【听力文摘】夏天的风

Why is it always (1)breezy at the beach? Find out on this Moment of Science.

I bet that the last time you went to the beach, the wind was blowing in off the water. Maybe it was just a pleasant breeze, maybe something a little stronger. But it was definitely coming in off the water. What’s more, a breeze will be coming in off the water the next time you go to the beach.

How do I know? Easy.

Wind is caused by differences in the temperature of air. If you have a lot of hot air in one location and a lot of cold air next to it, the line where they meet will be (2)windy. That’s because the hot air is rising and the cold air is rushing in to fill the space left behind. Whoosh!

Now, here we are at the beach. What do you notice? Well, the sand under your feet retains heat pretty (3)effectively. Once it is hot, it stays hot. Not so for ocean water, which is much harder to heat. Think of how cold the water feels when you step into it off a hot beach.

This distinction is true of land and sea in general. On a sunny day, the land stays hotter than the sea. That means the air over the beach will be hotter than the air over the water. And that means the air will be rising over the beach.

As the hot beach air rises up, the relatively cooler air over the water moves in to take its place. The result? A sunny day in summer creates its own breeze.

译文：

夏天的风，令人舒畅

我敢打赌，你最后一次去海滩的时候，海风正从水面吹来。或许是令人愉快的微风，也或许是更强一点的风。但是它的确来自于水面，更重要的是，你下次去海滩的时候微风又会徐徐吹来。
我为什么会知道？那太容易了。
    风是由空气的温差引起的。如果一个地方有大量的热空气，它的旁边又有大量的冷空气，那么冷热空气相交的地方就会形成风。因为热空气上升，冷空气就会迅速冲到热空气留下的位置里并填满整个空间。
    现在我们站在海滩上。你注意到了什么？你脚下的沙子能够有效的保持热量。一旦它变热了，它就会维持热度。可是海水却很难变热。想想当你从水中踏入炙热的沙滩时，会发现海水是多么的寒冷啊！
    总的来说，这就是陆地和海洋的真实区别。阳光明媚的日子，陆地比海洋要热很多，那意味着海滩上空的空气将会比水面上空的空气热，也就是说海滩上的热气将会上升。
    随着海滩上空热空气的上升，水面上相对寒冷的空气就会流动过来代替热空气的位置。结果是什么呢？在夏天一个阳光灿烂的日子里有微风吹过。

 

Notes:

(1)breezy['bri:zi] adj.有微风的；轻松愉快的；通风好的；活泼的
It was a lazy, breezy summer afternoon.
这是一个懒散的，起风的夏日下午。

(2)windy['windi]adj. 多风的，有风的；腹胀的；吹牛的
And I like windy weather, too.
我也喜欢有风的天气。

(3) [i'fektivli] adv.有效地，生效地；有力地；实际上
Allocate the time effectively.
有效地分配时间。