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Earth famously possesses three distinct circulation cells per hemisphere.

Now out of curiosity one could use a weather app, like windy, to display the wind structures at ground level globally, and the supposed return winds at around 250 hPa height.

When I do that, the picture is very messy and I cannot see any clear circulation cells.

I suppose, that all the other messy physics of the Earths atmosphere will overlap with the cells, but is there a time in the year or variable I can use to see the circulation cells in wind maps?
Or are they in the end just an idealised time-average, that we use to model the winds / (trade winds, famously..) and don't exist at any given time?

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    $\begingroup$ @gansub: But specifically I need the zonally averaged latitude height cross section, right? If I take only a cross-section, then I'm plotting the messy, daily variations that I see in a weather map as well. $\endgroup$ Oct 7, 2019 at 12:03
  • $\begingroup$ @gansub: Well, simple 2D (lon-lat) perturbation analysis shows that circulation cells must exist as large scale circulation features. Also trade winds exist. So I would have expected to see at least some aspects of the cells in a wind map. If you can lift this seeming contradiction, I bet that would make for a great answer! $\endgroup$ Oct 9, 2019 at 10:43
  • $\begingroup$ Would be interested in some details about that perturbation analysis - I can't really picture what it shows. Also, what sort of cell features would you expect/hope to see? You might need to look further away from the surface (e.g., 925 hPa) to get rid of some of the noise. $\endgroup$
    – Deditos
    Oct 9, 2019 at 16:14
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    $\begingroup$ @Deditos: A perturbation analysis like in my answer here earthscience.stackexchange.com/questions/992/… , which I've also applied to the planets of the solar system in my M.Sc. thesis (the more correct Rhines scale thoough) and it works well to predict the correct order of cell numbers. I've looked at various height levels at ventusky.com, but there were no clear patterns. It might also require the right projection, or time of the year, which I've included in the question. $\endgroup$ Oct 9, 2019 at 16:18
  • $\begingroup$ Ah yes, I know the sort of thing, showing that steady-state cells would exist even in a dry atmosphere. In the real atmosphere the upward branch is driven by moist convection, so is meridionally narrower, and eddys (barotropic, baroclinic) dominate the picture day to day. (You probably know better than I do how these cell/eddy length scales interact to produce a visually confusing picture rather than, say, banding.) I can see aspects of some of this on that website (there's also a nice Gill-like pattern at 300 hPa over the E Pacif at the mo). $\endgroup$
    – Deditos
    Oct 10, 2019 at 16:24

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Yes, the wind cells are just a toy model, where we can suppose that the homogenity of the Earth and other things. But there are other things and Earth isn't same on the all points, so the instantaneous winds don't follow their cells. Of course, it is possible (by pure statistics) that sometimes in the Earth history, the majority of the winds was aligned with their cells. But the cells are just averaged over the period of more decades and centuries.

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  • $\begingroup$ Sorry for late answer :) $\endgroup$
    – User123
    Mar 1, 2021 at 12:11
  • $\begingroup$ No worries, but the question was essentially already answered in the comments. $\endgroup$ Mar 2, 2021 at 18:59

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