另一方面，如果你见到一条常常的痕迹在空中持续一段很长的时间，这意味着大气层的水汽已经饱和不能在继续吸收多余的水分了。

On the other hand, if you see a contrail that lasts a long time, this means the upper atmosphere is already saturated with as much water vapor as it can hold.

youdao

另一方面，如果你见到一条常常的痕迹在空中持续一段很长的时间，这意味着大气层的水汽已经饱和不能在继续吸收多余的水分了。

On the other hand, if you see a contrail that lasts a long time, this means the upper atmosphere is already saturated with as much water vapor as it can hold.

youdao