The butterfly effect is a term used to describe the idea within chaos theory called sensitive dependence on initial conditions. It explains how single factors creates sensitivity to “initial conditions” such as situations in which events in one area of a network can cause major and unpredictable responses in other parts of the network. However, this principle became the cornerstone of the science of Chaos Theory.
In the context of weather, the scientist Edward Lorentz wrote in his study of weather predictions that within only a few days (accurate for a few days, but beyond six or seven they become speculative), there are so many factors to address that makes it impossible to predict how the weather will be for x numbers of days ahead. When Lorentz was studying the phenomena he found out that slightly different inputs can determine very different results. Lorentz wrote in his scientific papers how the butterfly flaps its wings in Amazonas rainforest can make a difference in whether or not a storm arises on the other side of the world. See also Chaos Theory, Complexity, Deep Ecology and System thinking.
Encyclopedia of Environment and Science