005 暴风雨天气

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School was over for the day. Will watched his friends open their umbrellas and head home

放学了。威尔看着朋友们撑开雨伞走回家。

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Will had forgotten his umbrella." It's a good thing Dad can pick me up today

威尔忘了带伞。“好在爸爸今天能来接我。

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The weather is terrible!" he thought and sat on a bench in the hallway." I wonder why."

天气真糟糕！”他心想，坐在走廊的长椅上。“真不知道为什么。”

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Will's science class was studying weather, so he started to read the chapter about storms while he waited

威尔的科学课正在学习天气，于是他边等边读关于暴风雨的章节。

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After only a few paragraphs, he fell asleep

才读了几段，他就睡着了。

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A gust of wind made Will open his eyes. All around him was the wide-open sky!

一阵风让威尔睁开眼。四周是广阔的蓝天！

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Glancing down, he realized he was in the basket of a hot air balloon, high above the ground

低头一看，他发现自己坐在热气球的吊篮里，高高悬在地面上方。

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Suddenly Will's phone beeped loudly. He pulled QT out of his pocket and said," Hi! The people down there look like bugs!"

突然威尔的手机大声响了起来。他从口袋里掏出QT，说：“嗨！下面的人看起来像小虫子！”

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" But they'll get bigger if we start to drop," QT warned

“但如果我们开始往下掉，他们就会变大了，”QT警告道。

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" Quick, pull the silver handles down to start the burners!"

“快，拉下银色手柄，启动燃烧器！”

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As soon as Will pulled the handles, huge flames shot out above him

威尔一拉下手柄，巨大的火焰就从他的头顶喷射而出。

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" I don't want to burn the balloon!" he yelled over the burners' noise, letting go of the handles

"我可不想把气球烧了！"他在燃烧器的轰鸣声中大喊，松开了手柄。

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An image of a hot air balloon lit up QT's screen

一个热气球的图像在QT的屏幕上亮了起来。

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" We need the burners to heat the air in the balloon

"我们需要燃烧器来加热气球里的空气。

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Hot air is lighter than the cold air outside the balloon

热空气比气球外面的冷空气轻。

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That makes the balloon float," QT explained

这样就能让气球浮起来，"QT解释道。

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" Hot air rising is very powerful. It also creates the weather, you know!"

"热空气上升的力量非常强大。你知道，天气也是这样形成的！"

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" Really?" Will asked." How does it create weather?"

"真的吗？"威尔问。"它是怎么形成天气的呢？"

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" The sun heats the planet, but some areas get hotter than others

"太阳加热了地球，但有些地区比其他地区更热。

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So the air in the hot regions rises, and cooler air moves in to take its place. We call this air movement wind."

所以炎热地区的空气会上升，而较冷的空气就会流过来填补它的位置。我们把这种空气的流动称为风。"

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" So that's what makes wind!" Will watched a cloud pass by." Does hot air make clouds too?"

“原来风是这样形成的！”威尔看着一朵云飘过，“热空气也会形成云吗？”

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" Not really. When the sun heats water, some of those particles evaporate

“不完全是。当太阳加热水时，一些水粒子会蒸发。

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That means they turn into a gas, called water vapor

也就是说，它们变成了一种气体，叫做水蒸气。

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The water vapor rises with the hot air. But the air cools with time

水蒸气随着热空气一起上升。但空气会逐渐冷却。

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When it's cold enough, the water vapor condenses, meaning it becomes liquid water again

当温度足够低时，水蒸气就会冷凝，也就是说又变回了液态水。

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But the tiny droplets are so light that they float, forming clouds."

但这些微小的水滴非常轻，它们漂浮在空中，就形成了云。”

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Will pointed to a low, gray cloud in the distance." That's water?"

威尔指着远处一朵低矮的灰色云问：“那是水吗？”

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" Yes. The cloud looks dark and gray because the water is blocking the sunlight

“是的。那朵云看起来又暗又灰，是因为里面的水阻挡了阳光。

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That feathery one high above us is actually made of ice crystals, not water, because it's much colder higher up," QT explained

我们头顶高处那朵羽毛般的云，其实是由冰晶组成的，不是水，因为高处要冷得多。”QT解释道。

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Gazing at the clouds, Will commented," I like the ones that look like cotton balls best. Their shapes are always changing."

威尔凝视着云朵，感叹道：“我最喜欢那些看起来像棉球一样的云。它们的形状总是在变化。”

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" That's exactly what makes them dangerous! That harmless-looking, little cloud can quickly become a huge thundercloud, over 12,000 meters tall!

这正是它们危险的地方！那朵看似无害的小云，能迅速变成超过12000米高的巨大雷雨云！

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Look to your left, and you'll see what I mean."

看看你的左边，你就会明白我的意思了。

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Will turned and saw a tall, dark cloud in the distance." Wow! That's huge."

威尔转过身，看到远处有一朵又高又黑的云。“哇！好大啊。”

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An image of a cloud appeared on QT's screen

QT的屏幕上出现了一朵云的图像。

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" Thunderclouds form when there's a lot of warm, humid air

“当有大量温暖潮湿的空气时，就会形成雷雨云。

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First a puffy, little cloud appears, like that one

首先会出现一朵松软的小云，就像那朵一样。

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If the cloud stays warmer than the air around it, it grows taller; warm air keeps moving up and up

如果这朵云保持比周围的空气更暖，它就会长高；暖空气会不断上升再上升。

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The water droplets combine with other droplets until they get too big and heavy. Then they fall to the ground

水滴会和其他水滴结合，直到变得太大太重，然后落到地面。

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Snow and hail also fall when they get too heavy," QT explained

雪和冰雹也是当它们变得太重时就落下来了，”QT解释道。

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" It's raining over there! I hope we don't get wet," Will said." What makes it snow?"

“那边在下雨！希望我们不会被淋湿，”威尔说。“是什么造成下雪的呢？”

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" Snowflakes form when a cloud's temperature is below freezing, so water vapor turns directly into ice without becoming drops of water first

“当云的温度低于冰点时，就会形成雪花，水蒸气会直接变成冰，而不先变成水滴。”

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The ice crystals give each snowflake a unique shape," QT answered

冰晶让每片雪花都拥有独特的形状。” QT 回答。

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" Hail is another kind of precipitation. It forms in thunderclouds

“冰雹是另一种降水形式。它形成于雷雨云中。

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Water droplets are carried by wind from warmer parts of the cloud into colder parts

水滴被风从云中较暖的区域带到较冷的区域。

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The droplets freeze, and when they fall back through the warm parts of the cloud

水滴结冰，当它们落回云中较暖的区域时，

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the little balls of ice are covered by a layer of water condensing around them

小冰球会被周围凝结的一层水包裹起来。

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If another wind carries the ice up again, that layer will freeze, making the hail bigger

如果另一阵风再次把这冰粒往上带，那层水就会结冰，让冰雹变得更大。

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After many cycles of this, hail can become as big as a baseball!"

经过多次这样的循环，冰雹可以变得跟棒球一样大！”

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" I hope that thundercloud doesn't create such big hail," Will muttered, nervously watching the dark cloud." It's coming this way!"

“希望那团雷雨云不会产生那么大的冰雹。” 威尔紧张地看着乌云，小声说道，“它朝这边来了！”

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" We'd better land. We don't want to be up here if that cloud produces lightning!

“我们最好降落。如果那团云产生闪电，我们可不想待在上面！

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Pull on that cord to release some hot air," QT instructed

拉一下那根绳子，放出一些热空气。” QT 指示道。

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Will pulled on the cord, and a vent at the top of the balloon opened. They began to descend slowly

威尔拉了拉绳子，气球顶部的排气口打开了。他们开始慢慢下降。

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" What causes lightning?" Will asked

“闪电是什么引起的？” 威尔问道。

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" Well, when rain starts to fall from a thundercloud, it pulls some air down with it

“嗯，当雨开始从雷雨云中落下时，会把一些空气一起往下拉。

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The falling air and water rubs against the rising air and water, which creates electric charges

下降的空气和水与上升的空气和水相互摩擦，这就产生了电荷。

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Lightning allows this energy to flow. The same basic thing happens when you touch a metal doorknob and feel a shock."

闪电让这种能量得以释放。这跟你触摸金属门把手时感到电击的基本原理是一样的。”

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Suddenly a lightning bolt escaped from the cloud, and thunder soon followed

突然，一道闪电从云中劈出，紧接着雷声传来。

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Will tried not to seem scared, asking," Why do we usually hear thunder after lightning?"

威尔尽量不显得害怕，问道：“为什么我们通常是先看到闪电才听到雷声？”

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" When lightning strikes, it heats the air around it to thirty thousand degrees Celsius!

“当闪电击中时，会把它周围的空气加热到三万摄氏度！

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That makes the air expand very quickly

这使得空气迅速膨胀。

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As it expands, it pushes the air around it, which creates a sound wave — thunder

当它膨胀时，会推动周围的空气，这就产生了声波——雷声。

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We see lightning first because light travels much faster than sound."

我们先看到闪电，是因为光速比声速快得多。”

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" I heard that you can measure how far away lightning is by counting the seconds between the lightning and thunder

“我听说可以通过数闪电和雷声之间的秒数来测量闪电有多远。

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If three seconds pass, the lightning struck about a kilometer away," Will said

如果间隔三秒，闪电就击中了大约一公里外。” 威尔说。

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" That's right, but we're almost to the ground! Get ready to land!"

“没错，但我们快到地面了！准备着陆！”

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Will grabbed the side of the basket and closed his eyes. The basket shook as it touched the ground

威尔抓住篮子的边缘，闭上了眼睛。篮子触地时震动了一下。

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Will opened one eye and saw his dad standing over him, gently shaking his shoulder." Time to go, sleepyhead," he said

威尔睁开一只眼，看到爸爸俯身站在他旁边，轻轻地摇着他的肩膀。“该走了，瞌睡虫。” 他说。

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" I hope it's still storming," Will said as he got up." Storms are really amazing, Dad!"

“我希望外面还在刮风下雨。” 威尔站起身说道，“暴风雨真的太神奇了，爸爸！”