《那些古怪又讓人憂心的問題》第24期:閃電(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.
然而位於這個陰影中並不意味著你就安全了——事實常常相反。當電流流到那個高高的物體上之後，它會接著四散流到地面上。如果你碰到了附近的地面，電流就有可能從你的身體中流過。2012年在美國因雷擊致死的28人中，有13個人是站在樹下面或附近。With all this in mind, let's look at possible lightning paths for the scenarios in the following questions.
有了這些基本知識，在接下來的幾個問題中，我們來看看在給定情況下閃電的可能路徑。
Q. How dangerous is it, really, to be in a pool during a thunderstorm?
Q．在電閃雷鳴的時候待在泳池裡到底有多危險？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．相當危險。水是可以導電的。但最大的問題不在於此——最大的問題在於如果你正在游泳，那麼你的頭會露在一大塊平整表面的外面。即使閃電擊中的是你周圍的水，那也是非常危險的。2萬安培的電流會向四周擴散——絕大部分沿著水面——但你在不同距離下各會受到多大程度的電擊是很難計算的。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.
我估計至少在幾十米的範圍內你會處於極度危險之中，在淡水中這個距離會更大，因為電流更喜歡從你電阻小的身體中流過。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時候被閃電擊中呢？水霧並不會威脅到你，它們只不過是空氣中一堆分離的水滴。真正對你產生威脅的是你腳底下的浴缸，以及和水管接觸的那攤水。Q. What would happen if you were in a boat or a plane that got hit by lightning? Or a submarine?
Q．如果我在船上或飛機上被雷擊了會怎麼樣？在潛艇上呢？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．沒有船艙的船安全性和平坦的高爾夫球場差不多。配備封閉船艙和閃電保護系統的船隻和汽車差不多安全，潛艇的安全性和水下的保險箱差不多。（不要把水下的保險箱和潛艇裡的保險箱搞混了：潛艇裡的保險箱可比水下的保險箱保險多了。）
