Abstract
The beautiful spherical blastwaves of theory are disrupted by interaction with density inhomogeneities and by thermal and dynamical instabilities. Various tricks, involving either Doppler shift velocities or model assumptions, make it possible to construct a 3-D picture of the structure from a 2-D image. This paper will discuss the expected nature of the density inhomogeneities and the consequences for the appearance of an SNR, along with the conditions for some instabilities, and it will present an example of attempts to sort it all out and discuss the role of interstellar turbulence.
