hoes does the wind mix to the surface at night or on a cloudy day?

Answer 1

Well, it does less of it than it would during the daytime or when it's sunny, but it's still possible. One way to do it is to have topographic obstructions, such as mountains, that create turbulence and can bring the upper-level winds down. Also, just because it's cloudy does not mean that there is not convection. But if you're talking about a situation with stratiform clouds in flat terrain on a calm night, there will be much less mixing to the surface.

Answer 2

Say What??

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