The daily morning journal and courier., 1901-10-24
MECHANISM OF A SUNSET.
Color Effects of Microscopic Dust Pa

Color Effects of Microscopic Dust Par < ticles
 Most people if they were asked to state the color of the sun would say that it was orange, and they would as confidently assert that the color of the Hfmosphere was blue. Recent re- searches and investigations, however, point to the conclusion that the real acolor of the sun is blue, while that of the atmosphere surrounding the earth < IS orange. Commonly the earth's at- #mosphere appears so transparent and Translucent that it is hard to realize Y the fact that it has as much effect on X the light and heat coming from the sun as if it were roof of thick glass. But the atmosphere is very far from being as colorless as it seems to be, and the best way of discovering its true tint is, not to gaze immediately overhead, but to look away toward the horizon By So doing the atmosphere will be seen, Y is only a small accumulation of it com- as 1t were, in bulk; for overhead there x pared with the many miles of thickness through which the vision travels when the eye looks toward the horizon.
 N The atmosphere surrounding the earth then may be likened to screen Of an orange color and it will readily be understood that any light passing through this screen will experience some notifications. Now, as already stated, it appears highly probable that $ supposing any one could see the sun rom a position outside the earth's at mosphere the light coming from this central luminary would be seen to be not white, but blue. This blue is, of course not a pure monochromatic blue, and the expression really means that 1t sims LID the dominant note in the col or scheme. What, therefore, the at nnosphere may be considered to do IS to stop out, or absorb, all the colors at the blue end of the spectrum, the resi- due Altering through to the earth as white light. When the rays of light first left the sun, the blue rays were t the strongest; but very soon after they entered the earth's atmosphere their nrogress was impeded, and Of all the rays journeying from the sun they n1,ickly became the weakest. on the other hand, the red rays which at flrst were inconspicuous had the facility Of y<enetrating the earth's atmosphere, an i, ,vera the most in evidence at the end of their long journey.
 The first step, accordingly, to De taken when investigating sunset is to realize that the white light rom the s,n which is commonly supposed to De composed of the seven primary colors should rather be thought ot as resi- due of the original radlations. A lur- +bar important point is to bear in mind +hat all radiations of light are of differ a,,+ wave lengths This fact indeed, .ls~ o+ the very foundation, so to speak, of all sunsets. and it is the prime aoencv by which their fiamlng' gor- peous tints and colors are produced N is due to this fact, for instance, that fin the neighborhood ot large towns AhS s,n nearly always appears to set as ,.ad hall of fire The rays of light at \+ba red end of the spectrum are of a Auch longer wave length than any or +ba,r fellow rays, and so are the pest qualified for penetrating the ueHse tonlx of haze which so commonly floats over all large towns and cltles' III s.cn localities. as the sun sinks to rest tne yreen rays are first absorbed oy thls hank of haze, and then the yellow ana 1astlv The orange and the red, the lat +ar more often than not, being the only o,aa to get through at all. A careful o,.sar,,,+ion of a sunset will reveal the seat thai the colors fade in the above mentioned order and the reason they do so is that they are of different wave lengths.