为什么冬天天上会飘下雪花？
Why do snowflakes fall from the sky in winter?
当高空气温冷到零度以下，云里的小水滴会冻成六角形的小冰晶。这些冰晶越聚越大，轻轻飘下来，就成了漂亮的雪花。
When the air high up is below freezing, the tiny droplets in clouds freeze into six-sided ice crystals. The crystals clump together and drift down gently as pretty snowflakes.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#雪 #冰晶 #冬天
为什么暴风雨过后空气特别清新？
Why does the air feel especially fresh after a storm?
雷电会把空气中的氧气变成少量清新的臭氧，带来下雨后特有的味道。同时雨水把灰尘和花粉洗到地上，风又把干净的空气吹了过来。
Lightning turns some oxygen in the air into a small amount of fresh-smelling ozone, giving that special after-rain scent. At the same time, rain washes dust and pollen to the ground while wind brings in cleaner air.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
戴树桂 主编,《环境化学》第2版,高等教育出版社,2006
Dai Shugui ed., Environmental Chemistry, 2nd ed., Higher Education Press, 2006
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9787040199567（按标识回读: 环境化学）
#雷雨 #空气 #臭氧
为什么风会吹起来？
Why does the wind blow?
太阳把地面晒热，热空气变轻往上升，旁边的冷空气就跑过来填补空位，这就形成了风。海边白天风从海上吹来，晚上又从陆地吹回去，特别有趣。
The sun warms the ground, and the heated air rises because it is lighter, so cooler air rushes in to fill the space — that is wind. At the sea, the wind blows from the ocean by day and back from the land at night, which is fun to notice.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#风 #空气 #太阳
为什么我们每时每刻都要呼吸？
Why do we need to breathe all the time?
我们身体里的每一个小细胞都需要氧气才能工作，呼吸就是把氧气送进去、把废气送出来的过程。如果憋住气太久，身体就会不舒服。
Every tiny cell in our body needs oxygen to work, and breathing brings oxygen in and sends waste air out. If we hold our breath too long, our body starts to feel unhappy.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#呼吸 #氧气 #身体
为什么清晨的空气凉凉的？
Why is the morning air cool and fresh?
夜里没有太阳，地面慢慢把白天存的热散掉，气温就降了下来。等到太阳升起，空气才又被慢慢晒暖。
At night there is no sun, so the ground slowly loses the heat it stored during the day, and the temperature drops. When the sun rises, the air is warmed up again little by little.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#清晨 #凉爽 #气温
为什么天上会飘着白白的云？
Why are there white clouds floating in the sky?
地上的水被太阳晒热，变成看不见的小水汽飞到天上。在高高的冷空气中，小水汽聚成无数小水滴，就变成我们看到的白云。
The sun warms water on the ground, turning it into tiny invisible vapor that floats up high. In the cold upper air, the vapor gathers into countless little droplets, and we see them as white clouds.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#云 #水汽 #天空
为什么下雨后有时会出现彩虹？
Why do rainbows appear after the rain?
太阳光看起来是白色的，其实藏着红橙黄绿青蓝紫七种颜色。雨后的小水珠像小棱镜，把阳光分开，就在天上画出弯弯的彩虹。
Sunlight looks white but hides seven colors — red, orange, yellow, green, blue, indigo, and violet. Tiny raindrops after a storm act like little prisms, splitting the light into a curved rainbow.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#彩虹 #阳光 #雨水
为什么沙漠白天很热、晚上却很冷？
Why are deserts hot by day but cold at night?
沙漠里植物和水很少，白天太阳把沙子晒得滚烫，热量散不出去。到了晚上，干燥的空气留不住热气，温度就很快降下来，变得冷飕飕的。
Deserts have little plant and water, so by day the sun makes the sand scorching and the heat has nowhere to hide. At night the dry air cannot hold the warmth, so the temperature drops quickly and it feels chilly.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#沙漠 #温差 #昼夜
为什么一年会有春、夏、秋、冬四个季节？
Why do we have four seasons — spring, summer, autumn, and winter?
地球是歪着身子绕太阳转的，所以一年里阳光照到每个地方的角度会慢慢变化。当阳光更斜、白天更短时，那里就进入了凉爽的秋天和冬天。
Earth is tilted as it travels around the sun, so the angle of sunlight on each place changes slowly through the year. When the light becomes slanted and days grow short, that place moves into cool autumn and winter.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#季节 #地球 #阳光
为什么高山上的空气让人觉得喘不上气？
Why does the air on high mountains feel hard to breathe?
我们头顶的空气越往上越稀薄，因为大部分空气被地球引力拉在了靠近地面的地方。爬到很高很高的山顶时，每一次呼吸吸到的氧气变少了，所以会觉得气短。
The air gets thinner the higher you go, because Earth's gravity pulls most of it down near the ground. At a very high peak, each breath holds less oxygen, which is why you may feel breathless.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#高山 #空气 #氧气
为什么有些花到了晚上会合拢花瓣？
Why do some flowers close their petals at night?
许多花在白天张开花瓣，吸引蜜蜂和蝴蝶来传粉；夜里变冷变暗，它们就合上花瓣保暖、也保护里面的花蕊。等到天亮温度回升，花瓣又会重新打开。
Many flowers open by day to welcome bees and butterflies for pollination; when night turns cold and dark, they fold their petals to stay warm and protect the center. As the morning warms up, the petals open again.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Prokop, Fedor,《Why do flowers close at night? Experiments with the Lesser celandineFicaria vernaHuds (Ranunculaceae)》, Biological Journal of the Linnean Society, 2016 (DOI: 10.1111/bij.12752)
Prokop, Fedor, 'Why do flowers close at night? Experiments with the Lesser celandineFicaria vernaHuds (Ranunculaceae)', Biological Journal of the Linnean Society, 2016, DOI: 10.1111/bij.12752
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1111/bij.12752
#花朵 #昼夜 #传粉
为什么强大的飓风喜欢在温暖的海面上生成？
Why do strong hurricanes form over warm ocean water?
海面越暖，海水蒸发越多，把大量热和水汽送进空气里。这些暖湿空气旋转着上升，就像给风暴的马达加了油，使风雨越来越大。
The warmer the sea surface, the more water evaporates and feeds heat and vapor into the air. This warm, moist air rises and spins like fuel for a storm's engine, making the wind and rain grow stronger.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#飓风 #海洋 #温暖
为什么太阳照着我们会觉得暖暖的？
Why do we feel warm when the sun shines on us?
太阳像一个巨大的火球，不停地把光和热送到地球上。照到我们身上的阳光，就把暖暖的能量传给了皮肤和衣服。
The sun is like a giant ball of fire that keeps sending light and heat to Earth. The sunlight that reaches us passes its warm energy into our skin and clothes.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
韩启德总主编《十万个为什么》(第六版),少年儿童出版社,2013
Han Qide chief ed., Ten Thousand Whys, 6th edition, Juvenile and Children Publishing House, 2013, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#太阳 #温暖 #能量