美国国家公共电台 NPR Scientists Know How Tornadoes Form, But They Are Hard To Predict

 

ARI SHAPIRO, HOST:

Last night, tornadoes² again touched down across the central U.S. In Prestonsburg, Ky., a roof torn from a building killed a person driving through downtown. We've been hearing stories like this all month - tornadoes leaving a trail of destruction from Texas, all the way up to Maryland. Scientists know how tornadoes form, but they're nearly impossible to predict. Patrick Marsh³ is a meteorologist at the National Oceanic and Atmospheric⁴ Administration's Storm Prediction Center. And I asked him why it's so hard to forecast where tornadoes will touch down.

PATRICK MARSH: So if you stop and think about it, before you can have a tornado¹, you have to have a thunderstorm, and to have a thunderstorm, there are four basic ingredients that you need to be able to assess and predict, and that's moisture, instability, lift and wind shear⁵. And so we have to track all four of those fields through the atmosphere and find where they're going to come together before we can even predict where the thunderstorms are going to occur. And then once we have a thunderstorm, we have to identify the subset of thunderstorms that could go on to produce tornadoes.

SHAPIRO: How unusual is it to have this many tornadoes in such a short period of time?

MARSH: It's actually quite unusual. We've had long stretches where we've had tornadoes over a long period of time, but the difference was we would have a day or two here or there where we kind of had a reprieve⁶. We're not seeing the reprieve this time, and that's what makes this outbreak so unique.

SHAPIRO: I know that climate change plays a role in exacerbating⁷ a lot of natural disasters, but it's a little murkier⁸ with tornadoes. Can you explain why that is?

MARSH: Even though the vast majority of the world's tornadoes occur in the United States, it's still somewhere on the order of about 1,200 tornadoes a year. And so when you think about how much real estate, how much land there is in the United States, that's not a lot of tornadoes for us to observe and predict. And so our dataset for tornadoes is actually quite limited. And for us to be able to do attribution studies to assess whether or not changes we see are related to climate change or other factors, we need a much bigger tornado dataset, or we need better statistics to assess this.

Hopefully, in the next few years, we'll be able to say something more definitive⁹, but at this time, we just don't have the tools to do so.

SHAPIRO: Is it your hope that in our lifetimes we'll be able to predict tornadoes as definitively¹⁰ as we can anticipate other weather events that may be less catastrophic?

MARSH: I would love to be able to tell somebody, you know, tomorrow there's going to be a tornado that's going to go through downtown Oklahoma City. But the atmosphere is inherently chaotic¹¹, and I don't know if we'll ever be able to get there. But we are working on ways to kind of mitigate¹² the fact that we won't be able to be as deterministic as people want. Some of the tools that we're developing is a process called Warn-On Forecast, an idea that we can run high-resolution numerical simulations out several hours in advance and be able to tell people there's a 20% chance of a tornado moving within a few miles of downtown Oklahoma City in the next two hours.

And hopefully, this allows things like hospitals to take safety precautions that they might not be able to implement¹³ if they only have a few minutes, which is what the current paradigm¹⁴ is. For example, you could cut down on elective surgery, so you don't run the risk of somebody being in surgery as a tornado hits. You can move patients out of their rooms into their hallways at a much slower pace, rather than the frenetic pace of a tornado bearing down on you. And that will also crack down on the amount of injuries and the risk for additional injuries.

SHAPIRO: Given that there will apparently¹⁵ always be uncertainty¹⁶ and some false alarms surrounding tornado forecasting, what's your best advice to people who might be living in zones that are prone¹⁷ to them?

MARSH: The best advice I can offer somebody is do not wait until severe weather is threatening you to figure out what you're going to do. Take a few minutes right now, as you listen to this interview, to talk to your spouse¹⁸, your significant other, your family about what you would do if tornadoes or other severe thunderstorms were to threaten you. In a nutshell, what you can do for tornadoes is you want to get into a well-built structure, you want to get to the lowest floor - and this does not necessarily mean below ground - and you want to put as many walls between you and the outside.

So in a nutshell, what I try to tell people is get in, get down and cover up.

SHAPIRO: Patrick Marsh, thanks so much for joining us today.

MARSH: Thank you very much for having me.

SHAPIRO: He's a meteorologist at the National Oceanic and Atmospheric Administration's Storm Prediction Center.

(SOUNDBITE OF YMORI'S "WEEKDAY")

1 tornado   

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 tornadoes   

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

3 marsh   

n.沼泽，湿地

参考例句：

• There are a lot of frogs in the marsh.沼泽里有许多青蛙。
• I made my way slowly out of the marsh.我缓慢地走出这片沼泽地。

4 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。

5 shear   

n.修剪，剪下的东西，羊的一岁；vt.剪掉，割，剥夺；vi.修剪，切割，剥夺，穿越

参考例句：

• Every spring they shear off the sheep's wool and sell it.每年春天他们都要剪下羊毛去卖。
• In the Hebrides they shear their sheep later than anywhere else.在赫伯里兹，剪羊毛的时间比其他任何地方都要晚。

6 reprieve   

n.暂缓执行（死刑）；v.缓期执行；给…带来缓解

参考例句：

• He was saved from the gallows by a lastminute reprieve.最后一刻的缓刑令把他从绞架上解救了下来。
• The railway line, due for closure, has been granted a six-month reprieve.本应停运的铁路线获准多运行6 个月。

7 exacerbating   

v.使恶化，使加重( exacerbate的现在分词 )

参考例句：

• This pedagogical understretch is exacerbating social inequalities. 这种教学张力不足加重了社会不平等。 来自互联网
• High fertilizer prices are exacerbating the problem. 高涨的肥料价格更加加剧了问题的恶化。 来自互联网

8 murkier   

adj.阴暗的( murky的比较级 )；昏暗的；（指水）脏的；混浊的

参考例句：

• If not, the outcome may be a lot murkier. 而如不然，结果可能就会更加含糊不清。 来自互联网
• This leads us into the murkier areas of human behaviour. 这让我们看到了人类行为较阴暗的领域。 来自互联网

9 definitive   

adj.确切的，权威性的；最后的，决定性的

参考例句：

• This book is the definitive guide to world cuisine.这本书是世界美食的权威指南。
• No one has come up with a definitive answer as to why this should be so.至于为什么该这样，还没有人给出明确的答复。

10 definitively   

adv.决定性地，最后地

参考例句：

• None of the three super-states could be definitively conquered even by the other two in combination. 三个超级国家中的任何一国都不可能被任何两国的联盟所绝对打败。 来自英汉文学
• Therefore, nothing can ever be definitively proved with a photograph. 因此，没有什么可以明确了一张照片。 来自互联网

11 chaotic   

adj.混沌的，一片混乱的，一团糟的

参考例句：

• Things have been getting chaotic in the office recently.最近办公室的情况越来越乱了。
• The traffic in the city was chaotic.这城市的交通糟透了。

12 mitigate   

vt.（使）减轻，（使）缓和

参考例句：

• The government is trying to mitigate the effects of inflation.政府正试图缓和通货膨胀的影响。
• Governments should endeavour to mitigate distress.政府应努力缓解贫困问题。

13 implement   

n.(pl.)工具，器具；vt.实行，实施，执行

参考例句：

• Don't undertake a project unless you can implement it.不要承担一项计划，除非你能完成这项计划。
• The best implement for digging a garden is a spade.在花园里挖土的最好工具是铁锹。

14 paradigm   

n.例子，模范，词形变化表

参考例句：

• He had become the paradigm of the successful man. 他已经成为成功人士的典范。
• Moreover,the results of this research can be the new learning paradigm for digital design studios.除此之外，本研究的研究成果也可以为数位设计课程建立一个新的学习范例。

15 apparently   

adv.显然地；表面上，似乎

参考例句：

• An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。
• He was apparently much surprised at the news.他对那个消息显然感到十分惊异。

16 uncertainty   

n.易变，靠不住，不确知，不确定的事物

参考例句：

• Her comments will add to the uncertainty of the situation.她的批评将会使局势更加不稳定。
• After six weeks of uncertainty,the strain was beginning to take its toll.6个星期的忐忑不安后，压力开始产生影响了。

17 prone   

adj.(to)易于…的，很可能…的；俯卧的

参考例句：

• Some people are prone to jump to hasty conclusions.有些人往往作出轻率的结论。
• He is prone to lose his temper when people disagree with him.人家一不同意他的意见,他就发脾气。

18 spouse   

n.配偶(指夫或妻)

参考例句：

• Her spouse will come to see her on Sunday.她的丈夫星期天要来看她。
• What is the best way to keep your spouse happy in the marriage?在婚姻中保持配偶幸福的最好方法是什么？