十万个为什么·科学阅读30篇（1）

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为什么先见闪电后闻雷声？

Lightning and thunder happen at almost the same instant during a storm, but we see light before hearing sound.
Light travels at 300,000 kilometers per second, while sound crawls at just 343 meters per second in air.
That huge speed difference means light reaches our eyes nearly instantly, even from several kilometers away.
Sound takes about three seconds to travel one kilometer, so counting seconds helps estimate storm distance.
A flash followed by a five-second delay means lightning struck roughly 1.7 kilometers away.
Sometimes thunder sounds like a sharp crack—this occurs when the bolt is very close and the sound hasn’t spread yet.
Rolling thunder happens when sound waves bounce off hills, buildings, and different layers of the atmosphere.
Studying lightning paths helps meteorologists improve early-warning systems for severe weather events.

听 → 读 → 学表达 → 懂 → 今天会说这一句 → 跟读录音 → 自己说一句。

Studying lightning paths helps meteorologists improve early-warning systems for severe weather events. 研究闪电路径有助于气象学家改进极端天气事件的早期预警系统。
A flash followed by a five-second delay means lightning struck roughly 1.7 kilometers away. 闪电后五秒听到雷声，说明闪电发生在约1.7公里外。
That huge speed difference means light reaches our eyes nearly instantly, even from several kilometers away. 如此巨大的速度差意味着光几乎瞬间到达我们的眼睛，即使来自数公里之外。

这篇中文题目最接近哪一句？为什么先见闪电后闻雷声？一次学校运动会的通知一份超市购物清单

课文第一句的意思更接近？雷电在风暴中几乎同时发生，但我们先看到光后听到声音。今天学校放假了。请把窗户打开。

这一课主要在讲什么？（看英文标题） What Makes Lightning Flash Before Thunder Rumbles? How to cook noodles A maths worksheet

Studying lightning paths helps meteorologists improve early-warning systems for severe weather events.

Studying lightning paths helps meteorologists improve early-warning systems for severe weather events.

第一版：录下来、回听、再听标准音。系统打分以后再加。

用今天的表达，自己说一句。

例子：Studying lightning paths helps meteorologists improve early-warning systems for severe weather events.