Edward N. Lorenz (1917-2008), an American meteorologist noted for his pathbreaking descriptions of the transfer of energy in the general circulation of the atmosphere. His book, The Nature and Theory of the General Circulation of the Atmosphere (1967) featured one of the first complete descriptions of atmospheric general circulation, including the equations governing atmospheric energetics. Computer programs and models developed later would use Lorenz's mathematical formulas to improve weather predictions. He formally introduced the notion of uncertainty and chaos into weather forecasting. In that regard, Lorenz is famous for his statement of the butterfly effect. Lorenz's theory was that an event as small as a butterfly flapping its wings in China could change the weather in the United States a few days later. This effect was possible because the butterfly moved a little bit of air, that moved more air, and so on, until the moving air reached the other side of the world. The butterfly effect, or the "sensitive dependence on initial conditions", is the essence of chaos.
- New York Times. Edward N. Lorenz, a Meteorologist and a Father of Chaos Theory, Dies at 90. April 17,2008.