At sunrise and sunset, when the sun has more distance to travel through the atmosphere, the shorter wavelengths are scattered out, leaving the longer oranges and reds. Refraction is the bending of light as it passes through two materials of different density. As the light passes from the less dense air to the more dense water, it slows down. This is why it is hard to spear a fish or pick up an object in the bottom of an aquarium. The refraction also causes the light to separate into colors.
White light is composed of all of the colors.
Students can study the Law of Reflection and Law of Refraction to better understand the optics involved in atmospheric phenomenon. See if they can explain how halos, sun dogs, solar pillars and glories are formed using the laws of reflection and refraction.