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What Makes Thunder Sound So Loud and Rumbling
雷声为何如此响亮且持续轰鸣？
精读先不看文字，完整听一遍。
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Thunder results from the rapid expansion of air heated instantly to over 30,000°C along a lightning channel.雷声源于闪电通道中空气瞬间被加热至30000°C以上而急剧膨胀。
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This superheated air explodes outward faster than the speed of sound, creating a powerful shock wave we hear as thunder.这种过热空气以超音速向外爆炸，形成我们听到的强烈雷声冲击波。
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Because lightning bolts are often several kilometers long and branched, sound arrives from multiple points at slightly different times.由于闪电常长达数公里且呈分叉状，声音从多个位置以略微不同的时间到达。
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Nearby thunder sounds like a sharp crack, while distant rumbles come from farther segments whose sound waves travel longer paths.近处雷声尖锐如爆裂，远处隆隆声则来自更远的闪电段，其声波传播路径更长。
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Hills, buildings, and temperature layers in the atmosphere can reflect and refract these sound waves, stretching them further.山丘、建筑物及大气中的温度层会反射和折射这些声波，使其传播更远。
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The low-frequency components travel farther than high ones, which is why thunder often deepens as it fades.低频声波比高频声波传得更远，因此雷声常随衰减而变得低沉。
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You can estimate distance in miles by counting seconds between flash and bang and dividing by five.可通过计算闪电与雷声间的秒数并除以五，估算距离（英里）。
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In rare cases, upward lightning or volcanic eruptions produce similar acoustic signatures, though with different origins.极少数情况下，向上发展的闪电或火山喷发也会产生类似声学特征，但成因不同。
精读 · 大约 10 分钟
听 → 读 → 学表达 → 懂 → 今天会说这一句 → 跟读录音 → 自己说一句。
③ 学 · 重点表达
- In rare cases, upward lightning or volcanic eruptions produce similar acoustic signatures, though with different origins. 极少数情况下，向上发展的闪电或火山喷发也会产生类似声学特征，但成因不同。
- Thunder results from the rapid expansion of air heated instantly to over 30,000°C along a lightning channel. 雷声源于闪电通道中空气瞬间被加热至30000°C以上而急剧膨胀。
- This superheated air explodes outward faster than the speed of sound, creating a powerful shock wave we hear as thunder. 这种过热空气以超音速向外爆炸，形成我们听到的强烈雷声冲击波。
④ 懂 · 选一选
⑤ 今天会说这一句
In rare cases, upward lightning or volcanic eruptions produce similar acoustic signatures, though with different origins.
⑥ 跟读并录音
In rare cases, upward lightning or volcanic eruptions produce similar acoustic signatures, though with different origins.
第一版：录下来、回听、再听标准音。系统打分以后再加。
⑦ 说 · 自己来一句
用今天的表达，自己说一句。
例子：In rare cases, upward lightning or volcanic eruptions produce similar acoustic signatures, though with different origins.
已记下。连续天数以后会显示在课表里。
陈老师指导
课程开发中，敬请期待。成人和孩子都可以先自学听读、精读。
这边的讲解音轨还在做。想先跟着老师走完固定 30 课，可以去陈老师带读社（和自学通行不是同一份会员）。
课程开发中，敬请期待。