The Butterfly Effect and the Weather

Because the atmosphere is chaotic, uncertainties, no matter how small, would eventually overwhelm any calculations and defeat the accuracy of the forecast.  This principle is sometimes called the "Butterfly Effect." In terms of weather forecasts, the "Butterfly Effect" refers to the idea that whether or not a butterfly flaps its wings in a certain part of the world can make the difference in whether or not a storm arises one year later on the other side of the world. Because of the "Butterfly Effect," it is now accepted that weather forecasts can be accurate only in the short-term, and that long-term forecasts, even made with the most sophisticated computer methods imaginable, will always be no better than guesses.