A certain city.

The weather was very cold, and although the snow last night was not heavy, it still turned the green belt on both sides of the street into a white expanse, which looked quite beautiful.

It doesn't snow very often in the city, only two or three times a year at most, and when it does, it always makes the people of the city happy.

This is true for adults, and even more so for children.

On the streets, there are occasional children passing by, reaching out to grab a handful of snow and playing with it in their hands, and they don't feel cold.

A tall, thin man in his thirties, with a teenage girl, was walking down a street.

The little girl seemed to be very interested in the snow on both sides of the road, holding the hands of the tall and thin man next to her, and her eyes were always staring at the snow on both sides of the road.

As she walked, the little girl tilted her head up, looked at the tall thin man next to her and asked, "Dad, why does it snow in winter?"

The tall and thin man smiled and replied, "Because the weather is very cold in winter, everything will snow." ”

The little girl said "oh", turned her head to look at the snow again, and after a while, she tilted her head again and asked, "Dad, why does it snow when it's cold?"

The thin man smiled and said, "Because... Because... This one... Because ......"

The tall and thin man's smile suddenly choked, because he found that he couldn't answer his daughter's question.

Everyone knows that it snows in winter because of the cold weather, but why does it snow when the weather is cold?

The tall and thin man thought that he should know the answer, so he didn't hesitate to answer just now.

However, when he really wanted to say it, he suddenly found that he couldn't say it clearly at all.

Why can't you say it when you feel like you should know the answer?

The tall and thin man thought about it and found the reason, it seemed that he didn't actually know the answer, just because it was a very simple natural common sense, which gave him the illusion that he knew the answer.

Or maybe he did know some concepts vaguely, but he couldn't express them accurately in words.

"Dad, why?" The tall and thin man's thoughts had just finished turning, and his daughter saw that he had not answered for a long time, so she urged again.

"This ......" The tall and thin man was a little embarrassed and anxious, and he could say, "Daddy doesn't know this either." ”

But saying this will not only disappoint his daughter, but also affect his glorious image of omniscience in his daughter's mind.

The tall and thin man didn't want things to turn out like this, but he couldn't just say an answer and get away with it.

How should this be?

The tall and thin man was a little anxious, subconsciously turned his head to look around, and found that there was a bookstore dozens of meters away in front of him, and the scale was quite large.

The thin and tall man's eyes lit up, and he remembered Li Fan's new book, the children's popular science enlightenment book "One Hundred Thousand Whys", which was officially released today.

There may be the answer he needs now.

He had indeed planned to take his daughter to the bookstore to read a book and buy one if she was interested.

Now, the time is right.

So he said to the little girl, "Yanyan, about this question, Dad wants you to find the answer yourself." Right in front of you is a bookstore with a book that might be able to find the answers you want to know. ”

"Really?" the little girl said with a blink of big eyes, "yes, yes, Daddy, let's go in quickly, I want to find the answer." ”

The tall and thin man breathed a sigh of relief, he finally passed the test temporarily, and it was best to have relevant answers on "One Hundred Thousand Whys", if not, he would have enough time to go to the Internet to find the answer.

The tall and thin man walked into the bookstore with his daughter and was about to ask a staff member where "One Hundred Thousand Whys" was.

Then he didn't ask.

Because, he has already seen "100,000 Whys", which is placed on the most conspicuous display case in the bookstore.

At this time, it was still early, and the bookstore had obviously just opened, and there were not many customers, and the display case of "One Hundred Thousand Whys" was still relatively empty.

The tall and thin man took the little girl's hand and walked to the front of the display case, picked up a copy of "One Hundred Thousand Whys" that had been opened on the display case for the guests to read, handed it to the little girl, and said, "Yanyan, it's this book, do you have any answers to look for it in this book?"

The little girl took the book, was very excited, said "yes", and then opened the book, looking for the answer she wanted.

The tall and thin man looked at his daughter, looking very serious, smiled with relief, and picked up another trial book himself, he was also going to find it, is there an answer to that question in it?

If not, he would like to take advantage of his daughter's current reading book to find relevant answers on the Internet.

When the book is opened, the tall and thin man's eyes light up, and the colorful patterns on the page are very interesting, vivid, and vivid, and should be very attractive to children.

However, if these patterns are just attractive to children, it is certainly not enough.

After all, this is a popular science enlightenment book, and those scientific knowledge should be the focus.

Otherwise, it is really the same as before, some people on the Internet worried about putting the cart before the horse.

And the relevant scientific knowledge, as revealed by those previous children's education experts, is in the form of a question and answer.

One question, one answer, and nothing else.

The tall and thin man frowned at first, fearing that his daughter would only focus on the patterns and ignore the scientific knowledge that accompanied them.

However, looking at it, he suddenly found that those scientific knowledge seemed to be the main body, and those supporting patterns were only serving the corresponding scientific knowledge.

In other words, there is no such thing as putting the cart before the horse.

Moreover, the scientific questions and answers that everyone thought would be very monotonous and boring before, now look at them with those patterns, but they will find it very interesting and attractive, and one question and one answer seems to be the best form of expression.

The tall and thin man was pleasantly surprised, worthy of Mr. Li Fan's work.

And at this time, the tall and thin man suddenly heard his daughter's surprised and excited voice, "Dad, Dad, I know, I know, I know why it snows when it's cold, you see, you see." ”

"Is there really an answer to that question?" said the tall and thin man, both surprised and ashamed.

The surprise was naturally that the daughter really found the answer on her own.

Moreover, the daughter is so excited at this time, obviously because it is the answer she found herself.

If she had told her the answer, it was obvious that she wouldn't have been so excited.

In this way, "One Hundred Thousand Whys" is indeed a very good work and definitely worth buying.

And the shame is that his daughter found the answer in the book before him, which made him a little embarrassed.

Then, the tall and thin man turned his head to look at the book in his daughter's hand, and on the page he was flipping through, there was indeed such a question:

"Why does it snow in winter?"

Here's the answer: In winter, the temperature is very low, and when the temperature in the clouds above the sky is below zero degrees Celsius, the water vapor in the clouds will condense into Xiaoice crystals and small snow crystals.

On the one hand, these Xiaoice crystals fall with the condensation and increase in weight, and on the other hand, they follow the horizontal air flow, the rising and falling air flow and the turbulent flow in the cloud.

In this way, the water vapor continues to condense on the surface of the ice crystals, and the ice crystals continue to grow and expand, and finally form snowflakes.

When the updraft is not strong enough to bear its weight, the snowflakes will keep falling, and when the surface temperature remains below zero degrees Celsius in winter, the snowflakes can fall from the sky all the way to the ground, and we can see the snow on the ground.

After reading the answer, the tall and thin man couldn't help but say in his heart: "I see. ”

He really didn't know the answer before, so it seemed that he needed to take a look at this "100,000 Whys".

......