The way things work in fluid dynamics is that the source of a movement is both the strongest and most orderly. This decays as we get farther away from the source, leading to turbulence and a weakening of the overall strength.
It follows that only local weather phenomena, relatively close to the surface of our planet can be attributed to solar radiation. Prevailing winds, higher up, must be due to something else because turbulent and relatively weak winds at the surface cannot generate strong and orderly winds higher up.
Furthermore, Earth's rotation cannot generate strong winds on its own. It must be coupled with something above or below. Something must connect onto the atmosphere to produce the prevailing winds. Additionally, we have the fact that winds close to the poles go west to east, while they go east to west closer to the equator. If Earth's rotation is a major factor, prevailing winds should go in one direction only.
It appears then that the source of prevailing winds cannot be Earth's surface. On the contrary, it must be external to Earth. A prime candidate for this would be the Birkeland currents connecting Earth to the Sun, visible as auroras at the poles of our planets. If the auroras are but a small fraction of the overall currents, and these currents connect to the atmosphere, then we would have strong orderly winds high up and weaker, more chaotic winds closer to Earth's surface.
The fact that such currents consist of counter rotating layers also explain why prevailing winds go in a different direction at the poles, relative to the equator. If the current rotates west to east close to the poles and east to west farther away, prevailing winds will do the same, as explained by Donald Scott in his latest video.
Prevailing winds on Earth
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