NOAA
Noaa: Pacific Marine Environmental Laboratory: What Is El Nino?
This page tells you what El Nino is, provides links to animations and videos on El Nino, explains how to recognize El Nino, and discusses the history of significant El Nino events.
NOAA
Noaa: Pmel: Noaa: What Is La Nina?
At this site from the Pacific Marine Environmental Laboratory, you can find out the characteristics of La Nina. You can find out about the lastest La Nina and the places it effected. Links are provided for additional information.