Sketchwise / Sketches

Why the Sky Is Blue

1. Sunlight looks white, but it contains all the colours of the rainbow.
2. On its way through the atmosphere, sunlight encounters countless tiny air molecules.
3. These molecules scatter some light, sending it off in many different directions.
4. Shorter wavelengths, like blue, scatter much more strongly than longer wavelengths, like red.
5. Blue light scattered across the sky reaches us from many directions above.
6. That scattered blue light is why a clear daytime sky looks blue.