Why is the sky blue during the day?

Q: Why is the sky blue during the day?

The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight travels through the Earth's atmosphere, it collides with gas molecules. These molecules scatter the light in all directions, but they scatter shorter wavelengths (blue light) more strongly than longer wavelengths (red light).This selective scattering means that:Blue light is scattered about 10 times more than red lightWhen we look at the sky, we see this scattered blue light from all directionsThe blue color appears more intense when looking straight up (where the atmosphere is thickest)This is also why the sun appears more reddish during sunrise and sunset - the blue light has been scattered away, leaving primarily red and orange wavelengths to reach our eyes.

Question

Accepted Answer

The sky appears blue due to a phenomenon called Rayleigh scattering. When sunlight travels through the Earth’s atmosphere, it collides with gas molecules. These molecules scatter the light in all directions, but they scatter shorter wavelengths (blue light) more strongly than longer wavelengths (red light).

This selective scattering means that:

Blue light is scattered about 10 times more than red light
When we look at the sky, we see this scattered blue light from all directions
The blue color appears more intense when looking straight up (where the atmosphere is thickest)

This is also why the sun appears more reddish during sunrise and sunset – the blue light has been scattered away, leaving primarily red and orange wavelengths to reach our eyes.