十万个为什么·科学启蒙30篇（1）

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雷声和闪电是如何产生的？

Lightning is a giant spark of electricity that jumps between clouds, within a cloud, or from a cloud to the ground.
It forms when rising and falling air currents cause ice particles and water droplets to collide inside storm clouds.
These collisions separate positive and negative charges, building up huge voltage differences across regions of the cloud.
When the electric field becomes strong enough, the air—normally an insulator—breaks down and conducts electricity suddenly.
That rapid flow of electrons heats the air to around 30,000°C, which is five times hotter than the Sun’s surface.
The superheated air expands explosively, creating a shock wave we hear as thunder.
Because light travels faster than sound, we always see lightning before hearing thunder.
You can estimate how far away lightning struck by counting seconds between flash and boom—every three seconds equals about one kilometer.
Lightning rods don’t attract lightning but safely direct its current into the ground if a strike occurs nearby.
About 100 lightning bolts hit Earth every second, yet fewer than 10% of them strike the ground directly.