Key Points
(Nanometers are billionths of a meter.) Within this range, our eyes interpret different wavelengths as different colors: red, orange, yellow, green, blue, indigo, and violet, in order from longest to shortest..
This means that when sunlight streams through the atmosphere, the reds and yellows will mostly pass straight through and the blues and violets get scattered..
When the sun is lower in the sky, the white light has to pass through more of the atmosphere, which scatters even more of the blue colors..
Actually, the sun produces higher intensities of light at larger wavelengths (red and green) than for smaller wavelengths (blue and violet)..
Since we really sense just three colorsred, green, and blue, our eyes arent as sensitive to the smaller wavelengths of purple as they are to blue..
