Rayleigh scattering

Rayleigh scattering is a phenomenon that occurs when light hits tiny particles in the atmosphere. This scattering is more effective at shorter wavelengths, such as blue and violet light. Because our eyes are more sensitive to blue light and because some violet light is absorbed by the ozone layer, the sky appears predominantly blue during the day. In contrast, during sunrise and sunset, the sunlight passes through more atmosphere, scattering shorter wavelengths and allowing longer wavelengths like red and orange to dominate, giving those times their beautiful hues.