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I'm not familiar enough with the correct terms I need to use, so forgive me if I ask this poorly. I'm building a fantasy world in which my MC is a healer, and I thought it would be fun to put her in a rainforest, since a lot of cool healing herbs can be found there. So I'm basing the rainforest loosely on what's in the Amazon, and the country she is in is based roughly on Peru in the sense that there are both mountains and a rainforest, only I've flipped it mirror image with the ocean and the mountains on the east and the rainforest to the west.

However, after studying prevailing winds and the Coriolus effect, I realized I have a problem. At latitudes between 0 and 30 degrees, where a rainforest needs to be, prevailing winds are easterlies - that is, they blow from the east. On our Earth, that means the prevailing winds bring a lot of rain into the Amazon. But with my world's mountain range being on the East, they're going to block the prevailing winds, and I'll have no rainforest.

So I'm wondering, if a habitable planet were tipped 23.5 degrees in the opposite direction of how our Earth is tilted, would that make the prevailing winds between 0 and 30 degrees latitude blow from the west? If not, what effect would a reverse axis tilt have?

Thanks, all!

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    $\begingroup$ What do you mean by "opposite direction", exactly? You mean that at apogee pole that is now closer to the sun would be farther from it? $\endgroup$ – Mołot Apr 24 '17 at 8:48
  • $\begingroup$ Welcome to WorldBuilding! If you have a moment please take the tour and visit the help center to learn more about the site (and earn a badge). Have fun! $\endgroup$ – Sec SE - clear Monica's name Apr 24 '17 at 8:50
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    $\begingroup$ If you want to change the wind direction, you need to change the direction of rotation of the planet. $\endgroup$ – Mike Scott Apr 24 '17 at 8:52
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    $\begingroup$ High mountains block humidity. Air rising over mountains cools down and moisture in it precipitates out, so you can't have a rain forest on the leeward side of a mountain range. You can have one on the windward side though. And changing the rotation indeed mirrors the prevailing winds (and also the Gulf stream and many other things). $\endgroup$ – Swier Apr 24 '17 at 9:01
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    $\begingroup$ Re the later edit: don’t ask more than one question in a post, and don’t change the question after answers appear. $\endgroup$ – JDługosz Apr 24 '17 at 19:28
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The direction relative to the sun (which drives the weather) is reversed every 6 months. Your geometry and suppositions make no sense. A more subtle effect is which hemisphere is pointing toward the sun when the Earth is at its closest vs farthest ends of the orbit. That changes over thousands of years as the axis precesses. But that has nothing to do with the Coriolis force.

illustration

To make the Coriolis force go the other way, you need to reverse the spin on the planet. That would also reverse the common meanings of East and West, so that doesn’t change anything really.

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    $\begingroup$ It depends if you define east and west relative to the planet's spin or relative to the north and south magnetic poles. You could certainly have a planet where the direction of spin around the north and south poles was reversed. $\endgroup$ – Mike Scott Apr 24 '17 at 19:26
  • $\begingroup$ It changes the meaning of east and west relative to local geography. $\endgroup$ – ApproachingDarknessFish Apr 24 '17 at 19:48
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    $\begingroup$ @MikeScott the magnetic poles reverse over time. This happens on the sun every 22 years or so, and they don’t change the meaning of East/West every few years. Mars has an East but no magnetic field. $\endgroup$ – JDługosz Apr 24 '17 at 19:52
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This is directed more to the question as asked in the title that what you are asking in the body.

I believe that currently, during the southern summer, the Earth is closer to the Sun. However, as a large percentage of the southern hemisphere's surface is covered by ocean, the greater potential for heating is moderated by the ocean absorbing and transporting the heat.

If the axis of the Earth is reversed (and this does slowly shift over long periods of time), this means that the northern summer with take place while the planet is nearest the sun.

With the much greater proportion of land surface to ocean surface in the northern hemisphere, the greater heat at this time would be much less moderated. Northern summers would be several degrees higher.

This is entirely dependent on the current configuration of the Earth.

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    $\begingroup$ I believe that currently, during the southern summer, the Earth is closer to the Sun If by southern summer you mean "January" then your belief is correct. $\endgroup$ – Binary Worrier Apr 24 '17 at 13:21
  • $\begingroup$ Not if but when, as this cycles every 25000 years or so. $\endgroup$ – JDługosz Apr 24 '17 at 13:30
  • $\begingroup$ @BinaryWorrier Is there another definition for summer in the southern hemisphere? Or is this just to clarify my statement, that could be easily interpreted as specifically talking about the current date in April rather than a much more general "current period" and its relationship between the Earth's axis and the Sun. $\endgroup$ – Michael Richardson Apr 24 '17 at 14:42
  • $\begingroup$ Apologies, I found the phrase "southern summer" relatively unclear, it took me a moment to decide that you understood what you are saying. I thought the phrase could be open to misinterpretation so I added the comment to avoid said misinterpretation and assert that your belief is correct. I am unaware of what the "correct" definition of summer is for the southern hemisphere, "southern summer" may well be it $\endgroup$ – Binary Worrier Apr 24 '17 at 14:50
  • $\begingroup$ The perihelionnis currently January 3. $\endgroup$ – JDługosz Apr 24 '17 at 19:54

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