The Long Race
During the day, when the sun is directly overhead, sunlight travels a relatively short distance through our atmosphere to reach your eyes. But as the Earth rotates and the sun appears to sink toward the horizon, that light has to run a much longer race. It must travel through much more air, dust, and moisture to reach you than it did at noon.
Filtering the Blues
As the sunlight takes this long journey through the atmosphere, the 'Scattering Game' we learned about earlier goes into overdrive. The atmosphere is so thick at this angle that almost all the blue and violet light is scattered away long before it reaches you. It’s as if the air is a filter that slowly removes colors one by one.
The Survivors: Red and Orange
Because red, orange, and yellow light travel in longer, lazier waves, they are much better at passing through obstacles like air molecules and dust. These 'survivor' colors are the only ones left to paint the clouds and the horizon. The more 'stuff' there is in the air—like salt from the ocean or dust from a desert—the more vibrant the colors become.