I watched such a beautiful sunset in Moscow yesterday. Every time I admire like a child.
True, from the point of view of physics, this beautiful phenomenon sounds quite simple and unattractive)
Sunset is a refracted visible light from the Sun in a certain way. At different hours of the day, the sun's rays travel different distances and during the day you will not see the sunset - the light does not have time to dissipate.
But in the evening - enough. And the more clouds the light meets along the way, the more the light is refracted, and the more red the sunset becomes.