granpa Posted January 15, 2009 Posted January 15, 2009 does jupiter have a jovian wind equivalent of the solar wind of the sun?
NowThatWeKnow Posted January 15, 2009 Posted January 15, 2009 Are you trying to compare the solar winds of the Sun with the surface winds of Jupiter?
granpa Posted January 15, 2009 Author Posted January 15, 2009 surface winds?? surely the meaning of my question was obvious. I'm asking if jupiter gives off a stream of plasma the same way that the sun does.
Klaynos Posted January 15, 2009 Posted January 15, 2009 surface winds?? surely the meaning of my question was obvious. I'm asking if jupiter gives off a stream of plasma the same way that the sun does. Not that I'm aware of, what would power this?
granpa Posted January 15, 2009 Author Posted January 15, 2009 well now that I think about it, even the earth should produce such a wind from its ionosphere. the speed of ions in the ionosphere must be far greater than the escape velocity of the earth.
Klaynos Posted January 15, 2009 Posted January 15, 2009 Escape velocity of earth (surface): 11.2x103m/s According to: http://www.springerlink.com/content/k557703p23h777g4/ There was a sudden increase in the particle flow speed to: x103m/s Due to an increased coupling effect from the solar wind. So even if that speed was increased it'd be due to the coupling so any "wind" from it would probably be classed as part of the solar wind itself.
NowThatWeKnow Posted January 16, 2009 Posted January 16, 2009 surface winds?? surely the meaning of my question was obvious... Not to me Not to Google either. Google did find where you asked the same question in a different forum and google found talk about surface winds. Did you ever get a reply in the other forums?
CaptainPanic Posted January 16, 2009 Posted January 16, 2009 well now that I think about it, even the earth should produce such a wind from its ionosphere. the speed of ions in the ionosphere must be far greater than the escape velocity of the earth. The mean velocity of nitrogen (as mentioned in another post) at room temperature (298K) is 474 m/s. The escape velocity of earth (at the surface) is 11000 m/s, which is more than an order of magnitude higher. So, the velocity of your average molecule is much lower than the escape velocity. And that is independent of the pressure up there... it's just dependent on the temperature and molecular weight. See the other post for the formula. But particles can escape, this is true. I described the mean velocity, so obviously there exist particles with a higher velocity, and also with a lower velocity. I'm not sure how the (statistical) distribution of the velocity around that mean is. Also, in the ionosphere, we're dealing with ions, not molecules, which will have an interaction with the earth's magnetic field. Again, I am not sure of the effect. I don't think that there exists an "earth wind" which is powered by earth. If anything, then high speed "space particles" (ions or photons) might hit some molecules or ions in our upper atmosphere, and knock them into space...
granpa Posted January 16, 2009 Author Posted January 16, 2009 470 m/s in the ionosphere? I dont think so.
Klaynos Posted January 17, 2009 Posted January 17, 2009 470 m/s in the ionosphere? I dont think so. How about my post where I give a reference to speeds in the ionosphere?
granpa Posted January 17, 2009 Author Posted January 17, 2009 according to that post 470 m/s is room temp. the ionosphere is much hotter.
D H Posted January 17, 2009 Posted January 17, 2009 Jupiter's atmosphere extends about 5,000 km above the 1 bar "surface" (~71,500 km at the equator). Assume the upper atmosphere is rotating at Jupiter's sidereal period, one rotation per 9.925 hours. At 76,500 km, this translates to 13.5 km/sec. Jupiter's upper atmosphere reaches temperatures of ~1200 kelvin. For protons (ionized hydrogen), this translates to a vrms of 5.5 km/sec. Adding this to the rotational velocity yields 19 km/sec, which is far less than 58 km/sec, Jovian escape velocity at 76,500 km.
npts2020 Posted January 17, 2009 Posted January 17, 2009 and how hot is jupiters ionosphere? Well, after googling jupiter/ionosphere the first hit is a lengthy, but interesting treatise by R. V. Yelle of Arizona University and S. Miller of University College of London. They seem to think the upper temperature limit of the ionosphere is the 1200 K mentioned by D H and that there is a large gradient through it, possibly as much as 800 k. This compares to 2200+ K that the Earth's ionosphere maxes out at. Why haven't we lost all of our atmosphere on Earth to space yet?
granpa Posted January 17, 2009 Author Posted January 17, 2009 ok. thanx for the replies. the answer seems to be no. here is an interesting read. especially the part about Thermal overheating. http://www.apl.ucl.ac.uk/research/planet_observation/questions.html
CaptainPanic Posted January 21, 2009 Posted January 21, 2009 470 m/s in the ionosphere? I dont think so. Well... I did provide a nice link to the other post, in which I provided a formula to calculate the mean velocity of a molecule (carrying zero charge) as a function of its molar mass and the temperature... I also wrote down several other issues that play a role here. You're welcome. No need to thank me. No need to agree. But you could at least have taken the time to write a slightly more eloquent reply than this. Sorry for grumpiness, I haven't had enough coffee yet.
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