どうして雨はふるの？ どこからやってくるの？ ぬれるとちょっと大変だけど、
雨は地球にとって、とても大切な「水のたび」の一場面。
左にしつもん、右にこども向けせつめいで、雨の正体をやさしく見てみよう。
Why does rain fall? Where does it come from?
Getting wet can feel annoying, but rain is a very important part of Earth’s “water journey.”
With questions on the left and easy answers on the right, let’s gently learn what rain really is.
🌧水のたびWater journey💧つぶのひみつDrop secrets👃雨のにおいSmell of rain🌈雨あがりAfter the rain
それが、私たちのところにふってくる雨なんだ。
Inside a cloud, there are many tiny drops of water.
When the drops stick together and become big and heavy,
they can’t float in the sky anymore, so they fall toward the ground.
Those falling drops are the rain that reaches us.
☁️コップの水をスポイトで落としてみると、「水のつぶ」が落ちる様子をまねできるよ。Use a dropper to let water fall from a cup. You can pretend each drop is like rain falling from a cloud.
2QUESTION
どうして雲の中に水があるの？Why is there water inside clouds?
空なのに、水たまりがあるのかな？It’s sky, not a pond, so where does the water come from?
上のほうで空気がひんやりしてくると、その水じょう気が小さな水のつぶにもどる。
このつぶのあつまりが、雲なんだよ。
Water in seas, rivers, ponds, and soil changes into water vapor
(an invisible gas) when the Sun warms it. The vapor rises up into the sky.
Higher in the sky, the air becomes cooler,
so the vapor turns back into tiny drops of water.
A big group of these tiny drops is what we call a cloud.
🌊やかんの湯気が冷たい窓ガラスに当たると水のつぶになるのと、考えかたは少しにているね。It’s a bit like steam from a kettle touching a cold window and turning into water drops again.
3QUESTION
雨つぶが大きい日と小さい日があるのはなぜ？Why are rain drops big on some days and small on others?
ポツポツの日と、バシャッ！の日。Some days go “pit-pat,” other days go “splash!”
風の強さや、雨つぶが落ちるあいだにぶつかる回数でも大きさが変わるんだ。
The size of drops depends on how many tiny drops come together in the cloud.
If many drops join, they make big raindrops.
If they stay small, they fall as fine, tiny rain.
The strength of the wind and how often drops bump into each other while falling
also change the size.
🔍かさに落ちる雨つぶをよく見ると、大きいのと小さいのがまざっているのがわかるかも。Look carefully at raindrops on your umbrella. You may see big drops and tiny drops mixed together.
4QUESTION
しとしと雨とザーザー雨は、何がちがうの？What’s the difference between gentle rain and heavy rain?
どちらも雨だけど、ようすはぜんぜんちがうね。Both are rain, but they look and sound very different.
ANSWER
しとしと雨は、うすい雲から落ちる細かい雨つぶが多い。
ゆっくり時間をかけてふることが多いよ。
ザーザー雨は、分厚い雲からたっぷりの大きな雨つぶが
いっきに落ちてくる雨。短い時間で地面がびしょびしょになることもあるね。
Gentle rain usually falls from thin clouds
and has many tiny drops. It often falls slowly for a long time.
Heavy rain comes from thick clouds with many big drops.
It falls quickly and can make the ground very wet in a short time.
🎧目をつぶって、しとしと・ザーザーの音のちがいを聞き分けてみよう。Close your eyes and listen carefully. Can you hear the difference between gentle and heavy rain sounds?
5QUESTION
雨のにおいって、なんのにおい？What is the “smell of rain”?
ふりはじめの、あの特別なにおい。That special smell when the rain starts to fall.
さらに、土の中にいる小さな生きものが作る物質のにおいも
まざっていて、それが「雨のにおい」として感じられているんだ。
On the ground and roads, dust and tiny bits build up over time.
When raindrops hit them, their smell floats up into the air.
Also, there are substances made by tiny living things in the soil.
Their smell mixes in too, and we feel it as the special “smell of rain.”
👃雨の前・雨の最中・雨あがりで、においのちがいをかいで比べてみよう。Smell the air before, during, and after rain. Can you notice how the smell changes?
6QUESTION
どうして急に雨がふり出すことがあるの？Why does rain sometimes start suddenly?
さっきまで晴れていたのに、いきなりポツポツ…。It was sunny just a moment ago, then suddenly “plip-plop”…
山のかげや建物のかげで、見えなかった雨雲が、
風でズズッと動いてきた、ということもあるよ。
Clouds move with the wind.
When a cloud that has many raindrops inside reaches the sky above you,
the drops can start falling all at once.
Sometimes a rain cloud is hidden behind a mountain or buildings,
then the wind pushes it over you, and it suddenly starts to rain.
👀雨がふりそうだと感じたら、空のどのあたりに黒っぽい雲があるかチェックしてみよう。If you think it might rain, look around the sky and check where the dark clouds are.
7QUESTION
雨の音が場所によってちがうのはなぜ？Why does rain sound different in different places?
屋根・道路・葉っぱ…耳をすますと全部ちがう音。On roofs, roads, and leaves, the sounds are all different.
雨は、たくさんの小さな打楽器がいっせいに鳴っているようなものなんだよ。
The sound changes because of the material and shape
of the place where raindrops hit.
On a metal roof it may sound like “clang, clang”,
on soil or grass it may sound like “sshhh”,
and in a puddle it may sound like “plop”.
Rain is like many tiny drums and instruments
all playing at the same time.
🎵家の中のいろいろな場所で、雨の音を録音して、どの音がどこか当てっこしてみよう。Record rain in different places and then play a game: guess which sound came from which place.
8QUESTION
雨がないと、どうなってしまうの？What would happen if there were no rain?
「たのしい水あそび」だけじゃない、大事な役わり。Rain is more than just fun for water play.
雨は、地球の水をぐるぐるめぐらせる大事なしくみ。
「ちょっとめんどうな お天気」でも、地球にとっては必要な時間なんだ。
If it never rained, rivers and ponds would lose water,
and plants would wilt and dry up.
We would not have enough drinking water either.
Rain is an important way to keep Earth’s water moving around.
Even if it feels like “annoying weather,” rain is a needed time for Earth.
🌍世界の中には、雨がほとんどふらない国もあることを、地図や図鑑で調べてみよう。Look at maps or books and find places in the world where it hardly ever rains.
9QUESTION
ほかに、雨についてどんな「なぜ？」があるかな？What other “whys” about rain can you think of?
雨の日は、じつは「考える日」にもできる。A rainy day can be a great day for thinking.
IDEAS
たとえば、こんな「なぜ？」もあるよ：
どうして雨のあとに、虹が出ることがあるの？
どうして山のほうが雨が多い場所があるの？
どうして同じ町の中でも、ふる場所とふらない場所があるの？
雨は、いつごろ雪に変わるの？
For example, you might ask:
Why does a rainbow sometimes appear after rain?
Why do some mountain areas get more rain?
Why can it rain in one part of a town but stay dry in another?
When and how does rain turn into snow?
📝雨の日に思いついた「雨のなぜ？」をノートに書いて、晴れた日に図鑑やインターネットで調べてみよう。Write your “why about rain” questions in a notebook on rainy days, and check books or the internet on sunny days.