Hello Mark, The seawater aerosol need to be activated (turned into drops), which happens in the regions of highest supersaturations, which are in the lowest few metres of the clouds.
Also, the less than 1um aerosol will not be able to settle against the updraughts that prevail in the clouds. So seeding has to be at cloud base. Airborne seeding has of course been successfully used in weather Mod work, but here we're talking of almost global scale seeding All Best, John. John Latham Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 Email: [email protected] or [email protected] Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 or (US-Cell) 303-882-0724 or (UK) 01928-730-002 http://www.mmm.ucar.edu/people/latham ________________________________________ From: [email protected] [[email protected]] on behalf of Mark Massmann [[email protected]] Sent: Friday, March 23, 2012 8:51 PM To: geoengineering Subject: [geo] Re: Possible Emergency MCB Response John- Thank you for your response. CCN dispersal using aircraft could pretty easily reach remote ocean regions where CCN concentrations are low. As you know, once aircraft have reached cruising altitude, the time and fuel necessary to fly far distances is relatively small (and airports could be utilized closest to targeted regions to help minimize flight duration). Can you please explain why CCN's would need to enter at cloud bases, as opposed to having them "settle downward" onto the clouds from above?? I would think that if the Lair/CCN mixture was released high enough above the target area, and since the expansion process into air should happen relatively quickly, it should be possible to control this process so that the CCN-laden air "settles-out" gently in place (basically "parking it" at the right altitude). Just a thought, but a scenario like this might be a way to achieve the benefits of MCB until the sail-powered vessels are ready for deployment. Best Regards, Mark On Mar 23, 11:28 am, John Latham <[email protected]> wrote: > Mark, > > Thank you for yr interesting comments. > > The natural clouds over land have much higher number concentrations > than over the remote ocean. Thus there needs to be a correspondingly > large increase in CCN concentration. Albedo-change is proportional > to ln(N/No) > > Wide dispersal is indeed an important issue, but we need also to have > CCN-laden air rising up into the clouds. I think using liquid air would > inhibit the upward motion. > > The extra CCN need to enter the clouds at their bases, not their summits. > > Cheers, John. > > John Latham > Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 > Email: [email protected] or [email protected] > Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 > or (US-Cell) 303-882-0724 or (UK) > 01928-730-002http://www.mmm.ucar.edu/people/latham > ________________________________________ > From: [email protected] [[email protected]] on > behalf of Mark Massmann [[email protected]] > Sent: Thursday, March 22, 2012 6:44 PM > To: geoengineering > Subject: [geo] Re: Possible Emergency MCB Response > > John- > Couldn't you quickly create the desired effect of MCB by injecting > salt particles using aircraft?? > > If the formation of salt particles could be done on a large enough > scale on land, it seems that aircraft could release them very > strategically to create maximum benefit. This might be more effective > than releasing by ships, because aircraft would release CCN's on the > top of marine stratocumulous (100% delivery rate), and the release > could be updated in real time to target regions with ideal background, > maximizing the albedo increase. > > The challenge might be disbursing the salt particles evenly. In > previous posts, I have suggested the idea of suspending the CCN's in > liquified air or liquid nitrogen, to take advantage of their 1,000 > time expansion ratio. This might disburse particles evenly and over > very large volumes, while also causing water vapor to condense on them > since they will be cold. > > Please let me know what you think. > > Thanks- > Mark > > On Mar 21, 11:24 pm, John Latham <[email protected]> > wrote: > > > > > > > > > > > [[email protected]] > > > Possible Emergency MCB Response > > Hello All, > > > I take the point raised by a number of contributions over > > the last few days that if a dire emergency arose we may > > need to try solutions that are far from ideal in some regards, and > > may have strong and justifiable opposition. Seeding the > > stratosphere or even the troposphere with sulphur could > > be such a solution. Ken’s point “Volcanoes did it and it > > worked” is a valid response to the query as to why we > > should focus major attention on this technique. > > > A positive feature of the MCB cloud brightening idea, in our > > view, is that the only raw material required is seawater, most > > of which would fall back into the oceans within a week of being > > sprayed into the air below the clouds, into which a significant > > fraction of the seawater aerosol rise. If MCB were ever deployed > > the spraying would have to be continuous. The spray production > > systems are central to this endeavour. Ideally we want to produce > > copious quantities of identically-sized seawater particles of > > diameter in the region of 0.5 um. We have two strong, > > independent spray-generation teams, headed by Armand > > Neukermans in California and Stephen Salter in Edinburgh. A > > great deal of progress has been made, but there remain a few > > problems yet to be resolved. It is hard to estimate the time-frame > > within which this work will be complete, especially since we have > > no external funding for it. > > > If a dire emergency should arise before the spraying systems are > > fully functional and tested it would be possible to brighten marine > > stratocumulus clouds by injecting them with aerosol much less > > benign than seawater. The commonly occurring “ship-tracks”, > > observed from a satellite and illustrated in the attached slide, show > > many bright streaks (regions of enhanced brightness) resulting > > from the entry into the clouds of the exhausts of ships sailing > > beneath them. Such observations show that MCB can work. We > > would be loathe to pollute the atmosphere with these materials, > > but in principle significant cooling could be fairly readily produced > > in this way if the situation was desperate. Such action might be > > better than doing nothing at all. It might usefully complement > > seeding of cloud-free regions by sulphur or sea-water aerosol - > > or other materials. > > > All Best, John. > > > John Latham > > Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 > > Email: [email protected] or [email protected] > > Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 > > or (US-Cell) 303-882-0724 or (UK) > > 01928-730-002http://www.mmm.ucar.edu/people/latham > > > Ship Tracks.ppt > > 256KViewDownload > > -- > 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 > athttp://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. -- 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.
