Red sky smoke TM

“At sunrise or sunset, sunlight takes a much longer path through the atmosphere than during the middle part of the day. Because an increased amount of violet and blue light is scattered out of the beam along the way, the light which reaches an observer early or late in the day is reddened. Thus, it could be said that sunsets are red because the daytime sky is blue. This notion is perhaps best illustrated by example: a beam of sunlight that at a given moment produces a red sunset over the Appalachians is at the same time contributing to the deep blue of a late afternoon sky over the Rockies.” (NOAA)