Date: Fri, 9 Feb 1996 02:34:56 -0800 From: CS Anonymous FTP
To: firstname.lastname@example.org Subject: WWW form from seitti.funet.fi EMAILADDR=Veikko.Makela@Helsinki.fi FULLNAME=Veikko Mäkelä MESSAGE= Hello! I found your nice pages of photos. I am especially interested in atmospheric optical phenomena and I would your rainbows (and perhaps reflections and shadows) pages to our meteorological mailing list ¨ home page. BTW. In rainbow image "Marvel" it seems there is not rainbow at all... It looks like another beautiful optical phenomenon, a halo phenomenon call circum- horizonthal arc.. I like your poetry view of natural wonders. Even I am ¨ interested in physics of these phenomena, I always get esthetical experiencies of these color and light in nature. regards, Veikko Mäkelä Helsinki, Finland
From: email@example.com Date: Wed, 02 Oct 96 17:19:42 cst To: firstname.lastname@example.org Subject: Rainbows versus Ice Optics content-length: 1345 Randy, I was recently exploring the net and found your page on rainbows. The page is beautiful and the poetry inspiring. Nice job. You have, however, made one mistake. Your picture titled Marvel is NOT a rainbow. It is an upper tangent arc and is formed by refraction of light within ice crystals rather than in water droplets. Notice that all of your other pictures involve water droplets. I suppose a really picky person would say they are really waterfall bows rather than rainbows. "Marvel" shows cirrus clouds. These consist of ice crystals. The hexagonal shapes of the crystals lead to some very interesting optical phenomena. There are halos, sun pillars, sun dogs, upper tangent arcs, parhelic arcs, and others. A book titled An Introduction to Meteorological Optics by Tricker descrbes and explains these in detail. One of the foremost experts in meteorological optics, and the owner of a really cool home page is Allistair Fraser found at: http://www.ems.psu.edu/~fraser/fraser.html Fraser gives a good refernce list w/ call numbers and several web links at http://www.ems.psu.edu/~fraser/Meteo471/Meteo471wRefMeteo.html Steve Stage
Date: Sun, 2 Feb 1997 12:04:14 -0800 (PST) From: Andrew Young
To: rywang@sequim.CS.Berkeley.EDU Subject: Re: rainbows Well, these are all plausible guesses. I'd vote against the circum-horizontal arc because it appears so high in the sky. I suppose I should take another look at your picture and see the order of the colors; but my recollection was that the radius of the arc seemed small. Generally, the most brilliant arcs involve no reflections, so the inside of the arc (red) is toward the Sun. Note that red is on the *outside* of the rainbow, because there is a reflection inside the water droplets. I'd also vote against the upper tangent arc for two reasons: the dispersion is so strong (i.e., colors so well separated) that it appears to be formed by refraction at the 90-degree dihedral angles of ice crystals rather than the usual 60-degree angles. Also, it's very rare for the upper tangent arc to appear without the rest of the small halo; though in this case the patch of cirrus seems pretty isolated, so there may not have been anyting in the right place to reveal the rest of the halo display. We see a nice circum-zenithal arc once or twice a year here in San Diego. Anyway, we are all in agreement that the display you have photographed is a halo form of some kind, caused by ice crystals. Why not send a request to Alistair Fraser, who has a nice set of Web pages on meteorological optics? There are also some books you could look up: Robert Greenler's "Rainbows, Halos, and Glories", or a book on halo phenomena by R.A.R.Tricker. And I believe Walter Tape recently published a book showing halos in Antarctica; maybe you could identify it from pictures there. Any university library should have these, and many big public libraries will have them too. > you are mistaken about the sunset bit though. it was taken around > noon with a wide angle camera. the real thing looked much bigger and > more prominent in colors. as i had never seen anything like it before > that, i was totally mesmerized... OK, your information is helpful. So you were facing *away* from the Sun, and the darkenss of the landscape is due to cutting the exposure to cope with the brilliance of the display? How wide-angle a lens was used? If we could estimate the angular radius fo the arc, we'd be in a better position to identify it. The time of day means the Sun was high in the sky. That argues more for the circumhorizontal arc than the circumzenithal one. I think you have enough information that someone more familiar with halo phenomena than I am could identify it right off the bat. Where was it taken and at what time of year? We'd need that to estimate the altitude of the Sun more accurately, which is needed to help identify what you saw. > you page is interesting too... Thanks. There's lots of interesting stuff in the sky, but so few people ever bother to look... -- Andy Young
From: "Veikko Makela"
Date: Fri, 11 Jul 1997 14:18:28 EET DST Subject: Re: hello Reply-to: Veikko.Makela@Helsinki.FI Thanks for you note.. I check the interesting discussion about the picture "Marvel", where I have also partipated. Well, Steve Stage and Andy Young (I am not sure, what is his final decision) are wrong. The phenomenon in the picture is a halo called circumhorizonthal arc, as I earlier said. The photo is taken toward the Sun, insn't it? And it is very high above the image area? If we are talking about halos, that phenomenon could not be a upper tangent arc. For some reasons: 1) the Sun should below the arc and I think the Sun should be visible in picture very near the horizon, 2) the curvature is also wrong, 3) the colors are in wrong order, 3) colors are too vivid for tangent arcs. Usually tangent arcs have only strong red, orange and yellow and further colors are mixed to white, blue if seen is very pale. Either the phenomenon is not be lower tangent arc due to colors. As in upper arc, colors are not so vivid. I have never seen circumhorizothal arc in nature, we are in that case unlucky here in Finland. The Sun can't reach the elevation needed for this halo, but I've many pictures of that halo. And all these look like the arc visible in your picture. And I have seen many times the upper companion, circumzenithal arc. The colors are very similar, pure and beautiful. No any other haloforms can win these "circum" arcs in their colors. Only few times sun dogs can rearch something similar. I would add that I have about 20 year experience in observing halos. regards, -VeikkoM-