WHY IS THE SKY BLUE
The sky is blue because of scattering of electromagnetic radiation the atmosphere. This radiation is not spread equally; the ones with shorter wavelengths are towards the blue and violet shades and tend to scatter more. This shown in the picture below. The light with longer wavelengths is towards the red and orange spectrum and is more visible when the light of the sun hits in an angle. At sunset the orange and red waves of light can be seen because of the dim lighting which makes the red and orange light easier to see. This process is called the Rayleigh scattering named after English physicist Lord Rayleigh who discovered it in 1871.

SJV why is the sky blue.jpg


Rainbows
Rainbows are made when rays of light hit a raindrop. The light is actually many different colors so we cannot normally see it but when it hits a raindrop in the correct angle it splits into different waves and making it visible to the human eye. The raindrop acts like a prism. Each of the different angles makes a different color. This is why you see seven colors, red, orange, yellow, green, blue, indigo and violet.
SJV rainbows.jpg
Glossary
Electromagnetic radiation- radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x-rays, and gamma rays.
Wavelengths-the length of waves or rays of light from the sun
Prism-
A transparent solid body, often having triangularbases, used for dispersing light into a spectrum or forreflecting rays of light.


Citations

Gerbis, Nicholas. "Why is the sky blue?" 07 October 2008. HowStuffWorks.com. <http://science.howstuffworks.com/nature/climate-weather/atmospheric/sky.htm> 27 September 2012. Web

Knight Judson and Neil Schlager, Science of everyday things : volume 2 : real-life physics, Detroit, MI., Gale Group,2002, Print

Hewitt Paul G., Conceptual physics : practicing physics, San Francisco, Addison-Wesley, 2002, Print