《那些古怪又让人忧心的问题》第24期:闪电(2)
This means you can calculate a lightning “shadow” around an object of height h on a flat surface.
Now, that doesn't mean you're safe within the shadow-often, it means the opposite. After the current hits the tall object, it flows out into the ground. If you're touching the ground nearby, it can travel through your body. Of the 28 people killed by lightning in the US in 2012, 13 were standing under or near trees.
然而位于这个阴影中并不意味着你就安全了——事实常常相反。当电流流到那个高高的物体上之后，它会接着四散流到地面上。如果你碰到了附近的地面，电流就有可能从你的身体中流过。2012年在美国因雷击致死的28人中，有13个人是站在树下面或附近。With all this in mind, let's look at possible lightning paths for the scenarios in the following questions.
有了这些基本知识，在接下来的几个问题中，我们来看看在给定情况下闪电的可能路径。
Q. How dangerous is it, really, to be in a pool during a thunderstorm?
Q．在电闪雷鸣的时候待在泳池里到底有多危险？A. PRETTY DANGEROUS. WATER IS conductive, but that's not the biggest problem-the biggest problem is that if you're swimming, your head is poking up from a large flat surface. But lightning striking the water near you would still be bad. The 20,000 amps spread outward-mostly over the surface-but how much of a jolt it will give you at what distance is hard to calculate.
A．相当危险。水是可以导电的。但最大的问题不在于此——最大的问题在于如果你正在游泳，那么你的头会露在一大块平整表面的外面。即使闪电击中的是你周围的水，那也是非常危险的。2万安培的电流会向四周扩散——绝大部分沿着水面——但你在不同距离下各会受到多大程度的电击是很难计算的。My guess is that you'd be in significant danger anywhere within a minimum of a dozen meters-and farther in fresh water, because the current will be happier to take a shortcut through you.
我估计至少在几十米的范围内你会处于极度危险之中，在淡水中这个距离会更大，因为电流更喜欢从你电阻小的身体中流过。What would happen if you were taking a shower when you were struck by lightning? Or standing under a waterfall? You're not in danger from the spray-it's just a bunch of droplets of water in the air. It's the tub under your feet, and the puddle of water in contact with the plumbing, that's the real threat.
如果你在洗澡或站在瀑布底下的时候被闪电击中呢？水雾并不会威胁到你，它们只不过是空气中一堆分离的水滴。真正对你产生威胁的是你脚底下的浴缸，以及和水管接触的那摊水。Q. What would happen if you were in a boat or a plane that got hit by lightning? Or a submarine?
Q．如果我在船上或飞机上被雷击了会怎么样？在潜艇上呢？A. A BOAT WITHOUT A cabin is about as safe as a golf course. A boat with a closed cabin and a lightning protection system is about as safe as a car. A submarine is about as safe as a submarine safe (a submarine safe is not to be confused with a safe in a submarine-a safe in a submarine is substantially safer than a submarine safe).
A．没有船舱的船安全性和平坦的高尔夫球场差不多。配备封闭船舱和闪电保护系统的船只和汽车差不多安全，潜艇的安全性和水下的保险箱差不多。（不要把水下的保险箱和潜艇里的保险箱搞混了：潜艇里的保险箱可比水下的保险箱保险多了。）
