Markov chain
From Glossary of Meteorology
Markov chain
A stochastic process with a finite number of states in which the probability of occurrence of a future state is conditional only upon the current state; past states are inconsequential.
In meteorology, Markov chains have been used to describe a raindrop size distribution in which the state at time step n + 1 is determined only by collisions between pairs of drops comprising the size distribution at time step n.