Why is the sky blue? I had that question as a kid and only my Mom could give me an intelligent answer, something like this:
The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.
However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.
As an artist, you must know that as you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.
Got it? Now when the next kid asks, you are ready!
I have painted the sky about every color there is, here is a sky with no blue at all. I used Azo red, Vermilion, Cadmium Red, Cadmium Red Light ( a very different color than cad red) and cadmium yellow. Then, thin streaks of white and various colors blended in for some variance. Use water or glazing medium to do this. Acrylic dries in the time it takes to run and get a drink, so the silhouetted figures can be painted on quickly. Painted for a good friend of ours, part two of this diptych next week.
Paints this week were from Lukas, who sells the paint in a squeeze bottle– excellent pigment and so inexpensive!! Also used Liquitex, great pigments as well.