#A -- I agree with Mike. My quick order-of-magnitude analysis also indicated that the energy inputs required for an effective LAIR system renders it infeasible.
On Sun, Jun 5, 2011 at 10:36 AM, Mike MacCracken <[email protected]>wrote: > Dear Mark: As I have noted before, you really need to do some order of > magnitude estimates and not just what you feel might be needed. > > Let's take your 2000 tons of Lair dispersed over 3 days over about the > area, > let's assume, of a good size of a city. The heat of vaporization (so heat > it > would take up to vaporize the Lair) is roughly 200 Joules per gram > (something you can find in physics references). Each ton is 10**6 grams, > and > each Joule is about 0.24 calories. Add maybe 24 calories/gram to raise the > temperature from the condensation point to a reasonable temperature, and > one > has maybe 70 calories per gram of total heat uptake. Multiply this out (so > 2000 tons times 70 calories per gram times 10**6 grams per ton) and one > gets > something like 1.5 times 10**11 calories. > > I switched to calories so I could make a comparison to a nuclear weapons > explosive power as we have had such events and had energy (heat rather than > cooling) added to the atmosphere and have a sense of the impact. So a > megaton is 10**15 calories, a kiloton is 10**12 calories, and Hiroshima and > Nagasaki blasts were of order 10**13 calories. If this is all right, the > amount of energy you are talking about, even if done all at once, is about > a > hundredth the size of the Hiroshima or Nagasaki events. You are proposing > this energy transfer would be spread over 3 days, so if the nuclear bomb > clouds took 5 minutes to dissipate, then divide by another 1000 or so (take > a smaller number here if you want). However, during the three days the air > is moving and this will greatly spread out your proposed influence. I just > do not understand how this would have any significant effect. > > As another example, let's take a guess at the amount of energy that a > tornado-generating convective storm processes. Assume a storm that covers > only 5 by 5 kilometers and generates 2.5 cm (1 inch) of rain per hour (both > very likely on the low side). So 2.5 cm times 25 square kilometers times > 600 > cal/g heat from condensation times 10**10 cm**2/km**2 and we get roughly 4 > times 10**13 calories--so Hiroshima or Nagasaki size, and injecting the > 2000 > tons would be 1% of that, and that is sort of the very highest possible > ratio--most of these storms are much, much bigger. Again, I don't see how > this might work. > > It would be good for you to work through on this and other order of > magnitude analyses, and for someone else to check this all, but if this is > anywhere near right, completely aside from the energy it would take to > create and insert the Lair, I just don't see how it would have any effect > on > a large scale or on the tornado scale. Until you can provide really > quantitative examples, I don't think advocating Lair is advancing the > discussion. > > Mike MacCracken > > > > > On 6/5/11 11:54 AM, "m2redmond" <[email protected]> wrote: > > > John and Mike- > > Thank you for taking the time to consider how Lair might be applied to > > increase global albedo or to possibly mitigate storm severity, as well > > as other potential applications such as "frosting" permafrost to make > > it more reflective or fighting wildfires by releasing liquid nitrogen > > (LN2). > > > > I think because Lair can provide a number of different benefits (which > > is a good thing), this has led to some confusion over how specific > > strategies might work. I¹ll take the blame on that- I¹ve probably > > tried to pack too much information in my previous posts. However, > > because Lair has these different possible applications, there is > > greater feasibility that one or more of them will provide important > > benefits. Performing field tests could answer many of these questions > > on short order. > > > > Please let me try to clarify what I think is needed: > > A. The amount of Lair we are considering is very large (100-ton > > payloads) and would include multiple heavy-lift aircraft to deliver > > enough Lair for the desired result. The specific amount and frequency > > would depend on the size and intensity of a particular storm, or in > > the case of creating clouds would depend on cloud lifetime. For > > example, to mitigate a large storm this might mean 10 aircraft making > > two sorties per day or 2,000 tons of Lair for 3 days. For global > > albedo, maybe 3 or 4 of these operations might be spaced evenly around > > the equator, so that 40 aircraft would deliver 8,000 tons per day on > > an ongoing basis (probably an upper bound of what would be needed). > > > > B. If necessary, certain regions may require a concurrent release of > > water vapor and/or CCN¹s (i.e. salt particles) along with Lair, to > > form clouds more effectively. > > > > C. For increasing cloud albedo, Lair could be released at any > > altitude- it¹s not limited to creating ice-clouds at high altitudes. > > It could also help to form low clouds through condensation and might > > increase the droplet density (and therefore reflectiveness) of > > existing clouds. > > > > D. It¹s important to note that the expansion ratio of Lair increases > > with altitude, so it expands about 870 times at sea level but 7,500 > > times at 50,000 ft. So IF thicker/higher clouds are beneficial, this > > could maximize cloud size and lifetime. Despite some opinions that > > contrails/cirrus may cause warming, I believe that assumption needs to > > be challenged with respect to much thicker and more reflective clouds > > at the same altitude (also with respect to 9/11 data which indicated > > contrails may actually provide cooling). This could be easily > > investigated as part of field-tests. > > > > E. It¹s also hoped that Lair can leverage existing natural processes, > > so that it becomes a catalyst for a much larger natural effect. For > > example, the mechanism of deposition causes a chain-reaction when > > saturated air is exposed to ice particles (this is how contrails > > grow). When Lair cools water vapor to below -40 deg F/C, this should > > form large amounts of ice nuclei, and deposition should then cause a > > much larger cloud of ice particles to form, the size of which will be > > dependent on resident humidity (higher humidity equals larger > > effect). A "bounding" example would be to consider releasing Lair at > > 28,000 ft (8.5 km), where it would fall and expand into cold air, > > cooling a region down to 25,000 ft (7.6 km) where the temperature is > > normally -30 deg F (-34 deg C). So if Lair (-319 deg F/-195 deg C) > > would cool this region by just 10 degrees, this would create ice > > nuclei that should initiate deposition, to form clouds over a larger > > region. > > > > F. Energy calculations for increasing cloud albedo are in work by > > Kevin Layton. The challenge here is considering the effects of Lair > > for different atmospheric conditions (i.e. different energy states). > > However, because the effect of Lair depends on so many variables > > (pressure, temperature, humidity, Lair amount, Lair expansion ratio, > > resulting deposition, latitude etc.) it might require a computer > > analysis to better-determine where it will and will not work. > > Ultimately, I believe that field testing will be needed on Lair to > > determine where it¹s most effective. > > > > G. In addition to cloud albedo, Lair might be used to help limit the > > severity of future storms. Since severe storms are commonly energized > > by the upward flow of water vapor, mixing large amounts of Lair into > > these regions should enable the cold air from Lair cause enough > > cooling and downward pressure to REDUCE this upward flow by some > > amount (this would require field tests and multiple payloads). IF it > > works, this could be used to help limit the size and height of storm > > systems to reduce hail and flooding, to help minimize the formation of > > tornados, and at a larger scale to reduce the severity of hurricanes. > > Lastly, by replacing Lair with LN2, the same planes and tank systems > > could be used to help fight wildfires that would otherwise burn out of > > control. > > > > Hopefully this helps to answer some questions related to potential > > feasibility. Would it help if I created a Wikipedia page that goes > > into these details? Or would a White Paper be more appropriate? > > > > Thanks- > > Mark > > > -- > 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. > > -- 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.
