Timeline for How can a remote planet with little to no sunlight have high wind speeds?
Current License: CC BY-SA 4.0
19 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 29, 2023 at 1:43 | comment | added | vengaq | @kingledion you said that "planet spin cannot drive winds in a rocky planet". does it mean that in gaseous planets their rotation are the cause of their winds? | |
| Sep 24, 2022 at 17:42 | comment | added | Arcturus | "Meanwhile, Venus has constant wind speeds around 300 km/h at the cloud tops, circling the planet every 5 hours or so. Earth's winds are obviously not that strong." Jetstream- Am I a joke to you? | |
| Sep 11, 2018 at 16:53 | history | bounty ended | Willk | ||
| Sep 9, 2018 at 22:29 | comment | added | kingledion | chat.stackexchange.com/rooms/82935/moving-magnetic-fields For all who want to talk more | |
| Sep 9, 2018 at 18:09 | comment | added | Physicist137 | @Willk - Forgive my laziness... could you kindly put the link here? :D. | |
| Sep 9, 2018 at 18:07 | comment | added | Willk | OK @Physicist137 I made a chat room. First time! Read you there, I hope. You too king if you are interested. | |
| Sep 9, 2018 at 17:26 | comment | added | Physicist137 | @Willk - I still do not understand what you want to say (maybe to have a chat?). The magnetic field is not caused by a spinning core, rather, by convection and Coriolis force in the mantle (or, outer core). So, the magnetic moment will point at roughly the same direction as the rotation axis (at least it is what this theory says). Unless you have other means to produce a magnetic field, I am not clear how you can re-orient it to an arbitrary direction. And even if you could, what then? There's still no wind: no work is done by a magnetic field. | |
| Sep 9, 2018 at 14:54 | comment | added | Willk | @Physicist137 - I am not really clear why the earths magnetic field is consistent around the earth; you can trust a compass most places. King is right - the core rotating as a piece like the earth does as a whole means field directed into or out of core. But what if there were rapid upwellings of hot metal which then fell as it cooled (convection?). You could orient these in a lot of ways, including such that the magnetic field pointed in a direction you want. | |
| Sep 8, 2018 at 18:49 | comment | added | Physicist137 | I was writing an answer and calculating at the same time (never do that), and then I arrived an impossibility (I couldn't move forward) (it does not work). Note to self: To do the calculations first and then to write an answer. King's answer requires a magical current $J$, and mine would require a magic way to uncharge the ocean surface. The reason why it does not work is simple: The energy to drive the winds has to come from somewhere. @Willk I can't think in a mechanism to steal planet's rotation to drive the winds (as you asked for). And, I didn't understand your idea about convection... | |
| Sep 8, 2018 at 18:24 | comment | added | Willk | Instead of the magnetic field rotating in parallel with the planet, it could rotate with convection currents moving outwards and upwards from the core, cooling and dropping back down. | |
| Sep 8, 2018 at 15:29 | comment | added | Physicist137 | This gave me just an idea. If the planet is rotating fast, then, from the point of view of the planet, the magnetic field would be rotating. By a (local) change of coordinate system fixed on the planet, there now exists an effective electric field in the radial direction. Current would (temporarily appear) creating a layer of charge in the surface of the water. And the magnetic field moves this layer of charge. I think it would be possible to calculate the needed rotation to drive the entire thing (I suspect it needs to be laaarge..). Want to try it? If not, I can try to give a shot.. | |
| Sep 8, 2018 at 15:14 | comment | added | kingledion | @Willk I think if the magnetic field of the planet was rotating, then the force vector would be directed either into or out of the core, so I don't think you can get water movement along the surface that way. I was totally staring at my hand trying to figure that out. | |
| Sep 8, 2018 at 13:54 | comment | added | Willk | I also wondered how the field would push water. But I get that the field could push something with a charge - like an eddy current brake pushes back on a train. I thought that you had the magnetic field of the planet rotating independent of the planet - if you had that then I don't think you would need the current in the water, right? | |
| Sep 8, 2018 at 0:14 | comment | added | kingledion | @Physicist137 Yes, electric current. I based the induced flow on the principles of an MHD drive. I'm disappointed that someone picked out the handwavey bits so quickly, I thought they would be better hidden :) | |
| Sep 8, 2018 at 0:11 | comment | added | Physicist137 | I think now I got it what you meant. Well, if you're assuming there exists a vertical electric current in the ocean, I think it would be nice to identify why it would exist in the first place (if it is not too much to ask :D). I for one can't think in any reason for it to exist. (Also.: I don't know what you meant to say in the beginning, but, just to be clear, J represents electric current flow, not a fluid current (of mass)). | |
| Sep 7, 2018 at 23:45 | comment | added | kingledion | @Physicist137 I'm using $J$ instead of $qV$ in the Lorentz Force equation, because $J$ represents current flow, not ionic particles. You can pass an electric current through seawater, especially if it is extra salty. Assume a current in the ocean, because....I'm sure there is a good reason to assume bottom to surface electric current flow in the ocean (assuming the magnetic north pole is at the true north pole to get westerly oceanic currents). Return current can go near the shore or bottom, where MHD motive force is reduced by friction/turbulence. | |
| Sep 7, 2018 at 21:54 | comment | added | Physicist137 | I don't understand why there is an ocean current. Could you explain me a bit better? Sure, a magnetic field would affect positive charges in a way, but also negative charges in the opposite way. And about salty ocean, there is charge conservation, so net charge is null. There would be an electric current yes, but there won't be a mass (or fluid) current because motion of positive and negative ions would be opposite to one another. From guiding center equations we need more complicated fields to achieve a drift velocity (and thus current). | |
| Sep 7, 2018 at 18:35 | comment | added | Clay Deitas | You said a lot of the things I was going to mention. May build off of your answer later. | |
| Sep 7, 2018 at 17:23 | history | answered | kingledion | CC BY-SA 4.0 |