I filled a tall glass with tap water and shone a white LED head torch up from below. From the side, the water looks clear.
From above you can still see the torch underneath. The LED is clearly white.
Then I stirred in a small amount of milk powder, maybe quarter of a teaspoon.
From above the bulb now looks red. This the sunset effect. White light is made up of a mixture of many colours of which red had the longest wavelength. The milk powder particles are able to knock the shorter wavelengths sideways. This is called scattering. Only the longer wavelength red wavelengths can reach the top.
Viewed from the side, the bottom of the glass had a bluish hue, that hasn't photographed well. The shorter blue wavelengths are scattered sideways most easily. Towards the top of the glass the edge looks yellowish.
