> Could you steer a hurricane by cooling one side and heating another - kinda > like how a tank steers by slowing down one track. Done early enough, even a > small change in angle would adjust the landfall by miles.
My guess is that a hurricane wouldn't keep moving the way you steer it, like a billiard ball under conservation of momentum. Rather, I think if you steered it, it would have the small change in angle only so long as you applied whatever steering mechanism you would be using. As for that, I have in mind that I've heard that hurricanes are steered mostly by high-altitude winds. Also, hurricane tracks are rather non-trivial to predict, so you might wind up steering it into New York City instead of away from. > Has anyone considered droppong a miniature atomic bomb; such as used in > artillery shells, down the middle of a hurricane before it makes landfall? Not I. What's that supposed to accomplish, and how? On Jun 7, 9:31 pm, "Eugene I. Gordon" <[email protected]> wrote: > Has anyone considered droppong a miniature atomic bomb; such as used in > artillery shells, down the middle of a hurricane before it makes landfall? > > -----Original Message----- > From: [email protected] > > [mailto:[email protected]] On Behalf Of Alvia Gaskill > Sent: Saturday, June 06, 2009 8:38 PM > To: [email protected]; dsw_s; Geoengineering > Subject: [geo] Re: Just in Time for Hurricane Season > > Some more info about the effect of hurricanes or more generally, tropical > cyclones on SST (sea surface temperature) from NOAA and the Wikipedia. Most > of the temperature decrease is due to the mixing of water in the upper layer > of the ocean by winds and most of the decrease occurs after the storm has > passed. Limited data show that the decrease from evaporation of water is > much less. NOAA also throws some cold water on artificial dissipation > strategies including the one that got this discussion started, ocean pipes. > They didn't address indirect approaches like the cloud ships and the desert > cover. > > http://www.aoml.noaa.gov/hrd/tcfaq/H7.html > > Subject: H7) How does the ocean respond to a hurricane and how does > this feedback to the storm itself? > Contributed by Joe Cione > > The ocean's primary direct response to a hurricane is cooling of the > sea surface temperature (SST). How does this occur? When the strong winds of > > a hurricane move over the ocean they churn-up much cooler water from below. > The net result is that the SST of the ocean after storm passage can be > lowered by several degrees Celsius (up to 10° Fahrenheit). > > Figure 1 shows SSTs ranging between 25-27°C (77-81°F) several days > after the passage of Hurricane Georges in 1998. As Figure 1 illustrates, > Georges' post storm 'cold wake' along and to the right of the superimposed > track is 3-5°C (6-9°F) cooler than the undisturbed SST to the west and south > > (i.e. red/orange regions are ~30°'C [86°'F]). The magnitude and distribution > > of the cooling pattern shown in this illustration is fairly typical for a > post-storm SST analysis. > > One important caveat to realize however is that most of the 3-5°C > (6-9°F) ocean cooling shown in Figure 1 occurs well after the storm has > moved away from the region (in this case several days after Georges made > landfall). The amount of ocean cooling that occurs directly beneath the > hurricane within the high wind region of the storm is a much more important > question scientists would like to have answered. Why? Hurricanes get their > energy from the warm ocean water beneath them. However, in order to get a > more accurate estimate of just how much energy is being transferred from the > > sea to the storm, scientists need to know ocean temperature conditions > directly beneath the hurricane. Unfortunately, with 150kph+ (100mph+) winds, > > 20m+ (60ft+) seas and heavy cloud cover being the norm in this region of the > > storm, direct (or even indirect) measurement of SST conditions within the > storm's "inner core" environment are very rare. > Thankfully in this case "very rare" does not mean "once in a > lifetime". Recently, scientists at the Hurricane Research Division were able > > to get a better idea of how much SST cooling occurs directly under a > hurricane by looking at many storms over a 28 year period. By combining > these rare events, HRD scientists put together a "composite average" of > ocean cooling directly under the storm. > > Figure 2 illustrates that, on average, cooling patterns are a lot > less than the post storm 3-5°C (6-9°F) cold wake estimates shown in Figure > 1. In most cases, the ocean temperature under a hurricane will range > somewhere between 0.2 and 1.2°C (0.4 and 2.2°F) cooler that the surrounding > ocean environment. Exactly how much depends on many factors including ocean > structure beneath the storm (i.e. location), storm speed, time of year and > to a lesser extent, storm intensity (Cione and Uhlhorn 2003). > While the estimates in Figure 2 represent a dramatic improvement when > it comes to more accurately representing actual SST cooling patterns > experienced under a hurricane, even small errors in inner core SST can > result in significant miscalculations when it comes to accurately assessing > how much energy is transferred from the warm ocean environment directly to > the hurricane. With all other factors being equal, being "off" by a mere > 0.5°C (1°F) can be the difference between a storm that rapidly intensifies > to one that falls apart! With that much at stake, scientists at HRD and > other government and academic institutions are working to improve our > ability to accurately estimate, observe and predict "under-the-storm" upper > ocean conditions. These efforts include statistical studies, modeling > efforts and enhanced observational capabilities designed to help scientists > better assess upper ocean thermal conditions under the storm. With such > improvements, it is believed that future forecasts of tropical cyclone > intensity change will be significantly improved. > > Reference > Cione, J. J., and E. W. Uhlhorn, 2003: Sea Surface Temperature > Variability in Hurricanes: Implications with Respect to Intensity Change. > Monthly Weather Review, 131, 1783-1796. > > Last updated August 13, 2004 > > http://en.wikipedia.org/wiki/Typhoons > > Tropical cyclones are characterized and driven by the release of large > > amounts of latent heat of condensation, which occurs when moist air is > carried upwards and its water vapour condenses. This heat is distributed > vertically around the center of the storm. Thus, at any given altitude > (except close to the surface, where water temperature dictates air > temperature) the environment inside the cyclone is warmer than its outer > surroundings.[2] > > Mechanics > > Tropical cyclones form when the energy released by the condensation of > > moisture in rising air causes a positive feedback loop over warm ocean > waters.[14] > A tropical cyclone's primary energy source is the release of the heat > of condensation from water vapor condensing at high altitudes, with solar > heating being the initial source for evaporation. Therefore, a tropical > cyclone can be visualized as a giant vertical heat engine supported by > mechanics driven by physical forces such as the rotation and gravity of the > Earth.[15] In another way, tropical cyclones could be viewed as a special > type of mesoscale convective complex, which continues to develop over a vast > > source of relative warmth and moisture. Condensation leads to higher wind > speeds, as a tiny fraction of the released energy is converted into > mechanical energy;[16] the faster winds and lower pressure associated with > them in turn cause increased surface evaporation and thus even more > condensation. Much of the released energy drives updrafts that increase the > height of the storm clouds, speeding up condensation.[17] This positive > feedback loop continues for as long as conditions are favorable for tropical > > cyclone development. Factors such as a continued lack of equilibrium in air > mass distribution would also give supporting energy to the cyclone. The > rotation of the Earth causes the system to spin, an effect known as the > Coriolis effect, giving it a cyclonic characteristic and affecting the > trajectory of the storm.[18][19] > > What primarily distinguishes tropical cyclones from other > meteorological phenomena is deep convection as a driving force.[20] Because > convection is strongest in a tropical climate, it defines the initial domain > > of the tropical cyclone. By contrast, mid-latitude cyclones draw their > energy mostly from pre-existing horizontal temperature gradients in the > atmosphere.[20] To continue to drive its heat engine, a tropical cyclone > must remain over warm water, which provides the needed atmospheric moisture > to keep the positive feedback loop running. When a tropical cyclone passes > over land, it is cut off from its heat source and its strength diminishes > rapidly.[21] > > Chart displaying the drop in surface temperature in the Gulf of Mexico > > as Hurricanes Katrina and Rita passed over > The passage of a tropical cyclone over the ocean can cause the upper > layers of the ocean to cool substantially, which can influence subsequent > cyclone development. Cooling is primarily caused by upwelling of cold water > from deeper in the ocean because of the wind. The cooler water causes the > storm to weaken. This is a negative feedback process that causes the storms > to weaken over sea because of their own effects. Additional cooling may come > > in the form of cold water from falling raindrops (this is because the > atmosphere is cooler at higher altitudes). Cloud cover may also play a role > in cooling the ocean, by shielding the ocean surface from direct sunlight > before and slightly after the storm passage. All these effects can combine > to produce a dramatic drop in sea surface temperature over a large area in > just a few days.[22] > > Scientists at the US National Center for Atmospheric Research estimate > > that a tropical cyclone releases heat energy at the rate of 50 to 200 > exajoules (1018 J) per day,[17] equivalent to about 1 PW (1015 watt). This > rate of energy release is equivalent to 70 times the world energy > consumption of humans and 200 times the worldwide electrical generating > capacity, or to exploding a 10-megaton nuclear bomb every 20 > minutes.[17][23] > > While the most obvious motion of clouds is toward the center, tropical > > cyclones also develop an upper-level (high-altitude) outward flow of clouds. > > These originate from air that has released its moisture and is expelled at > high altitude through the "chimney" of the storm engine.[15] This outflow > produces high, thin cirrus clouds that spiral away from the center. The > clouds > > ... > > 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 -~----------~----~----~----~------~----~------~--~---
