Also worth noting that this is not a necessary effect; particles with less forward scattering would reduce the effect, as i understand it, and in principle might do so a lot. Given this I'm not sure you can say ab initio that stratospheric geoengineering would alter sky appearance in any perceptible way at all.
On Thursday, 8 January 2015 03:11:12 UTC, Mick West wrote: > > Here's something similar done to a photo. The left is straight from the > camera, the right is overlaid with a pure white rectangle, at 10% > transparency. I've left in the photoshop panels so you can see the setup. > [image: Inline image 1] > > On Wed, Jan 7, 2015 at 6:55 PM, Ken Caldeira <[email protected] > <javascript:>> wrote: > >> Here is an attempt: >> >> The left square is 100% blue. The right square adds in 10% green and red >> to try to make something like blue with 10% added white. This is the most >> whitening that we got in any calculation. >> >> >> >> >> Saying it would 'whiten' the skies is exercising a bit of poetic license. >> >> >> >> >> >> _______________ >> Ken Caldeira >> >> Carnegie Institution for Science >> Dept of Global Ecology >> 260 Panama Street, Stanford, CA 94305 USA >> +1 650 704 7212 [email protected] <javascript:> >> http://dge.stanford.edu/labs/caldeiralab >> https://twitter.com/KenCaldeira >> >> My assistant is Dawn Ross <[email protected] <javascript:>>, >> with access to incoming emails. >> >> >> >> On Wed, Jan 7, 2015 at 3:32 PM, Andrew Lockley <[email protected] >> <javascript:>> wrote: >> >>> Another way of looking at this is to create a standard. >>> >>> UK pint glasses are always the same shape and size. UK semi skimmed milk >>> is always the same fat content. >>> >>> So there must be an accurate amount of milk you can put in a pint glass >>> of water that gives you the right colour when you look at the sky through >>> it. >>> >>> To keep it simple we might use a doubling of CO2 from pre industrial, >>> using only sulphur. >>> >>> So, physicists: How much milk in my pint? >>> >>> A >>> On 7 Jan 2015 22:34, "Mick West" <[email protected] <javascript:>> >>> wrote: >>> >>>> I understand that color varies greatly by view context, lighting, and >>>> display device. But surely an A/B side-by-side comparison could accurately >>>> demonstrate the magnitude and general direction of the change? >>>> >>>> On Wed, Jan 7, 2015 at 1:34 PM, Doug MacMartin <[email protected] >>>> <javascript:>> wrote: >>>> >>>>> Ben calculated the resulting spectrum of diffuse light for a range or >>>>> aerosol concentrations and sizes; see attached. Also has a comparison >>>>> with >>>>> Pinatubo, and with urban aerosols. >>>>> >>>>> >>>>> >>>>> We were originally planning on putting colour patches into the paper, >>>>> but concluded that the resulting colour depends too strongly on the >>>>> monitor >>>>> on which it is viewed or the printer used; even a pdf printed on the >>>>> exact >>>>> same printer by two different computers winds up looking quite different. >>>>> >>>>> Furthermore, perceived colour depends on context. So fair to say that it >>>>> will look whiter, and closer to what people in urban areas are already >>>>> used >>>>> to, but hard to come up with a picture that is actually realistic. >>>>> >>>>> >>>>> >>>>> (And, of course, it also depends on how much geoengineering you do, >>>>> whether it is 0.5 Wm-2 or 4 Wm-2) >>>>> >>>>> >>>>> >>>>> Doug >>>>> >>>>> >>>>> >>>>> Alan has a photo from Mauna Loa during Pinatubo. >>>>> >>>>> >>>>> >>>>> *From:* [email protected] <javascript:> [mailto: >>>>> [email protected] <javascript:>] *On Behalf Of *Mick West >>>>> *Sent:* Wednesday, January 07, 2015 1:26 PM >>>>> *To:* Ken Caldeira >>>>> *Cc:* Andrew Lockley; geoengineering >>>>> *Subject:* Re: [geo] Explaining geoengineering to normal people >>>>> >>>>> >>>>> >>>>> Perhaps a simulated before and during image might work. Here's one >>>>> with barely perceptible whitening. Are there calculations of the actual >>>>> magnitude of the change? Or measurements (or even, ideally comparative >>>>> photos) from Pinatubo. >>>>> >>>>> [image: Inline image 1] >>>>> >>>>> >>>>> >>>>> On Wed, Jan 7, 2015 at 1:10 PM, Ken Caldeira < >>>>> [email protected] <javascript:>> wrote: >>>>> >>>>> The sky will not look hazy white. >>>>> >>>>> >>>>> >>>>> It did not look hazy white after Mt Pinatubo. It is whiter, but still >>>>> blue. Maybe "slightly hazy blue" would be more accurate. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Wed, Jan 7, 2015 at 1:08 PM, Mick West <[email protected] >>>>> <javascript:>> wrote: >>>>> >>>>> Regarding #1 "The sky will look hazy white, like it's viewed through >>>>> a jug of water with a teaspoon of milk in it " >>>>> >>>>> >>>>> >>>>> There's a few issues with that. For one, the sky actually does look >>>>> hazy white a lot of the time, and in a lot of directions - most notably >>>>> horizontal, with there being more atmosphere in that direction, and also >>>>> in >>>>> the direction of the sun, as there's more light. >>>>> >>>>> >>>>> >>>>> With Twitter, I've found using annotated images is the best way of >>>>> getting a point across. For example: >>>>> >>>>> >>>>> >>>>> [image: Inline image 1] >>>>> >>>>> >>>>> >>>>> Then "a jug of water with a teaspoon of milk in it" has a HUGE range >>>>> of possible transparencies with variants on jug size, and milk type. >>>>> Ideally you'd have an illustration that accurately reflects the computed >>>>> magnitude. Is it one of these? >>>>> >>>>> [image: Inline image 3] >>>>> >>>>> [image: Inline image 2] >>>>> >>>>> >>>>> >>>>> Feel free to use any of these images. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Wed, Jan 7, 2015 at 12:07 PM, Andrew Lockley <[email protected] >>>>> <javascript:>> wrote: >>>>> >>>>> I've been trying to answer some basic questions from a lay inquirer on >>>>> Twitter. I thought I'd share some of the explanations I've used. >>>>> >>>>> I'd really value comments, corrections, ideas and feedback >>>>> >>>>> A >>>>> >>>>> ------- >>>>> >>>>> 1. The sky will look hazy white, like it's viewed through a jug of >>>>> water with a teaspoon of milk in it >>>>> 2. SRM is much more about controlling future temperature rises than >>>>> winding back old ones (near term). >>>>> 3. Although sulphur injections aren't physically ideal, the fact that >>>>> they're nature-identical reduces the risks of unforeseen consequences >>>>> 4. Nobody working in geoengineering seriously believes it's an >>>>> alternative to mitigation >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "geoengineering" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected] <javascript:>. >>>>> To post to this group, send email to [email protected] >>>>> <javascript:>. >>>>> Visit this group at http://groups.google.com/group/geoengineering. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "geoengineering" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected] <javascript:>. >>>>> To post to this group, send email to [email protected] >>>>> <javascript:>. >>>>> Visit this group at http://groups.google.com/group/geoengineering. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "geoengineering" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected] <javascript:>. >>>>> To post to this group, send email to [email protected] >>>>> <javascript:>. >>>>> Visit this group at http://groups.google.com/group/geoengineering. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "geoengineering" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected] <javascript:>. >>> To post to this group, send email to [email protected] >>> <javascript:>. >>> Visit this group at http://groups.google.com/group/geoengineering. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> > -- *This e-mail may contain confidential material. 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