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Welcome back.
欢迎回来。
All right, this weather can be sort of spooky and you might see it in an old scary movie.
好吧，这种天气可能有点诡异，你可能会在一部古老的恐怖电影中看到这种天气。
When it's happening it's sort of like a cloud has formed really close to the ground and it makes it hard to see.
当这种天气发生时，它就像一朵云在离地面很近的地方形成，这使得它很难被看到。
Can you name that weather, Squeaks?
你能说出那种天气的名字吗，吱吱？
What's that?
那是什么？
Oh, you want to ask all our friends watching to help you figure out the answer.
哦，你想让我们所有观看视频的朋友帮你找出答案。
Okay, can you all out there name that weather?
好了，你们都能说出那种天气的名字吗？
It sounds like they're saying fog, Squeaks.
听起来像是他们在说雾，吱吱。
What do you think?
你认为如何？
Yeah, you all got it. It's fog.
是啊，你知道是什么了。是雾。
Thanks, everyone.
谢谢大家。
Now, here's Jesse to tell us all about it.
现在，杰西来告诉我们关于雾的知识。
Have you ever looked outside only to see that the air was thick and gray and you could barely see?
你是否有过这样的经历:望向窗外，只见空气浑厚而灰暗，你几乎什么也看不见?
Squeaks and I looked out of the Fort window this morning and that's exactly what we found.
今天早上，我和吱吱从堡垒的窗户往外看，这正是我们发现的。
It was such a strange and different thing to see.
这是一件如此奇怪和与众不同的事情。
Normally we can see a few trees outside and even a road.
正常情况下，我们可以看到外面的几棵树，甚至一条路。
But today we could barely see the closest tree.
但今天我们几乎看不到最近的一棵树。
It was a little bit spooky and the news put out a warning to be careful when driving on the roads.
这有点吓人，新闻发出警告，在路上开车要小心。
All of this was because of the gray mist covering everything.
所有这一切都是因为灰色的薄雾笼罩着一切。
And it's called fog.
这就是雾。
Fog can make it hard to see outside.
雾会让人很难看到外面。
And walking through it can make you feel a bit damp or cold.
穿过雾会让你感到有点潮湿或寒冷。
When I walk through fog, I always imagine that I'm walking through a big rain cloud that's right, Squeaks it seems that way because fog does look a lot like clouds except really close to the ground.
当我在雾中行走时，我总是想象我正在穿过一片巨大的雨云没错，听起来是这样的，因为雾看起来确实很像云，只是离地面很近。
In fact, clouds and fog are made of the same thing, tiny droplets of water.
事实上，云和雾是由同样的东西组成的，都是微小的水滴。
From far away clouds might sometimes look like thick fluffy pillows or even cotton candy.
从远处看，云有时看起来像厚厚的绒毛枕头，甚至是棉花糖。
But really walking through a cloud wouldn't feel fluffy or comfortable at all.
但真正在云层中行走并不会让人感到蓬松或舒适。
You get really wet.
你会浑身湿透的。
There's always some water in the air.
空气中总有一些水。
Except it's not a liquid. It's usually a gas.
只是它不是液体。通常是一种气体。
The same type of thing as the air itself which is why we can't see it.
就像空气本身一样，这就是我们看不到它的原因。
We call that type of water, water vapor.
我们称这种水为水蒸气。
But when there's too much water in the air it condenses or pulls together really close to become a bunch of super tiny droplets of liquid.
但当空气中有太多的水时，它就会凝结或靠近，形成一团超微小的液滴。
When this happens high up in the sky all those little droplets form what we call a cloud.
当这种情况发生在高空时，所有这些小水滴都形成了我们所说的云。
This can happen much closer to the ground too.
这也可能发生在离地面更近的地方。
Which is when we call it fog.
这就是我们所说的雾。
It just doesn't happen as often.
只是这种情况不会经常发生。
For fog to form there needs to be a lot of water that's just reached the ground.
要形成雾，需要有大量刚刚到达地面的水。
That's right.
没错。
Just after a rainstorm, is the perfect time for fog to happen?
暴风雨过后，是产生雾的最佳时间吗?
There's all that water on the ground, plus there's a lot of water vapor that's still in the air.
地面上有所有的水，另外还有大量的水蒸气仍在空气中。
Next the water vapor has to get pretty cold very quickly.
接下来，水蒸气必须很快变冷。
If the temperature drops the water, vapor in the air starts to collect into those little liquid droplets.
如果温度降低水，空气中的水蒸气开始聚集成那些小液滴。
You can see this happen in real life if you have some cold water in a glass.
如果你在玻璃杯里放一些冷水，你可以在现实生活中看到这种情况。
Pretty soon the outside of the glass will be wet but that water doesn't come from inside the glass. It comes from the air.
很快，杯子的外面就会变湿，但水不是从杯子里面流出来的。它通过空气出来。
The cold glass makes water vapor in the air collect into liquid drops.
冷的玻璃使空气中的水蒸气凝结成水滴。
When this happens in the air outside the little droplets are so small that they can float through the air and we can see them all spread out and that's fog.
当这种情况在外面的空气中发生时，小水滴非常小，它们可以漂浮在空气中，我们可以看到它们都散开了，这就是雾。
It really is just like a cloud on the ground.
它真的就像地面上的一朵云。
There are lots of different types of fog and each happens in different places with different amounts of cold air.
有很多不同类型的雾，每一种都发生在不同的地方，有不同数量的冷空气。
The most common kind is called radiation fog.
最常见的一种是辐射雾。
This is the kind of fog that sets in overnight when air with a lot of water vapor in it cools down.
这种雾是在含有大量水蒸气的空气在夜间冷却时形成的。
In the morning when the sunlight warms the air again, the radiation fog disappears.
早晨，当阳光再次使空气变暖时，辐射雾就会消失。
Good question, Squeaks.
问得好，吱吱。
Where does the water go when the fog disappears?
当雾消失时，水去了哪里？
When the water in the fog starts to heat up, it begins to evaporate or turn back into water vapor and spread out.
当雾中的水开始变热时，它开始蒸发或重新变成水蒸气并扩散开来。
When the water vapor is spread out again in the air, we can't see it it's too small for our eyes.
当水蒸气再次扩散到空气中时，我们就看不到它了，它太小了，我们的眼睛看不见。
But just you wait Squeaks, I hear it's supposed to get pretty cold tonight and I bet we'll get some more fog.
但你就等着吧，吱吱，我听说今晚会很冷，我打赌会出现更多的雾。
