I am wondering exactly what features and properties are required for an area for a rainforest to be able to believably develop. So can people here please inform me of the known requirements, with citations to different writings if possible.

I am asking here to know what areas I should be able to believably place Rainforests. Without it seeming absurd. People don't want be to use Hard Science, so please try to give me citations or such despite this only asking for science-based. I like having more reliable sources to look into as well rather than just relying on random people online.

  • $\begingroup$ Hard science and Science based are mutually exclusive tags. I have taken out the most strict, in terms of requirements toward the answers. You can switch to the other if you disagree. $\endgroup$
    – L.Dutch
    Dec 30, 2021 at 3:55
  • 3
    $\begingroup$ That apart, as written now this is a plain Earth Science or Geography question, with 0 worldbuilding content or background. $\endgroup$
    – L.Dutch
    Dec 30, 2021 at 4:05
  • $\begingroup$ @Zoey if you switch the "hard science" tag to "science based" I would vote to reopen.. There is really no way biology can determine exactly what would be required for a new rain forest to appear. Humans never built a rain forest, so there is no hard science method, to predict things. But you could get a science answer, without hard-science. There are certain conditions to optimize, like temperature.. vicinity of large rivers.. biodiversity in the soil.. maybe you won't need formulae at all, "science based" will also yield sound references about the subject. $\endgroup$
    – Goodies
    Dec 31, 2021 at 0:04
  • 1
    $\begingroup$ Rainforests are one of Earth's "self-sustaining ecosystems" they continue to exist because they're there already and contain/create feedback loops that sustain them with minimal external inputs, we don't really know how they originally form(ed). $\endgroup$
    – Ash
    Dec 31, 2021 at 2:55
  • $\begingroup$ But I highly doubt that there aren't theories as to the conditions advantageous to their formation. $\endgroup$
    – Zoey
    Dec 31, 2021 at 2:59

2 Answers 2


Well, first you need rain. So, an ocean or other large body of water, plus heat to evaporate the water.

Next you need a mechanism to cool the atmosphere so that water vapor will condense into rain drops. Adiabatic cooling from orographic lifting works well. (I.e. air rising as it crosses mountains)

Next, for plant life to flourish you need rich soil. And finally, life itself in the form of plants or their seeds.

How much detail are you looking for?

  • $\begingroup$ Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. $\endgroup$
    – Community Bot
    Dec 30, 2021 at 5:24
  • $\begingroup$ Hmm… what key word in my answer triggered this bot to respond? $\endgroup$ Dec 30, 2021 at 5:48
  • 1
    $\begingroup$ The bot was probably triggered by your lack of links pointing toward documents or whatever information that would support the information in your answer, which it probably looks for in any answer posted to questions with the hard-science tag, at least that's how I think it works $\endgroup$
    – Lemming
    Dec 30, 2021 at 12:32
  • $\begingroup$ Rainforest soil is some of the poorest on the planet. $\endgroup$
    – Ash
    Dec 31, 2021 at 2:48

Tropical Rainforests

They need:

  • Ample sunlight and moisture
  • Temprature between 21° and 30°C (70° and 85°F)
  • A river or lake nearby

as explained here

Sunlight strikes the tropics almost straight on, producing intense solar energy that keeps temperatures high, between 21° and 30°C (70° and 85°F). High temperatures keep the air warm and wet, with an average humidity of between 77% and 88%. Such humid air produces extreme and frequent rainfall, ranging between 200-1000 centimeters (80-400 inches) per year. Tropical rainforests are so warm and moist that they produce as much as 75% of their own rain through evaporation and transpiration.

or here

Such forests are found in Asia, Australia, Africa, South America, Central America, Mexico and on many of the Pacific Islands.

Temperate Rainforests

They need:

  • An ocean nearby
  • Mountains nearby

so that warm, moist air comes in from the coast and is trapped by nearby mountains causing a lot of rainfall as explained here

As their name implies, temperate rainforests are much cooler than their tropical cousins, averaging between 10° and 21°C (50° and 70°F). They are also much less sunny and rainy, receiving anywhere between 150-500 centimeters (60-200 inches) of rain per year. Rainfall in these forests is produced by warm, moist air coming in from the coast and being trapped by nearby mountains.

Here are 12 examples of pristine temperate rainforests found across the world.

  1. Pacific Coast Range

  2. Taiheiyo Evergreen Forests

  3. Appalachian Temperate Rainforest

  4. Atlantic Oakwood Forest

  5. Valdivian Temperate Rainforest

  6. Fiordland and Westland Temperate Rainforests

  7. Baekdu Mountain Range

  8. Fragas do Eume

  9. Taiwan Mountain Rainforests

  10. Eastern Australian Temperate Forest

  11. Knysna-Amatole Rainforests

  12. Caspian Hyrcanian Mixed Forests


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