It's kind of like stirring a mixture of two fluids.

这有点像搅拌两种液体的混合物。

This is a dangerously parochial attitude, for the atmosphere is but one of two fluid systems circulating above Earth's solid surface.

这是一种危险的狭隘态度，因为大气只是在地球固体表面上方循环的两个流体系统之一。