Hello All, A further possibility is to attempt to emasculate incipient hurricanes by cooling oceanic surface waters in regions where hurricanes spawn. One way of doing this would be to seed low-level shallow clouds in appropriate regions so as to increase their droplet number concentration and thereby their albedo. Exploratory GCM exploration of this idea yields the highly provisional result that a cooling of one or two degrees (perhaps more) could possibly be achieved: which could be significant vis-a-vis hurricane development..
Other cooling ideas could prove to be of importance. Cheers, John. Quoting Mike MacCracken <mmacc...@comcast.net>: > > You need to get more creative. Lowell Wood's idea some decades ago was > orbiting mirrors in space that would redirect sunlight on to the storm. The > problem remains, however, storm energy is huge, and it is not at all clear > that such efforts could trigger a change, much less one would want and be > able to predict. > > Mike M > > > On 6/13/09 6:35 PM, "dsw_s" <ds...@yahoo.com> wrote: > >> >> Does a hurricane live moment-to-moment, running entirely on the power >> it dissipates? Or does it accumulate energy, and have its ability to >> release energy depend not only on how much it's dissipating but also >> on how much it has accumulated? >> >> If it depends on accumulated energy, an intervention only has to >> affect an amount of power on the order of the difference between power >> in and power out. If an intervention can make even a small difference >> in energy accumulation rate, then having it run for a long time would >> make a larger difference in the amount of energy accumulated. >> >> My latest thought is to warm the top of the hurricane by suspending >> sheets of black plastic in the air. If we could suspend a square >> kilometer of plastic sheet, the sunshine heating it would be less than >> the power the hurricane dissipates by a factor of something like >> 10**7. That's still a lot of effect-multiplier needed: brute-force >> alteration of the whole hurricane is out of the question, as always. >> A good choice of where to heat the air might let us decrease the >> efficiency with which the storm turns the dissipated heat into >> mechanical work. One way to get some multiplier effect might be to >> use a bunch of smaller sheets to nucleate convection cells and turn a >> region of just-barely-stable air into a region of scattered cumulus >> clouds. Maybe the same thing could be done in the area where >> hurricanes form: instead of having convection cells merge into a >> tropical depression, perhaps they could be managed so that there would >> be enough room for air to sink in between the cells. Or we could go >> the opposite way, making tropical depressions form at the very >> beginning of the season or at the fringes of the area of hurricane >> formation, so that they grow only into moderate tropical storms >> instead of strong hurricanes, and then the sea surface would be cooler >> when hurricanes pass over it. >> >> Replacing a few powerful hurricanes with a larger number of weak >> tropical storms could be a part of overall geoengineering: the smaller >> storms might mix less heat down into the ocean, so that less heat is >> transported to the poles. >> >> On Jun 12, 8:42 am, Mike MacCracken <mmacc...@comcast.net> wrote: >>> Dear Denis‹You really need to do some order of magnitude estimating: >>> >>> Based on the earlier email on the energy involved in and dissipated by >>> hurricanes, the heat release of a hurricane (on average‹big ones are higher >>> by a good bit) is on order of 5.2 * 10**19 Joules per day. Convert that to >>> calories, assume you want to dissipate 10% of the energy to slow the storm >>> down a bit (and this would really mean increasing the natural dissipation >>> rate by a factor of 40‹which is lot given that the drag of the surface >>> ocean is now the major sink of drag energy‹that this factor is so large >>> should give you real pause). But any way, to deposit the energy you are >>> talking about as heat in the ocean, your drag devices would have to >>> warm the >>> upper 10 meters of the ocean over an area having a radius of 300 km by >>> roughly 0.3 C‹that is a very great amount (just think how much effort the >>> Sun takes over the seasonal cycle to warm a bit thicker layer by somewhat >>> more). We are talking about huge amounts of energy‹so, on this argument, I >>> am on the side of David saying ³nonsensical.² >>> >>> Your arguments on CO2 lifetimes, etc. are being addressed by others. >>> >>> Mike >>> >>> On 6/12/09 3:24 AM, "Bonnelle Denis" <dbonne...@ra.ccomptes.fr> wrote: >>> >>>> About this "beyond nonsensical" idea: >>> >>>> I was just commenting a post which dealt with angular momentum and which >>>> proposed to use kite devices. About this point, I only added the adjective >>>> "strong". About ships, their being submitted to storm winds isn't, indeed, >>>> necessary for my idea: submarines could do the job as well. And they could >>>> more easily move between inside the hurricane's eye - where the surface >>>> winds >>>> are weaker - and outside the whole hurricane - where the crew could safely >>>> join the rest of the world. Reversed propellers and other hydrodynamic >>>> brakes, >>>> in order to exchange angular momentum, could be fitted to >>>> submarines as well >>>> as to ships. >>> >>>> Their "strength" and the kites' one is a matter of design, but mainly of >>>> size >>>> and finally of materials quantities. I do not pretend that I have done the >>>> least beginning of an economic appraisal, but if anyone was willing to, it >>>> would be a good thing. >>> >>>> Best, >>> >>>> Denis. >>> >>>> De : David Schnare [mailto:dwschn...@gmail.com] >>>> Envoyé : jeudi 11 juin 2009 13:09 >>>> À : Bonnelle Denis >>>> Cc : ds...@yahoo.com; geoengineering; lmich...@vortexengine.ca >>>> Objet : Re: [geo] Re: Just in Time for Hurricane Season >>> >>>> For those of us who have been on a ship, on the ocean and near a >>>> hurricane, >>>> much less under it, the idea of having any ship, much less many of them, >>>> flying kites and reversing engines in some kind of large circle is beyond >>>> nonsensical. It's sort of like having the government control GM - might >>>> sound >>>> like a good idea, but really! >>> >>>> d >>> >>>> On Thu, Jun 11, 2009 at 5:59 AM, Bonnelle Denis <dbonne...@ra.ccomptes.fr> >>>> wrote: >>> >>>> This analysis is interesting, but I'd split the first sentence in three >>>> parts: >>>> "To have harmful wind speeds, a hurricane needs to have a large >>>> underpressure >>>> air column in its middle, and this underpressure has to be >>>> protected by the >>>> centrifugal force, which results from a lot of angular momentum". >>> >>>> However, when these ideas are being translated to figures (numbers), an >>>> important parameter comes in : the radius. The centrifugal force effect is >>>> negligible at the beginning of the air path (when Coriolis's force builds >>>> the >>>> angular momentum up) and at the end of the same path. It is only in its >>>> middle, i.e. at a middle altitude (maybe from 1000 m to 8000 m) that this >>>> effect is maximum. >>> >>>> So, if you'd like to use some strong kites to create a drag, a >>>> useful device >>>> could be to have some boats along a circle in the hurricane's eye, being >>>> drawn >>>> by kites 1000 or 2000 m high, using their propellers as brakes (and even >>>> transmitting some mechanichal power to an electrical engine which >>>> would act >>>> as >>>> a power generator). This would transfer the hurricane's angular momentum - >>>> at >>>> the point where this momentum is most implicated in the hurricane's >>>> self-stability - to the sea, i.e. it would create an interesting angular >>>> drag. >>> >>>> Conversely, I am not very much convinced by angular momentum >>>> exchanges with >>>> the upper layer of the hurricane's air. >>> >>>> Best, >>> >>>> Denis Bonnelle >>>> denis.bonne...@normalesup.org >>> >>>> -----Message d'origine----- >>>> De : geoengineering@googlegroups.com >>>> [mailto:geoengineer...@googlegroups.com] >>>> De la part de dsw_s >>>> Envoyé : mercredi 10 juin 2009 10:55 >>>> À : geoengineering >>>> Objet : [geo] Re: Just in Time for Hurricane Season >>> >>>> To have harmful wind speeds, a hurricane needs to have lots of angular >>>> momentum. If some of the angular momentum could be dispersed to >>>> farther from the center of the storm, wind speeds would be lower. If >>>> I understand it right, a hurricane has air coming in from the >>>> periphery at low altitude, rising in the middle, and dispersing at >>>> higher altitude. If the storm is remaining steady or strengthening >>>> (in terms of the total angular momentum of its winds), the outgoing >>>> air must have less angular momentum than the incoming air by an amount >>>> at least equal to the angular momentum lost to drag at the surface. >>>> Suppose we have something for drag suspended at an altitude where air >>>> is moving inward, from balloons at an altitude where air is moving >>>> outward. That should transfer angular momentum from the inward-moving >>>> air to the outward-moving air. >>> >>>> Alternatively, one could fly over the edges of the storm and drop long >>>> ropes with a kite on one end and on the other end a weight of >>>> approximately the same density of water. The kites would fly >>>> themselves for a while before being destroyed, creating drag and >>>> decreasing the angular momentum of the air they came in contact with. >>>> As the air moved in toward the center of the hurricane, the change in >>>> wind speed would be multiplied according to conservation of momentum >>>> just as the wind speed itself is. >>> >>> >> > > > > > > > -- John Latham lat...@ucar.edu & john.latha...@manchester.ac.uk Tel. 303-444-2429 (H) & 303-497-8182 (W) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
