十万个为什么·科学阅读30篇（4）

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为什么避雷针有时会在云地闪击前触发向上先导？

As thunderclouds build negative charge overhead, strong electric fields induce positive charge buildup on tall grounded objects.
Sharp tips on lightning rods enhance local field strength enough to ionize surrounding air molecules and start upward streamers.
These conductive plasma channels rise tens to hundreds of meters, seeking connection with downward leaders from clouds.
Not all streamers connect—but successful ones create low-resistance paths that guide lightning safely to ground.
High-speed cameras show upward leaders initiate 10–100 milliseconds before the main strike occurs.
Tall structures without rods rarely launch streamers because their rounded shapes lack sufficient field concentration.
Modern rod designs optimize tip curvature and grounding resistance to maximize reliable streamer initiation.
Failure to launch a timely streamer increases risk of side flashes damaging nearby electronics or structures.
This process demonstrates how controlled ionization prevents chaotic, destructive discharge paths.
Engineers simulate these dynamics using computational electrodynamics models before installing protection systems.

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

This process demonstrates how controlled ionization prevents chaotic, destructive discharge paths. 该过程体现了可控电离如何避免混乱、破坏性的放电路径。
Engineers simulate these dynamics using computational electrodynamics models before installing protection systems. 工程师在安装防雷系统前，会借助计算电磁学模型模拟这一动态过程。
High-speed cameras show upward leaders initiate 10–100 milliseconds before the main strike occurs. 高速摄像显示，向上先导通常在主雷击发生前10–100毫秒启动。

这篇中文题目最接近哪一句？为什么避雷针有时会在云地闪击前触发向上先导？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？雷雨云在上方积聚负电荷时，强电场会使高大接地物体表面感应出正电荷。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） Why Do Lightning Rods Sometimes Trigger Upward Streamers Before Cloud-to-Ground Strikes? How to cook noodles A maths worksheet

This process demonstrates how controlled ionization prevents chaotic, destructive discharge paths.

This process demonstrates how controlled ionization prevents chaotic, destructive discharge paths.

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：This process demonstrates how controlled ionization prevents chaotic, destructive discharge paths.