National Weather Digest ALPJ::NGLOW: A RARE SUNSf:.'T

Isador~ L. Sonnier (1) Department of Science Education University Ot Southern Mississippi Southern Station, Box 82u2 Hattiesburg, MS 394Ub-820i ana

Harola Romero (2) Department of Physics University of South~rn Mississippi Southern Station, Box 504b Hattiesburg, MS 3940b-Su4b

ABSTRACT ers may enjoy a few moments of unparalleled experience, and pass it on to a friendl An alpenglo~ gives one an empty feeling o( gloom and despair. Although periods o( We've all heard the adage, -Rea skies at drought create a condition (or an almost night, sailor's delight; red sky in the daily occurence o( this pheno.enon, most o( morning, sailors take warning-. The alpen­ us miss it because oe our preoccupation with glow is a very special -red sky-. Ana, -living- and our windoor w habits. Too, it there's truth to this aaage. lasts (or but minutes in the lowlands where most o( us live. One reason (or noting the Consider that al~ across the United States event is that there's truth to the adage, most of our weather comes from the west. -Red sky at night, sailor'S delight; red sky That's because we live in the Westerly Wind in the morning, sailors take warning.­ Belt of our hemisphere. Although an alpenglow is created by the same conditions as red sunrises and sunsets, it Consider further the possibility that a occurs less (requently. weather system is coming toward us from below our horizon. Rising up into the It is an unusual conaition that causes the western skies for as much as six to eight sky to be red. Ana, from time to time the miles, such a disturbance would block out sky even glows, giVing one an empty feeling the sun's light. of gloom and despair. With obvious reference to this morbia feeling, it has been dubbed Next, consider a clear western sky for -teinte caoavereuse- in the Alps (3). several hundred miles to the west. This would greatly expand the transmission paths Although an alpenglow can be seen just about of the light of the setting sun. anywhere in the world, it is called that because it is most commonly seen on mountain Another important factor to consider is that summits. air molecules wi~l scatter light, the short­ er (blue) wavelengthS being scattered more Because of the time of day, our "inooor" than the longer (reo) wavelengths. This habits prevent most of us from ever seeing causes the sky to appear blue throughout the this spectacular event. Or, if we chance to day and red with the rising and setting sun. see it, we generally have more on our mindS than to stano in awe of this quite natural When the sun is near the horizon, the light event. has traveled througn so much of the atmos­ phere that the blue light is all but scat­ Since it lasts for only a few minutes in the tered away. This causes the sun to have a lowlands, one must be outside at precisely deep red appearance, as comparee to its the right time after sunset or before sun­ bright white appearance when it is higher in rise to see it. In the highlands, it COUld the sky. occasionally last for the better part of an hour. Since most of us live in the lowlandS, Scattering is probably the best explanation the event goes mostly unnoticed, is little for reo sunsets and maybe alpenglows too. understood, and seldom talked about. However, an observer of alpenglows in the Alps wrote of the rocks and snow having a As in observing a beautiful sunset, one must "livid appearance" in the blues, after which lend his entire being to the event in order Ci:lme the reds and rosy pink of "recolora­ for it to have a personal meaning. A sunset tion" or the "afterglow" (3). He said fur­ is too much of a commonplace event for it to ther ~hat the order is reversed at sunrise. make much of an impact on most of us. This leaves a distinct possibility that the tinted sky of alpenglows may be both red ane Perhaps, thic can be changedI Maybe at its blue, of tOQ two vi&ual spectrum ext[emes. next occurrence, at least some of the read- The added eviaence is that colored photo-

8 Number 3 graphic slices taken during sunset or true for westerly W1no regions--not for sunrise could noticably be tinted either tropical or polar easterlies. The opposite olue or rea. is true there.

One can also observe a rather spectacular Of course, the alpenglow is not just any red post-sunset glow during the event of an sky. However, the drought conaitions of re­ overcast. Tne light is not only intense, but cent years should have created this condi­ possibly refracted from far below the hori­ tion into an almost daily occurrence in some zon as well. places. It WOUld be interesting to corrobo­ rate these postulations. With the conditions of a clear sky to the west, apparently we get red sunsets, the Even though it may give us an eerie feeling, distance and the amount of clearing affect­ it i~ still a signt to behOld. Anu, yiven a ing the intensity of the red. And, if it is better understanding and appreciation of the clear toward the east, we get a reo sunrise. event, it COUld add to the small pleasures Because we have the potential for at least of life. one front going past us every 3 to 5 days, it is not likely that we'd eno up with both REFERENCES AND FOOTNOTES a clear western horizon as well as a clear eastern horizon. 1. Dr. Isadore L. Sonnier earned his Ed.D. at the Universit~ of Northern Colorado. His That's why red skies at night me""n "sailor's abiding interest in earth and environmental delight". There are probably no fronts sciences has led to a wide diversity of approaching anc the weather is more than publication topics, including his book likely to be nice for at least a cay or two. -Holistic Education: Teaching of Science in the Affective Domain-. On the other hana, when the clear horizon is far toward the east, it means that we've 2. Dr. Harold ROltlero received his Ph.D. at likely not had a front to pass over our area the Universit~ of Nissouri-Rolla. He has for at least a couple of days. Therefore, worked in design of filters and evaluation that greatly increases the chances for one of container materials for solar and in the immediate future. And, that's why a radiation studies. red sky 1n the morning means "sailors take warning". 3. Anon., 1913: -The Alpenglow,- Scientific American, 108:484; Hay 24. If you think about it, the adage is only

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