十万个为什么·科学阅读30篇（1）

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为什么沙漠白天酷热，夜晚却极度寒冷？

Deserts cool rapidly at night because dry air holds very little water vapor to trap heat.
During daytime, sand absorbs solar energy efficiently but cannot store it for long.
At sunset, the ground radiates heat back into space with almost no atmospheric 'blanket' to slow loss.
Clear skies—common in deserts—allow infrared radiation to escape freely and unimpeded.
Humid regions retain warmth longer because water vapor absorbs and re-emits outgoing heat.
Temperature swings of 30°C within 12 hours are normal in places like the Sahara or Gobi.
Plants and animals adapt with burrowing, nocturnal activity, or reflective surfaces to manage extremes.
Satellite data shows desert surfaces lose heat three times faster than forests or oceans do.
This rapid cooling also explains why frost sometimes forms in deserts despite annual averages above freezing.
It’s not the lack of sun—but the lack of moisture—that makes desert nights so chilling.