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Squeaks, I think I hear something.
吱吱，我想我听到一些声音。
Oh! Hi there! Squeaks and I were just sorting the seashells that Squeaks found during his trip to the beach.
噢! 你好啊！我和吱吱正在整理吱吱去海滩旅行时发现的贝壳。
Where did they come from?
它们来自哪里？
Great question, Squeaks!
伟大的问题，吱吱！
They were probably washed ashore by waves.
它们可能是被海浪冲上岸的。
Yeah, waves!
是的，海浪！
Not only are those waves fun to play in, they also bring all kinds of things from deeper in the ocean right up to the shore.
这些海浪玩起来不仅很有趣，它们还可以把各种各样的东西从海洋深处带到海岸上。
The up and down motion we see in the water is called a wave.
我们看到的水流上上下下的运动被称为波动。
The top of the wave is called the crest, and the bottom is the trough.
波动的顶部称为波峰，底部称为波谷。
And one neat thing about them is that the water itself doesn’t move forward with the wave.
一个神奇之处在于，水本身不会随着海浪向前移动。
The water moves up and down as the wave travels through the water.
当波浪在水中穿行时，水会上下运动。
Think about when you floated in the water.
想想你在水里漂浮的时候。
When the waves went past you, you bobbed up and down instead of just moving all the way back to the shore.
当海浪从你身边经过时，你会上下起伏，而不是一直移动到岸边。
Yeah Squeaks, that’s right!
是的，吱吱，没错！
We can see waves in lakes and ponds too, not just in the ocean.
我们也可以在湖泊和池塘中看到波浪，而不仅仅是在海洋中。
Any time there is a body of water and wind, you can have waves.
任何时候只要有水和风，就会出现波动。
Great question!
问得好！
There are a few different reasons that waves can happen.
有几个造成波浪产生的原因。
And one of them is around us any time we go outside: Wind!
每当我们走到外面，有一种东西围绕着我们: 风!
As the wind passes over the water’s surface, the wind tugs on the water, creating waves.
当风吹过水面时，风就会拉动水面，形成波浪。
The size of the wave depends on the strength of the wind and how long it blows.
波浪的大小取决于风的强度和吹动时间。
So lots of wind can make really big waves!
所以大风可以掀起很大的波浪！
Most of the waves we see on the beach are caused by the wind.
我们在海滩上看到的大部分海浪都是由风引起的。
But can you guess something else that can make waves?
但你能猜到其他能掀起海浪的东西吗？
I’ll give you a hint: It’s big and round, and we can see it at night time.
我给你一个提示：它又大又圆，我们可以在晚上看到它。
It's the Moon!
月亮！
I’ll tell you how!
我来告诉你怎么掀起海浪！
The Moon makes waves when its gravity pulls on Earth.
当月球引力作用于地球时，会引起波动。
Gravity is the force that pulls things together.
引力是把东西拉在一起的力。
It’s everywhere!
到处都存在引力！
Here, let’s all stand up, and jump up as high as you can do safely!
现在，让我们都站起来，尽可能在安全范围内跳到最高的地方！
When you jumped, you didn’t just float away. You fell back down!
当你跳起来时，你不会就这么飘走了。你会再次下落！
That happened because Earth’s gravity pulled you down.
这是因为地球引力把你拉了下来。
Everything on Earth is held down by gravity, including the ocean.
地球上的一切都受到重力的压制，包括海洋。
The heavier something is, the more gravity it has, and planets are pretty heavy.
物体越重，其引力就越大，地球就相当重。
That means Earth’s gravity is tugging on the Moon.
这意味着地球的引力在拉动月球。
But the Moon has gravity too, and the Moon’s gravity is tugging right back!
但月球也有引力，月球的引力也在往回拽！
Our moon’s gravity pulls on Earth as it orbits around us.
月球在绕地球运行的同时也会受到地球的引力。
It pulls on us, the land, the Fort, and even the ocean.
月球牵引着我们，陆地，堡垒，甚至海洋。
And even though it doesn’t pull hard enough to move us, or the ground, the water it pulls on does move.
即使月球的引力不够大，不足以移动我们、地面，但会让水流移动。
Which means that sometimes when you’re at the beach, the moon is pulling the water closer to where you are on the shore, which is called high tide.
这意味着有时当你身处海滩时，月球引力会把水拉得更接近你在岸上的位置，这就是所谓的涨潮。
You might notice that the beach isn’t as big as usual at high tide.
你可能会注意到，涨潮时海滩不像平时那么大了。
That’s because the ocean is covering more of the beach!
那是因为海洋覆盖了更多的海滩！
But if the moon is pulling the water at a different place on the planet, the water will move away from where you are on the beach.
但如果月球把水牵引到地球上另一个方向，水就会从你所在的海滩上移开。
That’s called low tide, and low tide can mean that all sorts of things that are usually underwater are visible.
这就是所谓的退潮，退潮可能意味着所有水下的东西都是可见的。
Yeah, Squeaks, that’s why the tracks from your wheels from early in the day got covered up by the water by the time you left.
是的，吱吱，这就是为什么你一大早离开的时候，车轮留下的痕迹被水淹没了。
The tide came in!
潮水涌了进来！
After high tide, or when big waves hit the shore, like after a big storm, they can bring lots of cool objects to the surface with them!
涨潮后，或当海浪冲击海岸时，比如在大风暴之后，海浪可以把许多物体带到水面上！
Those can be great times to look for things washed up on the beach.
这可能是寻找冲上海滩之物的绝佳时机。
Like Squeaks did on his trip!
就像他旅行中的吱吱一样！
And sometimes, waves can get really big, too.
有时，海浪也会变得很大。
Let me tell you about tsunamis, the biggest kinds of waves that ever happen.
让我给你讲讲海啸，这是巨型海浪。
Tsunamis are really big waves caused by one-time events, like an earthquake or underwater volcano erupting.
海啸实际上是由如地震或水下火山喷发等一次性事件引起的巨浪。
When the waves hit the shore, they can be 30 meters tall.
当海浪冲击海岸时，它们可以有30米高。
That’s as tall as two fire trucks stacked on their ends!
与两辆消防车的高度一样高！
Good question!
问得好！
Tsunamis don’t happen just anywhere.
海啸不会发生在任何地方。
Tsunamis are more common in some parts of the world than others, like the Ring of Fire in the Pacific Ocean.
海啸在世界上的一些地区更高发，比如太平洋火环区域。
That’s because there are lots of underwater volcanoes there.
那是因为那个水域下有很多火山群。
Tsunamis are very dangerous, just like other extreme weather like tornadoes and hurricanes, and can cause whole towns to be evacuated.
海啸像龙卷风和飓风等其他极端天气一样危险，可能会导致整个城镇被疏散。
You should never be on a beach when a tsunami is coming.
当海啸来临时，你永远也不要站在海滩上。
Oh yeah, Squeaks, waves are pretty amazing and powerful!
哦，对，吱吱，海浪很神奇，同时威力巨大！
Maybe we can even learn to surf and ride waves next time we go!
也许我们下次去的时候还可以学冲浪呢！
How about you? Have you ever found anything cool at the beach? Or played in the waves?
你们呢？你在海滩上发现过什么很酷的东西吗？还是在海浪中嬉戏呢？
Thanks for learning about waves with us, and watching this episode of SciShow Kids.
感谢与我们一起了解海浪，感谢收看本期的《少儿科学秀》节目。
You can ask a grown up to help send questions to us. They can get started at patreon. com/scishowkids.
你可以请一位成年人帮忙把问题发送给我们。可以登录patreon.com/scishowkids向我们发送。
And thank you all for joining us here at the Fort!
感谢大家来到沃斯堡!
