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EARL'S CURLS

Where's the show? Did ya'll forget it was Tuesday?

Your show on today?

I posted my idea on Mythbusters forum.

Seems ole Hugh Willoughby made it there somehow.



quote:
Originally posted by Chizzleface:
I had a reply from Dr Willoughby about the discussions Patrick had with him over this device...

quote:
Yes, I have spoken with Patrick, and, yes, a scheme somewhat like the one he describes could weaken hurricanes threatening places like Miami that have strong western-margin currents just offshore. There are, however, numerous qualifications.

The scheme that we discussed involved an array of several rows devices across the Gulfstream. Each device would be a rectangular duct 140 m long and 10 by 14 m in cross section. Normally the devices would be moored horizontally at a depth of 100m with their long axes aligned with the current flow. They would be nearly neutrally buoyant. When a hurricane approached, ballast at the downstream end of the channel would be released, allowing the device to float up to a 45 deg angle. Cold water entering the upstream end would flow up to the surface and mix with the warmer water there. Since the mixture would be negatively buoyant, it would sink. But mixing due to several (3-10) lines of these devices could cool the surface waters of the Gulfstream by 1-2C, enough to weaken an Andrew-like hurricane from category 5 to category 3. A rough calculation indicates that a device every 100 m on each line of moorings (~1000 devices per ~100 km line) and 3-10 lines of moorings would be required. My guess is that it would cost $250K to fabricate and deploy a single device, but there might be economies of scale. One might also be able to optimize the size and spacing of the devices.

Let's say that careful calculation told us that 4 lines of 1000 devices each would do the trick. At $0.25M per device, the cost works out to 4*1000*($0.25M) = $1000M. The actual cost might range from a few hundred million to a small multiple of a (US = 1000M) billion. One would want to do a detailed simulation before defining the scope of the project, but the basic notion is conversion of some of the kinetic energy of the Gulfstream into gravitational potential energy of the mixed water column. Again, I've not done that detailed simulation, only back-of-the-envelope calculations.

Activation of the array would require accurate forecasting since it would take several days for the effect to make its way from south of the Dry Tortugas (optimum location for protecting the maximum amount of shoreline) to the landfall point.

South Florida gets hit by a category 4 or 5 hurricane at every few years, but the really damaging ones like Andrew tend to be once-a-generation events, or less frequent. The array would need to be deployed and maintained for a long time between activations that actually safeguard property, although false alarms would not be particularly costly. Annual maintenance could easily exceed 10% of initial deployment cost. Bear in mind that Key West to Jacksonville is the only stretch of US coastline where this strategy would work. The other vulnerable sites, Houston-Galveston and New Orleans, lack the necessary strong offshore currents. While Georgia and the Carolinas also experience many hurricane landfalls and have the Gulfstream offshore, most of these cyclones are already weakening because of vertical shear of the horizontal wind so that a second installation north of Jacksonville would be much less useful.

There has been a lot of talk about using wave and current energy to cool the ocean ahead of hurricanes. My general conclusion is that while these ideas might be made to work, the proponents underestimate the scope of the required effort, as well as the political will and recurring cost necessary to keep the project going in the long intervals between really damaging hurricanes. Skeptic that I am, I think that wiser land-use policy and more rigorous building standards are much more cost-effective and more politically feasible. A proof-of-concept that might entail deploying a half dozen devices has some appeal, but I think that there are more promising ways to spend disaster-prevention money.

Best regards,

Hugh Willoughby


Link

I couldn't find a better place to ask this question, so here goes:
What is there about my area (zip 53004) that whenever there is any reasonable 'chance' of rain listed, it turns out to be a zero percent chance of not raining on my hay(yes, this is partially facetious ...the hay part)? What do the terms "30 percent chance of thunderstorms" or "50 percent chance" mean, exactly? What are the main variables these refer to? Is it a 50 percent chance that it will rain in this region, or does it mean rain will hit approximately 50 percent of the land area? AFAICT, it means that rain will fall on my farm and not on my neighbors: every time. (Yes, I am aware of the "fooled by randomness" hypothesis, and this ain't one of those times.)