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kilotesla t1_j696fnt wrote

Reply to comment by agate_ in Why is wind energy generation greater during the night? by ZeroTheHero524

Thanks, that's a fantastic explanation of a really interesting phenomenon!

I wanted to see a graph of it and found this plot of wind speed by hour of the day at different heights above the ground, and it very clearly shows exactly what you're describing, with the neutral point between the two trends at about 150 m. Not all wind turbines are tall enough to be above that, but I'm not sure how representative that particular data is, and the height of a wind turbine tower is often augmented by putting it on a hill.

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agate_ t1_j6a7c2x wrote

Neat, I hadn’t seen the data presented that way before. Your graph also shows an important difference between land and sea: because the sea surface is usually smoother than the land (no trees and hills), there’s less turbulent mixing and the boundary layer is usually thinner. So the neutral point you’re talking about is much lower at sea.

The weaker, thinner boundary layer also means the overall wind speed is much higher at sea, which is why people go to the trouble of building offshore wind turbines.

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