Rayleigh Scattering

The scattering of photons as light moves through the atmosphere.

Rayleigh scattering is stronger for shorter wavelengths of light, so blue light wavelengths will scatter faster than red wavelengths. Some practical examples:

• We cannot see the stars during the day because of the sunlight that has scattered through the atmosphere. Without Rayleigh scattering (and clouds), we would be able to see the stars during the day easily.
• The sky is blue because the blue wavelengths of the sun’s white light is scattered more readily than the red light.
• Sunrises and Sunsets appear red because the light must pass through more atmosphere to reach your eye when the sun is low on the horizon. More atmosphere means more blue wavelengths are scattered, which leaves red wavelengths to come directly from the sun.