Scattering of sunlight
Also called: Rayleigh scattering · Topic: Solar Radiation, Heat Balance and Temperature · NCERT: Class 11, Ch 8 "Solar Radiation, Heat Balance and Temperature"
Meaning
Scattering happens when tiny gas molecules and small particles in the air bounce sunlight in all directions. Very small air molecules scatter short blue waves much more strongly than other colours. This is called Rayleigh scattering, and it makes the daytime sky blue. At sunrise and sunset, light travels a much longer path through the air. Most of the blue is scattered away before it reaches us, so mainly red and orange light is left.
Example
On a clear day over the Arabian Sea coast at Mumbai, the sky is blue at noon and turns red and orange at sunset. On hazy winter days in Delhi, larger dust and smoke particles make the sky look white or grey.
Don't confuse with
- Mie scattering: here larger particles of haze, dust and cloud scatter all colours almost equally. So the sky looks white or grey, not blue.