Why Is the Sky Blue: An Exploration of Atmospheric Science

Music Hi, it's KCB. You're watching Why Tell Me Why. Have you ever wondered why the sky is blue or the sun is yellow or your shirt is red? Well, we have an answer for you this week on Why Tell Me Why. Color is determined by which frequencies or which colors of the rainbow are present in the light that comes to us from some object. All objects absorb some kinds of light and reflect other kinds of light. And we see what comes back to us, that combination of spectra or that combination of colors, and assign to it a single color or some kind of a color mix that depends on what frequencies are actually reflected back to us rather than being absorbed by that material. So, white light from the sun comes along and reflects off any object that we see. If that object happens to reflect a lot of the light, all colors, then whatever it is looks white. For example, clouds look white because they reflect all of the colors pretty much equally. On the other hand, when the light goes through simply straight through the sky, through all the very low density molecules of gas in the upper atmosphere, a good bit of the red and even the green continues to go on through without being scattered or affected. On the other hand, blue light is scattered much more by the atmosphere, by the gases in the upper atmosphere, and comes down, gets scattered down towards us. So, when we look back up at the sky, it looks blue because we don't see as much of the red and green light. When we look at a sunset, sunsets look red because as the sunlight comes through the atmosphere, a lot of the blue, almost all of the blue in fact, gets reflected out, gets scattered out, and even much of the green gets scattered out, leaving only the red. So, red light is then the color of a sunset, and blue is the color of the sky for the same reason. That blue is more predominantly scattered by the atmosphere than red. So, in the case of water, the light in the, at least in the top parts of the ocean, but more red is absorbed than blue or green, so water would tend to look blue or bluish green, depending upon exactly how you view it. Chlorophyll, which is what makes grass green, is actually produced by absorbing a reddish color, and perhaps a little bit of the blue. Which makes the green? Which makes the green. Thanks for watching. Any questions you have, you can email me at ytummyyatdiscovery.com, and I will do my best to answer those questions for you on air.