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远古时候,每当久旱不雨,土地龟裂的时候,人们总盼望着能有呼风唤雨的神灵出现。后来人们在长期的实践中认识到,雨是云的产物,云是空中水库,但把空中那朵朵白云化为甘露,却是由一个偶然发现的。1946年7月,美国科学家谢弗在冰箱里作实验。那天天气特别热,冰箱的温度降不下来,于是他将一块本身温度为一79℃的干冰(固态二氧化碳)放了进去,想降低温度。刹那间,冰箱里出人意料地出现了成千上万的冰晶。谢弗欣喜若狂,他想到,若是在低于0℃的云层里人为地使用少量催化剂,也会使云中增加许多冰晶,当冰晶相
In ancient times, people always looked forward to the appearance of gods who could do what they want when there is no rain and the land is cracked. Later, people realized in the long-term practice that the rain is the product of the cloud and the cloud is the air reservoir. However, turning the blossoming clouds into the nectar in the sky was discovered by chance. In July 1946, American scientist Xie Fu experimented in the refrigerator. It was particularly hot that day and the temperature in the refrigerator did not drop, so he put in a piece of dry ice (solid carbon dioxide) at a temperature of 79 ° C and tried to lower the temperature. Suddenly, thousands of ice crystals appeared in the refrigerator unexpectedly. Shaaver ecstatic, he thought, if in the clouds below 0 ℃ artificially use a small amount of catalyst, but also make the cloud to add a lot of ice crystals, when the ice phase