Sources

 

Barrymore, John.  "UV Radiation 101." HowStuffWorks.com. 20 Aug. 2009. Web. 18 April 2013. <http://health.howstuffworks.com/skin-care/beauty/sun-care/uv-radiation.htm>.

 

Ronca, Debra.  "How Radiation Works." HowStuffWorks.com. 23 Jul. 2008. Web. 18 Apr. 2013. <http://science.howstuffworks.com/radiation.htm>. 

 

Science Mission Directorate. "Ultraviolet Waves" Mission: Science. 2010. National Aeronautics and Space Administration. Web.17 Apr. 2013. <http://missionscience.nasa.gov/ems/10_ultravioletwaves.html>.

What are Ultraviolet waves?

 

Ultraviolet radiation is often shortened and written as UV. UV lies between visible light waves and X-rays on the electromagnetic spectrum. UV cannot be seen by the human eye, but when it falls on certain materials it may cause them to glow and reflect visible light back to the eyes. UV can be beneficial to health, as it stimulates the production of vitamin D, but excessive exposure can harm unprotected skin. That’s why we need sunscreen when we go out in the sun.