely monitor storm fronts
气象学家密切监视高风险地区的
in high-risk areas
风暴锋面
and try to forecast possible tornadic events.
并试图预测可能的龙卷风事件
In doing so, they help mitigate damages to neighborhoods
这不仅减轻了龙卷风对社区造成的损害
and save countless lives,
也挽救了无数人的性命
even in the face of one of nature’s most formidable.
即使面对的是最可怕的自然灾害之一

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视频概述

龙卷风是如何形成的?龙卷风有哪些种类?龙卷风能造成多大的破坏?人类面对龙卷风能做些什么?看完本片你都会了解!

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