. Elementary physical geography . rticles happento be very abundant, even the coarser rays of yellow lightmay be scattered ; and under rare conditions of very smokyair the entire sky may assume a brassy color. Since thelight is obliged to travel through a greater distance of aisnear the time of sunset than in midday, the color of thewestern sky in the late afternoon is often yellow, while that of midday was adull hazy blue (). Among the mostbeautiful of lighteffects in the atmos-phere is that of thesunset colors, whichare due to the scat-FlG- 16- tering of the waves Diagram to show that
. Elementary physical geography . rticles happento be very abundant, even the coarser rays of yellow lightmay be scattered ; and under rare conditions of very smokyair the entire sky may assume a brassy color. Since thelight is obliged to travel through a greater distance of aisnear the time of sunset than in midday, the color of thewestern sky in the late afternoon is often yellow, while that of midday was adull hazy blue (). Among the mostbeautiful of lighteffects in the atmos-phere is that of thesunset colors, whichare due to the scat-FlG- 16- tering of the waves Diagram to show that the suns rays pass through a „>, ; ny. hc^ra + >> a ,i .. j. , 1 , t WiliOll lldvc bile greacer thickness of atmosphere at sunset and sun-rise than at midday. (Thickness of atmosphere smaller lengths. Asgreatly exaggerated). a ^^ Qf ^ ^ coarser yellows and reds come to us, the reason for the scat-tering being the fact that the light at the time of sunset andsunrise passes through a great thickness of air, and hence the. THE ATMOSPHERE. 27 waves encounter a greater number of dust particles. Whenthe atmosphere contains much dust, the morning and eveningcolors are often very intense, but an increase in the quantityof dust beyond a certain point tends to dull the tints. Withclouds in the horizon at sunset or sunrise, these colors of redand yellow are often reflected in infinite variety of shadeand tint. Other phenomena, such as the twilight arch, theglow and the afterglow, are associated with the setting ofthe sun. Another property of light is that of reflection, and as aresult of this many interesting optical effects are light of the moon depends upon the reflection of sun-light from its surface. The earth also reflects light, andthis is one of the reasons for the illumination of places thatare in the shadow of the direct rays of the sun. Otherplaces which are illuminated reflect some of their light tothe parts that are in shadow. Clouds also reflect the li
Size: 2111px × 1184px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthortarrralphsralphstockm, bookcentury1900, bookdecade1900
