I'm working on an earth-like world that has a two main continents akin to Eurasia+Africa. but centred on the Equator. Basically, the premise is to shift the east-west axis of diffusion that exists on Earth across the Eurasian steppe south to the tropics. Therefore, I'm looking to maximize savannah and/or hot steppe climates, although tropical rainforests are by no means unwelcome. (if anyone's interested, I'm trying to create a world that goes counter to the popular idea that agriculture and thus civilization can only arise in mediterranean/temperate zones; I'm reading Tropical Forests in Prehistory, History and Modernity which has really changed the way I understand both agriculture and tropical climates -- a PDF can be found for free online :-) )

enter image description here

In all respects aside from the continental layout the world is like Earth. The highest mountains are at the collision of the "African" and "Eurasian" plates. I haven't yet worked out montane climate zones nor sea ice.

I've taken a crack at the climate method outlined in Artifexian's videos on the subject, but after taking a look through Geoff Eddy's climate cookbook, I think I may be missing some nuance, especially when it comes to such large equatorial continents. I've read that rainforests produce more than 50% of their own rain, so I've tried to give less import to onshore winds and generally make the regions near the equator wetter than my instincts would lead me to. My climate map after a couple of iterations looks like this:

enter image description here

Am I on the right track? In particular, is my distribution of tropical rainforest and hot desert right? Is the continent big enough that the interior would be dry out of sheer size? Related: how are my ocean gyres? There are some narrow seas in between continents that it's not obvious to me how water would circulate in; getting these right will help me properly situate my deserts & fine-tune my Ferrel cell climates.



1 Answer 1


Overall I think this is realistic, but given the prevailing winds and position of mountain ranges, I think you've overestimated the extent of the rainforest and underestimated the arid and desert.

Deserts and Rainshadows

  • A: Your hot deserts will feed dry air to the south, extending the arid and tropical savannah regions more toward the equator. Remember also that continental interiors are generally drier: the Amazon and Congo rainforests are dwarfed by their surrounding savannahs.

  • B: These mountains should produce a rainshadow effect as they block moist winds coming from the south. If there are glacier-fed rivers in the western valley you could expect thin strips of savannah (not shown).

I would expect something more like this:

Revised Tropics and Deserts

But arid climates so close to the equator? Peru, Equador, southern Somalia, and Kenya have 'em.

There are some narrow seas in between continents that it's not obvious how water would circulate in.

The opposite direction from what you expect, but I'm not entirely sure why. The surface currents of the Mediterranean, Caspian, and Black Seas, and Hudson Bay, circulate counterclockwise, though oceans at the same latitude circulate clockwise:

Caspian Sea surface currents Black Sea surface currents Mediterranean Sea surface currents Hudson Bay surface currents

If your continent were shifted 30°+ north or south I'd imagine these inland seas would have a notable impact on local climate, but aligned as they are in the tropics I wouldn't expect it.

  • $\begingroup$ thanks, I expanded the desert and arid zones like you suggested ! $\endgroup$
    – fred die
    Mar 13, 2021 at 21:03
  • $\begingroup$ as for the inland sea currents, is this realistic? [1]: i.stack.imgur.com/zJmbO.jpg $\endgroup$
    – fred die
    Mar 14, 2021 at 0:49
  • $\begingroup$ That was my first thought as well. Pangaea was a lot like this and it was thought to have pretty big interior arid zones simple because there was land so far from the ocean in the hot equator. $\endgroup$ Mar 14, 2021 at 2:57

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