Suppose there's an Earth-like planet. In the middle of the desert, a wizard/sorcerer/etc has enchanted a 30-mile-long rectangular area, so that, for two hours a night, clouds form and gently rain in this zone, for some reason. (Maybe it was to establish a mining community where valuable minerals/gems are, or to create a kingdom from unused land.)

What effects would this have on the environment and vegetation, both inside and outside the zone?

  • $\begingroup$ You can magically gather as much clouds as possible and it will only produce lightnings no rain lol and then you can collect glass(silica) $\endgroup$ – user6760 Oct 7 '15 at 12:02
  • $\begingroup$ Let me know if you get a good answer, because I have been wondering a very similar question myself. Specifically if a mining community in the middle of the desert is connected to a coastal city by a permanently open magic gate or even a big enough tunnel, then every night the air in the desert will cool faster than the humid air from the transport system and create localized thunderstorms or rain depending on the capacity of the transport. I've been wondering about the effects and how they scale with capacity. $\endgroup$ – Ville Niemi Oct 7 '15 at 13:58
  • $\begingroup$ Realized that my issue is not only similar to yours, it becomes identical if we assume that magical gates interfere with each other and need to be spaced apart and create a reason for there to be lots of gates. The area is actually an enclave and head quarters of a magical guild having monopoly over gate magic in large areas. International or even interdimensional. They might have a gate to every major city in the world or several worlds. Huge impact on climate and local ecology. $\endgroup$ – Ville Niemi Oct 7 '15 at 14:08
  • $\begingroup$ Is this a sandy or stony desert? Is this a hot or cold desert? I can provide a definitive (it has been produced) answer to a sandy, hot desert. $\endgroup$ – Mikey Mar 4 '17 at 7:30

I live in the U.S. southwest. The terrain is considered desert. Rainfall for much of the year can be minimal, but during "monsoons" daily rainstorms often happen. During this time of the year grasses, flowers and other "annuals" quickly grow and propagate. Trees and shrubs absorb the water they can, and put out new growth and propagate. Different types of cactus also blossom and propagate. Once the storms stop, all the grasses and small annual plants die and dry up. The trees and bushes and cacti settle back to just getting most of their water from deep roots. In areas where there is more plentiful water (running streams or ponds), the plant life will be have trees, bushes, and grasses that are green except for during the winter. In these places cacti do not grow very well, as their roots can actually rot away if subjected to too much water.


Plants grow where there is the right amount of sun, soil and water that they need to survive. Having a light rain every night in the middle of a desert will create an oasis. It will stay green and if it happens long enough even a sandy dessert will build up soil. As the soil gets richer more and larger plants will be able to be sustained. As the plants grow and increase so too will the animals living there. If it happens long enough it might turn into a forest, partly depending on the amount of rain that falls.

How much it affects the area outside will largely depend on how much of the water actually leaves the 'area'. Most likely there will be a gradual tapering off as from the edge unless the magic prevents most of the moisture from leaving.

  • $\begingroup$ How do plants convert sand into soil? $\endgroup$ – Andrew Recard Jul 9 '16 at 5:04
  • $\begingroup$ Lichen make soil on bare rocks, then come mosses, then other plants. $\endgroup$ – bowlturner Jul 9 '16 at 12:29


1st, what do these could do gently in the night in that zone? ;) Well fun aside, I thing they do drop drops of water.

So... even more interesting, what kind of desert this may be? And whats below? Sand Deserts, while the ones, that people think of if they hear the word "desert", just made a small part of our worlds deserts. So it's likely that's a rocky wasteland. It could be an ice-desert too.

What does desert mean? If I recall right, its a place with fairly few natural appearances of water. Long time ago my teacher try to teach me what a desert make a desert, and all that's left is a vague impression of an area that contains pretty few water and does encounter even less atmospheric fallout. An arid environment. Guess I was way to busy daydreaming in school.

What does this tell us? The ground, while he might soak up some of this, will be likely to refuse soaking up even more thanks to millenia of dry... ehm... whats the word... compression?

Never mind - your Rain would gather together and flow away without having much of an effect. Temporary Rivers in deserts caused by this seems to make more people drown in a desert than actually die of thirst. In Australia you should immediately leave your piece of desert, if you see heavy rain far away, because few time later (hours?) you will be greeting by a muddy flood. Well, just follow the kangaroos, they know how to survive this.

Back to topic - when your Rain-Wizard aims for a valley, he might create a lake. When every night as much water is refilled as evaporated during day-time, you might get a real oasis over time. But once the rain overnight cuts off, it's likely to dry out again. And your plants will die.

And for the effects... if you create this rain out of nothing, you will encounter a rise in sea-level in a few thousand years. But when you just soak this from air humidity, ... hard to say. Because its an arid environment, there will not much humidity you could catch. Maybe collect this over day.

But anyway, 30 Miles is a pretty cute size compared to a planet wide climate. And at the end, that water will find its way back to the circle of water, so for me I would not except much changes. Okay, for the sake of story-telling, you could go with the usual cloud movement and look whats there. A rainforest would barely notice your two hours of gently rain, but an arid area with inhabitants that need these drops you claim for your desert may find themselves a bit shorter of water supply than usual. Which may be pretty unpleasureful.

Maybe a suggestion... even if the surface of a desert is dry as... a desert, you may find a pretty river if you go in the other direction: not for clouds, but for the underground. Down there its cool and the water wont evaporate.

Another think - when your desert is surrounded by mountains, you will get your water using a... darn... there a kind of well, that looks for aquifer of mountains. Because the part of this located in the mountain is much higher than the one below your desert, all you need to do is drill a hole and let physics move the water up. -EDIT- Ah, an Artesian Well, thanks Layna!-/EDIT-

A last word: if you don't use the lake-variant and make sure the ground is solid, your water will fall down through the cavernous ground and join the aquifer. If you just rain at a random area, it will most likely flow away. Sand and Stone and Wastelands do not own ground that can store water at their own. You need ... topsoil (?) that will appear though many years of plants claiming their place. MANY years.

  • 1
    $\begingroup$ Are you looking for an artesian well in your second to last paragraph? $\endgroup$ – Layna Oct 7 '15 at 11:38
  • $\begingroup$ Guess I should have been clearer. The desert is sand or dirt, not rock or ice. The water/moisture is magically created, not taken away from anywhere. $\endgroup$ – user24353 Oct 7 '15 at 23:07

Rainforest Oasis

Lets say 'gentle' rain for two hours is a quarter inch, or about 6 mm. 6 mm per day for a month is 180 mm per month. 180 mm a month every month for a year is 2160 mm.

2160 mm per year is a little less than what they get in Manaus, Brazil, which happens to be in the heart of the Amazon.

A 30km long rectangle (presumably it is at least a few km wide) is a pretty substantial piece of land. A lot of the rain that fell here would be picked up by trees and transpired back into the atmosphere. Then, some of it would fall into the forest; more would fall into the desert. In whatever direction the prevailing winds went, there would be a 100 km or more trail of vegetation as transpired water passed away from the forest and rained into this previous desert.

Obviously, excess water would run off as rivers. Depending on the size of the desert, that would probably end up drying up before it reached anything else. There would be gallery forests and swamps along the course of the river, whichever way that went as well.

As for animal life, small rainforest animals would move into the rainforest. Large herbivores would take advantage of the lower rainfall zones and swampy rivers for grazing. Large carnivores would eat the large herbivores.

All in all, you would have an amazing oasis in the middle of your desert.


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