Global Twitter Heartbeat [facebook.com] is the "first ever" visualization that combines population, tone and geographic analytics together on an animated heat map. And it is based on the analysis of about 50 million tweets per day with the help of an "impressive machine with a maximum of 4,096 cores".
In other words, the visualization reflects the locations and the sentiments discovered in the tweets that were sent during a specific timeframe, and renders them as rainbow-colored clouds. Two different heatmaps have been generated so far: one that tracks the tweets during the US 2012 Presidential Election, and one that focuses on the days after hurrican Sandy made its landfall. In theory, one can thus correlate the actual position of the hurricane to the changing emotions of the people living closeby.
One note: check your audio volume setting before hitting play.
More information about this project is available at Huffington Post.