408/409. You can simulate refraction and total internal reflection at
http://www.ps.missouri.edu/rickspage/refract/refraction.html
There is also a comprehensive list of refractive indices of many different substances. Feel free to post interesting links on physics topics.

Global warming and climate modelling

Find out more at physicsweb.org
• Mankind to blame for global warming
http://physicsweb.org/articles/news/11/2/3
• A model approach to climate change
http://physicsweb.org/articles/world/20/2/3/1