VOA慢速英语2019--什么是极涡？

What Is the Polar Vortex?

Record cold weather in the United States is forcing schools and businesses to close. The “polar vortex,” as it is called, has also canceled flights and suspended¹ mail delivery².

The temperature in Fargo, North Dakota, dropped to -35 degrees Celsius³. In Chicago, Illinois, it was -28 degrees Celsius, but strong winds made the air feel like -50 degrees.

The U.S. National Weather Service warns that a wind chill⁴ of -32 degrees Celsius could freeze a person’s skin within 15 minutes. Officials turned city buses into mobile⁵ warming shelters to help keep homeless people safe.

The cold weather was linked to at least 20 deaths, including a man who froze to death in Wisconsin.

It all started with misplaced heat from Morocco, says winter storm expert Judah Cohen. He works⁶ for Atmospheric⁷ and Environmental Research in Massachusetts.

Last month, Cohen explains, the usually cold air some 30 kilometers above the North Pole quickly warmed by about 70 degrees Celsius. The area of air is known as a polar vortex. There is also a polar vortex above the South Pole.

The quick temperature change was the result of hot air flowing in from the south. The warmer air split⁸ the polar vortex, leaving smaller pieces of it to move around. By Tuesday night, one of those vortex pieces reached the middle of the United States.

The unusually cold air could stay around for several weeks. “I think at a minimum⁹, we’re looking at mid-February, possibly through mid-March,” Cohen said.

Americans first began hearing the words “polar vortex” five years ago. In early 2014, the temperatures dropped to -27 degrees Celsius in places like Chicago. Weather experts, who had been using the term for many years, began using it on social media.

But the National Weather Service says there is nothing new about it. It says the years 1977, 1982, 1985 and 1989 also brought unusually cold temperatures caused by a polar vortex.

What about global warming?

As Americans dealt with the extreme cold, President Donald Trump¹⁰ called for the return of global warming. He wrote on Twitter: “In the beautiful Midwest, windchill temperatures are reaching minus 60 degrees, the coldest ever recorded. In coming days, expected to get even colder. People can’t last outside even for minutes. What the hell¹¹ is going on with Global Warming? Please come back fast, we need you!”

John Cook is a professor of climate change at George Mason University in Virginia. He said Trump’s comment about the cold weather ignores the larger picture of a warming planet¹². He compared the president’s comment to someone saying that “nighttime proves the sun doesn’t exist.”

Climate scientist Victor Gensini said, “This is simply an extreme weather event and not representative of global scale temperature trends.”

Gensini, who works at Northern Illinois University, told the Associated Press, “The exact opposite is happening in Australia right now.”

Last week, the city of Adelaide, Australia reached 46.6 degrees Celsius, the highest temperature ever recorded in a major Australian city. But it was even hotter in nearby Port Augusta, where temperatures reached 49.5 degrees Celsius.

Another climate scientist, Zeke Hausfather of Berkeley Earth, said it was important to remember the difference between climate and weather.

“In a warming world, you’re still going to have unusually hot and unusually cold events happening in a particular part of the world,” Hausfather said. “Weather is not going away.”

I'm Ashley Thompson.

Words in This Story

mobile - adj. able to move from one place to another

1 suspended   

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。

2 delivery   

n.交付；投递；分娩；解救者；演讲的风格

参考例句：

• The strike caused a great delay in the delivery of the mail.这次罢工严重地延误了邮件的投递。
• He was employed at the local grocery store as a delivery boy.他受雇于当地杂货店当送货员。

3 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

4 chill   

vt.使变冷，使冷却，使沮丧；n.寒冷，风寒

参考例句：

• With the chill factor,it's nearly minus forty here.加上风寒指数，气温接近零下40度。
• The bad news cast a chill over the whole family.这坏消息使全家人感到沮丧。

5 mobile   

adj.可移动的，易变的，机动的；n.运动物体

参考例句：

• The old lady sits on a mobile chair every morning.那位老妇人每天上午坐在一把可携带使用的椅子上。
• She's much more mobile now that she's bought a car.自从她买了汽车后，活动量就大多了。

6 works   

n.作品，著作；工厂，活动部件，机件

参考例句：

• We expect writers to produce more and better works.我们期望作家们写出更多更好的作品。
• The novel is regarded as one of the classic works.这篇小说被公认为是最优秀的作品之一。

7 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。

8 split   

n.劈开，裂片，裂口；adj.分散的；v.分离，分开，劈开

参考例句：

• Who told you that Mary and I had split up?谁告诉你玛丽和我已经离婚了？
• The teacher split the class up into six groups.老师把班级分成6个小组。

9 minimum   

adj.最低的，最小的；n.最小量，最低限度

参考例句：

• What is the minimum price?最低价是多少？
• Today's minimum temperature is 10℃.今天的最低气温是10℃。

10 trump   

n.王牌，法宝；v.打出王牌，吹喇叭

参考例句：

• He was never able to trump up the courage to have a showdown.他始终鼓不起勇气摊牌。
• The coach saved his star player for a trump card.教练保留他的明星选手，作为他的王牌。

11 hell   

n.地狱，阴间；用以咒骂或表示愤怒，不满

参考例句：

• It's a hell of a hike from Sydney to Perth.从悉尼到珀斯的徒步旅行简直苦死了。
• The boss really gave me hell today.老板今天着实数落了我一通。

12 planet   

n.行星

参考例句：

• Neptune is the furthest planet from the sun. 海王星是离太阳最远的行星。
• Rubbish, however, is only part of the problem of polluting our planet. 然而, 垃圾只是我们这个星球的污染问题的一个方面。