时差N小时 大雁的V字形（在线收听）

If you've ever seen a bicycle race, you might have noticed the riders lining up behind each other instraight columns.

如果你看过自行车比赛，你或许注意到自行车手们都一个跟着一个排成一队。

Bicycle racers spend much of their energy overcoming wind resistance, so this lining up makesgood sense.

自行车手们耗费了很大的能量来克服风的阻力，所以这样的排队方式是很合理的。

If you ride directly behind your opponent, she'll cut through the air resistance for you, letting you save up energy for the finish line.

如果你直接骑在对手的后面。他能够为你阻挡空气的阻力，为你冲刺终点保留体力。

What's true for bicycle racers is true for otherthings too.

对于自行车手适用的道理也同样适用于其他方面的事情。

Going in straight line formation is the best way to overcome wind resistance.

以直线的队列行进是克服风阻力的最好办法。

Which brings us to those silly geese.

这让我们想到了那些愚蠢的大雁！

Like bicycle racers, geese fly in formation mainly to saveenergy.

就如自行车手们那样，大雁们以节省能量的队形飞行。

The formation they prefer however is shaped like the letter “V.”

然而它们喜欢的队形却是“V”字形。

What's going on? Aregeese just plain dumb?

这是怎么回事？难道大雁是傻瓜？

Not at all!

不是这样的。

Remember, geese don't only need to worry about air resistance—they need to stay aloft as well.

记住，大雁不仅需要担心空气阻力-他们同样也需要停留在高空。

To do this, goose wings are curved and tapered like those of an aircraft.

为了做到这一点，大雁的翅膀如弯曲的锥形的飞机机翼一般，

The top surface bulges upward while the bottom stays flatter.

表面凸起向上，底部保持平整。

Air rushes more quickly over the wing'sbulging top, and this creates a kind of upward suction.

空气很快从其翅膀顶部凸起的部分掠过，这就造成了一种向上的吸力，

This phenomenon is called “lift,” and it's agoose's secret for staying aloft.

此现象就叫做“牵引”，这就是大雁能够停留在高空的秘密。

Lift, however, is a peculiar thing.

然而“牵引”是一种很特殊的东西。

While most of it tugs upward on the goose, some of it spills awayfrom the wing tips as a kind of updraft.

大多数的引力牵引着大雁向上，一些引力则以上升气流的形式从翼尖流出。

This lingering updraft spreads out behind the goose in aV-shape like the wake of a boat.

这些残留的上升气流像船的尾迹一样在大雁的身后呈V字形伸展开。

If another goose puts its wings inside this updraft wake, it gets anadded upward boost itself.

如果另一只大雁也在这样的上升气流中展开翅膀，它会获得额外的升力来助推自己。

What's the best formation to take advantage of this?

什么样的队形能够最好地利用这个优势？

It's not astraight line, it's a “V”!

不是直线，而是“V”字形。