Darken the room and shine a flashlight through the milky water.
Look into the glass from above.
The picture exaggerates the color a bit - it looks blue, but not neon blue!
The Earth's atmosphere is filled with dust and water drops. These particles bend the light from the sun, causing it to appear blue. In this demonstration, the milk provided the particles to bend the light from the flashlight.
At sunset, the angle of refraction changes and you're able to see colors from the other end of the spectrum - reds and oranges.
And, if you've ever watched a sunset in a region where there have been forest fires, you'll notice even more intense colors - more particles (smoke from the fire), causing more refraction.