| ★ wanayoo — archive 1999 http://www.howstuffworks.com/question39.htm | Nouvelle recherche | Portail wanayoo |
Q&A ArchiveAsking Questions |
Question
Why is the sky blue?
Answer
Here is something interesting to think about. When you look at the sky at night it is black, with the stars
and the moon forming points of light on that black background. So why is it that, during the day, the sky
does not remain black with the sun acting as another point of light? Why does the daytime sky turn a bright
blue and the stars dissappear?
The first thing to recognize is that the sun is an extremely bright source of light - much brighter than the moon. The second thing to recognize is that the atoms of nitrogen and oxygen in the atmosphere have an effect on the sunlight that passes through them. There is a physical phenomena called "Rayleigh scattering" that causes light to scatter when it passes through particles that have a diameter 1/10th of that of the wavelength (color) of the light. Sunlight is made up of all different colors of light, but because of the elements in the atmosphere the color blue is scattered much more efficiently than other colors.
So when you look at the sky on a clear day, you can see the sun as a bright disk. The blueness you see everywhere else is all of the atoms in the atmosphere scattering blue light toward you (but not scattering red light, yellow light, green light, etc. nearly as well).
Interesting links:
|
|
||||||||||||||||||||||||||||
|
 |
How Stuff Works (http://www.howstuffworks.com) is a production of Howstuffworks.com, Inc. P.O. Box 40492 - Raleigh, NC 27629 See http://www.howstuffworks.com/contact.htm for contact information |
© 1999 Howstuffworks.com, Inc. All rights reserved.
