Every year, coastal regions brace themselves for violent windstorms known as hurricanes. But how do these storms form and grow?
每年，沿海地区都要准备迎接狂风暴雨，它们被称之为飓风。但这些飓风是如何形成和增强的呢？
The oversimplified answer: Warm ocean water plus the Earth’s eastward rotation.
最简单的回答是：温暖的海水加上地球自转向东。
“They’re heat engines,” said meteorologist Jeff Masters of the websiteWeather Undergroundin aprevious interview. “They take heat from the oceans and convert it to the energy of their winds. They’re taking thermal energy and making mechanical energy out of it.”
“飓风被称为热力发动机”，在之前的采访中‘地下气象站’网的气象学家杰夫·马斯特这样说。“它们从海洋获得热能然后转换为风能。飓风产生于热能然后释放为机械能。”
The natural engine that is a hurricane is fueled by warm, moist air. The storms move heat from the ocean surface high into Earth’s atmosphere. They can travel thousands of miles from the tropics toward the Earth’s poles.
天然引擎飓风源于湿热的空气。风暴推动洋面上湿热的空气直达大气层，它们可以从赤道跋涉万里到达两级。
According toNOAA’s National Hurricane Center, the average hurricane eye—the still center where pressure is lowest and air temperature is highest—stretches 20 to 30 miles across, with some even growing as large as 120 miles wide.
据NOAA国家飓风中心表示，飓风眼通常无风，而且表面压力最小顶端温度最高，它的直径一般从20英里到30英里，有时甚至可成长到120英里。
The strongest storms, equivalent to Category 5 on the Saffir-Simpson scale, have sustained winds that exceed 155 miles an hour.
最高级别的飓风，是撒佛-辛普森等级的第5级，持续风速可超过156英里每小时。
Why Are Hurricanes Dangerous?
为什么飓风如此危险？
While hurricanes are categorized based on their wind speeds, wind isn’t typically the most dangerous part of such storms. “It’s the storm surge,” said Kerry Emanuel, an atmospheric scientist at MIT, in an earlier interview. The storm surge is the bulge of water built up in front of a cyclone or hurricane courtesy of its winds.
虽然飓风是按照风速进行等级划分，但风速却还不是这种风暴最危险的地方。“是风暴潮，”在此前接受媒体采访时，麻省理工大学的大气科学家克里·伊曼纽这样表示。风暴潮是由气旋或飓风涌起的海面异常升降。
It’s the number one killer in hurricanes, Emanuel explained. “That’s what killed people in Katrina, it’s what killed people in Sandy and in Haiyan.”
它是飓风中的头号杀手，伊曼纽解释道。“风暴潮才是在卡特里娜飓风中杀死人们的凶手，同样也是在桑迪飓风和海盐飓风中杀死人们的凶手”
Emanuel likened a storm surge to a tsunami. One just happens to be caused by earthquakes (tsunamis), while the other is generated by hurricanes.
伊曼纽把风暴潮比喻成海啸，只不过海啸是由海底地震引起，风暴潮是由海面飓风引起。
Flash flooding caused by intense rains is also a major killer, Emanuel said. “Hurricane Mitch [in 1998] killed 12,000 people and it was all from flash flooding.”
由强降雨造成的山洪也是飓风中的一大杀手，伊曼纽说。1988年的米奇飓风造成了12000人死亡，这全是由山洪爆发导致的。
Then comes wind that blows around debris. Hurricane Andrew in 1992 is an example of this. “It didn't really cause too much of a storm surge,” the atmospheric scientist said, “but boy did it blow a lot of buildings down.”
接下来的一大杀手是裹挟着碎片的大风，1992年的安德鲁飓风就是这样的一个例子。“它并没有造成太大的风暴潮，但是却摧毁了很多的建筑”，伊曼纽这样说道。
Climate change will likely increase the frequency of “the high-end hurricanes,” Emanuel said.
“气候变化可能会增加大型飓风的出现频率”，伊曼纽说。
And those powerful storms have the potential to produce a lot of rain, flooding, and strong storm surges.
而那些强大的风暴有可能产生强降雨，洪水和较强的风暴潮。
Is That a Hurricane or a Cyclone?
到底是飓风还是气旋？
What’s the difference between hurricanes, cyclones, and typhoons? Actually, they’re all the same weather phenomenon. Scientists just call these storms different things depending on where they occur.
飓风，龙卷风和台风之间的区别是什么？其实，他们都是同样的气候现象。科学家们只是根据它们发生的地点不同进行分别命名。
In the Atlantic and northern Pacific, the storms are called hurricanes, after the Caribbean god of evil, named Hurrican.
大西洋和北太平洋地区的风暴被称为飓风，飓风一词源自加勒比海的恶魔——飓风。
In the northwestern Pacific, the same powerful storms are called typhoons. In the southeastern Indian Ocean and southwestern Pacific, they are called severe tropical cyclones.
在西北太平洋，同样强大的风暴被称为台风。在东南印度洋和西南太平洋，它们被称为强热带气旋。
In the northern Indian Ocean, they're called severe cyclonic storms. In the southwestern Indian Ocean, they're just called tropical cyclones.
在印度洋北部，他们被称为强气旋风暴。在西南印度洋，他们仅仅被叫做热带气旋。
To be classified as a hurricane, typhoon, or cyclone, a storm must reach wind speeds of at least 74 miles an hour.
如果想要被叫做飓风，台风，或者气旋，风速必须达到至少74英里每小时。
If a hurricane’s winds reach speeds of 111 miles an hour, it is upgraded to an “intense hurricane.”
如果飓风的风速达到111英里每小时，就被升级为“强飓风”。
If a typhoon hits 150 miles an hour—as Usagi did in 2013—then it becomes a “supertyphoon.”
如果像2013年的台风天兔那样达到150英里没小时，就变成了“超强台风”。
While the Atlantic hurricane season runs from June 1 through November 30, the typhoon and cyclone seasons follow slightly different patterns.
而飓风季节是从6月1日一直到11月30日，台风和气旋与之大致相同。
In the northeastern Pacific, the official season runs from May 15 to November 30. In the northwestern Pacific, typhoons are most common from late June through December. And the northern Indian Ocean sees cyclones from April to December.
在东北太平洋，飓风的官方季节是从5月15日到11月30日。在西北太平洋，台风常见于6月下旬一直到12月。在印度洋北部，气旋发生在4月到12月。
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