英语听力：探索发现 科学新发现：我们的大气层-12

 Our atmosphere is in constant motion; the moving air that causes our weather circulates between the ground and 50,000 feet. It is the sun that drives this movement. When solar energy reaches earth, it heats the surface and atmosphere, but it does so unevenly¹. This temperature difference causes the air to move. Hot air near the equator expands and rises; cold air at the poles becomes denser² and sinks. Noah’s Marty Ralf can track its movement over the globe on the revolutionary science on a sphere simulator. 

Portrayal³  

What we are seeing here is a portrayal of the air surface temperature, and red and warm colors are warm temperatures like we see in the tropics here, up in the poles you see the blues⁴ and greens, those are the colder surface temperatures. So we can watch this, and actually see the warm air moving northward⁵, the cold air moving southward, and we can see the changes in the seasons. 

 

If the atmosphere didn’t move, the poles would be 45 degrees cooler, and the equator, 25 degrees warmer. The great deserts of the Sahara, Atacama and Mojave would expand dramatically. Northerly cities like London or Boston would be locked in an icy winter. It is only the atmosphere’s circulation that prevents this. It regulates the temperature, moving the air to create the weather that covers our globe.

1 unevenly   

adv.不均匀的

参考例句：

• Fuel resources are very unevenly distributed. 燃料资源分布很不均匀。
• The cloth is dyed unevenly. 布染花了。

2 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

3 portrayal   

n.饰演；描画

参考例句：

• His novel is a vivid portrayal of life in a mining community.他的小说生动地描绘了矿区的生活。
• The portrayal of the characters in the novel is lifelike.该书中的人物写得有血有肉。

4 blues   

n.抑郁，沮丧；布鲁斯音乐

参考例句：

• She was in the back of a smoky bar singing the blues.她在烟雾弥漫的酒吧深处唱着布鲁斯歌曲。
• He was in the blues on account of his failure in business.他因事业失败而意志消沉。

5 northward   

adv.向北；n.北方的地区

参考例句：

• He pointed his boat northward.他将船驶向北方。
• I would have a chance to head northward quickly.我就很快有机会去北方了。