Can a triangular continent (sharp part oriented south) the size of Australia and located exactly at the equator be entirely desert if it is surrounded by two mountain ranges (comparable to the Himalayas) extending from its southern edge to its Its northeast and northwest corners due to the rain shadow?

the shape of the continent:


I already know that the equator is often rainforest and very humid, but is it possible for this continent to be a desert? And if it is, what might its climate be?


3 Answers 3


Assuming that the continent is somewhere on Earth.

First, "rain shadow" has limited applicability so near the equator, because there is very little wind there. Certainly not in the northern part of the continent, which is squarely in the inter-tropical convergence zone.

If the two mountain ranges are comparable to the Himalayas, then (1) they are very very young, and (2) they are hundreds of kilometers across.

Australia has an area of about 7,700,000 km²; the triangular continent being about the size of Australia, this makes the length of each of the three sides about 3,000 km. The continent extends from about 8° northern latitude to about 15° southern latitude.

  • 8,000 meters tall mountains will surely have glaciers on them. Those glaciers will drain both towards the sea and towards the interior. There will be significant rivers draining the interior of the continent; how large will those river be is an authorial choice. If you want them to be lost in the desert like the rivers which drain the Pamirs to the north, so be it.

  • The two coastal mountain chains being so young, this means that the continent is being actively squeezed from the west and from the east; this will of course raise the land between the mountain chains, so that the southern third of the continent will be a high plateau, comparable with the Tibetan plateau on Earth. Whatever the climate will be there, it won't be what we normally think of as tropical.

  • There may be extensive lowlands in the northern half of the continent, unless the entire continent is an ancient elevated craton like Africa. If there are lowlands in the northen part of the continent, they will likely be typical equatorial jungle, as they have no reason not to be. Think the north-western part of Borneo.

  • What the middle part of the continent will look like is anybody's guess. It can be low, it can be hilly. It can be well irigated by the rivers coming down from the lofty mountains. Or it can be a semi-arid savannah if you like. My bet is that it will look like the land around Lake Victoria.



kenya topo map and landform

Kenya is like what you describe but the triangle is rotated. Kenya is right on the equator. The relevant rain shadows are to the north and west.

I put in a topo map of Kenya and rotated my version of your triangle to overly the mountain ranges causing the rain shadow. Then google map of Kenya so you can see the desert.

  • $\begingroup$ That triangle is about 10 times too small. The length of one side of the triangle is about 800 km, whereas the triangular continent in the question is about 2600 km north to south. $\endgroup$
    – AlexP
    Jun 22, 2022 at 19:22

The Amazon forest is right next to the Andes in South America, and it doesn't look like it has any desert due to rain shadow: the mixing caused by Coriolis force would ensure that some moist air would go past the mountains' shield.

Therefore I doubt that your configuration would achieve the result you hope. It would probably be a tad less rainy, but not completely dry as you would expect from a desert.

  • 1
    $\begingroup$ The prevailing winds in equatorial South America are from the east. The Sechura/Coastal/Atacama desert(s) is the Andes' rain shadow $\endgroup$
    – dspeyer
    Jun 22, 2022 at 18:43

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