Question

 

(1) Why the sky is blue based on our understanding of E&M dipole radiation?

(2) In this explanation also indicate why the sunset is red.

(3) Finally, there should be an explanation of how the sky is polarized, and why this is based on E&M dipole radiation.

Answer 1

A) when an oscillating electric field falls on molecules they get polarized and force them to vibrate with the same frequency.So they become small radiating dipole in the sky whose radiation we see in the sky thats why they are called EM dipole radiations.

Now this scattering of sunlight causes diffuse sky radiation, due to which the colour of sky appears to be blue because for direct sunlight incidence the blue light scattered the most rest are absorbed.

B) during sunrise or sunset time the light incidence tangentially so the trajectory of sunlight through the atmosphere becomes elongated and blue and green colour gets scattered away from the from the line of perceveble visible light and red light reaches to observer. Thats why it appears to be red.

C) the molecule or atoms present in the sky , specially molecules , they have positive and negative charge centre so they act as a dipole , due to oscillating electric field of EM radiation these positive and negative charge centre gets seperated and the molecule gets polarized , and thats how whole sky gets polarized.