"Few natural phenomena change so radically and unpredictably as the daily weather. Meteorologists had long understood how the atmosphere in a given locality could be capricious and unstable from hour to hour. As one authority explained in 1957, tiny disturbances in the air, far below the limits of observation, could grow into large weather systems within a few days. Nobody could predict these unstable processes, so "there is an effective time barrier beyond which the detailed prediction of a weather system may well remain impossible." Beyond that limit, which might be only a few days, one could only look to statistics, the probability of rain or frost in a given month."

It was weather that prompted a deeper delving into chaos theory. After a few days, predictions go to--well, they're just not reliable, unless they are.