圣艾尔摩之火

陈延洲

For those not familiar， “St. Elmos Fire” is a name for the glow1 that looks like blue violet fire surrounding the top of pointed metal objects during a storm.

为那些不熟悉它的人说明一下，“圣艾尔摩之火”是指在暴风雨中金属物尖端周围所产生的如火焰般的蓝紫色光。

This phenomenon2 can trace its name back to an Italian saint3 “St. Elmo” or “St. Erasmus” around 300 A.D.， the patron4 saint of early Mediterranean sailors. This glow tended to appear on the tops of the masts5 of ships during a thunderstorm. People believed that if St. Elmo appeared， it was a good omen6 and an answer to the sailors prayers7， as the seas would begin to die down and the winds would calm. If he （the glow） appeared during times of good weather， it was said that St. Elmos guiding hand was warning of a storm.

這种现象的名称可以追溯到公元3世纪左右的意大利圣人“圣艾尔摩”，又名“圣伊拉斯谟”，他是早期地中海水手的守护神。在雷雨期间，这种光往往出现在船桅顶端。人们认为，如果圣艾尔摩出现，那就是个好兆头，是对水手祈祷的回应，因为大海将平静下来，风将逐渐平息。如果这种光在天气好的时候出现，据说那是圣艾尔摩的指引之手正发出警告，一场暴风雨即将到来。

Charles Darwin even wrote about the phenomenon in a letter. He wrote about a night spent on a ship during a thunderstorm， “Everything was in flames， the sky with lightning， the water with luminous8 particles9， and even the very masts were pointed with a blue flame.”

查尔斯·达尔文甚至在一封信中写到了这种现象。他写到了雷雨中在一艘船上度过的一晚，“每样东西都像是着了火，天空在闪电，水里闪烁着发光的微粒，甚至连桅杆顶端都有蓝色的火焰。”

Scientifically， this phenomenon is known as a “point discharge”. It can， and commonly does， happen at the tip of any conductive10 surface during thunderstorms. It can be seen on the tops of church steeples， lightning rods， the tips of airplane wings， and even blades of grass and the horns on cattle！

从科学上讲，这种现象被称为“尖端放电”。在雷雨期间，这种现象通常发生在任何导电的物体表面。在教堂的尖顶、避雷针的顶端、飞机机翼的尖端，甚至草叶和牛的尖角上都可以看到它！

Benjamin Franklin was the first to more or less correctly describe the phenomenon in 1749. He thought the “fire” was a way lightning rods would “draw out” a thunderstorms electricity slowly before it built up enough charge11 to form a strike.

在1749年，本杰明·富兰克林是第一个或多或少正确描述这个现象的人。他认为“火焰”是避雷针在雷暴积累足够电荷以形成雷电之前，缓慢释放雷暴电的一种方式。

So why does this happen during thunderstorms， and why does it happen more easily with pointed metal objects？

那么为什么在雷暴期间会发生这种情况呢？它又为什么会更容易发生在尖锐的金属物体上呢？

A pointed conductor12 will have more electrons13 than an object that doesnt have a pointed tip， and therefore more charge， at its tip.

尖锐的导体比没有尖端的物体带有更多的电子，因此在它的尖端会有更多的电荷。

During thunderstorms， free electrons， positively charged ion clusters14 （at the surface of the ships mast） and the surrounding air， all colliding15 with each other in a form of matter known as plasma16. Plasma will give out light and give life to St. Elmo and his “fire”！

在雷雨期间，自由电子、（船桅表面的）正电荷离子簇和周围的空气，都以一种称为等离子体的物质形式相互碰撞。等离子会发光，从而点亮圣艾尔摩之火！

The color will depend on the type of gas present. Since our air is made up of mainly nitrogen17 and oxygen， it will glow blue violet.

颜色将取决于存在的气体类型。因为我们的空气主要是由氮和氧组成的，所以它会发出蓝紫色的光。

In the end， St. Elmo and his amazing blue violet fire is only a natural phenomenon.

最终，圣艾尔摩和他那令人惊叹的蓝紫色火焰仅仅只是自然现象。

（英语原文选自：www.todayifoundout.com）