]> Accumulation In general, an equation expressing a balance of quantities in the sense that the local or individual rates of change are zero. A complex system is a system composed of interconnected parts that as a whole exhibit one or more properties (behavior among the possible properties) not obvious from the properties Processes by which traces gases or particles are transferred from atmosphere to a surface. Disturbance process that multiple substances are in contact and have some consequence Interaction Any departure introduced into an assumed steady state of a system. The magnitude is often assumed to be small so that product terms in the dependent variables may be neglected. Removal System is a set of interacting or interdependent entities, real or abstract, forming an integrated whole. Oscillation, usually of a small amplitude, about a reference state. In mechanics, a state in which the vector sum of all forces, that is, the acceleration vector, is zero. In hydrodynamics, it is usually further required that a steady state exist throughout the atmospheric or fluid model. The equilibrium may be stable or unstable with respect to displacements therefrom. See also hydrostatic equilibrium, geostrophic equilibrium, instability. 2. In thermodynamics, any state of a system that would not undergo change if the system were to be isolated. Equilibrium property describing unstable conditions, such as in the atmosphere Instability The characteristic of a system if sufficiently small disturbances have only small effects, either decreasing in amplitude or oscillating periodically; it is asymptotically stable if the effect of small disturbances vanishes for long time periods. System dynamics is an approach to understanding the behaviour of complex systems over time. It deals with internal feedback loops and time delays that affect the behaviour of the entire system. What makes using system dynamics different from other approaches to studying complex systems is the use of feedback loops and stocks and flows. These elements help describe how even seemingly simple systems display baffling nonlinearity