pagiven@drutx.UUCP (10/31/84)
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Can anyone out there explain the atmospheric phenomenon known as
the "rosy fingers of dawn" in reasonably plain English (that is,
without invoking quantum chromodynamics or other esoteric theory)?
In case this beautiful morning sight is known by another name, let
me explain: On a cloudless morning, just before the limb of the sun
breaks the horizon, deep pink shafts of light radiate from the hor-
izon to just beyond directly overhead but not quite to the western
horizon. There appears to be four or five very sharply defined
shafts of light, alternating with deep blue, growing with intensity
as the horizon is neared. One is reminded of the "rising sun"
Japanese flag symbol. Interestingly enough, I have never seen this
at sunset. Can it happen then, too?
I have only seen this about three times in my life. Having seen it
for the third time just yesterday, my curiosity screams for an
answer.
Thanks in advance.
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Paul Given {ihnp4, houxe, stcvax!ihnp4}!drutx!pagiven
AT&T Information Systems Laboratories
11900 N. Pecos, Rm 1B04, Denver 80234 (303)-538-4058
-----------------------------------------------------------------rpw3@redwood.UUCP (Rob Warnock) (11/02/84)
+--------------- | Can anyone out there explain the atmospheric phenomenon known as | the "rosy fingers of dawn" in reasonably plain English (that is, | without invoking quantum chromodynamics or other esoteric theory)? +--------------- I'll give it a go, though I don't know how accurate this is... +--------------- | In case this beautiful morning sight is known by another name, let | me explain: On a cloudless morning, just before the limb of the sun | breaks the horizon, deep pink shafts of light radiate from the hor- | izon to just beyond directly overhead but not quite to the western | horizon. There appears to be four or five very sharply defined | shafts of light, alternating with deep blue, growing with intensity | as the horizon is neared. One is reminded of the "rising sun" | Japanese flag symbol. Interestingly enough, I have never seen this | at sunset. Can it happen then, too? | Paul Given {ihnp4, houxe, stcvax!ihnp4}!drutx!pagiven +--------------- I believe what you are seeing may be literally the shadows of the contours of the Earth just below the eastern horizon. That is, there will be places (below the horizon) which are lower than others, and through those "gaps" sunlight will stream overhead (your head) before the sun is completely above that "further horizon". (I'm not explaining this very well, am I?) Since raw sunlight in such beams is very much brighter than the general scatter of the false dawn, you will see these shafts of light (due to scatter), much like a searchlight. A similar phenomenon occurs towards the end of a total solar eclipse, when the Sun begins to peek out from behind the Moon, producing what is called the "wedding ring" (bright "hot spots" where sunlight is actually shining through valleys or mountain passes at the horizon of the Moon). If is indeed seen more often in the morning, it is probably because the air is more still then than at the corresponding time in the afternoon (after the Sun has heated up the local earth and water and stirred up all sorts of thermals and currents), and the still air allows a clearer definition of the "rosy fingers". [ O.k., I've stuck my neck out... anybody want to chop it off? ;-} ] Rob Warnock UUCP: {ihnp4,ucbvax!amd}!fortune!redwood!rpw3 DDD: (415)572-2607 Envoy: rob.warnock/kingfisher USPS: 510 Trinidad Ln, Foster City, CA 94404
jlg@lanl.ARPA (11/02/84)
> > - > Can anyone out there explain the atmospheric phenomenon known as > the "rosy fingers of dawn" in reasonably plain English (that is, > without invoking quantum chromodynamics or other esoteric theory)? > In case this beautiful morning sight is known by another name, let > me explain: On a cloudless morning, just before the limb of the sun > breaks the horizon, deep pink shafts of light radiate from the hor- > izon to just beyond directly overhead but not quite to the western > horizon. There appears to be four or five very sharply defined > shafts of light, alternating with deep blue, growing with intensity > as the horizon is neared. One is reminded of the "rising sun" > Japanese flag symbol. Interestingly enough, I have never seen this > at sunset. Can it happen then, too? I have seen this a number of times at both sunrise and sunset. On one very dramatic occasion the cause of the phenomon was also directly in view. It was a distant mountain who's contours cast a shadow on the lower atmosphere. In the places where the mountain was lower, the sunlight reaches lower into the air above me, and a brighter shaft of light was produced. I don't know if this is the only cause of the phenomon, but it is certainly A cause. Try looking around for large obsticles on the horizon and position yourself so that it is between you and the setting (or rising) sun. You should be a sufficient distance away for the object to cast shadows on you only when the sun is at or below horizontal. Your best chance is on a day with thermal inversion layers in the atmosphere so that the difference in scattering between one atmospheric level and the next is most apparent. (This may be why you have only seen the effect at sunrise. Inversion layers form over cities at night, but are usually burned off by the sun during the day. Only in regions with shallow valleys bordered by mountains do inversion layers form during the day.) Good hunting!