Random portals of spherical shape are found on the surface of the planet, they are pitch black and have a diameter of 3 meters.

Once something enters any of the many random portals, they are "teleported" in the sky in the location right above the portal, kind of, it really works as a wormhole or gate not really a teleportation.

The portals never teleport anything further than the atmosphere.

But still, if a rock falls into a portal it will be teleported above it and then fall into the portal again, and again, and again until something moves it out of the way, until it melts and evaporates or until the portal starts losing power and dissapears.

Portals lose power the more often they are used by the amount of weight entering them. Some portals have a limit of a few kilograms others can last million of megagram, and they reform naturally over decades.

Now I want a creature who specifically evolved the niche to use those portals, possibly without killing themselves. Not just some bird who happens to go unto the portal by mistake, but an animal who is linked to the portals for survival.

This is not an edit to the original question, but just an highlight

"linked to the portals for survival" means that the animal would die or somehow go extinct without the portal the same way hermit crabs die if they don't find shelter or how leaf cutter ants would die without their mushrooms.

What use could these portals ever offer to such creature? I have no idea, that's what I'm asking.

The world is the same as planet earth in therms of composition, gravity and everything regarding physics, except the portals which are magic.

how the portals work

The portal acts as door or fenester always open. If a person put their head inside their portal they could see the rest of their body from way above, but if they by mistake fall onto the portal then it's gonna be an eternal fall until they die or until they deviate the fall and hit the ground.

Portals always remain the same place until they dissipate their strength and then one is reformed in a random place on the surface of the earth. The reformation of a portal can take up to several years or decades depending on how much weight could a portal sustain.

Portals lose power the moment solid matter enters it by penetrating them. Water splashes on the portal instead of penetrating it, dust just builds up until the wind blows it off and bugs or small creatures can enter the portal if they push really hard. Entering the portal takes roughly the same effort as penetrating a leaf, but nothing is being really penetrated, is just a small resistance from the portal, If a person steps foot in the portal before it vanishes, their foot will be dismembered and fall on their head.

  • $\begingroup$ cant they use it to defense against predator ? make them get the same experience with the rock, at least it can delay them from chasing, or use it to trap their prey for easy catch? $\endgroup$
    – Li Jun
    Commented Jun 14, 2020 at 8:03
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    $\begingroup$ you should really define how the portals wear off and close, especially since you wrote that some only take few kilograms. Let's say I'm a base jumper entering a "light" portal, what happens when the few kilograms of my lower body are into it, but my torso is not? will I be snagged there forever? will I be dismembered? will I pass and only after that the portal will disappear? $\endgroup$
    – carlo
    Commented Jun 15, 2020 at 16:15
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    $\begingroup$ If rain can fall into the portal it would probably be >1000kg per inch of rain. $\endgroup$
    – Warcupine
    Commented Jun 15, 2020 at 17:37
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    $\begingroup$ This question has been used as an example for a proposed tag in Meta. $\endgroup$
    – JBH
    Commented Jun 15, 2020 at 20:19
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    $\begingroup$ Absolutely not! Leave your question as-is. As I thought through the Meta post I came to realize it's a good example of what we should be allowing (and basically do, just not with a tag). My purpose behind my last comment was to direct interest to the Meta question to facilitate discussion and, hopefully, support. $\endgroup$
    – JBH
    Commented Jun 16, 2020 at 2:10

11 Answers 11


Portal trees.

Plants need sun. They compete with one another to get higher and get the sun. And plants struggle with herbivores. Stuff shows up (especially bugs!) and eats their leaves.

The portal offers a fix for both problems. A portal tree takes root by the portal and sends thru roots or branches. These appear high in the sky. There is so much sun up there! And it is breezy, and difficult for bugs to get too. Very difficult for deer and rabbits. The issue with getting water up to the sunniest branches is solved because from the perspective of the portal tree, water is going down to the sunniest branches.

The portals would quickly fill up with portal trees hanging their limbs down thru the portals. The tangles of leafy limbs high in the air will give rise to their own ecosystems.

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    $\begingroup$ Oh, that's a darn good idea. $\endgroup$
    – JBH
    Commented Jun 14, 2020 at 19:10
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    $\begingroup$ The bugs would crawl through the portals. Both for food and as a convenient method of transportation. Eventually trees might be able to plug them (unless the trees do it early by the intention of their genes), but until then ... free elevator! $\endgroup$ Commented Jun 14, 2020 at 20:00
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    $\begingroup$ They need not be trees, really. I would think that something like English Ivy would do really well in this sort of circumstance. $\endgroup$
    – Some Guy
    Commented Jun 15, 2020 at 2:37
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    $\begingroup$ @Vesrei - This idea however hangs on the working details of the portal. If I stick my arm in it, does my arm alone appear high in the heavens? Or do I need to enter completely before I'm teleported? From what I understand there is no visible counter-portal in the sky, so this is unclear... $\endgroup$
    – Vilx-
    Commented Jun 15, 2020 at 9:14
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    $\begingroup$ @Vesrei - Portals are finicky things, they come with a lot of unintended side effects. Just read John Dvorak's comment. Does air pass through the portal? Does the pressure difference cause air to be sucked in? Does it count against a portal's "mass limit"? If I stuck my head through (but not the rest of my body), would I be able to see the ground far below? Would my head be visible in the sky? If not, how does the portal determine where my body ends and the "surroundings" start? Does my clothing count? What if I hang on to a rope that's tied around a nearby tree? Are the edges sharp? Etc. $\endgroup$
    – Vilx-
    Commented Jun 15, 2020 at 12:03

Edit 3: I answered before OP explained how it worked exactly.

I'm guessing that using the portal conserve the momentum and that throwing an object in the portal will make it exit with the same speed and direction. I also assume portals are one-way.

Long-range communication

A lot of species use the portal by throwing different objects into the portals.

Herd-hunting coyotes can indicate to fellow hunters that they find something by pushing a tumbleweed into the portal. The rest of the group know the direction and the approximative distance of the prey with the direction and the horizontal speed the scout pushed the plant or the signaling object into the portal.


Flying squirrels are squirrels that can glide and control their fall speed. They can fall from literally any high. They often enter the portal to glide far away from it. This is useful to escape predators or cross a massive obstacle such as a large river, a small mountain, or just a dry piece of land where they are visible hence vulnerable. An even better situation is when two portals are close enough that a squirrel can reach one by gliding from the other's exit point. In that case, they can gather food from the richest area (forest, etc), and stash it on the safest area (cliff, mountain, etc)

It's cool. Literally.

Portals are pitch black. I'm guessing it's because the (re)emit no light. In that case, they don't radiate heat either. On hot sunny days, some dominant mammals love to chill in its shadow for this reason: not only you don't have the sun directly in your face, but it also feels like it's pumping heat from you (you naturally radiate heat to it, but contrary to any other room-temperature object, it doesn't radiate back its own heat). Some small mammals like to bury food in its shadow: the soil is always very cold, and it works as a "fridge" for buried fruits. But careful not to be seen! They are very vulnerable when doing so, and predators know it's a good place for their preys to be. If you're a good hunter, you can leverage the fact that the portal hides your light AND most of the sound. Also, most stashing mammals spy on their peers to steal their buried food! Flying squirrels stash a lot because they can escape predators instantly by jumping into the portal. Another reason the food lasts long when buried directly under the portal? It's super dry. All the rain falling on the portal never reach the ground after all...

Get free energy for dissemination

If you suspend a paper sheet vertically, air molecules bounce from right to left and left to right all the time, canceling each other pressure. On the surface of the portal, the molecule going into the portal (from left-to-right) never come back. And there's no molecule going in the other direction (from inside the portal's black entry sphere to outside) to cancel it out. This means permanent low pressure at the surface of the portal (and high pressure around the exit point). To sum up, there is a permanent breeze coming into the portal. It's a vacuum cleaner to the sky!

For plants, it means that if you are near the portal, your spores have a chance to enter the portal and be widely disseminated! A rule of thumb is that you can see the effects up to 50m around the portal. A fun fact to observe is that in that zone, the further away from the plant from the portal, the lighter and smaller its spore, to better leverage this effect. Plants can't count much on the flying insects near the portal to disseminate the spores, as they are most of the time sucked into the portal.

Magic food dispenser

Remember how a lot of flying insects are sucked into the portal? Birds know that. Some hang around the exit point and wait for insects to come out. From the ground, it's easy to spot a portal: follow the insect-eating birds: they cluster up in a specific zone in the sky, and below is a portal. On the ground, spiders know that too. Building a web close to a portal is always a great idea for a spider. Most of them have super dark webs (no pun intended) to match the color of the portal and catch even more insects. Yum!

A fancy place to raise your kids as a bird

A lot of bird species raise their kids in a nest. When fully grown up, they jump out of the nest and have to learn how to fly... on-the-fly. A lot of them fail even if their parents invested a lot of time and energy. If you manage to build your nest above a portal, you kids have all the time they need to stabilize and make a kickass landing a few kilometers below.

Migration guide

Electromagnetic field, heat, light, and sound are all emitted on the exit point of the portal. This makes it easy to spot for migrating birds. They can use them to orient themselves in long migrations.

BONUS: How animals spot a portal?

  1. See insectivorous birds clusters above it
  2. Follow the wind
  3. Feel the cold on your skin **
  4. Echolocation ***
  5. Lack of electromagnetic field (it's absorbed too and emitted on exit)
  6. Sometime ground-level fog pours out of the exit point

** When you are in front of a fire by a cold night, you feel hot on the fire-facing side of your body and cold on the back. It's because the fire almost doesn't warm the air, you just have direct radiation from the fire. If you hold a piece of paper in front of your face, you will feel cold on your face again! Animals can develop a specialized organ to detect this sharp contrast in heat radiation in their field of view.

*** Bats use their voices and ears as a sonar. The portal will have no echo, which makes it easy to spot even for these almost-blind creatures.

EDIT: BONUS 2: Clouds and fire

Portals will pump ground-level air in a particular point of the sky. Not a specialist, but I think this relatively hot air meeting the cold air in altitude can produce clouds and often even thunderstorms. When this happen, the thunder can spark a fire. And if the fire reach the portal, a lot of incandescent embers can start fire far from the original portal. Luckily, most of it will be washed by the heavy rain of the thundercloud before it reaches the ground again. But in some rare occasions, maybe a big burning branch can fall into the portal and get carried by violent thunder cloud winds to start a fire elsewhere, if it serves your story. If you think portal-induced fire are common, then the whole flora and fauna will have adapted to it, like the eucalyptus. If you think clouds are enough, it will be easier to spot portals from afar, and the often raining clouds can bootstrap and sustain a very diverse ecosystem. Another alternative is that since portals are not only pumping hot air in the sky but also dust, insects and small particles, the continuous cloud seeding could continuously empty the cloud as it's forming, so no problem. I have the intuition that would still electrically charge the area (the reason behind thunder in the first place) and that travelers would be zapped upon arrival, but I'm not sure of that and maybe the charge can be evacuated with the continuous very light rain. (I would love to have confirmation by a meteorologist.)

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    $\begingroup$ "your spores have a chance to enter the portal" Spores are used by fungi and some varieties of protozoa, never by plants. Perhaps do you mean seeds? That being said, I can easily imagine lots of fungi from phylums Basidiomycota and Ascomycota living in the shadow of the portals. $\endgroup$ Commented Jun 15, 2020 at 14:39
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    $\begingroup$ Yes, I guess I meant that. I'm not a biologist :P. $\endgroup$
    – Akita
    Commented Jun 15, 2020 at 14:40
  • $\begingroup$ @TheDaleks Moss and ferns use spores. But yes, fungi would thrive better in the shadow. $\endgroup$
    – No Name
    Commented Jun 16, 2020 at 0:17
  • $\begingroup$ Actually any animal that is small enough would benefit from such portals - since they have no problem falling down from any height it is a safe way to hide from a predator that is of large size... On other hand cat-sized predators would use it to hunt wider area... $\endgroup$ Commented Jun 16, 2020 at 0:45
  • $\begingroup$ @NoName Good point, "never" was too strong of a term. $\endgroup$ Commented Jun 16, 2020 at 0:57

Portal-Salmon, which aren't actually fish...

Terrestrial salmon spawn in rivers, live in the ocean,and when it's time to die they swim upstream to their original spawning ground to mate, incubate, and die. Let's run with this example.

Portal-salmon are actually an insect (a big insect, weighing up to 0.5 pounds or 0.23 Kg) that are fertilized in the air. Male sperm and female eggs are both released at high altitudes where they mix (creating genetic diversity). The fertilized eggs fall to the ground with a wide spread allowing for least competition from fellow portal-salmon and least possibility of threat from predators. The fertilized eggs of portal-salmon are a bit more like seeds than fish, bird, or insect eggs, in that they need a bit of time to germinate, growing a root for nutrients, before hatching into the portal-salmon's larval state.

The portal-salmon lives its life on the ground and in the air, but always avoiding the portals. Too much altitude kills the portal-salmon — not enough oxygen (or that sudden stop at the bottom of the drop, either one). However, during the portal salmon's life it senses the strength of each portal it comes near, always remembering the strongest portal it encounters.

At the end of the portal-salmon's life, the insect is drawn to the most powerful portal it came across, there to join with like-minded portal-salmon to be thrust heavenward to begin its last descent, giving of itself that its progeny might live. In other words, the process of releasing sperm and eggs is something like a balloon popping. It's a bit... dramatic... but that swelling of sperm and egg is part of the life-span trigger that causes the portal-salmon to seek the best portal.

Intelligent natives have learned to follow the portal-salmon to find these strongest portals. They use them to open the rare but succulent rock-clams. The natives learned that by throwing the rock-clams into the portals at just the right angle and with just the right spin (putting a little "English" on the rock-clam, if you know what I mean), the descending rock-clam will land nearby with a satisfactory cracking sound, allowing access to the otherwise inaccessible delicacy. Thanks, portal-salmon!


Neverland Birds: A family of birds with an uncanny ability to sense portals.

  • The Neverland bird is an enormous dragon-like predator who feeds off the many large birds and flying fish abundant on the planet. It uniquely almost never lands once it takes flight, but it's enormous size means it is incapable of taking off on its own. When the birds reproduce, their young are parachuted to the ground to feed and fend for themselves. As these small predators grow, they live on the ground. Once they mature, they seek out the portals present on their homeworld and go through. From that day they never again touch the surface of their world if they can help it. Those that do land must again seek a portal to once again get to the sky.
  • Relatives of the neverland bird exist who land and lay eggs, but then seek out portals to go airborne after the young mature. Males hunt and feed their young and females by dropping food to the nest.
  • Other members of this family of birds are aggressive predators of land animals, seeking out the kills of other predators and landing to drive off lesser predators with their great size. These birds are almost incapable of flight due to their large size, and must repeatedly climb through portals and glide until they spot new prey.
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    $\begingroup$ This was also where my mind went, gliding squirrels that never land but just spend their entire lives free-falling through the air, gliding from one portal to another. $\endgroup$
    – Dast
    Commented Jun 15, 2020 at 16:12
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    $\begingroup$ @ Dast I considered that; flirted with using flying tigers based on the reputed ability of cats to survive falls :) A group would be called a squadron. $\endgroup$
    – DWKraus
    Commented Jun 15, 2020 at 16:24

Flying squirrels.

The presence of one of these portals near their nest would allow them to more freely forage near the ground, as they wouldn't need to climb a tree to be able to take off (in case of imminent danger for instance). That means a much bigger abundance of food for the same area (anything that is found on the ground and not on trees). They would probably evolve to have better ground mobility whilst keeping a decent amount of air control or maybe even grow bigger, as climbing trees fast wouldn't be as important.

It also would allow them to expand their territories by travelling between portals (assuming portals would form within gliding distance of each other).


A narration derived from remote audio surveillance, anthropological mission W44/21.3 commissioned by the Rigellian Collegiate Council, AE 32,182, to further understand the unique cultural leanings of the Nahini peoples.

Son, your Shenduai into manhood is approaching, and I need to tell you the epic of the Ocutage1

For the whole of your youth, my son, you have watched the mighty Ocutage fly with great speed into the Eye of God — and each time God made the Ocutage appear high into the heavens. Over and over the Ocutage dove into the Eye, faster and faster he sped, until after the fifth passage through the Eye of God, the Ocutage streaks to heaven, there to be blessed by God forevermore.3

It was Mehaman, blessed by God to become our First Elder many generations ago and to bring the Way to Heaven among us, who taught us the Shenduai.4 Adorn thyself as the Ocutage. Be free like unto he. Dive through the Eye and be judged by God — for if you fly to the heights of Aden5 you are a man in the eyes of God, worthy to take your place among the honored elders of the Nahini and clean like the air and the water.

But I must warn you, my son, for if you are not prepared with courage, having begged forgiveness of God, then you shall not be allowed to pass through the Eye like the Ocutage and shall be damned,6 bringing much sorrow to the tribe.

But my son, you must not fear. For those who fear and choose to spurn the Shenduai are deemed most unclean and cast out of the tribe.7

Spend the night in prayer, my son, and upon the dawn we shall behold your flight to heaven!

1The ocutage is Nahini2 for "Bird of Heaven."

2The Nahini tribe of the upper Barosh continent is a sedentary stone-age tribe of approximately 2,500 individuals spread across roughly 2,000 hectare area expressing an unique religious belief they call "kolainu." (Excerpt from the "Galactic Gazetter" published by the Rigellian Collegiate Council, AE 32,167.)

3It was ascertained in zoological mission J811/19.9, AE 32,172, that the Ocutage did not, indeed, fly to heaven, but rather entered the lower bounds of the planetary troposphere to allow a symbiotic but parasitic fungus that grows on the underside of its primary feathers to succumb to heightened photosynthesis and cleansing in the high UVA light available at that altitude. Said flights last less than 20 standard minutes but result in rapid new growth of the fungus, which helps to seal the primaries and produce longer flight time. Old fungus growth, often diseased in the higher moisture and heat of the lower altitudes, is quickly extruded from beneath the primaries, which are disinfected by the UVA light, and burnt away. The bird then rejoins its flock.

4Very cautious research during this expedition (which conformed to Non Contamination Protocols per SSC22491.6.6) uncovered a heretical teaching that suggests Mehaman did not, indeed, invent the prevailing philosophy. It was one Kolani, using the Ocutage to justify his prophetic connection with God, who created the essence of the philosophy and tried to emulate the bird by diving off the cliff above anomaly Z25/6/6/211. The heresy suggests he missed his target. His first acolyte, Ukali believed the bird had more to do with it and was the first to don wings. It is said he passed through the anomaly once but died against the cliff on the second pass. The heresy teaches it was Mehaman who modified the bird suit for better flight control and was first to successfully pass five times through the anomaly and then glide to the bluff, 18 Km NNW from the anomaly. The heresy teaches Mehaman is therefore the one to create the distilled form of the Shenduai we see today. Ardent supporters of the current philosophy vigorously seek those who believe in the heresy and, in a curious twist of the philosophy mimicking history, cast them off the cliff without the bird suit. Those who survive passage through the anomaly five times are deemed forgiven. It's rumored that one person did make it through the anomaly five times without the bird suit — but died (obviously) due to instability when reaching terminal velocity. We think this is an Urban Legend to teach children it's impossible to avoid the heretic's fate.

5We apologize for omitting this reference earlier. Aden is the Nahini name for the bluff 18 Km NNW of anomaly Z25/6/6/211.

6It should be pointed out that like all cliffs, the wind surrounding anomaly Z25/6/6/211 is frequently strong and unpredictable. The Ocutage use this anomaly no more frequently or less than any other and we surmise that the Nahini use it only because of the convenient cliff. However, the often unpredictable winds tends to result in frequent deaths before five passes through the anomaly are achieved. Consequently, there is an unusually high ratio of females to males among the Nahini peoples. We believe this is the reason for the development of institutionalized polygyny among the tribe. See earmark BB25/A-7 for our request for a follow-up anthropological study to better understand Nahini mating practices in association with the Shenduai.

7Note the settlement in map grid FFE-266 that we suspect is a group of exiles from the tribe that sourced the above excerpt. It appears they periodically raid the camp to kidnap females for breeding purposes. Analysis of this group is also a part of earmark BB25/A-7. It should be noted that we find this complex socio-political dependency as a derivative of a single avian species' need to manage and control a symbiotic but parasitical growth to be fascinating.

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    $\begingroup$ My thanks to @Ambu for the core reference for this response (birds gaining altitude). $\endgroup$
    – JBH
    Commented Jun 14, 2020 at 19:08

In a countries with developed public transportation and a stable population of street dogs (read: Eastern Europe and former USSR) one can easily meet a dog that regularly catches a bus or a metro train.

From a dog viewpoint, the bus is a portal and the dog pretty much has the ability to use it.

  • 6
    $\begingroup$ But dogs don't fly $\endgroup$
    – user76440
    Commented Jun 14, 2020 at 23:17
  • $\begingroup$ @Vesrei in your world, they'd glide $\endgroup$ Commented Jun 15, 2020 at 18:33

Also, note that some creatures like ravens are known for dropping hard prey (e.g. shellfish or turtles) from a great height onto a hard rock to break it open. The portals offer an easy way to do this, if a portal is located next to a rock or other hard surface: all a creature has to do is look down through the portal at the nearby rock and then throw the prey at it. It will fall from a great height and strike the rock, at which point the creature can feast on its insides, without having had to fly up to a great height in order to drop it. (The creature might not even need be capable of flight.)


Any even semi-intelligent species capable of tool use could find the portal to be a source of free energy, at least for a while. Consider, for instance, a waterwheel or generator located between the input and output of the portal. All one has to do is dump a bucket of water, sand, or gravel on it periodically (or even rain will do), and then reap the benefits of the wheel spinning constantly until either the water or the portal itself evaporates. This could be used for anything from grinding grain to sandblasting to generating electricity. If this happens for long enough, the species could culturally begin to depend on it.


Imagine this, if the portal only teleport something to above the portal like wormhole, I imagine a lot of flora , will take advantage of this, for pollination and such, to spread their seed ( higher altitude probably with wind can help spread them more ). And such flocks of bird or bees can learn this and try to catch those seeds to eat and wait them near portal.

Felines or other land animals that would normally only able to catch birds when they land, can learn this behavior and maybe evolve parts of their body , like legs, ear or sight to enhance their chance of catching the prey after they leap into the portal and to have a safe landing, after the hunt.


Vertical fish.

If a stream happens to flow into a portal, it will become a waterfall, with gradually increasing capacity until the portal can't hold any more water (its entire two-dimensional surface is filled with falling water) and starts losing water around the edges, which would form a pool around the lower portal and continue to flow downstream if possible. Similar things might happen if a portal formed under a lake, or formed on the ground in a location which becomes flooded during part of the year.

Any fish which are caught in this situation will be in freefall until the portal exceeds its weight capacity and finally evaporates (at which point the fish will fall from the sky into a suddenly flooded area with possibly an outgoing stream, or into a lake). Other contents of the water (vegetation, insect larvae, other marine life, sand, rocks, etc.) could be in the falling water as well.

If the fish were capable of gliding (e.g. like Earth's Flying Fish) they could also use this falling time to find a new pond or stream and fly to it. Or they could fly out of the stream briefly, snatch some insects (or birds?) from the air, and then rejoin the stream before it entered the portal again.

Note that such fish might be somewhat easy targets for predator birds, which might be willing to dive, osprey-like, through the column of water to catch falling fish (or any other small creature that found itself suddenly airborne for that matter), or wait until a fish emerged from the cascade after an insect. On the other hand, smaller birds that tried this might become victims of larger flying fish that decided to go after them instead.

It is not clear to me how fast such a column of water could fall: on Earth, the limiting factor is "terminal velocity" due to air resistance, but in this case, the column of water's only friction would be with its outside boundary against the surrounding air, and with each cylindrical shell of water against the one outside of it. The inside of the fall might be traveling much, much faster than the outside. This friction might possibly heat the water a bit. (Or more than a bit...? Perhaps to the point of steam (which would cause pressure or even an explosion!)) The tension of the portal surface itself might slow down the fall of water slightly, but it seems that this would be greatly overwhelmed by the acceleration of gravity over the distance between the two portals if they were very far apart.

A strong wind might upset this phenomenon for a while, causing some water to miss and therefore not immediately enter the lower portal, or at least to hit the surrounding landscape and then have to drain back in.

Something else to consider: Such a cascade of water also might act as a lightning rod, possibly triggering thunderbolts from passing storms to be conducted along it to the ground. This might fry some fish, birds, or whatever creatures were on the ground near the lower portal.


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