|MadSci Network: Earth Sciences|
Hello Carly First, lets talk about light. White light is a combination of all the colors of the spectrum (rainbow). When light passes from one material (air) into another material (water) it is bent because it speed changes. This is called refraction and is the reason your straw looks bent in a glass of water. Each color of light is bent at a different angle. Short wavelength light (violet) is bent the most and long wavelength light (red) is bent the least. This allows us to see a rainbow when it rains or when we shine light through a prism. The color of the sunset has to do with the way light from the sun enters our atmosphere. When the sun is overhead and the angle that the light enters is small, the shortest wavelength light (violet and blue) are bent slightly and are scattered by the air molecules and dust in the air to give us a blue sky. If there is a lot of dust in the air, more light is scattered making the sky appear less blue and sometimes even close to white. After a rain when the air is clean the sky is a much brighter blue. When the sun is setting, the light is passing through much more air than when the sun is overhead. More air allows more scattering of the light. Since the red light is scattered last the sunsets appear reddish. The more stuff in the air the prettier the sunsets. Since purple is at the shorter wavelength end of the spectrum, it is scattered first and little is left for the sunset. Sometimes when the conditions are right and there is reflection of the light off clouds high up in the atmosphere we can see some of the shorter wavelengths giving us those rare pinks and purples. I have attached some web sites that explain this topic more. Light and Color BlueSky-PinkMountains Why is the Sky Blue?
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