J-curve

A curve in which values depart from expected growth at some point in time and move upward or downward at a more rapid rate than extrapolation would indicate. The point at which this change in slope occurs is sometimes called a “takeoff point” or the “knee of the curve” and curves of this sort are sometimes called “hockey sticks.” Sometimes such growth is propelled by positive feedback. For example: the more computers there are, the smarter society becomes, and the smarter society becomes, the more computers there are. Or consider: the warmer the planet becomes, the more methane is released from permafrost and other natural sources, and the more methane, the warmer the planet becomes. The futurist Ray Kurzweil has described many such curves of technological development that grow or wane exponentially and lead toward a technological singularity. Also, after a currency suffers a drop in its exchange rate, the term is used to describe the subsequent drop and recovery of the balance of trade.