In the early 1960 the american mathematician and meteorologist Edward N. Lorenz built a mathematical model of the way air moves in the atmosphere. As lorez studied weather patterns he began to realize that they did not always change as predicted. Minute variations in the initial values of variables in his twelve-variable computer weather model would result in grossly divergent weather patterns, the weather uas unpredicteble in short term and impossible to anticipate at a long therm basis. This sensitive dependence on initial conditions came to be known as the butterfly effect and later debated as deterministic chaos or the chaos theory. In December 2010, about 85 milion internet users visited weather websites, representing more than 40% of the US online population.