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I'm working on an earht-like map and I'm having a hard time understanding where to put the high and low pressure zones. Here's some background info first.

Axial tilt: 25 degrees

Tropics latitude: 25 degrees

Polar circle latitude: 65 degrees

How would axial tilt affect the location of the Hadley cell, Ferrell cell, and etc?

Does it impact the location of pressure zones? If so, by how much?

Would I need to shift the latitude of the pressure zones? Or would the high and low pressure zones remain at 30 and 60 degrees respectively

Would the be larger because of the slightly more extreme seasons?

I've tried following Azélor on Cartographer's Guild and Artifexian on Youtube but no one has answered the question regarding axial tilt.

Thank you so much for any help and if there is any information I should add here or if I put the wrong tags please let me know. Thank you!

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  • $\begingroup$ Lot of questions. Low evidence that you did any research yourself. $\endgroup$
    – puppetsock
    Feb 6, 2020 at 14:39

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The earth itself actually gets really close to the 25° you mention. According to NASA the obliquity of Earth's axial tilt varies between 22.1° and 24.5° over roughly 40000 year cycles.

There really isn't much (if any) information out there about correlation between axial tilt and how it'd influence the atmospheric phenomena you're asking about. This probably has something to do with the lack of comparable examples. We only have earth to work with.

However, Venus also has Hadley cells and its tilt is 177° and what seems to be a bigger factor is that venus has a way thicker atmosphere which makes it so it has only two hadley cells. Hadley cells on Venus

Another major influence on the layout of pressure systems is the land configuration on your earth. The image below shows the ideal distribution of pressures on earth if its surface was uniform on the left, and the actual recorded pressures and hadley cells on actual earth. Ideal earth vs actual earth

Conclusion: There are other factors that probably have a lot more influence on these patterns than a slight deviation in axial tilt, which would only make seasons slightly more pronounced. If you're working on a fictitious world with a whole new layout different from earth, it's basically guesswork what will happen where exactly, though understanding these phenomena and extrapolating the recurring patterns on earth could help you make a realistic estimation about what prevailing winds reign in certain areas of your world and how pronounced the effects are on your climate and pressure zones.

Regarding air pressure. 910hPa - 1090hPa should still be your pressure range given your atmosphere is equal in composition, density and height as Earth's atmosphere. (Mind that the values given here are the absolute extremes on earth since measurements started).

But you can deviate a little from Earth's pressures given the layout of your lands permits such circumstances (which would basically be guesswork since no data can be acquired from non-existing land).

Sources - In case you like more information on the subject.

https://www.britannica.com/science/Ferrel-cell https://www.seas.harvard.edu/climate/eli/research/equable/hadley.html https://www.wunderground.com/blog/weatherhistorian/world-and-us-lowest-barometric-pressure-records.html https://www.wunderground.com/blog/weatherhistorian/world-and-us-anticyclonic-high-barometric-pressure-records.html

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  • $\begingroup$ I don't think that a thick atmosphere would have anything to do with the number of hadly cells. They are a result of the coriolis effect after all, so the day length matters most. Note additionally that Titan switches between having one global circulation cell and a two hadly cell setup depending on the season. $\endgroup$
    – TheDyingOfLight
    Feb 6, 2020 at 18:10
  • $\begingroup$ Thickness of the atmosphere is but one factor of many that influence how many cells form and their properties. That's more the point I'm trying to make with the different examples. $\endgroup$
    – Hyfnae
    Feb 6, 2020 at 19:37
  • $\begingroup$ In other words, I could probably get away with making the same way you'd make a pressure zone map of earth, only making sure it abides by my land masses, correct? $\endgroup$
    – Ashley
    Feb 6, 2020 at 23:26
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    $\begingroup$ pretty much. You could always deviate them a little if it serves purpose in the world you're building for some regions to have a certain climate or certain prevailing winds. But if your planet is comparable to earth in size, rotation and atmosphere, very similar patterns would occur if the main difference is the slightly greater obliquity of the tilt. $\endgroup$
    – Hyfnae
    Feb 6, 2020 at 23:43
  • $\begingroup$ Thanks so much, this was incredibly helpful. You broke it down into more digestible portions. $\endgroup$
    – Ashley
    Feb 8, 2020 at 8:09

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