Newsgroups: lter.ced Path: LTERnet!rnott From: Bruce Hayden Subject: CED 3.2/3 Message-ID: <1994Feb28.202406.12578@lternet.washington.edu> Sender: rnott@lternet.washington.edu (Rudolf Nottrott ) Organization: Long Term Ecological Research Date: Mon, 28 Feb 1994 19:48:44 GMT ***************************************************************** ***************************************************************** *** *** *** *********** *********** ********** *** *** * * * * *** *** * * * * *** *** * * * * *** *** * ********* * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** * * * * *** *** *********** *********** ********** *** *** *** ***************************************************************** ***************************************************************** Vol.3 No.2/3 ::::: January/February Issue :::::: March 1, 1994 ***************************************************************** ***************************************************************** CED METADATA ---- CED is the Climate/Ecosystem Dynamics bulletin board of the LTER network. In CED, you will find exchanges of ideas, information, data,bibliographies,literature discussions, and a place to find experts within the LTER community. We are interested in both climate controls onecosystems and ecosystem controls on climate. As this is an inter-disciplinary activity,we hope to provide things that you might not come across in your work atyour LTER site. CED is a product of the LTER climate committee and contributions to CED for general e-mail release may be sent to either David Greenland of Andrews LTER [Greenlan@oregon.uoregon.edu] or to Bruce Hayden of the Virginia Coast Reserve LTER [bph@envsci.evsc.virginia.edu]. We expect that the scope of CED will evolve and reflect the interests of the contributors and users of this service. CED will be issued as the preparation work gets done (usually monthly). Back-issus of CED may be requested from Daniel Pommert [daniel@lternet.washington.edu] by the file name given in the masthead. Daniel can also add people to the CED mailing list. Feedback on CED from LTER scientists is welcome (non-$$$$ contributions also welcome.) For example, please forward citations of climate & ecosystem publications on your site. We are keeping a LTER wide bibliographyon Climate/Ecosystem Dynamics that we pass on via E-mail. ***************************************************************** ***************************************************************** *** *** *** *** *** CED's DAY OFF *** *** *** *** *** ***************************************************************** ***************************************************************** The stress of a February 3, 1993, 6-year LTER renewal proposal deadline precluded an issue of CED at the end of January. The current issue is proudly named the January/February issue. Welcome back. With some determination LTER augmentation proposals will not require another CED hiatus. ***************************************************************** ***************************************************************** *** *** *** *** *** GREEN THUNDERSTORMS *** *** *** *** *** ***************************************************************** ***************************************************************** Bohren, Craig F., and Allstair B. Fraser. 1993. Green Thunderstorms. Bull. Amer. Meteor. Soc. 74(11):2185-2193. Anytime you see Craig Bohren's name on an article, sit up and take notice. Friends who have attended his classes in atmospheric optics at Penn State (Department of Meteorology) rave with out ranting. Also, truck down to your local book monger and see if he has any of Bohren's books and fork over the cash if you have any otherwise use plastic. It will be worth it. Consider this little gem of a title: Colors of snow, frozen waterfalls, and icebergs. What a titanic little steamer that one must be. The intrepid mind will find it in J. Opt. Soc. Amer. 73:1646-1652. (1983). What about Fraser? Well, he can turn a good article title as well. Try this one. Fraser, A. B. 1978. Why green thunderstorms are severe. [Tropical Meeting on Meteorological Optics, Keystone, CO. Opitcal Society of America, MA6-1--MA6-4.] CED backtrackers will recall CED's answers to a Colorado LTER reader about green clouds. Bohren and Fraser are pros at this stuff so listen-up. CED in the past has offered the explanation of green clouds of Minnaert in 1954 [The Nature of Light and Color in the Open Air. Dover 362 pp.]. Love that Dover publisher. Minnaert observed that "thick" clouds cruising across a well illuminated, almost Irish-green surface, with a burst of sunlight in an opening in the clouds produced a green airlight below the cloud. Now this just the wearing of the green by the air below the cloud not the cloud itself. CED also related Professor Went's idea that organic debris incorporated into the outer surfaces of the clouds caused the clouds, severe ones, to be dark in color and sometimes greenish. Went's theory, to my knowledge, has not been tested. Bohren and Fraser, in their paper, first thumb through the folk-lore of green thunderstorms and their causes and note that explanations offered suffer from the "most widespread form of defective reasoning", i.e. "the post hoc ergo propter hoc fallacy!" That is if two things happen at the same time, well hells bells one must cause the other! Fraser put forward his theory on green thunderstorms first (1978). His model was that the green light was produced by the backscatter of light to the observers eye from the scatterers in the air between the eye and the cloud. If the cloud is a good and dark one, the green airlight is easily seen. So the geometry is like this. The sun is above you and shines on the air between you and the cloud [on the cloud too but it doesn't make it white! [see dark clouds in earlier CEDs] If the air is real clean, i.e. not many scatters, the sun needs to be low on the horizon and behind you. If the air is hazy with plant hydrocarbons (visibility about 20 km), often the case around thunderstorms, even with the sun high in the sky, but still over your shoulder, the light spectrum from the backscatter (airlight) has a peak at green wavelengths! Bohren's theory comes from a paper he read on green icebergs. (Antarctic icebergs! Palmer LTER might be our eyes on this one.) Liquid and solid water is intrinsically blue. Illuminate the stuff with reddened light and you get green. You have to look through a couple of meters of the stuff to see the blue. Study of a glass of water or a ice cube will not cut it. Now a cloud is made up of water drops. But in a cloud, if look through a straight path of cloud substance you look through centimeters of water not meters! But the drops scatter the light all over the place and you see don't a straight path. Just like the numbered ping pong balls in the lottery machine, the actual path length adds up to meters. Big, thick thunderstorms, severe ones, offer enough drops to pass through to sum up to meters of path length. Clouds are blue if thick enough. Get to see one of these cumulonimbus honeys around sundown when the light is red from dust scattering of the light and the red light is on that long path length through the water of the drops of the cloud, it becomes green. Bohren says you need a thunderstorm about 10 km tall with about 1 g of water per cubic meter. That is about 1 cm of water top to bottom of the cloud. Squeeze all that water out and it would be a puddle about 1 cm deep. If you want a really good green thunderstorm get one with about 1.5 cm of water perhaps 15 km tall and 60 miles in diameter. Bohren and Fraser's abstract, after claiming that both of their theories of green thunderstorms valid, finishes with "These two explanations do not exclude one another but allow for multiple causes, including those not yet identified." How nice that they don't claim their own theories to be the be-all-and-end-all end of the line. These are nice guys. ***************************************************************** ***************************************************************** *** *** *** *** *** RECYCLED RAIN REVISITED *** *** *** *** *** ***************************************************************** ***************************************************************** All Scientists Meeting goers and CED readers remember discussions about recycled rain. Evapotranspiration matters and matters a lot to rainfall. This is an idea some 500 years old and was revisited by the U.K.-based Natural Environment Research Council, based on their GCM study, and blabbed about it at the annual meeting of the British Association for the Advancement of Science on August 31 of the year just passed. Their conclusion, with just an edge of hype, was "Simply put, rain exists because of the rainforests, not the other way around." That is heady stuff to the terrestrial ecologist. ***************************************************************** ***************************************************************** *** *** *** *** *** CED SUPPORTS REGIONALIZATION *** *** *** *** *** ***************************************************************** ***************************************************************** LTER PIs with eye on their e-mail know of the LTER regionalization project. An electronic volume of site contributions text and color images will be published on the Network MOASIC and due to the interest of Jerry Franklin in this project, as a colorful paper-book version. The selection of regions is the various sites business but climate as a basis for selection is worth some thought. John Aber of Harvard forest is regionalizing his site based on rainfall-chemistry regional patterns. BNZ and its boreal forest is climatically a place with arctic and continental polar air masses in Fall, Winter and Spring and maritime polar air in summer. Our Toolik Lake friends live with arctic and continental polar air masses in all months of the year [except when they winter at Woods Hole]. CPR and Konza are bathed in the desiccated westerlies which flow across the Rockies. Coweeta thrives in the maritime tropical air in summer and return polar air in winter and represent the area of the deciduous forests of the U.S that gets most of their winter precipitation in the liquid form. The regionalization committee (Hayden and Burke) hope that the sites will select the region(s) their sites represent on the basis of their site research and sound science. Keep watching your e-mail for more advice. As soon as the first several site contributions to our electronic volume come in we will put them up on Moasic for the other sites to study and compare. ***************************************************************** ***************************************************************** *** *** *** The great tragedy of Science: *** *** The slaying of a beautiful hypothesis by an ugly fact. *** *** *** *** T. H. Huxley *** *** *** ***************************************************************** ***************************************************************** My mother, beginning in the 1950s, was a diabetic. I grew up knowing about carbohydrate exchange units. A gram of potato = a gram of lentils = a gram of ice cream= a gram of lima beans. I learned early on that all carbohydrates were equal. The blood sugar roller-coaster was the same for all grams of all carbohydrates. My mother scooped, weighed and ate. I just ate. In the early 1980s I taught a course at the University of Virginia titled Environment and Your Health to about 200 students per offering. I learned in my study for that class that my knowledge of carbohydrate equality for diabetes was natural history lore and not natural science. I read a paper which proclaimed that not all carbohydrates were alike and that there had been no published study [EVER] that showed it to be so. A gram of potato did not = a gram of lentils did not = a gram of ice cream did not = a gram of lima beans. Lentils don't drive blood sugar anywhere near as high as the same amount of glucose in the glucose tolerance test. My mother was treated by natural historians of the medical persuasion. Most people still are except that they are permitted some fructose sweeteners these days. Her treatment worked, general carbohydrate intake were controlled but brute force and blood sugar levels were kept in check. Insulin helped. But, it wasn't based on hypothesis testing or systematic measurement of blood sugar in response to different carbohydrate diets. That wasn't done until the 1970s. ***************************************************************** ***************************************************************** *** *** *** *** *** WHEN IT IS COLD AND HUMID IT IS THE COLDEST! *** *** *** *** *** ***************************************************************** ***************************************************************** When the relative humidity is high and the temperature is low it feels so much colder then when the relative humidity is low and the temperature is just the same. So moist, cold air is bone-chilling. Now my wife, a natural historian when it comes to feeling cold, would salute if I ran this notion up the flagpole. So here I come, the natural scientist, and I say to her, "Having more water vapor in the air has nothing to do with how cold you feel." Talk about deaf ears. So I plod along. The conductivity of the air is inversely proportional to the density of the air (Smithsonian Meteorological Tables, 1965: page 394). I knew I had to give you a reference on that one. If you add more water vapor to the air and keep the temperature the same, the density increases and so the conductivity must decrease! Moist air is "less good" at conducting heat away from your body than dry air! Natural history and natural science are at odds again. Can't we trust our senses. Doesn't my wife know bone chilling cold when she feels it. I try to tell her that dry days are sunny days and with a bit of a radiation load on your body you have more heat to work with and your rate of heat loss is modest so you don't feel cold. On a damp cloudy day with only the most diffuse light falling on you, your heat gain from light is low to nil and your heat loss rapid and you feel cold. For the most part I make my wife stand at attention when I explain things like this to her. She tends to nod off at my natural science when she is seated or prone. ***************************************************************** ***************************************************************** *** *** *** *** *** LIGHT AND DARK SNOW FLAKES *** *** *** *** *** ***************************************************************** ***************************************************************** It snowed in Virginia two days after the first CED of the 1994 was sent out over our LTER electronic super highway which is at this writing just a two-lane blacktop country road (no images even in two dimensions yet). The snow was wet . The flakes were big. Actually the flakes were bunches of flakes, and they were easy to see. As they fell they changed from dark and ugly to white and nice. Well, they did not actually change their brightness, lightness or darkness or anything else. It was me. My psychology bested my physics. My eyes said natural history and my mind had to be encouraged to think natural science. My mind judges brightness or lightness and darkness of objects relative to their background. We don't see absolute brightness, lightness or darkness of objects we only see relative brightness, lightness or darkness. When the background of the falling flakes is bright, like the illuminated-from-above clouds that produce the snow, then the flakes look dark. As the flake approaches the ground, it is contrasted with the horizon of trees, fields, hill and homes -- dark things all, then the flakes look nice and white against this darker background. Actually, the flakes are scattering the most light to your eye when directly above and well illuminated and as they fall they have more cloud between them and the sun and they scatter less light to your eye. The sky should seem darker but the actuality is it seems lighter. When they cross the horizon they brighten a lot all at once because the are in contrast to a darker background. So we see that brightness differences are relative not absolute Our eyes can detect a 2% brightness difference. ***************************************************************** ***************************************************************** *** *** *** *** *** NATURAL HISTORY VS. NATURAL SCIENCE *** *** *** *** *** ***************************************************************** ***************************************************************** If you have stayed with me this far, the following will not startle you. I have long been bothered by the different conclusions reached by natural historians and natural scientists. I have a good friend who is a birder. Don't we all? Hank Shugart would call him a dikey-birder. Not being a birder my self, I don't know what Hank is talking about. My friend is a great observer of birds. He knows lots abut what they do in his back yard, which direction they fly in from, what seeds they eat. That sort of stuff. Now this guy has taken almost no science in college. He was a history major and now a 6th grade teacher. He has become a natural historian as we use the term. A lot of the things he says are really sort of touchy-feely. He draws conclusions that I don't. Now, I admit I find a lot of the natural history stuff just charming. It is interesting stuff. If you were to overlap, in Venn diagram style, the domain of natural history and natural science you would find lots and lots of common ground. What makes me curious is the part that doesn't overlap. Why we see things differently and disagree on some conclusions is what I am interested in. Well, I have come to believe that it involves a special kind of subjectivity. What I call psychological subjectivity. I came to this conclusion while considering how bright snowflakes are. When I watch snowflakes, I am a natural historian and I make natural historian conclusions. If I could make optical measurements with fine instruments I would become a natural scientist. As a natural scientist I wold find that my observations are consistent with the known laws of physics. My conclusions based on my life as a natural historian would violate the laws of physics. I would appreciate comments on this stuff from CED readers. I will find it interesting. ***************************************************************** ***************************************************************** *** *** *** *** *** HYPOTHESIS MAKER *** *** *** *** *** ***************************************************************** ***************************************************************** I have come to view the Natural Historian inside me and in others as a first order hypothesis maker. What you see leads you to conclude, to hypothesize. Seeing the same thing, e.g. snow falling and changing brightness, a thousand times would only add to your natural history conviction and adherence to your conclusions and hypotheses. My wife is the natural historian of our household. She has a quick mind, she remembers everything, she is great at Jeopardy and she is a blatant conclusion-jumper. My household physics is no match for her household natural history convictions. Electricity, magnetism, microwaves, you name it I watch my step. I have learned to bite my tongue and keep my natural science to myself. I obey the laws of Physics when she isn't watching. I try to avoid doing things when she is within eyesight. I think she thinks I am lazy. She doesn't function by objective testing of ideas and hypotheses or by laws application. It goes without saying that the natural historian and the natural scientist can co-exist with the proper level of benign neglect and transgression forgiving. We are approaching our 25th year together. When we go to bed at night and turn off the light, the room gets very dark. Pitch black. Later, when you pop open your eyes, you marvel at how bright the room is. The illumination did not change but the brightness did. Brightness in your head. If there is a 2% difference between objects you see them as separate. My wife would conclude that the mice come out and play when the brightness of the darkened room is great. Bohren would say that my wife's conclusion that the mice come out to play after the lights-off-darkness changes to bright darkness is that she has fallen prey to the post hoc ergo propter hoc fallacy. Please note that my wife does not get to read my CEDs.