英语听力精选进阶版 14336

Weather 'behind ozone¹ hole'

Summary

13 December 2013

Scientists have been puzzled by the hole in the ozone layer, which forms each year over Antarctica, but has been changing in size from year to year. Now Nasa researchers say the changes are mostly due to the weather - not the ozone-destroying chemicals in the atmosphere. The findings were presented at the American Geophysical Union Fall Meeting in San Francisco.

Reporter:

Rebecca Morelle

Report

Ozone-damaging substances - such as CFCs - began to be phased out 20 years ago. Since then, the hole in ozone layer stopped getting bigger. However there haven't yet been signs of a full recovery - and damaging UV rays from the sun are still streaming through. 

Now scientists from Nasa believe that the weather also plays a key role. Satellite images show that fluctuating² air temperatures and winds change the amount of ozone that sits above Antarctica. This means the size of the ozone hole changes year on year. 

The team thinks the weather will continue to be the dominant³ driver in the process until 2030. But after that, as the long-lasting chemicals in the atmosphere finally start to clear, the layer could recover by 2070.

1 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

2 fluctuating   

波动，涨落，起伏( fluctuate的现在分词 )

参考例句：

• Fluctuating prices usually base on a fickle public's demand. 物价的波动往往是由于群众需求的不稳定而引起的。
• In many applications a fluctuating DC current is undesirable. 在许多应用场合，波动的直流电是讨厌的。

3 dominant   

adj.支配的，统治的；占优势的；显性的；n.主因，要素，主要的人(或物)；显性基因

参考例句：

• The British were formerly dominant in India.英国人从前统治印度。
• She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。