Why Autumn Skies Are So Blue

Why Autumn Skies Are So Blue Have you ever noticed that fall skies appear to be a deeper, more saturated blue than normal?   What sorts of things can make the sky appear bluer, specifically during the fall season? Here are a few contributing factors: Falls Lower Humidity Fall is notorious for its pleasant weathernamely, its cooler temperatures and lower  relative humidity. As air temperatures cool, the amount of moisture that the air can hold  lessens. Less moisture means fewer clouds and haze occupying skies in September, October, and November. With little to no clouds or haze to veil the sky, its blue hue appears purer, and the sky itself, more open and vast. Falls Lower Sun Position As we progress  through autumn, the sun sits lower and lower in the sky. With the sun no longer directly overhead, you could say that more of the sky is significantly angled away from the sun. The Rayleigh scattering directs more blue light towards your eyes, while the indirect sunlight decreases the incoming levels of red and greenthe result of which is a more intense blue sky. Falls Foliage Believe it or not,  the very presence of  falls red, orange, and gold leaves actually  help give the skys blueness  a color boost. According to color theory, primary colors appear more brilliant when theyre  in contrast with their complementary colors.  Looking at a color wheel, you can see that  violet and blue (which are the two wavelengths of sunlight that are scattered for us to see and thus give the sky its characteristic blue hue) correspond to the  complementary colors of yellow, yellow-orange, and orange. Seeing any one of these leaf  colors against the backdrop of a clear blue sky makes the blue of the sky pop  that much more.