Theories of shock formation in the solar atmosphere

Models for the generation of coronal shocks by large-scale, disruptive solar events are reviewed. The theoretical requirements for shock formation in the corona are discussed. Various approaches used to model the shock-initiating events are analyzed with distinctions drawn between the driving mechanisms in the theories. The importance of the preevent coronal magnetic field configuration and magnitude in influencing the subsequent coronal response and shock structure is also discussed. Particular emphasis is placed on the information furnished by the theories which can be compared with observations and, similarly, the observational results which provide critical tests for the theory. Such comparisons will be shown to suggest a revised representation of the shock-transient association. Recent models of the observed spatial relationship of type IIs and transients are examined. 67 references