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. On Jun 9, 8:02 pm, "Alvia Gaskill" <[email protected]> wrote: > http://science.discovery.com/tv-schedules/series.html?paid=48.15725.2... > > NextWorld > Future Danger > TV-G > > Future Danger enters a world where robots safeguard our cities, massive > underwater heating and cooling systems break up hurricanes before they hit > land, and advanced rocket interceptors protect the planet from asteroids that > could wipe out humanity. > > Air times in the U.S.: June 7, 9pm, June 8, 12am and June 9, 4 am. 60 > minutes. > > The program referenced above aired last weekend and I watched it. Since my > original message spawned a great deal of interest, I thought I'd provide a > summary. > > Future Danger examines some potentially beneficial and harmful technological > breakthroughs that are thought to be likely in the 21st century. Topics > covered in this episode included whether or not superintelligent computers > might decide to make us their slaves (they already have, it's called the > Internet), can we prevent killer asteroids from striking the Earth and can we > save the seeds of important crops in case GW and/or something else wipes out > the original plants. The latter is actually being done in Svalbard, north of > the Arctic Circle. A typhoon in the Philippines destroyed some key rice seed > lines so a global repository is probably a good idea, although one has to > wonder if there is any point to this on a much larger scale in a depopulated > world with a wacked out climate. > > The segment on hurricanes was brief and not particularly informative. Ross > Hoffman, VP of Atmospheric Environmental Research and author of several > articles on weather and hurricane modification said their goal was to make > hurricanes change their track or intensity. AER's computer models showed > that a 1 degree change (assumed to be F) in the hurricane itself and not SST, > would make a large difference in the path and intensity. Actually, I thought > that the path is largely determined by steering currents, i.e. upper level > winds and neighboring high and low pressure systems. > > The two mitigation options presented were beaming energy via satellites to > the location where a hurricane is forming or placing giant tubes into the > ocean in front of an existing hurricane's path. No explanation of how the > energy from space approach would work was given, but further research > indicates it is intended to heat the cloud tops of the storm, thereby > reducing the temperature differential between the top and the bottom of the > storm that drives the circulation. A similar idea involves releasing carbon > black over the top of the storm and there are variations on this that involve > releasing the carbon black elsewhere. > > The giant tubes idea is the same concept as promoted by Atmocean and > Lovelock/Rapley, that the natural bobbing motion imparted by waves would > cause cold water to be carried upwards whereupon it would spill out over the > top of the tubes and spread out on the surface, robbing the hurricane of some > of its strength. > > The narrator then says that contrails from jet aircraft can also heat and > cool the atmosphere. What was the point of this? Hoffman then says it is > uncertain where a hurricane whose path was artificially changed to avoid, say > Miami, might strike. Perhaps the Bahamas he speculated. > > AER newsletter where on page 2, the claim is made that in their computer > models they have successfully reduced intensity and changed tracks of > hurricanes. > > http://www.aer.com/news/newsletter/AER_Insight_volume7_issue2.pdf > > Hoffman also an advisor to that turkey movie on the Disco Channel, Superstorm > along with Kerry Emanuel and Chris Landsea. > > http://dsc.discovery.com/convergence/superstorm/qanda/qanda.html > > The three experts also answered questions about weather modification in an > online forum: > > http://community.discovery.com/eve/forums/a/cfrm/f/3831925909 > > Except for the idea of a movable space sunscreen to cool water ahead of > hurricanes, there weren't many new ideas advanced. Landsea's own take on > hurricane mitigation is below. The carbon black idea was used in the movie, > not to weaken the storm, but to create a low pressure system to make the > hurricane change its course. In the movie, intense cloud seeding was used to > weaken the eye wall. > > "There have been numerous techniques that we have considered over > the years to modify hurricanes: seeding clouds with dry ice or > Silver Iodide, cooling the ocean with cryogenic material or > icebergs, changing the radiational balance in the hurricane > environment by absorption of sunlight with carbon black, exploding > the hurricane apart with hydrogen bombs, and blowing the storm > away from land with giant fans, etc. As carefully reasoned as some > of these suggestions are, they all share the same shortcoming: They > fail to appreciate the size and power of tropical cyclones. For > example, when Hurricane Andrew struck South Florida in 1992, the eye and > eyewall devastated a swath 20 miles wide. The heat energy released around > the eye was 5,000 times the combined heat and electrical power > generation of the Turkey Point nuclear power plant over which > the eye passed. The kinetic energy of the wind at any instant was > equivalent to that released by a nuclear warhead. Perhaps if the time > comes when men and women can travel at nearly the speed of light to > the stars, we will then have enough energy for brute-force intervention > in hurricane dynamics. > > Human beings are used to dealing with chemically complex biological > systems or artificial mechanical systems that embody a small amount > (by geophysical standards) of high-grade energy. Because hurricanes > are chemically simple --air and water vapor -- introduction of > catalysts is unpromising. The energy involved in atmospheric dynamics is > primarily low-grade heat energy, but the amount of it is immense in terms of > human experience. > > Attacking weak tropical waves or depressions before they have a chance > to grow into hurricanes isn't promising either. About 80 of these > disturbances form every year in the Atlantic basin, but only about > 6 become hurricanes in a typical year. There is no way to tell in advance > which ones will develop. If the energy released in a tropical disturbance > were only 10% of that released in a hurricane, it's still a lot of > power, so that the hurricane police would need to dim the whole world's > lights many times a year. > > Perhaps some day, somebody will come up with a way to weaken > hurricanes artificially. It is a beguiling notion. Wouldn't it be wonderful > if we > could do it ? > > Perhaps the best solution is not to try to alter or destroy the tropical > cyclones, but just learn to co-exist better with them. Since we know > that coastal regions are vulnerable to the storms, building codes that can > have houses stand up to the force of the tropical cyclones need to be > enforced. The people that choose to live in these locations should be > willing to shoulder a fair portion of the costs in terms of property > insurance - not exorbitant rates, but ones which truly reflect the > risk of living in a vulnerable region. In addition, efforts to educate > the public on effective preparedness needs to continue. Helping poorer > nations in their mitigation efforts can also result in saving > countless lives. Finally, we need to continue in our efforts to better > understand and observe hurricanes in order to more accurately predict their > development, intensification and track. > > Sincerely, > Chris Landsea" > > I'm not certain that Chris's comments and recommendations apply to developing > nations like India and Bangladesh where for reasons of commerce and > habitation the people have no choice but to live in the path of these storms. > > Links to articles about hurricane modification from AER's website: > > http://www.telegraph.co.uk/news/worldnews/1566898/Scientists-a-step-c... > > http://www.aer.com/news/inTheNews/2005/2005-09-14-newscientist.pdf > > http://www.aer.com/news/inTheNews/2005/2005-01-10-Time165-2p52.pdf > > http://www.aer.com/news/inTheNews/2005/2005-09-14-tallahassee.pdf > > This explains a little further Hoffman's ideas, based on modeling funded by > NASA and says that the space-based heating would be done using microwaves and > that the air adjacent to the storm would be heated, causing its path to > change. This is different than what was said earlier, so who knows. > > In the course of doing this "research" I also looked into the potential > impact of stratospheric aerosols on hurricanes. Since the sea surface > temperature would be reduced and the transient Pinatubo aerosol cloud > apparently had a much longer lasting impact on depressing SST than was > initially thought, what was the result in terms of tropical cyclone > development? > > Tropical cyclones form in several locations globally, including the N. > Atlantic, the Northeastern Pacific (affecting Mexico, Calif. and Hawaii > primarily), the Indian Ocean and the Western Pacific (storms that affect the > Philippines, Taiwan and Japan). The complete list of locations and annual > average numbers is shown below: > > http://en.wikipedia.org/wiki/Tropical_cyclone > > Season lengths and seasonal averages[31][34] > Basin Season start Season end Tropical Storms > (>34 knots) Tropical Cyclones > (>63 knots) Category 3+ TCs > (>95 knots) > Northwest Pacific April January 26.7 16.9 8.5 > South Indian November April 20.6 10.3 4.3 > Northeast Pacific May November 16.3 9.0 4.1 > North Atlantic June November 10.6 5.9 2.0 > Australia Southwest Pacific November April 9 4.8 1.9 > North Indian April December 5.4 2.2 0.4 > > Note that these are not cumulative, i.e. the total number of storms are the > tropical storms and the others are subsets of it. > > The Atlantic hurricanes seem to follow a multi decadal cycle of 30-50 years > and the early 90's were near the end of the "down period." However, that > wasn't the case elsewhere, so a decrease in activity from August 1991 when > the aerosol cloud first began to cover a significant area to December 1992 > when it was beginning... > > read more » --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
