STEM与日常科技·英语30篇（6）

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为何外观相似的云朵有的降雨、有的却始终干燥

Rain formation requires cloud droplets to grow large enough to overcome updrafts and fall as precipitation.
Collision-coalescence dominates in warm clouds, where larger droplets absorb smaller ones during turbulent mixing.
In cold clouds, the Bergeron process prevails: ice crystals grow at the expense of supercooled water droplets.
Scientists use Doppler radar to detect vertical air motion and particle phase inside clouds remotely.
Aerosol concentration determines initial droplet count—too many tiny droplets inhibit growth to raindrop size.
Cloud base height and temperature profile affect whether freezing nuclei trigger ice formation early in development.
Satellite-derived microphysical data help refine weather models predicting drizzle versus downpour intensity.
Even visually identical cumulus clouds may differ internally in droplet distribution and updraft velocity.
Field campaigns deploy instrumented aircraft to sample cloud chemistry and ice nucleation activity directly.
Understanding these variables improves flood forecasting and reveals how pollution subtly reshapes regional hydrology.