Thank you, The required amount of liquid N2 would probably be gigantic, its production would reject more heat in the atmosphere than the hurricane is consuming, and all it would achieve would be to create, at the surface of the ocean, some cold water, which would very quickly dive down and be replaced by new warm water coming from just under it. So, this option can be written off very quickly.
I don't know whether the two others face such criticism. Best, D. Bonnelle De : Andrew Lockley [mailto:andrew.lock...@gmail.com] Envoyé : mardi 5 mai 2009 11:13 À : Bonnelle Denis Cc : geoengineering; f.m.maugis; lmich...@vortexengine.ca Objet : Re: [geo] stopping hurricanes There are already various hurricane-busting programmes. Off the top of my head, these are: 1) Using lasers to discharge lightening in the precursor storms 2) Burning soot in the outer wall to make it absorb heat and cool down 3) Pouring liquuid N2 onto the surface of the sea Sadly these are not detailed on wikipedia, but you can find a summary at http://www.cbc.ca/doczone/hurricane.html Further discussion of whether these may help reduce AGW would be welcome. A 2009/5/5 Bonnelle Denis <dbonne...@ra.ccomptes.fr<mailto:dbonne...@ra.ccomptes.fr>> Dear Andrew, First, I think your call for something to be done is not only about stopping hurricanes (i.e., when they are fully mature - I can't guess any easy way to achieve this), but also preventing them from developing at once. This seems more thinkable. Basically, it means cooling the upper layer of the oceans down, before the beginning of the hurricane season. One method has already been presented to this group, but I had answered that, by burying the heat deeper into the sea, it would contribute to ocean dilatation. If not downwards, one may try to dispose of this heat upwards. A solution could be derived from that which had been frequently advocated here by F. Maugis: the atmospheric vortex engine (AVE - also developed by L. Michaud, from Canada). I have long been a fierce critic of AVE, which, in my opinion, would be highly unstable as long as a shortcut from high to low pressures wouldn't be prohibited. Indeed, prohibiting it provides the solution, which is, finally, as follows: 1 - moist air, coming from the surface of the ocean, rises (first, it is either drawn, or pushed, upwards - several initializing options are possible) through a middle-sized (200 to 300 m high) chimney, which also contains wind turbines and is shaped so that the flow lines look like spirals; 2 - still rising above the chimney, this spiraling air creates some centrifugal force, so that a region of low pressure develops at its centre, and keeps on attracting new air from the system's bottom; 3 - moving upwards, i.e. being adiabatically cooled, this moist air reaches the altitude where its vapor content begins to condensate, which liberates latent heat; from now on, its temperature will quite stop diminishing, so that this operating air will soon become warmer than the ambient air, and thus buoyant; 4 - our hypothetical central low pressure is now justified in three respects: from above (1 in the figure hereunder), it is justified by the condensing moist air buoyancy; from under (3), it is consistent with the idea that more moist air has to be attracted so that the system should keep on working (and even produce renewable energy by drawing the turbines); and from the outer space at the same altitude (2), it is justified by the cumulative effect of the centrifugal force; [cid:image001.png@01C9CD73.833A29D0] 5 - However, there remains a problem along the (4) path: the low pressure at the chimney exit is jeopardized by the high pressure just before the air goes through the turbine, and the whole air system can be destabilized by some Kelvin-Helmholtz instability; 6 - Hence, we must bar this path. The solution is to add a horizontal annulus around the chimney's top, with radii ranging from R to around 2.5 R. This annulus can be filled with buoyant gases, and, anyway, it will face much less winds than if the same material were raised vertically in order to create a greater "chimney effect"; 7 - Indeed, this is our real purpose: using, like in a real hurricane, the air's centrifugal force, as a material wall which isolates the inner low pressures from the outer high ones. Thanks to friction, air rotation develops not only inside the first cylinder (black flow lines in the figure), but also outside it (grey lines), which enhances the total centrifugal contribution to the central low pressures. So, we have a virtual chimney effect, which, when the 1 to 6 stages are completed, will undergo a positive feedback (from energy budgets, this feedback requires that the annulus radii, as a minimum, range from R to 2R, that's why I had written previously: "from R to around 2.5 R"). 8 - When this positive feedback begins to operate, the structured air motion can develop, like a natural hurricane, until this "virtual chimney" reaches the tropopause, which is a real achievement as we had begun with a solid chimney only 200m - 300m tall, and its annulus which is not much greater. 9 - To prevent real hurricanes to develop, such systems can be located closer to the equator (where Coriolis's force is too small to provide a natural hurricane with enough angular momentum, which is not a problem for an AVE, as, inside, it is shaped so that the flow lines become spirals), and, usefully, in the regions where very warm waters are ready to move towards hurricane regions (i.e., off the northern coast of Brazil, where Mexico Gulf hurricanes are being prepared). Any comments, especially doubtful ones, are welcomed. Best, Denis Bonnelle denis.bonne...@normalesup.org<mailto:denis.bonne...@normalesup.org> De : geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com> [mailto:geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>] De la part de Andrew Lockley Envoyé : mardi 5 mai 2009 03:16 À : geoengineering Objet : [geo] stopping hurricanes This paper http://www.pnas.org/content/early/2009/04/27/0808914106.abstract suggests that hurricanes cause global warming. I suggest that using geo-eng to stop this happening would be socially acceptable, fundable and desirable. There are several promising ideas for doing this, and I'd like to hear views on the implications of this research for the debate on geoeng and the practical implementation of suitable techniques. A --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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