I'm trying to figure out how quickly a planet could rotate while also having a single air flow cell, such as Hadley cells, that would circle from hot pole to cold pole, etc. as in the case of Tidally Locked Planets and Venus. I.e. what is an estimate minimum time one area of a planet must bake under a star to form the required temperature differential for a single air cell, assuming an Earth-like atmosphere and oceans to regulate it to some degree. Or, how much could you increase Venus's rotational rate without disturbing the single wind cell.
I don't understand a lot of the math around atmospherics, so I'm going off of what I can glean from papers and what we know about Venus and planets tidally locked to red dwarfs. I'm trying to ride the fine line of a planet being somewhat hostile, but still livable. So long "days" and "nights" and near constant winds that are strong, but not Venus's ridiculous wind speed strong nor temperatures that will fry or freeze a person. In the setting I'm working on the subject planet was terraformed for the sake of emulating Earth conditions, so it wouldn't make sense for said planet to have been chosen if the end product was near inhospitable. Desperation/limited options can justify this to some degree, but to the extent of walk outside an instantly die.
As I understand it, a global wind cell would feature a constant, slowly migrating cloud layer following under the hot pole slowly migrating parallel with the equator, creating seasons of "day-summer" and "night-winter". Axil tilt negligible no for simplicity's sake. Any given point on the planet would essentially have constant wind flow that, throughout the planets day-night period, would slowly shift its angle throughout all 360 degrees, ignoring geographical feature of course.
I'm just not sure if I can handwave a "day" of say 90~ 24 hour periods without making the planet inhospitable due to wind strength/temperature. Also, the presence of extremely frequent hurricanes/cyclones formed along the vertical equator? I've read mixed things on that regard. My current work around is focusing on habitable east-west bands between the central hot-pole storm and possible vertical equator storms, but again wind speed and temp remain a concern.
The paper "ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL ANDATMOSPHERIC PARAMETERS", seems like it might have some answers, and did shed some light on some things, but a lot of it is beyond me. Seems like at 1/16th rotation rate you already get some pretty significant leveling out of longitudinal temperature differences, at least.