Why Deserts Get So Cold at Night

课文

1. Deserts cool rapidly after sunset because they lack moisture, clouds, and vegetation — all of which trap heat near Earth’s surface.

   沙漠日落后迅速降温，因为缺乏水分、云层和植被——而这些都能将热量滞留在地表附近。

2. Dry air holds very little water vapor, and since water vapor is a strong greenhouse gas, it cannot re-radiate much heat back downward.

   干燥空气含水汽极少，而水汽是一种强效温室气体，因此无法向下辐射大量热量。

3. Sand and rock absorb intense solar energy during the day but also lose it quickly at night through infrared radiation.

   沙石白天吸收强烈的太阳能量，但夜间又会通过红外辐射快速散失。

4. Without cloud cover to reflect outgoing heat, that energy escapes directly into space, causing sharp temperature drops.

   没有云层反射地表散发的热量，这些能量便直接逸散至太空，导致气温骤降。

5. In some deserts, temperatures may fall more than 30°C between afternoon and pre-dawn hours.

   某些沙漠午后至黎明前的温差可超过30°C。

6. This large diurnal range makes desert survival challenging for plants and animals, driving adaptations like nocturnal activity.

   如此巨大的昼夜温差使动植物生存艰难，从而演化出夜行等适应机制。

7. Thermometers placed just above hot sand at noon may read over 70°C, yet dip below freezing before sunrise.

   正午时分，置于灼热沙面之上的温度计读数可能超70°C，而日出前却可降至冰点以下。

8. Satellites clearly detect this effect: desert surfaces emit far more longwave radiation at night than humid regions do.

   卫星清晰观测到这一现象：沙漠地表夜间释放的长波辐射远高于湿润地区。