木曜日は、マリーのはてな日記/Marie the Scientist
How do airplanes make clouds?」
How do airplanes make clouds?
Today, on my way home from school, I saw clouds behind an airplane.
My friend Haruto and I thought it was so cool.
Then I started to wonder how they were made.
“Haruto, do you know what those clouds are made of?”
I’m not sure.
Maybe the airplane has a cloud-making machine.”
How about asking your father?
His job is to fix airplanes, right?”
My father knows everything about airplanes.
Come to my house tomorrow and let’s ask him.”
“Welcome to our home, Marie.
I heard from Haruto that you have a question for me.”
“That’s right, sir.
How do airplanes make clouds?”
“The clouds behind airplanes are called contrails or vapor trails.
But first, let me ask you a question.
Do you know what all clouds are made of?”
“I don’t know.”
“I’ll change the question.
Have you seen your breath become white like a cloud on a cold winter day?”
“Yes, I have.”
“Has that happened on a hot summer day?”
“No, why is that?
Oh, I know.
The temperature is different.”
You see our body temperature is about 36 degrees celsius.
So our breath is about that temperature.
Usually, we don’t see water in our breath but it’s there.
When our warm breath meets cold air, the water in our breath quickly cools down.
It becomes very small drops of water that we can see.”
“That’s why our breath looks like clouds.”
“The clouds from airplanes are the same thing.
Do you know that air high above the ground is very, very cold?”
“Dad, people on TV climbing Mt Everest were wearing really warm clothes.”
“That’s right, Haruto.”
“Mt Everest is about 8,800 meters high.
And most airplanes fly at about 10,000 meters.
The temperature there is about minus 50 degrees celsius.”
“That’s really cold.”
“The air coming out of airplane engines is really hot.
So the water in that air turns into clouds when it leaves the engines.”
“So airplanes don’t have machines that make clouds then.”
“Well, I guess in a way.
The airplane engines are like cloud-making machines.
If the airplanes have two engines, then you will see two lines of clouds.”
“Do you understand now, Marie?”
“Yes, I do.
Thank you, sir.”
“Let’s play a game now.”
“I’m going home.
I’m going to write everything I learned in my diary.
See you tomorrow, Haruto.”
I bought your favorite chocolate.”
“Haruto, maybe next time.”
I’m so happy I talked to Haruto’s father.
Now I can’t wait for winter.
Then I can see my breath become a cloud.