1
$\begingroup$

I'm imagining a world where magic lets massive skyscraper-sized crystals hover in the air. They're not tethered in any way - the wind is free to blow them around. I'm imagining that having specific crystals in close proximity would benefit the populace, so I'm trying to find a way for the same crystals to pass by frequently. Ideally a given crystal would remain within range (50 miles) of a settlement for a week out of every month.

My question is this: is it possible for wind patterns to exist such that the crystals are blown past the same location at predictable intervals?

Here are the specific reasons why I'm skeptical that this could exist:

  • I worry that something so massive won't be moved appreciably by the wind.

  • I've found evidence for large-scale circular wind patterns in the real world, but for my case I need small local loops. I worry that the scale is too small, and unbelievable.

  • I worry that even if a crystal started moving along the path, its momentum would be too great for such a tight circle, and it would continue forward when the wind changes direction, leaving the path.

I've read a bit on wind patterns and the Coriolis effect, and it seems like it's possible to have large scale wind cycles, but I don't know if something as small scale as what I'm talking about is possible. I haven't been able to find much on the physics of wind blowing skyscraper-sized chunks of hovering rock around.

Improve this question
$\endgroup$
11
  • $\begingroup$ Please edit your post to ask a single specific question that meets the rest of our requirements on questions. You can find out more about how our site works by taking the tour and in the help center $\endgroup$
    – sphennings
    Commented Oct 31, 2023 at 3:05
  • 1
    $\begingroup$ Thanks, I've updated to try and be more specific on what my question is. I have reviewed the question guidelines, so please let me know if there are ways I can further improve the question. $\endgroup$
    – Jozomby
    Commented Oct 31, 2023 at 4:12
  • $\begingroup$ You're still asking multiple questions at once. We have a strict one question per post policy. $\endgroup$
    – sphennings
    Commented Oct 31, 2023 at 5:28
  • 1
    $\begingroup$ Thanks @Joachim, that's definitely what I was trying to do here. I can remove all the bullet points if it works better just to ask the question and leave it with that, but I was trying to point out what I thought the problems with the situation might be. I figured that saying "these are the problems I see here" would be helpful for people wanting to answer the question. $\endgroup$
    – Jozomby
    Commented Oct 31, 2023 at 14:24
  • 1
    $\begingroup$ The cyclical wind patterns in the Indian ocean were the basis for the Arabic traders going between Africa and India (and the basis for our word, monsoon, which comes from their description of this cycle). $\endgroup$
    – David R
    Commented Oct 31, 2023 at 15:36

2 Answers 2

Reset to default
2
$\begingroup$

Since our atmospheric currents don't have a lot of floating megaliths in real life, we should probably consider our oceans in answering your question. There are lots of circular ocean currents, but the one that comes immediately to mind is North Atlantic Gyre, which courses a 600 mile wide circle in the Atlantic Ocean. The current is powered by heat differentials between our frozen northern waters and the equatorial warm waters to the south. It is six times larger than what you are looking for but with magic at your disposal, that can be easily remedied. Perhaps a great collection of fire crystal megaliths float to the south of your civilization and an equally large collection of ice crystal megaliths float to the north. It seems reasonable that a body of air trapped between such diametrically opposed extremes might develop a very stable circular pattern.

Now to your questions...

  • winds can definitely move massive things. Your crystals are floating without tether, so the only thing the wind needs to defeat is air resistance and inertia. The wind is the air in question, so resistance will be minimal. As for inertia, a constant light breeze can have a powerful cumulative effect. Perhaps the crystals were motionless a thousand years ago, but they've been slowly speeding up for ten centuries. They are currently going whatever speed your story needs them to be going, but will slowly increase in speed as time goes on.

  • I've already answered the "can circular currents exist" question above and have described how we can scale that circle down to your desired size with a little help of more magical crystals.

  • Will the ever increasing momentum of each crystal eventually allow it to escape from the circular wind pattern? Probably. But as stated above, accelerating a crystalline megalith up to escape velocity will take a very long time. So set your story among the centuries BEFORE such escape happens.

As for further research, switch your search from wind patterns to ocean current patterns. There are lots of real life examples of floating megaliths in our real world oceans. Abandoned Ships (Mary Celeste), Icebergs and even the Great Garbage Patches.

Improve this answer
$\endgroup$
3
  • $\begingroup$ Thank you! I hadn't thought to look into ocean currents. That's a really good idea. $\endgroup$
    – Jozomby
    Commented Oct 31, 2023 at 14:19
  • $\begingroup$ The circular movement would naturally negate a fair amount of the momentum gain. Momentum in one direction doesn't directly translate to momentum in a different direction. Some might be converted, but much will be lost as the object slows down and reverses direction. $\endgroup$
    – Flywheel25a
    Commented Nov 2, 2023 at 21:15
  • $\begingroup$ In general I agree, but there are several flaws: in particular the mall breeze will not build up as you say (unless you have Jupiter-size hurricanes) because push would be null as soon as the floating object travels at the same speed of the breeze; the only force (i.e.: actual wind felt on the floating megacrystal) would be the need to change momentum and send the thing back along it's route. I fear anything massive enough to have a sizable inertia compared with surface exposed to wind will have to travel very slowly to remain in a stable pattern. $\endgroup$
    – ZioByte
    Commented Nov 2, 2023 at 22:48
0
$\begingroup$

Have a look at Buckminster Fuller's Cloud Nine plans. Geodesic spheres (structures of triangular components arranged to make a sphere) become stronger as they become bigger, because of how they distribute stress over their surfaces. As a sphere gets bigger, the volume it encloses grows much faster than the mass of the enclosing structure itself. Fuller suggested that the mass of a mile-wide geodesic sphere would be negligible compared to the mass of the air trapped within it. He suggested that if the air inside such a sphere were heated even by one degree higher than the ambient temperature of its surroundings, the sphere could become airborne. He calculated that such a balloon could lift a considerable mass, and hence that 'mini-cities' or airborne towns of thousands of people could be built in this way.

You could actually make a floating city of the type you describe. It would probably go wherever the wind goes, but you can vary the lift - venting warm air or letting it build up - and adjust your height. The wind at different levels will probably be in somewhat different directions, which would allow you to chose your course. This is how hot air balloons steer a course.

Improve this answer
$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .