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为什么有些云会降雨，而另一些却始终干燥？

Rain forms only when cloud droplets grow heavy enough to fall before evaporating.
Tiny water droplets usually stay suspended unless they collide and merge into larger drops.
Clouds over oceans often contain more salt particles, which act as better condensation nuclei.
In dry air below clouds, raindrops may evaporate completely—a phenomenon called virga.
Cumulonimbus clouds rise high and cool rapidly, allowing ice crystals to form and trigger snow-rain cycles.
Stratus clouds are shallow and stable, so droplets rarely reach falling size without strong updrafts.
Wind shear and humidity layers determine whether droplets survive the descent to ground.
Scientists use radar to track droplet size distribution and predict rainfall likelihood accurately.
Pollution can create too many tiny nuclei, leading to many small drops that never coalesce.
That’s why some polluted cities see frequent drizzle but rarely heavy downpours.

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In dry air below clouds, raindrops may evaporate completely—a phenomenon called virga. 云层下方的干燥空气中，雨滴可能完全蒸发，这种现象称为‘雨幡’。
That’s why some polluted cities see frequent drizzle but rarely heavy downpours. 正因如此，一些受污染的城市常有毛毛雨，却很少出现暴雨。
Rain forms only when cloud droplets grow heavy enough to fall before evaporating. 只有当云滴增长到足够重、能在蒸发前下落时，才会形成降雨。

这篇中文题目最接近哪一句？为什么有些云会降雨，而另一些却始终干燥？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？只有当云滴增长到足够重、能在蒸发前下落时，才会形成降雨。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 Some Clouds Rain While Others Stay Dry? How to cook noodles A maths worksheet

In dry air below clouds, raindrops may evaporate completely—a phenomenon called virga.

In dry air below clouds, raindrops may evaporate completely—a phenomenon called virga.

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：In dry air below clouds, raindrops may evaporate completely—a phenomenon called virga.