科学素养与生活应用·英语30篇（2）

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为什么雷声总在闪电之后才传来？

Lightning heats air instantly to over 30,000°C, causing rapid expansion and shock waves.
These shock waves travel outward as sound — what we hear as thunder.
Light travels nearly one million times faster than sound, so we see lightning first.
The delay between flash and boom helps estimate storm distance in miles or kilometers.
Sound moves at about 343 meters per second in dry air at 20°C.
Humidity, temperature, and wind affect thunder’s speed and how far it carries.
Long rumbles occur when sound reflects off hills, buildings, or layers of air.
If thunder arrives within three seconds, the storm is dangerously close — under one kilometer.
Sometimes lightning is silent because it’s too far for sound to reach clearly.
Scientists use microphone arrays to map lightning paths by analyzing thunder arrival times.