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On a real world Earth, the seasonal changes in temperature of continents create high-pressure areas during winter in that hemisphere, and low-pressure areas during summer in that hemisphere.

Should an Earth-like planet have a continent, that is stretched across the equator, having significant area in both hemispheres, would it form two different pressure centers due east from its longitudinal middle? For example, during January, would it have high-pressure area in the north and low-pressure area in the south?

To be specific, let's suppose the continent is an elliptic blob, that reaches latitudes of at least 45 degrees in both hemispheres, and its length along the equator is at least 10000 kilometers.

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  • $\begingroup$ You might have better luck asking this question on Earth Science.SE. They seem to allow meteorology questions there, and you will probably find more people who specialize in that area. Worldbuilding generally accepts broader kinds of questions and "what if" scenarios, but you probably will not find as many people who are experts in any particular area as you would on a site dedicated to that area. For example, if you have a chemistry question, you will find more chemistry experts on Chemistry.SE than Worldbuilding. $\endgroup$ – John Locke Feb 9 at 15:58
  • $\begingroup$ @JohnLocke You might be right, but this is such a "what if" question, that I am unsure it would be appropriate for Science SE. $\endgroup$ – Heagon Feb 9 at 16:01
  • $\begingroup$ I asked on the Earth Science.SE chat if this question would be on-topic. chat.stackexchange.com/transcript/message/48955068#48955068 $\endgroup$ – John Locke Feb 9 at 16:09
  • $\begingroup$ I believe there are two trans-equitorial continents on Earth, South America and Africa. Perhaps studying their pressure zones would be helpful. $\endgroup$ – M. A. Golding Feb 9 at 18:24
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    $\begingroup$ Could you draw a map and edit your question to include it? I'm having trouble understanding why the weather over North+South America or Eurasia+Africa doesn't answer this question? $\endgroup$ – JBH Feb 10 at 18:38
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Let's talk about atmospheric circulation

enter image description here

Image courtesy Slideplayer.com, and the slideshow would be well worth your visit (especially slide #3). Click on the image to get a bigger view. Click on the link above to visit the slideshow.

As you can see, circulation pulls air away from the equator, both to the north and to the south. Ignoring the dynamics of weather for a moment: you tend to get high pressures at the poles and near the equators and low pressure zones near the tropics (of Cancer and Capricorn). They move around for lots of reasons, but the point I'm making is that it's unlikely to get a high above the equator and a low below the equator at the same time at the same longitude because that's not what the air wants to do.

Curiously, we can replace your test case continent with open ocean, like the Pacific. It's a large, uniform "surface" that crosses the equator. If you can get the climatic condition you want with one, you can get it with the other. Bit of rambling there, back to the story....

Now, I say unlikely because the pretty picture isn't taking into account axial tilt, which shifts the "center" of where sunlight strikes on the planet. Depending on the season, the "center" is either slightly above or slightly below the planetary equator. That shifts things up and down (simplistically, very simplistically). I'm also not taking into account oceanic currents, which contribute to atmospheric flow nor the tendency of a planet to form a jet stream, which is rotational wind that slides around things because nothing is actually smooth. When you combine all these (and without doubt others) you have the ability to position a high on one side of the equator and a low on the other — but atmospheres are dynamic, so it wouldn't last because (and this is my opinion), it's not a stable condition. As mentioned above, you would expect a high/high above and below the equator and lows at the tropics.

Conclusion

Briefly (aka, days) you could have the situation you're looking for, but not for a long period of time.

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