雪花,是一种美丽的结晶体。空气中的水汽要形成降雪,不是温度低于0℃就可以了,还必须具备两个条件:一个条件是水汽饱和。饱和的空气冷却到露点以下的温度时,空气里就有多余的水汽变成水滴或冰晶。另一个条件是空气里必须有凝结核。1949年,国际水文协会所属的国际雪冰委员会召开 Snowflake is a beautiful crystal. The formation of snowfall from the water vapor in the air is not a temperature below 0°C. It must also have two conditions: one condition is water vapor saturation. As saturated air cools below the dew point, there is excess moisture in the air that turns into water droplets or ice crystals. Another condition is that there must be condensation nuclei in the air. In 1949, the International Snow and Ice Committee of the International Hydrographic Association was convened